hvac system functional design description_commentes_gusto_110202.pdf

7/26/2019 HVAC System Functional Design Description_commentes_Gusto_110202.pdf

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: FPSO Cidade De Paraty

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: This document is part of VDB :

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Extra Notes :

Vendor Document Revision 0

Total Pages 28

Applicable Tag Number (s)

[email protected]

Vendor P.O. Reference 01.39490.0043

Vendor Document Number

Document Description HVAC SYSTEM FUNCTIONAL DESIGN DESCRIPTION

Client Revision Not Applicable

(Other) Not Applicable

Vendor (Company) Name ABB AS OSLO

Vendor Document Handler Arun.B.R.

E-Mail adress

SBM Revision Number 0 #N/A

Client Document Code Not Applicable

Client Document Type Not Applicable

SBM P.O. Description LER

SBM CDR Code + Sequence Number

SBM Document Type #N/A

Project

Project Number HI.39490 Client Petrobras

SBM Purchase Order Number HI.39490 0043


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System Design Specification HVAC System 1

HVAC System Functional Design Description

Table of Contents

Section Description Page

1. General

2. Fire and Gas Detection Philosophy

3. HVAC Equipment

4. Control of ACCU

5. Temperature & Humidity Regulation

6. Constant Volume Electric Reheater

7. Pressure Regulation

8. Compressor Capacity Regulation and Condensing System Protection

9. System Start Up and Capacity Regulation

10. Pump Down Operation11. Transformer Room Ventilation System

12. F & G Dampers and Shut Off Dampers

13. Unit Control Panel for HVAC System

14. HVAC UCP Interface to F&G, PCS and ESD

15. Alarm Management

16. Password Protection

17. Instruments

18. ACMV System for Battery Room

ABBREVIATIONS

AHU Air Handling Unit

ACCU Air Cooled Condensing Unit

UCP Unit Control Panel

PLC Programmable Logic Controller

HVAC Heating, Ventilating and Air Conditioning

PCS Process Control System

F & G Fire & Gas

ESD Emergency Shut Down

ESB Emergency Stop Button

HMI Human Machine Interface

ATM Atmosphere

PDT Pressure Differential Transmitter

PDS Pressure Differential Switch

PDG Pressure Differential Gauge

SAD Supply Air Duct

RAD Return Air Duct

EAD Exhaust Air Duct

FAD Fresh Air Duct


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1.0 General

The HVAC system is designed for two storey Local Equipment Room of FPSO CIDADE DE PARATY Project

and that consists of the following compartments:-

LER Level - 1

1. HVLV Switch Board Room,

2. Transformer Room,

3. Battery Room, and

4. Air Lock1.

LER Level - 2

1. Unit Control Room and

2. Air Lock2.

The requirement of HVAC and pressurization level for compartments are as follows:-

Sr.No Room Description Air Conditioning Mech. Ventilation Pressurization

Level - 1

1 HVLV SB Room Yes. No. +50 Pa @ ATM

2 Transformer Room No. Yes. +25 Pa @ ATM

3 Battery Room Yes. Mech. Exhaust +15 Pa @ ATM

4 Air Lock - 1 Yes.

No. +25 Pa @ ATM

Level - 2

5 Unit Control Room Yes. No. +50 Pa @ ATM

6 Air Lock - 2 Yes. No. +25 Pa @ ATM

Power Supply : 440 V / 3 Ph / 60 Hz

Power Supply : 220 V / 2 Ph / 60 Hz

Hazardous Area Classification : Class I Zone 2 Gas Group IIA T3 ( Outdoor )

: Safe ( Non Hazardous ) Area ( Indoor )

: Class I Zone 1 Gas Group IIC ( Battery Room )

The HVAC system for LER consists of two sub-systems:-

The System1is designed for cooling, dehumidifying, re-heating and pressurization requirement for HVLV

switchboard room & Air Lock1 at LER level -1 and Unit Control Room & Air Lock2 at LER level -2.

The mechanical ventilation system is designed to remove heat radiated from transformer rooms

equipments by means of ventilation and arranged slight positive pressure is maintained inside the system.

The System2is designed for cooling, dehumidifying and pressurization requirement for Battery room

at LER level - 1. The mechanical exhaust air system is designed for Battery room to extract air from thecompartment and there is no return air to the air conditioning equipments.

Reference shall be made to DEF49100 - FPSO HAZARDOUS AREA LAYOUT.

Class 1, Zone 2, IIA, T3


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2.0 Fire and Gas Detection Philosophy

2.1 Fire and Gas Detection Philosophy ( System1 )

The gas detection instruments ( xxx-GD-001, xxx-GD-002 ) shall install inside the fresh air stream located at the

LER level2.

By gas detection at the intake of the LER HVAC system and depends on the level of gas detected, the vessel

F&G system will gives the LER HVAC UCP ( xxx-UP-01 ) as follows:-

1. Confirmed fire in HVLV Switchboard Room and vessel F&G system shall gives the shutdown signal to

HVAC UCP - 01, then HVAC UCP will gives close signal to all dampers inside the system1 and the

entire HVAC system1 will shutdown.

2. Confirmed fire in Unit Control Room and vessel F&G system shall gives the shutdown signal to

HVAC UCP - 01, then HVAC UCP will gives close signal to all dampers inside the system1 and the

entire HVAC system1 will shutdown.

3. Confirmed fire at False Floor ( fire detected under the module ) and vessel F&G system shall gives the

shutdown signal to HVAC UCP - 01, then HVAC UCP will gives close signal to all dampers inside the

system1 and the entire HVAC system1 will shutdown.4. Confirmed Gas Detected at Fresh Air inlet of the System -1 OR 2 and vessel F&G system shall gives

the shutdown signal to HVAC UCP - 01, then HVAC UCP will gives close signal to all dampers inside

the system1 and the entire HVAC system1 will shutdown.

5. Confirmed fire in Transformer Room and vessel F&G system shall gives the Fire Detected inside the

Transformer Room signal to HVAC UCP - 01, then HVAC UCP will gives close signal to all dampers

inside the Transformer Room ventilation system and the mechanical ventilation system will shutdown.

2.2 Fire and Gas Detection Philosophy ( System2 )

The gas detection instruments ( xxx-GD-003, xxx-GD-004 ) shall install inlet of the Air Handling Unit - 2

located at the LER level2.

By gas detection at the intake of the Battery Room ACMV system and depends on the level of gas detected, the

vessel F&G system will gives the ACMV UCP ( xxx-UP-02 ) as follows:-

1. Confirmed fire in Battery Room and vessel F&G system shall gives the shutdown signal to

ACMV UCP - 02, then HVAC UCP will gives close signal to all dampers inside the system2 and the

entire ACMV system2 will shutdown.

2. Confirmed fire at False Floor ( fire detected under the module ) and vessel F&G system shall gives the

shutdown signal to ACMV UCP - 02, then ACMV UCP will gives close signal to all dampers inside

the system2and the entire ACMV system2 will shutdown.

3. Confirmed Gas Detected at Fresh Air inlet of the System -1 OR 2 and vessel F&G system shall givesthe shutdown signal to ACMV UCP - 02, then ACMV UCP will gives close signal to all dampers

inside the system2 and the entire HVAC system2 will shutdown.

3.0 HVAC Equipment ( System1 )

The HVAC system - 1 is designed for continuous operation with two independent direct expansion (DX) type

air conditioning systems ( 1 x 100% duty and 1 x 100% stand by unit ).

Each unit has 100% capacity of cooling load, air flow and pressurization requirement for the system.

The mechanical ventilation system for transformer room is designed with one set of mechanical supply air fan

with one set of mechanical exhaust air fan. Exhaust air fan is sized to maintain slight positive pressure inside the

compartment.

All AHU & ACCU are fabricated with galvanized material painted suitable for marine and offshore application.

should be stainless steel

Pay attention on the length of the inlet duct between gas sensors and gas tight damper.


