EMERGENCY STOP SYSTEM

DEFINITION

An emergency stop function is intended:

• to avert arising or to reduce existing hazards to persons, damage to machinery or to work in progress;

• to be initiated by a single human action when the normal stopping function is inadequate for this purpose.

• normal shut-down switch shuts down all systems in an orderly fashion and turns the machine off without damaging it.

• But an emergency stop switch is designed and configured to completely and as quickly as possible abort the operation, even if this damages equipment and be operable in a manner that is quick, simple & be obvious even to an untrained operator or a bystander.

• Many kill switches feature a removable barrier or other protection against accidental activation (e.g., a plastic cover that must be lifted or glass that must be broken).

Location

• They should be positioned for easy access by the operator or anyone who may need to use them, however, they should not be located where

their use could endanger the user.

Remember that the person using the emergency stop may not necessarily be the person in danger! It may, therefore, be prudent to position an emergency stop near an adjacent machine, or machine zone in the case of a complex system, giving the neighbouring operator the opportunity to stop the machine if the operator gets into trouble.

Where this is done, the zone of effectiveness of the Emergency Stop must be clearly indicated to avoid confusion.

TYPES by BS EN 418

• Stop category 0:-• Uncontrolled stop -- stopping by immediate removal of power to

the machine • actuator(s), all brakes and/or mechanical stopping devices being

applied. •

• Stop category 1:-• Controlled stop -- with power available to the machine actuator(s)

to achieve • the stop and then removal of the power when the stop is achieved. •

• Stop category 2:-• Controlled stop -- with power left available to the machine

actuator(s).

DNV-OS-D201ELECTRICAL INSTALLATIONS

APRIL 2011—no single failure will cause loss of duplicated essential or important equipment.

— The control circuits for emergency stop of duplicated equipment shall be arranged as two separate circuits with separate cables. A common stop button with several contacts (separate for each consumer) will be accepted.

— The emergency stop signal shall act independently of any software based control system for the same consumer.

— A computer based emergency stop systems shall be independent from other computer based systems with control functions for the same consumers. It shall have facilities to detect failures that will set the system inoperable, and give alarm to the main alarm system. See DNV-OS-D202.

— Alarm for loss of power shall be provided for normally open emergency stop circuits.

DNV GUIDANCE

Emergency stop systems may be based on both normally open (NO) and normally closed (NC) circuits.

Systems, which can be stopped without any hazard,should be based on NC circuits,

emergency stop of systems having effect on propulsion motors and thruster shouldbe based on NO circuits.

DNV

• — fuel oil transfer pumps• — fuel oil feed and booster pumps• — nozzles cooling pumps when fuel oil is used as coolant• — fuel and lubrication oil purifiers• — pumps for oil-burning installations• — fans for forced draught to boilers• — all ventilation fans• — all electrical driven lubrication oil pumps• — thermal oil circulating pumps• — hydraulic oil pumps in machinery space.

CARGO PUMPS

• BRIDGE CONSOLE AFT• CARGO CABINET MAIN DECK

• when we press the emergency stop button, the corresponding breaker for the circuit at cargo switch board will be tripped, hence the pump stops. . for restarting the pump we have to reset the emergency stop button that we pressed.

• usually there will be 2 independent pumps each can be controlled separately.

• but emergency stop is common for both pumps ,

CO2 SYSTEM

• It is a system used to protect the main engine room from fire .

• At the occurrence of fire CO2 will be released manually .

• But we know that increased concentration of CO2 in inhaling air can

cause coma and death for persons inside engine room. engine room should be isolated from nearby

compartments and from ventilation ducts .warning should be given to the crew at the spot to

evacuate immediately.

PUSH BUTTON

SEALING

FRONT PLATE

FIXING NUT

SWITCHING ELEMENT