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3.1 Air Handling Units

Ref. Document : Ducting & Instrument Diagram (D & ID), Air Flow Diagram

The air handling system is 2 x 100% and designed according to air capacity requirement for cooling and

pressurization requirement of the building. Both units will install at LER level - 2. In normal operation, one unit

will acts as duty and the other unit remains on stand-by.

The unit can be started and stopped independently. The AHU can be started even if the air cooled condensing

system is not running. All AHUs supply airfans have stop, running and failure signal.

Air Handling Unit is designed to be horizontal, continuous operating, draw through type complete with air

mixing section, air filtration section, cooling section and blower section c/w motor and power transmission

assembly. The AHU is designed to use both fresh air and re-circulating air. The AHU is direct expansion type of

refrigerant R407 C and complete with supply air blower fan and cooling coil.

The supply air outlet from blower fan is passed through the non return dampers and connect to the common

plenum box with internal insulation to prevent condensation and noise level transmission.

The unit has return air and fresh air connection and shut off damper is equipped at the common fresh air duct.

The AHU has the following components for proper functioning of HVAC system.a. Shut off damper at fresh air intake,

b. Non Return Damper at fresh air connection to AHU,

c. Non Return Damper at AHUblower fans inlet,

d. Non return damper at blower fans outlet,

e. Pressure differential switches.

The fresh air intake is fitted with bird screen, coalescing filters, gas detectors ( by other ) and is guided to the

mixing section of the AHU. The fresh air duct is connected to mixing section of the AHU through an isolation

shut off damper ( xx-SOD-001 ).

In mixing section, the fresh air is mixed with return air from the LER level1 & level - 2. The mixed air

entered the filtration section, it consists of HVAC air filter before it enters the direct expansion cooling coil.

The by-passing of air to AHUs can be prevented by installation of non return dampers at each inlet and outlet of

the AHU respectively.

The non return dampers for duty AHU will be opened during operation and that for standby unit will be closed.

The mixing air is conditioned (cooling and dehumidification process) while passing through the cooling coil.

The duty centrifugal type blower fan conveyed conditioning air to the designated rooms/spaces via sheet metal

duct work.

The external supply air duct is fabricated with 3 mm thickness SS 316L material and complete with 50 mm

thickness internal insulation and the internal one is fabricated with 1.2 mm thickness galvanized material

complete with 25 mm thickness external insulation.The supply air duct is fitted with electric operated type fire & gas dampers if duct passing through class rated

bulkhead and deck head, manual operated volume control dampers is fitted on each main duct and branch duct

for proper balancing of the supply air to all serving rooms/spaces and supply air grilles.

The return air duct is fitted with electric operated type fire & gas dampers if duct passing through

class rated bulkhead and deck head, manual operated volume control dampers for proper balancing

of the return air from all serving rooms/spaces, modulating damper ( xx-MD-101 & xx-MD-201 )

( to regulate the return air flow rate to maintain required positive pressure inside the building ), humidity &

temperature transmitter ( xx-MTT-101 & xx-MTT-201 ) ( to maintain constant return air temperature and

displayed humidity level ) and return air grilles.

The main supply air ducts and return air ducts to/from the AHU are routed outside of the building and guided to

first floor and second floor of the LER building.

Rotate duty monthly.


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All F&G and shut off dampers, remotely controlled with a fail safe actuator ( Fail Close ).

When 24 VDC power is energized to the electric actuator and the damper will be in opened position. The

electric actuator will close automatically if loss of power supply because of built-in spring return actuator

( fail safe actuator ).

All F&G dampers are powered and controlled directly from the HVAC control panel ( xx-UP-01 ). The F&G

system is responsible for safe operation of the HVAC system by giving separate shutdown signal mentioned

above.

The list of F&G damper & shut off dampers are as follows:-

Sr.No Description Tag No Location ( Wall or Deck )Power &

Control

Roof ( Outside )

1 Shut Off Damper xx-SOD-001 FADRoof ( Outside ) HVAC UCP-01

LER Level - 1

2 F&G Damper xx-FD-001 SADRoof ( Outside ) ~ HVLV HVAC UCP-01

3 F&G Damper xx-FD-002 RADHVLV ~ Roof ( Outside ) HVAC UCP-01

4 F&G Damper xx-FD-003 SADHVLV ~ Air Lock - 1 HVAC UCP-01

LER Level - 2

5 F&G Damper xx-FD-004 SADRoof ( Outside ) ~ LER Level - 2 HVAC UCP-01

6 F&G Damper xx-FD-005 RADLER Level2 ~ Roof ( Outside ) HVAC UCP-01

7 F&G Damper xx-FD-006 SADUCR ~ Air Lock - 2 HVAC UCP-01

Transformer Room

8 F&G Damper xx-FD-007 FADOutside ~ Transformer Room HVAC UCP-01

9 F&G Damper xx-FD-008 EADTransformer Room ~ Outside HVAC UCP-01

The operator interface consists of a series of high visibility indicating lights, push buttons, selector function and

touch screen panel located at the unit control panel.

The PLC control system processes related input and outputs, control, protect and monitor the system with a

number of programmable settings, e.g. temperature & humidity transmitters, pressure transmitters, modulating

dampers, pressure switches, AHU start/ stop, control & monitoring of the air conditioning system.

The pressure differential switches c/w indicators are fitted across the filters to monitor the condition of filters.

Item Tag No. Location Alarm Set Pt. Alarm Message Remark

1 xx-PDS-001 Fresh Air Filter xxx Pa ( H ) Fresh Air Filter Dirty

2 xx-PDS-002 Main Air Filter xxx Pa ( H ) Main Air Filter Dirty AHU - A

3 xx-PDS-004 Main Air Filter xxx Pa ( H ) Main Air Filter Dirty AHU - B

According to ABS "Facilities on offshore installations" must also be capable of being closed

manually from both sides of the bulkhead or deck.


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When the value reading from the respective pressure differential switch is higher than the alarm set point

mentioned above and a general alarm will be generated at the UCP and PCS ( common fault alarm ). The UCPs

HMI will indicate the respective filtershigh differential pressure alarm message and the panel mounted Buzzer

will generate an intermittent sound.

The pressure differential switches are also fitted across the supply air blowers to monitor the proper functioning

of blower to prevent loss of pressurization. .


1 xx-PDS-003 Blower Fan - A xxx Pa ( Low ) Blower Fan A Fault

2 xx-PDS-005 Blower Fan - B xxx Pa ( Low ) Blower Fan B Fault

When the value reading from the pressure differential switch is lower than the alarm set point mentioned

above and a general alarm will be generated at the UCP and PCS ( common fault alarm ). The HMI will indicate

the respective blowerslow differential pressure alarm message and the panel mounted Buzzer will generate an

intermittent sound (common alarm to PCS) and initiate automatic change over to standby system after a time

delay of 60 seconds.

If the HVAC system is operating in AUTO mode, either one of the Trip function ( HMI will specify which Trip

function ) will Stop the duty system and change over to operate the Standby system as duty automatically.

The electric motors inside the AHU is Exe protection and all electrical components and instruments equipped

are suitable to operate in Hazardous Area Zone 2.

3.2 Air Cooled Condensing Units

Ref. Document : Piping & Instrument Diagram ( P & ID )

The air cooled condensing system is 2 x 100% independent refrigeration circuit and designed according to heat

rejection requirement of system.

Both units are installed at the open deck of LER level - 2. In normal operation, one unit acts as duty and the

other unit remains on stand-by.

The unit can not be started independently without running respective AHU in auto mode but it can be performed

functional or rotation check on maintenance ( Test/Manual ) mode. The unit can be started only if the duty air

handling unit is in running.

The operator interface consists of a series of high visibility indicating lights, pushbuttons, selector functions and

touch screen panel located at the unit control panel.

The PLC control system processes related input and outputs, control, protect and monitor the systemwith a number of programmable settings, e.g. Temperature transmitters, Pressure Switches, etc,.

The electric motors inside the ACCU is Exe protection and all electrical components and instruments equipped


The condensing unit equipment starter and overload protection are installed inside the HVAC unit

control panel. Space heater power supply for motor of capacity 5.5 kW and above are fed from the same UCP.

All ACCU fans, compressor motor have stop, running and failure signal. The ACCU is controlled by PLC

based UCP and each system ( duty or standby ) consists of one set of open type reciprocating compressor direct

coupling driven by electric motor, four sets of condenser fans c/w driving motors, one piece of refrigeration

liquid line solenoid valve on each refrigeration circuit and others refrigeration system components, accessories

and instruments.

The ACCU work as a slave of the respective AHU.


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4.0 Control of ACCU

The air cooled condensing unit compressor motor, condenser fan motor starter and overload protection are

housed within the UCP. The UCP will be able to START or STOP the motor during maintenance mode for

functional check or rotational check only.

Power supply for motors anti-condensation heaters are fed from the UCP.

4.1 ACCU START

The UCP will monitor the temperature and humidity reading from the moisture-temperature transmitters

mounted inside the return air stream on each deck.

Item Instrument Tag No. Location Set Parameter Remark

1 xx-MTT-101 RADFirst Floor T = 24oC & RH = 50 %

2 xx-MTT-201 RADSecond Floor T = 24oC & RH = 50 %

These transmitters measure the temperature and humidity of the return air. When the return air temperature

(average reading from the 2 transmitters) rises above 24oC ( adjustable ), the UCP will gives signal to start the

duty ACCU while the duty AHU is in operation.

The refrigeration compressor and condenser fan will operate simultaneously. The compressor operation is

interlocked with condenser fans operation and it will not started without running all duty condensing fans.

4.2 System Safety Protection

During the duty ACCU is in operation, the UCP will continuously monitor the respective system low refrigerant

pressure via low refrigerant pressure switch ( xx-PSL-001A or B ) mounted on the refrigeration suction line and

high refrigerant pressure via high refrigerant pressure switch ( xx-PSH-001A or B ) mounted on the refrigeration

discharge line.

When the reading on the low refrigerant pressure switch fall below set point, the UCP will activate pump down

function and stop the compressor. When the refrigerant pressure rises above set point, the compressor will be

able to restart automatically.

When the reading on the high refrigerant pressure switch goes above xx.x bar (g), the UCP will stop the

compressor. When the refrigerant pressure drop below xx.x bar (g), the compressor will be able to restart but it

required manual reset on PLC touch screen to eliminate high refrigerant pressure cut off alarm.

The compressor cant be restarted within 5 mins (adjustable) with auto restart operation ( e.g compressor

auto cutoff when temperature reach set parameter or pump down activated due to low refrigerant pressure

reaches set point ).

4.3 Liquid Line Solenoid Valve Operating Sequence

The liquid line solenoid valve is installed on each refrigeration circuit and will be opened once received the

START command from UCP and all the refrigeration system operating parameters are in normal condition.

4.4 Crankcase Heater Operating Sequence

Before first start up, the crankcase heater shall energize for 24 hours. When the duty compressor is running, the

respective crankcase heater will be de-energized and the stand by compressors heater shall be energized.

4.5 Condenser Fan Operating Sequence

All duty condenser fans are started simultaneously with respective compressor.


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4.6 Refrigeration Lube Oil Level

The UCP will monitor the refrigeration oil pressure in the system via oil differential pressure switch mounted on

the system. The oil pressure should reach correct level within a few seconds after first start up the compressor.

During the first start, the correct lube oil differential pressure is not reached in 15 ~ 20 seconds , stop

compressor immediately and check oil system & accessories.

During normal operation and when the compressor starts, refrigeration oil differential pressure shall reach to

satisfactory level within 120 seconds. If the oil differential pressure fall below set point, the oil level switch will

trip the compressor and show an alarm message at UCP ( common alarm to PCS ) and need to be reset manually

from UCP.

4.7 List of Refrigeration System Safety Components

Sr.No Description Tag No. Set Pt. Alarm (UCP) Remark

1 High Refrigerant Pressure Switch

( SystemA/B ) ( High ) xx-PSH-001 A/Bxx.x bar (g)

( High )

Refrigerant Pr.

High

( SystemA/B )

Manual

Reset

2 Low Refrigerant Pressure Switch

( SystemA/B ) ( Low )xx-PSL-001 A/B

xx.x bar (g)

( Low )N.A

Auto

Reset

3 Lube Oil Differential Pressure

Switch ( Time Delay = 120 sec ) xx-ODPS-001 A/Bxx.x bar (g)

( Low )

Lube Oil Pr. Low

( SystemA/B )

Manual

Reset

When the value reading from the above instruments is higher / lower than the set point mentioned above, a

general alarm will be generated.

The UCP will indicate the respective alarm at the HMI and the panel mounted Buzzer will generate an

intermittent sound.

The common fault alarm is transmitted to the PCS.

If the HVAC system is operating in AUTOmode, either one of the Trip function ( HMI will specify which

Trip function ) will Stop the duty system and change over to operate the Stand-by system as duty

automatically.

5.0 Temperature & Humidity Regulation

The duct mounted temperature and relative humidity transmitters ( xx-MTT-101 on LER 1stFloor, xx-MTT-201

on 2nd

Floor ) are installed inside the return air stream of first floor and second floor ( HVLV Room and Unit

Control Room). When the reading (average of the 2 readings) is higher than set point ( 24oC ) and the

compressor will be in operation to bring down the temperature and humidity level inside the buildings. When

the reading value reach set point ( 24oC ) or below, the refrigerant suction pressure will drop accordingly due to

less cooling and dehumidification load. Based on the refrigeration suction pressure and control oil pressure, the

compressor will be regulated in unload operation by factory assembled hydraulic capacity control unloader

system to maintain humidity level inside the building. The compressor will load again if the cooling load

demand increases. During fully unload condition and temperature reading falls below minimum set point

( 18oC ), the system will be pump down and compressor will be STOP in operation. The compressor will restart

automatically when the sense temperature reaches above set point or the high temperature ( over 28oC ) alarm

message will be displayed at UCP HMI and panel mounted Buzzer will generate an intermittent sound.


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6.0 Constant Volume Electric Re-Heater

The electric re-heater are installed inside the supply air stream of LER level 1 & 2. The function of re-heater is

programmed by UCP together with room temperature transmitter installed on each level. If temperature reading

on the temperature transmitter falls below set point, it will send the signal to UCP. The UCP will send signal to

activate the respective re-heater if all heater safety devices are normal. The heater will be de-activated if the

respective temperature transmitter reading reaches set point.

The power requirement of the heater is provided by xx-UP-01.

The safety devices are housed in the heater casing for proper functioning and control requirement of heater.

The power supply for heater capacity of 3 kW and above shall be 440V/3 Ph/60 Hz and that below shall be

220V/1 Ph/60 Hz.

Heater Safety devices are as follows:-


1 Temperature Switch N.A 87oC N.A Auto Reset

2 Temperature Switch N.A 120oC Heater Fault Manual Reset

3 Air Flow Switch N.A 25 Pa Heater Fault Heater will not work if no air flow.

4 Door Switch N.A N.A Heater Fault Heater will not work if door opened.

The list of heater and controlled temperature transmitter are as follows:-

Sr.No Location Heater Tag No. TT Tag. No Set Pt. Remark

1 Level1, LER xx-DH-001 xx-MTT-101 20oC Heater activate if temp. < set pt.

2 Level2, LER xx-DH-002 xx-MTT-201 20o

C Heater activate if temp. < set pt.

7.0 Pressure Regulation

7.1 Pressure Regulation ( HVLV Room )

The compartment is pressurized to 50 Pa( +/- : 10 / 15 Pa ). The supply and return air flow rate inside this

compartment is balanced during testing and commissioning. The room differential pressure transmitter

( xx-PDT-101 ) is installed inside the HVLV room. During auto operation, this differential pressure transmitter

monitors the room pressure. It also used as signal to modulating damper ( xx-MD-101 ) to regulate return air

flow ( by opening or closing dampers ) and make sure the rooms are pressurized. When the value on the PDT is

lower than minimum set point ( 35 Pa) after a time delay of 60 seconds ( adjustable ), a general alarm will be

activated. The UCP HMI will show alarm message and Buzzer will generate an intermittent sound.

The room low pressure differential alarm is transmitted to PCS.

Supply air required to the air lock-1 is served by HVAC system and maintain +25 Pa above atmosphere by

arranging no return air from the air lock.

7.2 Pressure Regulation ( Unit Control Room )

The compartment is pressurized to 50 Pa( +/- : 10 / 15 Pa ). The supply and return air flow rate inside this

compartment is balanced during testing and commissioning. The room differential pressure transmitter

( xx-PDT-201 ) is installed inside the unit control room. During auto operation, this differential pressure

transmitter monitors the room pressure. It also used as signal to modulating damper ( xx-MD-201 ) to regulate

return air flow ( by opening or closing dampers ) and make sure the rooms are pressurized. When the value on


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the PDT is lower than minimum set point ( 35 Pa) after a time delay of 60 seconds ( adjustable ), a general alarm

will be activated. The UCP HMI will show alarm message and Buzzer will generate an intermittent sound.

The room low pressure differential alarm is transmitted to PCS.

Supply air required to the air lock-2 is served by HVAC system and maintain +25 Pa above atmosphere by

arranging no return air from the air lock.

8.0 Compressor Capacity Regulation and Condensing System Protection :-

8.1 Capacity Control

The refrigeration compressor is fitted with hydraulic capacity control system it regulates according to changing

load demands.

8.2 Condensing System Protection Devices

a. Compressors Electric Motor Protection Devices,

b. High Refrigerant Pressure Safety Device,

c.

Low Refrigerant Pressure Safety Device,d. Low Lube Oil Differential Pressure Safety Device,

e. Crankcase Heater.

8.3 Check before starting:-

1. Refrigeration Lube Oil Level,

2. Setting and function of safety and protection devices,

3. Setting of timing,

4. Setting of refrigerant pressure safety devices,

The compressor lubrication should be checked immediately after starting. Maximum and recommended oil level

during operation shall be within the sight glass range mounted of the compressor.

Minimum oil level is monitored by an oil differential pressure switch.

The time delay period for oil level switch is set to 120 seconds after start up the compressor. If there is not

enough oil pressure and the refrigeration compressor must stop immediately.

8.4 Crankcase Heater

The crankcase heater must be energized during standstill. The crankcase heater in the compressor prevent high

refrigerant dilution of the oil during standstill. It shall only be switched on if compressor is filled with oil.

Note:If the oil pressure switch cuts-out during the starting stage or the oil level falls below recommended sight glass

level, this indicates a severe lack of lubrication. It may happen due to small pressure difference. Check the oil

return line before adding additional amount of lube oil or danger of liquid slugging.

9.0 Compressor Start Up and Capacity Regulation

The refrigeration compressor will start up if the following conditions are TRUE.

The duty AHU is in operation,

All system protection devices and operation parameters are normal,

No alarm active,

Respective Liquid line solenoid valve is opened.

The compressor operating sequence and capacity regulation is mainly controlled by


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1. Low Refrigerant Pressure,

2. Average Return Air Temperature

Condition 1

If Refrigerant Suction Pressure > / = 5 bar(g) ANDAverage Return Air Temperature > 24oC

( adjustable Set Point ) ANDLiquid Line Solenoid valve is Opened

Then : Refrigeration Compressor : START

The compressor will be in loading / unloading operation condition according to changing load demands.

Condition2

If Refrigerant Suction Pressure > / = 2.5 bar(g) ANDAverage Return Air Temperature > 2 + 24oC

( adjustable Set Point ) ANDLiquid Line Solenoid valve is Opened,

Then : Refrigeration Compressor : Operate in Full Load Condition

Condition 3

If Refrigerant Suction Pressure > / = 2.2 bar(g) ORAverage Return Air Temperature > 1 + 24oC


Then : Refrigeration Compressor : Operate in Unload condition

Condition4

If Refrigerant Suction Pressure < / = 1.4 bar(g) ANDAverage Return Air Temperature< / > / = 24oC


Then : Refrigeration Compressor : Activate Pump Down & Stop the Compressor

for 5 minutes

The cycle is repeated automatically.

10.0 Pump Down Operation

10.1 Pump Down Mode

The UCP can control the pump down sequence manually in the MAN mode. Operator has to access the

maintenance control page in the HMI to control and start pump down operation.When pump down is activated, the liquid line solenoid valves will close, the compressor will keep running till

the suction pressure reaches 1.4 bar(g) and the low pressure switch ( xx-PSL-001A or B ) will stop the

compressor.

10.2 Pump Down System

Pump down system is required when danger of liquid migration exists for system where the compressor or parts

of the suction line and suction accumulators can reach a lower temperature than the evaporator.

The refrigerant suction pressure reaches 1.4 bar (g) ( the lowest temperature which shall occur ) and the system

requires automatic pump down.

During pump down, the compressor is controlled as a function of suction pressure . In case of a capacity demand

during standstill, the liquid line solenoid valve ( liquid injection) to the corresponding duty evaporator is


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opened first. The suction pressure increases up to a preset value, at which the compressor is switched on by

means of suction pressure switch.

When decreasing cooling load demand by reaching required temperature level, the solenoid valves

closed and the evaporator is pump down to a preset pressure then the compressor will be switched off.

11.0 Transformer Room Ventilation System

The heat radiated from the equipments inside the transformer room is removed by mechanical ventilation

system. The supply air fan capacity is estimated based on amount of heat radiated from the equipments and the

average room temperature inside the compartment is maintained 8oC above average outside ambient air

temperature.

The exhaust air fan capacity is estimated based on amount of supply air to offset the air leakage through door

cracks and any opening inside the compartment as well as to maintain slight positive pressure inside the

transformer room.

The transformer room ventilation system is powered and controlled by HVAC system 1 unit control panel

( xx-UP-01 ). The F&G dampers ( xx-FD-007 & 008 ) are installed inside the supply and exhaust air stream.

Temperature Regulation

The temperature transmitter ( xx-TT-101 ) is installed inside the transformer room.

When the reading on the temperature transmitter is higher than various set point and the ventilation fans will be

in speed regulating operation according to requirement. If the temperature reaches ( 45oC ) and high temperature

alarm message will be displayed at UCP HMI and panel mounted Buzzer will generate an intermittent sound.

Pressure Regulation

The compartment is maintained slight positive pressure relative to atmosphere and slight negative pressure than

that of HVLV room. This room has a dedicated supply air fan ( xx-EMF-001 ), exhaust air fan ( xx-EMF-002 )

and it works as a slave of the supply air ventilation fan.

The pressure differential switches ( xx-PDS-006 ) and ( xx-PDS-007 ) are installed across the supply air fan and

exhaust air fan respectively.

During auto mode, the fan operation is interlocked function with supply air duct and exhaust air duct fire

dampers.

When ventilation fan fail ( Pressure Differential Switch Reading < Set Pt.), the respective pressure switch will

send the signal to UCP, generate an alarm after a delay of 90 seconds.

The slight positive pressure in this room is achieved by balancing and manual adjustment of volumetric supply

air flow rate and the exhaust air flow rate during commissioning. The supply air amount is designed toovercome leakage air to the external walls and doors.

Conditions for the ventilation fan to start ( auto mode ) are ,

1. Fire & Gas Damper inside the ventilation air streams are opened,

2. Safety Protection Devices for fans are healthy ( if not, HMI will display the alarm message and Buzzer

will generate an intermittent sound).

12.0 Fire & Gas Dampers and Shut Off Damper

All fire & gas dampers and fresh air line shut off damper are electric type with 24 VDC electrical actuator

operated and equipped with fail safe mechanism ( fail to close ). The power supply to the dampers shall be

wired from HVAC UCP and send the all dampers close status to PCS via hard wired signal.

The dampers are equipped with limit switches connected to UCP. The status for each damper can be read from


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HVAC UCP.

13.0 Unit Control Panel for HVAC System ( xx-UP-01 )

The HVAC UCP ( xx-UP-01 ) is located in the HVLV Switchboard Room.

This UCP acts as the main interface to the vesselscontrol and safety system.

Indicator Lightson the front panels are as follows:-

Normal Power Supply Incoming Light ( Red, Yellow, Blue ),

Normal Power Supply Available Light ( Red, Yellow, Blue ),

UPS #1 Incoming Light ( White ),


UPS Outgoing Light ( White ),

DC Power Outgoing Light ( White ),

Supply Air Fan(s) Status Indication Light ( Run, Stop, Trip ),

Condenser Fan(s) Status Indication Light ( Run, Stop, Trip ),

Compressor(s) Status Indication Light ( Run, Stop, Trip ),

Ventilation Fan(s) Status Indication Light ( Run, Stop, Trip ).

Other Features

HMI panel,

Voltmeter,

Ammeter,

Cabinet Ventilation Fan,

Cabinet Air Intake c/w Filter,

Auto / Manual Selector Switch,

Buzzer,

System Start Push Button,

System Stop Push Button,

Alarm Acknowledge Button,

Alarm Reset Button,

Lamp Test Button,

Earth Leakage Relay,

Under Voltage Relay, Emergency Stop.

When the Feeder is turn on from the LV switchboard, the respective Feeder incoming light will also be turn ON

to indicate the present of power supply. The power supply available light will be turn ON after the main isolator

inside the UCP had been switch ON to indicate power available to the equipmentscircuit breaker.

The DC power outgoing light will be turn on accordingly.

Document Reference : System Electrical Block Diagram,

Electrical Single Line Diagram,

System Control Diagram / Schematic


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When there is an Alarm in the HVAC system, the Buzzer on the front panel will be activated.

PLC

The UCP has a single PLCs Central Processing Unit ( CPU ) and communication units.

The controller is a PLC based Allen Bradleys CompactLogix.

The controller CPU together with the power supply and communication module will be housed in one chassis

whilst the I/O cards modules and their corresponding modules will be housed in a separate chassis of its own.

HMI

The HMI ( Panel View Plus 1000 ) is fitted in UCP to indicate status of equipments and accessories

( run, stop and fault conditions ).

The HMI is being used as an interface to the PLC for configuration settings.

System Start / Stop

The HVAC system shall be operated locally from the system START and STOP push buttons on themain UCP front panel.

Emergency Stop push button is located on UCP front panel and it is hard wired in series with the field

emergency stop push buttons located near the HVAC equipments. Emergency Stop contact is hard wired in

series with system START command contact and will remain opened until being reset to its normal position

manually.

A Trip Alarm will be generated, the HMI will indicate the corresponding Emergency Stop Alarm message and

Buzzer will generate an intermittent sound.

Power Supply

The HVAC UCP is fed from three independent power source.

Normal 440 V / 3 Ph / 60 Hz ( xx-xx-xx)

UPS #1 220 V / 2 Ph / 60 Hz ( xx-xx-xx)

UPS #2 220 V / 2 Ph / 60 Hz ( xx-xx-xx)

In the main UCP, the UPS # 1 & # 2 feeder will supply 220 VAC to the following :-

PLC chassis,

DC power supply modules,

AC control,

3 pin switch socket outlet.

The two DC power supply units supply 24 VDC through Meanwell power supply module and Meanwell DC

redundant module to power up :-

The interposing relays,

PLC sub rack,

Transmitters,

Other components and accessories in the UCP

When there is a loss of one UPS feeder or a faulty DC power supply, the DC redundant module will

still be able to maintain the 24 VDC supply as long as there is a UPS feeder to a healthy DC power


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supply.

System Start Up

Before start up the system, PLC will check on the pre-start conditions. If these conditions are fulfilled, the PLC

control system will operate the HVAC system to start up as per requirement.

In case of HVAC system shut down due to external factors ( i.e,. power failure, etc,. ), the HVAC system will

automatically restart upon power resume.

First Start / Restart Operation

When power is energized to the UCP for the first time, the PLC will check on the Black Start Bit in the PLC

Ladder Logic Software.

If the Black Start Bit is turn ON, it means that the HVAC system was running before it was shut down due to

external factors.

Upon power resume, the HVAC system will automatically restart as per start up sequence without any operator.

If the Black Start was OFF, it means that the HVAC was Stop by operator or tripped / shut down due to F&Gsystem or internal causes and will start by either one of the following method:-

Pressing the System START push button at the UCP,

Pre Start Condition

Black Start / Manual Operation

Before operating the HVAC system, the conditions that need to be checked manually during pre start conditions

are :-

Isolator switch at the HVAC equipments,

Emergency stop push button status,

To energize refrigeration crankcase heater for minimum 24 hours.

Normal Start / PLC Check Operation

The PLC will check for the following pre start condition and give a permit to start indication on UCP HMI,

Isolator is to be switched on,

Fault should not be present to enable permit to start signal and it is checked by PLC code,

HVAC not running status is checked by Start HVAC,

PCS and Emergency STOP signal shall not be present,

No active pressure alarm, No trip alarm ( All trip functions reset ),

All the F & G dampers and shut off dampers are healthy according to zoning / grouping.

If the pre start conditions are fulfilled, the PLC control system will be standby to start up the HVAC and turn

ON a permit to start bit in the PLC ladder logic software.

This permit to start bit information will be copy to the memory map.

This permit to start bit information will also be displayed at the HMI main menu.

AUTO - MANUAL MODE

On the main UCP HMI, the system operation mode can be selected to AUTO or MANUAL.

In Auto mode, the system will be able to change over from duty to standby when conditions are met

( by time, by fault, by HMI or by PCS ).


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The automatic changeover of system can only be performed in AUTO mode.

Changeover will occur when any one of the event is activated :-

1. Operator selects the standby HVAC equipment as the duty at the HMI,

2. Duty HVAC equipment runtimeweekly timer expired,

3. The duty AHU had a trip alarm

The alarm can be one of the following in AHU:-

a. AHU fan feeder fault alarm,

b. AHU duty blower fan low flow differential pressure alarm.

c. The duty ACCU had trip alarm.

The alarm can be one of the following in ACCU:-

a. High refrigerant pressure alarm,

b. Fault in lubrication system,

c. Compressor feeder fault alarm,

d. Activate Emergency Stop push buttons to the duty unit.

In the HMI main menu, select the system setting soft button to go to the setting page. Within this system setting

page operator has to perform the following:-

1. Select the Duty HVAC system to run,

2. Set the time period to perform a change over between the duty / standby HVAC units,

3. Set the operator accessible parameter.

Start Up Sequence

With the Permit to Start Bit ON, the HVAC can be started by either one of the following :-

1. Press the system START push buttons on the front panel of the UCP,

In the event of receiving command from UPS & PCS at the same time, the following shall apply :-

Commend from UCP Commend from PCS / F&G Action of HVAC

System START push button Shut Down Signal Stop HVAC

System STOP push button Shut Down Signal Stop HVAC

Once the HVAC is started, the PLC ladder logic will

1. Turn ON a HVAC running bit,

2. Turn ON the Black Start Bit,

When the HVAC system running bit is ON, the duty AHU will start. After the duty AHU is running and

confirmed healthy, the system will continue with the following:-

1. The duty ACCU will start. The ACCU starting sequence will be depend on capacity control by bring in

operation of one or more compressor. Each compressor is protected by the safety protection devices

( refrigerant low pressure, refrigerant high pressure and refrigeration oil safety system ),

2.

The ventilation fans will start.

3. The ventilation fan is interlocked with respective F&G damper inside the air stream. Fan will not start


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when the F&G damper is closed and it will stop immediately if the fan is in running position. The below

table shows interlock between fans and respective F&G dampers :-

Item Tag No. Fan Description Inhibit Fan Run When damper Closed.

1 xxFD007 Transformer Room Supply Air Fan F&G damper at Supply Air Stream.

2 xxFD - 008 Transformer Room Exhaust Air Fan F&G damper at Exhaust Air Stream.

14.0 HVAC UCP Interface to F&G and PCS

Sr.No From UCP To PCS Remark

1 HVAC Common Alarm Signal N.O Volt Free Contact

2 HVAC Run Status Signal N.O Volt Free Contact

3 HVAC Fault/Available Signal N.O Volt Free Contact

4 Dampers Close Status Signal N.O Volt Free Contact Confirmed All Dampers are Closed.

5 Loss of Room Pressurization

Level - 1N.O Volt Free Contact

6 Loss of Room Pressurization

Level - 2N.O Volt Free Contact

7 Ventilation Fans Run Status

SignalN.O Volt Free Contact Transformer Room Fans

8 Ventilation Fans

Fault/Available Status SignalN.O Volt Free Contact Transformer Room Fans

9 Isolate Transformer RoomN.O Volt Free Contact

Confirmed Transformer Rooms Fans

Stopped and Dampers Closed.

From F&G To UCP

10 Shut Down Signal 24 VDC

1. Confirmed Fire in HVLV

2. Confirmed Fire in UCR

3. Confirmed Fire in False Floor

4. Confirmed Gas Detected at HVACInlet

11 Shut Down Signal 24 VDC1. Confirmed Fire in Transformer

Room ( Isolate the Compartment )

From PCS To UCP

12 Time Synchronization Signal


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15.0 Alarm Management :-

Alarm indication / message is displayed at the UCPs HMI and which serves as the operator interface.

Alarm management is handled by the PLC and HMI mounted on the UCP. Buzzer is installed at the front door

of the UCP. Warning and/or fault message will appears on the HMI in the event of a warning or shutdown to

indicate the actual fault. Alarm at the UCPs HMI and common fault alarm to the PCS shall be implemented

with time delay to prevent nuisance alarm due to specific fluctuations in measurement values.

When warning alarm is activated, Buzzer will sound and fault message is prompted on the HMI. By pressing the

Alarm Acknowledge Push Button, buzzer will go silent but the alarm message remain on the touch screen.

Once the fault is rectified, press the RESET button mounted on the front panel of UCP to reset the HVAC

system.

All the alarms generated in the UCP are visible as common fault alarm on the PCS but RESET can be done only

from UCP.

Time Synchronization:

PCS sends a time synchronization signal to UCP to synchronize the timing of the UCP with the PCS.

16.0 Password Protection :

Password protection is provided in the Log In / Log Out of the Touch Screen Panel View. This is to ensure that

only authorized and trained personnel are allowed to enter the system control section for the operation of the

HVAC system and changes of setting values.

17.0 Instruments:

When the instrument sensor is faulty, the analog input signal to the PLC will be out of the range which is

between 4 ~ 20 mA. The PLC reads an open circuit sensor as 3.6 mA and the PLC logic will consider it as a

sensor alarm and put the control to a safe state of operation.

18.0 ACMV System for Battery Room

ACMV Equipment ( System 2 )

The ACMV system - 2 is designed for continuous operation with two independent direct expansion (DX) type

air conditioning systems ( 1 x 100% duty and 1 x 100% stand by unit ).

Each unit has 100% capacity of cooling load, air flow and pressurization requirement for the system.

The mechanical ventilation system for battery room is designed with one set of mechanical exhaust air fan.Exhaust air fan is sized to maintain slight positive pressure inside the compartment.

All AHU & ACCU are fabricated with galvanized material painted suitable for marine and offshore application.

18.1 Air Handling Units & Air Cooled Condensing Unit

Ref. Document : Ducting & Instrument Diagram (D & ID), Air Flow Diagram

The Air Handling Section and Air Cooled Condensing Section are mounted on the same skid.

The ACMV system is 2 x 100% and designed according to air capacity requirement for cooling and

pressurization requirement of the battery room. Both units will install at LER level - 2. In normal operation, one

unit will acts as duty and the other unit remains on stand-by.

The unit can be started and stopped independently. The AHU Blower can be started even if the air cooled

condensing section is not running. All AHUs supply air fans have stop, running and failure signal.

Rotate duty monthly.

should be stainless steel


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Air Handling Unit is designed to be horizontal, continuous operating, draw through type complete with air

intake section, air filtration section, cooling section and blower section c/w motor and power transmission

assembly. The AHU is designed to use only 100% fresh air and no re-circulating air. The AHU is direct

expansion type of refrigerant R407 C and complete with supply air blower fan and cooling coil.

The supply air outlet from blower fan is passed through the non return dampers and connect to the common

plenum box with internal insulation to prevent condensation and noise level transmission.

The AHU has the following components for proper functioning of HVAC system.

a. Non Return Damper at fresh air connection to AHU,

b. Non Return Damper at AHU blower fans inlet,

c. Non return damper at blower fans outlet,

d. Pressure differential switches.

The fresh air intake is fitted with bird screen, gas detectors ( by other ) and is guided to the intake section of the

AHU.

The fresh air entered the filtration section, it consists of HVAC air filter before it enters the direct expansion

cooling coil.The by-passing of air to AHUs can be prevented by installation of non return dampers at each outlet of

the AHU respectively.

The non return dampers for duty AHU will be opened during operation and that for standby unit will be closed.

The fresh air is conditioned (cooling and dehumidification process ) while passing through the cooling coil.

The duty centrifugal type blower fan conveyed conditioning air to the battery room via sheet metal duct work.

The external supply air duct is fabricated with 3 mm thickness SS 316L material and complete with 50 mm

thickness internal insulation and the internal one is fabricated with 1.2 mm thickness galvanized material

complete with 25 mm thickness external insulation.

The supply air duct is fitted with electric operated type fire & gas dampers if duct passing through class rated

bulkhead and deck head, manual operated volume control dampers is fitted on each main duct for proper

balancing of the supply air to battery room and supply air grilles.

The temperature transmitter ( xx-TT-102 ) is installed in the room to control room air temperature.

All F&G and shut off dampers, remotely controlled with a fail safe actuator ( Fail Close ).

When 24 VDC power is energized to the electric actuator and the damper will be in opened position. The

electric actuator will close automatically if loss of power supply because of built-in spring return actuator

( fail safe actuator ).

All F&G dampers are powered and controlled directly from the ACMV control panel ( xx-UP-02 ). The F&G

system is responsible for safe operation of the ACMV system by giving separate shutdown signal mentioned

above.The list of F&G dampers are as follows:-

Sr.No Description Tag No Location ( Wall or Deck )Power &

Control

Battery Room

1 F&G Damper xx-FD-009 SADRoof ( Outside ) ~ Battery Room ACMV UCP-02

2 F&G Damper xx-FD-010 EADBattery Room ~ Roof ( Outside ) ACMV UCP-02

The operator interface consists of a series of high visibility indicating lights, push buttons, selector function and

Eliwell temperature controller located at the unit control panel.

The control system processes related input and outputs, control, protect and monitor the system with a


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number of settings, e.g. temperature sensor, pressure transmitters, pressure switches, AHU start/ stop, control &

monitoring of the air conditioning system.

The pressure differential switches c/w indicators are fitted across the filters to monitor the condition of filters.


1 xx-PDS-006 Main Air Filter xxx Pa ( H ) Main Air Filter Dirty AHU - A

2 xx-PDS-008 Main Air Filter xxx Pa ( H ) Main Air Filter Dirty AHU - B

When the value reading from the respective pressure differential switch is higher than the alarm set point

mentioned above and a general alarm will be generated at the UCP and PCS ( common fault alarm ). The UCP

mounted pilot light will indicate the respective filters high differential pressure alarm message and the panel

mounted Buzzer will generate an intermittent sound.

The pressure differential switches are also fitted across the supply air blowers to monitor the proper functioning

of blower to prevent loss of pressurization. .


1 xx-PDS-007 Blower Fan - A xxx Pa ( Low ) Blower Fan A Fault

2 xx-PDS-009 Blower Fan - B xxx Pa ( Low ) Blower Fan B Fault

When the value reading from the pressure differential switch is lower than the alarm set point mentioned

above and a general alarm will be generated at the UCP and PCS ( common fault alarm ). The UCP mounted

pilot light will indicate the respective blowers low differential pressure alarm message and the panel mounted

Buzzer will generate an intermittent sound (common alarm to PCS) and initiate automatic change over to

standby system after a time delay of 60 seconds.

If the ACMV system is operating in AUTO mode, either one of the Trip function ( UCP will specify which Trip

function ) will Stop the duty system and change over to operate the Standby system as duty automatically.

The electric motors inside the AHU is Exd protection and all electrical components and instruments equipped


Air Cooled Condensing Section

Ref. Document : Piping & Instrument Diagram ( P & ID )

The air cooled condensing system is 2 x 100% independent refrigeration circuit and designed according to heat

rejection requirement of system.

Both units are installed at the open deck of LER level - 2. In normal operation, one unit acts as duty and the

other unit remains on stand-by.

The unit can not be started independently without running respective AHU in auto mode but it can be performed

functional or rotation check on maintenance ( Test/Manual ) mode. The unit can be started only if the duty air

handling unit is in running.

The operator interface consists of a series of high visibility indicating lights, pushbuttons, selector functions and

Eliwell electronic temperature controller located at the unit control panel.

The control system processes related input and outputs, control, protect and monitor the system

with a number of settings, e.g. Temperature sensors, Pressure Switches, etc,.


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The electric motors inside the ACCU is Exe protection and all electrical components and instruments equipped


The condensing unit equipment starter and overload protection are installed inside the HVAC unit

control panel. Space heater power supply for motor of capacity 5.5 kW and above are fed from the same UCP.

All ACCU fans, compressor motor have stop, running and failure signal. The ACCU is controlled by hardwired

based UCP and each system ( duty or standby ) consists of one set of open type reciprocating compressor direct

coupling driven by electric motor, one set of condenser fan c/w driving motor, one piece of refrigeration

liquid line solenoid valve on each refrigeration circuit and others refrigeration system components, accessories

and instruments.

The ACCU work as a slave of the respective AHU.

Control of ACCU

The air cooled condensing unit compressor motor, condenser fan motor starter and overload protection are

housed within the UCP. The UCP will be able to START or STOP the motor during maintenance mode for

functional check or rotational check only.Power supply for motors anti-condensation heaters are fed from the UCP.

18.2 ACCU START

The controller will monitor the temperature reading from the temperature sensor mounted inside the battery

room.

Item Instrument Tag No. Location Set Parameter Remark

1 xx-TT-102 Battery Room T = 25oC

The sensor measures the temperature of the room air. When the room air temperature rises above 25oC

( adjustable ), the UCP will gives signal to start the duty ACCU while the duty AHU is in operation.The refrigeration compressor and condenser fan will operate simultaneously. The compressor operation is

interlocked with condenser fans operation and it will not started without running all duty condensing fans.

18.3 System Safety Protection

During the duty ACCU is in operation, the UCP will continuously monitor the respective system low refrigerant

pressure via low refrigerant pressure switch ( xx-PSL-002A or B ) mounted on the refrigeration suction line and

high refrigerant pressure via high refrigerant pressure switch ( xx-PSH-002A or B ) mounted on the refrigeration

discharge line.

When the reading on the low refrigerant pressure switch fall below set point, the UCP will activate pump down

function and stop the compressor. When the refrigerant pressure rises above set point, the compressor will be

able to restart automatically.

When the reading on the high refrigerant pressure switch goes above xx.x bar (g), the UCP will stop the

compressor. When the refrigerant pressure drop below xx.x bar (g), the compressor will be able to restart but it

required manual reset on UCP - 02 to eliminate high refrigerant pressure cut off alarm.

The compressor cant be restarted within 5 mins (adjustable) with auto restart operation ( e.g compressor

auto cutoff when temperature reach set parameter or pump down activated due to low refrigerant pressure

reaches set point ).

18.4 Liquid Line Solenoid Valve Operating SequenceThe liquid line solenoid valve is installed on each refrigeration circuit and will be opened once received the


23/28


START command from UCP and all the refrigeration system operating parameters are in normal condition.

18.5 Crankcase Heater Operating Sequence

Before first start up, the crankcase heater shall energize for 24 hours. When the duty compressor is running, the

respective crankcase heater will be de-energized and the stand by compressors heater shall be energized.

18.6 Condenser Fan Operating Sequence

All duty condenser fans are started simultaneously with respective compressor.

18.7 Refrigeration Lube Oil Level

The UCP will monitor the refrigeration oil pressure in the system via oil differential pressure switch mounted on

the system. The oil pressure should reach correct level within a few seconds after first start up the compressor.

During the first start, the correct lube oil differential pressure is not reached in 15 ~ 20 seconds , stop

compressor immediately and check oil system & accessories.

During normal operation and when the compressor starts, refrigeration oil differential pressure shall reach tosatisfactory level within 120 seconds. If the oil differential pressure fall below set point, the oil level switch will

trip the compressor and show an alarm message at UCP ( common alarm to PCS ) and need to be reset manually

from UCP.

18.8 List of Refrigeration System Safety Components


1 High Refrigerant Pressure Switch

( SystemA/B ) ( High )xx-PSH-002 A/B

xx.x bar (g)

( High )

Refrigerant Pr. High

( SystemA/B )

Manual

Reset

2 Low Refrigerant Pressure Switch

( SystemA/B ) ( Low )xx-PSL-002 A/B

xx.x bar (g)

( Low )N.A Auto Reset

3 Lube Oil Differential Pressure

Switch ( Time Delay = 120 sec ) xx-ODPS-002 A/Bxx.x bar (g)

( Low )

Lube Oil Pr. Low

( SystemA/B )

Manual

Reset

When the value reading from the above instruments is higher / lower than the set point mentioned above and a

general alarm will be generated.

The UCP will indicate the respective alarm with pilot light and the panel mounted Buzzer will generate an

intermittent sound.

The common fault alarm is transmitted to the PCS.

If the ACMV system is operating in AUTOmode, either one of the Trip function ( UCP will specify which

Trip function ) will Stop the duty system and change over to operate the Stand-by system as duty

automatically.

18.9 Temperature Regulation

The room mounted temperature transmitters ( xx-TT-102 Battery Room, LER 1stFloor ) are installed inside the

compartment. When the reading is higher than set point ( 25oC ) and the compressor will be in operation to bring

down the temperature and humidity level inside the compartment. When the reading value reach set point

( 25oC ) or below, the refrigerant suction pressure will drop accordingly due to less cooling and

dehumidification load. Based on the refrigeration suction pressure and control oil pressure, the compressor will


24/28


be regulated in unload operation by factory assembled hydraulic capacity control unloader

system. The compressor will load again if the cooling load demand increases. During fully unload condition and

temperature reading falls below minimum set point ( 22oC ), the system will be pump down and compressor will

be STOP in operation. The compressor will restart automatically when the sense temperature reaches above set

point or the high temperature ( over 30oC ) alarm Buzzer at the UCP will generate an intermittent sound.

18.10 Pressure Regulation ( Battery Room )

The battery room is maintained at slight positive pressure relative to atmosphere and slight negative that of

adjacent rooms. This room has 2 dedicated exhaust fans (2 x 100% duty) and each works as a slave

of the duty supply air blower fan in auto mode. The slight positive pressure in this room is achieved by

balancing and manual adjustment of volumetric supply air flow rate during testing & commissioning and by

varying the exhaust air flow rate by changing the exhaust fan speed during operation. Room Pressure differential

transmitter (xx-PDT-102) is installed inside the battery room. During auto mode, the fan operation is

interlocked function with function of AHU supply air fan & exhaust air duct fire damper and its operation is

monitored by pressure differential switch ( xx-PDS-016/017 ) mounted downstream of the exhaust air duct.When AHU blower fan is in operation and exhaust fan fail ( Pressure Switch Reading < Set Pt.), the

pressure differential switch will send the signal to UCP, generate alarm after a delay of 60 seconds and

and initiate to start the standby fan.

Conditions for the exhaust fan to start (auto mode) are ,

1. AHU is in operation,

2. Fire & Gas Damper inside the exhaust air stream is opened,

3. Safety Protection Devices for fans are healthy ( if not, UCP will display the alarm message and Buzzer

will generate an intermittent sound).

18.11 Compressor Capacity Regulation and Condensing System Protection :-

18.11.1 Capacity Control

The refrigeration compressor is fitted with hydraulic capacity control system it regulates according to changing

load demands.

18.11.2 Condensing System Protection Devices

a. Compressors Electric Motor Protection Devices,

b. High Refrigerant Pressure Safety Device,

c. Low Refrigerant Pressure Safety Device,

d.

Low Lube Oil Differential Pressure Safety Device,e. Crankcase Heater.

18.11.3 Check before starting:-

1. Refrigeration Lube Oil Level,

2. Setting and function of safety and protection devices,

3. Setting of timing,

4. Setting of refrigerant pressure safety devices,

The compressor lubrication should be checked immediately after starting. Maximum and recommended oil level

during operation shall be within the sight glass range mounted of the compressor.

Minimum oil level is monitored by an oil differential pressure switch.

The time delay period for oil level switch is set to 120 seconds after start up the compressor. If there is not


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enough oil pressure and the refrigeration compressor must stop immediately.

18.11.4 Crankcase Heater

The crankcase heater must be energized during standstill. The crankcase heater in the compressor prevent high

refrigerant dilution of the oil during standstill. It shall only be switched on if compressor is filled with oil.

Note:

If the oil pressure switch cuts-out during the starting stage or the oil level falls below recommended sight glass

level, this indicates a severe lack of lubrication. It may happen due to small pressure difference. Check the oil

return line before adding additional amount of lube oil or danger of liquid slugging.

18.12 Compressor Start Up and Capacity Regulation

The refrigeration compressor will start up if the following conditions are TRUE.

The duty AHU is in operation,

All system protection devices and operation parameters are normal,

No alarm active,

Respective Liquid line solenoid valve is opened.

The compressor operating sequence and capacity regulation is mainly controlled by

3. Low Refrigerant Pressure,

4. Room Air Temperature

Condition 1

If Refrigerant Suction Pressure > / = 5 bar(g) ANDAverage Return Air Temperature > 25oC

( adjustable Set Point ) ANDLiquid Line Solenoid valve is Opened

Then : Refrigeration Compressor : START

The compressor will be in loading / unloading operation condition according to changing load demands.

Condition2

If Refrigerant Suction Pressure > / = 2.5 bar(g) ANDAverage Return Air Temperature > 2 + 25oC


Then : Refrigeration Compressor : Operate in Full Load Condition

Condition 3If Refrigerant Suction Pressure > / = 2.2 bar(g) ORAverage Return Air Temperature > 1 + 25

oC


Then : Refrigeration Compressor : Operate in Unload condition

Condition4

If Refrigerant Suction Pressure < / = 1.4 bar(g) ANDAverage Return Air Temperature< / > / = 25oC


Then : Refrigeration Compressor : Activate Pump Down & Stop the Compressor

for 5 minutes


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The cycle is repeated automatically.

18.13 Fire & Gas Dampers

All fire & gas dampers are electric type with 24 VDC electrical actuator operated and equipped with fail safe

mechanism ( fail to close ). The power supply to the dampers shall be wired from HVAC UCP and send the all

dampers close status to PCS via hard wired signal.

The dampers are equipped with limit switches connected to UCP. The status for each damper can be seen from

HVAC UCP.

18.14 Unit Control Panel for ACMV System ( xx-UP-02 )

The HVAC UCP ( xx-UP-02 ) is located in the HVLV Switchboard Room.

This UCP acts as the main interface to the vessels control and safety system.

HVAC control panel shall be hard wiring type. Control panel enclosure shall be according to Rittal

manufacturer standard.

The control panel complete with electrical components and accessories shall be installed inside the HVLV room

that classified as non hazardous safe area.

Indication Light on the front panel are as follows:-

Normal Power Supply Incoming Light ( Red, Yellow, Blue ),

Normal Power Supply Available Light ( Red, Yellow, Blue ),



UPS Outgoing Light ( White ),

DC Power Outgoing Light ( White ),

Supply Air Fan(s) Status Indication Light ( Run, Stop, Trip ),

Condenser Fan(s) Status Indication Light ( Run, Stop, Trip ),

Compressor(s) Status Indication Light ( Run, Stop, Trip ),

Ventilation Fan(s) Status Indication Light ( Run, Stop, Trip ).

Unit1, Loss of Air Flow Status Indication Light,

Unit2, Loss of Air Flow Status Indication Light,

Room Temperature High Status Indication Light,

F&G Damper Status ( Open/Close ) Indication Lights,

Loss of Room Pressurization Status Indication Light

Other Features

Voltmeter,

Ammeter,

Digital Displayed Electronic Temperature Controller,

Emergency Stop,

Buzzer,

Alarm Acknowledge Button,

Trip Reset Buttons,

According to ABS "Facilities on offshore installations" must also be capable of being closedmanually from both sides of the bulkhead or deck.


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Duty and Standby Selector Switch,

When the feeder to the HVAC panel is turned on from the source, the respective feeder incoming light will also

be turn on to indicate the present of power supply. The main MCCB inside the ACMV control panel is switch

on and the power is available to the equipments circuit breakers.

When there is malfunction alarm in the HVAC system and the buzzer on the front panel will be activated.

System Start / Stop

The ACMV system shall be operated locally from the system START and STOP push buttons on the main UCP

front panel.

Emergency Stop push button is located on UCP front panel and it is hard wired in series with the field

emergency stop push buttons located near the ACMV equipments. Emergency Stop contact is hard wired in

series with system START command contact and will remain opened until being reset to its normal position

manually.

Power Supply

The HVAC UCP is fed from three independent power source.

Normal 440 V / 3 Ph / 60 Hz ( xx-xx-xx)

UPS #1 220 V / 2 Ph / 60 Hz ( xx-xx-xx)

UPS #2 220 V / 2 Ph / 60 Hz ( xx-xx-xx)

18.15 ACMV UCP Interface to F&G and PCS

Sr.No From UCP To PCS Remark

1 ACMV Common Alarm Signal N.O Volt Free

Contact

2 ACMV Run Status Signal N.O Volt Free

Contact

3 ACMV Fault/Available Signal N.O Volt Free

Contact

4 Dampers Close Status Signal N.O Volt Free

ContactConfirmed All Dampers are Closed.

5 Loss of Room Pressurization N.O Volt Free

Contact

6 Ventilation Fans Run Status

Signal

N.O Volt Free

ContactBattery Room Exhaust Air Fan

7 Ventilation Fans Fault Status

Signal

N.O Volt Free

ContactBattery Room Exhaust Air Fan

From F&G To UCP

8 Shut Down Signal 24 VDC1. Confirmed Fire in Battery Room

2. Confirmed Fire in False Floor


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3. Confirmed Gas Detected at HVAC

Inlet

18.16 Alarm Management

The ACMV control panel front mounted buzzer is activated when there is an alarm in the ACMV system and

which serves as the operator interface. Alarm management is handled by ACMV control panel. Alarm from the

pressure differential switches ( mounted across filters, blowers, room ) shall be implemented with time delay to

prevent nuisance alarm due to specific fluctuations in measurement value.

When warning alarm is activated, buzzer will sound and fault indication is prompted on the ACMV panel. By

pressing the alarm acknowledged push button, buzzer will goes silent but fault indication is remained on. Once

the fault is rectified, press the reset button on the front panel of ACMV control panel to reset the ACMV system.

Differential pressure alarm generated due to high air pressure drop across the air filters and higher room

temperature alarm shall be visible on the ACMV control panel as common fault. Loss of room pressure alarm,

ACMV Unit A Fault alarm and ACMV Unit B Fault alarm generated in the ACMV control panel are visible as

individual fault alarm in the PCS but reset can be done only from ACMV control panel.

18.17 Password Protection

Password protection can be done on the electronic temperature controller. This is to ensure that only authorized

and trained personnel are allowed to enter the system control section for the operation of the ACMV system and

changing of setting values.

18.18 Sensors

When the sensor is faulty, there is no input signal to the electronic temperature controller error massage will be

displayed on the respective controller.

hvac system functional design description_commentes_gusto_110202.pdf

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