04 battery room standard 41-644

8/13/2019 04 Battery Room Standard 41-644

http://slidepdf.com/reader/full/04-battery-room-standard-41-644 1/20

Note: Concerns queries and comments on this document should be referred to the compilerWhen downloaded from Transmission database, this document is uncontrolled, responsibility lies with theuser to ensure that it is the authorised version.

When downloaded from the EDC website, this document is uncontrolled and the responsibility rests with the user to ensure it is in linewith the authorised version on the website. Note: This document has not been through the EDC processes prior to authorisation.

STANDARDDocumentClassification:CONFIDENTIAL

Title: STANDARD FOR BATTERY ROOMS Unique Identifier: TST41-644

Document Type: STANDARD

Revision: 0

Effective date: JUNE 2007

Total pages: 19

Review date: JUNE 2012

COMPILED BY FUNCTIONAL RESP. AUTHORIZED BY

….................................BN JONGATECHNOLOGY &SUPPORT -DC

…...........................A DE LA GUERREM&C MANAGER

….................................N KLEYNHANSPMC MANAGER

DATE:…....................... DATE:…....................... DATE:….......................

CONTENTS PAGEForeword ......................................................................................................................................................33 1. Purpose ..................................................................................................................................................33 2. Applicability .............................................................................................................................................33 3. Normative references .............................................................................................................................33 4. Definitions and abbreviations .................................................................................................................33 4.1 Definitions…………………………………………………………………………………………………………24.2 Abbreviations……………………………………………………………………………………………………..25. Requirements .........................................................................................................................................33 5.1 General……………………………………………………………………………………………………………25.2 Civil Requirements……………………………………………………………………………………………… 35.3 Electrical Requirements…………………………………………………………………………………………8

5.4 Safety and Maintenance………………………………………………………………………………………...96. Revision Information ...........................................................................................................................1212 7. Authorisation .......................................................................................................................................1212

Annexures

Annexure A ..............................................................................................................................................1313 Annexure B ..............................................................................................................................................1515 Annexure C.1 ...........................................................................................................................................1616



STANDARD FOR BATTERY ROOMS Unique Identifier: TST41-644Revision: 0Page: 2 4 of 19

Note: Concerns queries and comments on this document should be referred to the compilerWhen downloaded from Transmission database, this document is uncontrolled, responsibility lies with theuser to ensure that it is the authorised version





Foreword

This document is derived from:

NWG 7014: Rev 0; Design guide for battery rooms - 1990 – Leon Drotsché

1. Purpose

The purpose of this standard is to assist design engineers in the design of battery rooms that will housestationary, vented lead acid and nickel cadmium batteries.

2. Applicability

This standard is applicable to battery rooms at all Transmission substations.

3. Normative References

The following documents contain provisions that, through reference in the text, constitute requirements ofthis standard. At the time of publication, the editions indicated were valid. All standards and specificationsare subject to revision, and parties to agreements based on this standard are encouraged to investigatethe possibility of applying the most recent editions of the documents listed below. Information on currentlyvalid national and international standards and specifications can be obtained from the Information Centreat Megawatt Park.

Standard for maintenance of DC systems .

Procedure for maintenance of DC systems.

4. Definitions and Abbreviations

4.1. Definitions

4.1.1. Type ‘e’: Equipment that does not produce arcs sparks, or dangerous surface temperatures innormal service, and which has been provided with certain additional protective features in order toincrease its safety to a level that is suitable for use in potentially explosive atmospheres.

4.2. Abbreviations

4.2 .1. BVR: Basic Ventilation Rate

4.2.2. RVR: Recommended Ventilation Rate

4.2.3. OHSACT: Occupational Health and Safety Act

5. Requirements 5.1. General

i) Battery rooms shall provide easy access for batteries and battery stands. In addition, battery roomsshall be dry, well lit, well ventilated and protected against the ingress of dust and foreign matter.

ii ) Only flat or stepped single row single tier, double row single tier ,three row centre terraced and fourrow centre terraced wooden stands (normally ordered from the battery manufacturer at the time thebatteries are ordered) shall be used.





iii) Battery rooms shall provide for possible future expansion / refurbishment, therefore it shall be locatedat the end of the building. Battery rooms shall be situated as near to the associated loads andrectifier equipment as possible.

vi) Every endeavour shall be made to ensure that the battery room is situated on the coolest side of thebuilding.

v) Separate battery rooms shall be provided for batteries with different types of electrolyte, i.e. nickelcadmium and lead-acid batteries shall not be installed in the same room. Two or more batteries withthe same type of electrolyte may be installed in the same room but on separate battery stands.

An access passage at least one metre wide to all battery rows and a minimum of one metre betweenrows of battery stands shall be provided.

Only single row or stepped double row single tier battery stands may be positioned against a wall.The step shall be such that the top of the cell plates of the back row is exposed.

The minimum distance between any battery terminal and the nearest water supply point shall be two

metres.

ix) Rows of battery stands shall be positioned such that they do not jeopardize or obstruct the doorway.

x) Wherever possible the stands shall be positioned perpendicular to the entrance wall. The batteryarrangements shall comply with the layout drawing, showing the positioning of the different batteries.

5.2. Civil Requirements

5.2.1. Floors Construction

i) Expansion joints shall be avoided.

ii) When the battery room is located at ground level, the floor shall comprise a concrete surface bed laidon compacted earth. When the battery room is situated above ground level, the floor shall comprisea reinforced concrete slab.

iii) Due to the mass of the batteries the floor shall be absolutely stable. Subsidence of the floor at pointsof load shall not take place, as this will cause settling and tilting of the batteries with consequentstraining of the battery connection.

iv) The floor shall be given a uniform fall, end to end, of not less than 1:200, by applying a cementscreed to the concrete. The lower end being that where the tapped water supply is located. Acrossthis lower end of the floor, a white glazed fire clay block channel or epoxy lined concrete channelshall be provided, sloping towards the outlet. This outlet shall discharge into a PVC drainpipe thatshall be built through the external wall of the battery room, and shall lead to a dedicated drainagesystem, designed and installed to prevent contamination of groundwater.

v) To prevent fluid discharge from the battery room, a lip of at least 25 mm shall be placed on the insideof the door entrance. Alternatively a water channel, complete with a non-corrosive grid cover, shall beinstalled along the wall.

5.2.2 Floor Protection

i) In lead-acid battery rooms, the electrolyte shall be sulfuric acid (H2SO4).

ii) As concrete is highly vulnerable to corrosion by this acid, the floor shall be given a protective coatingof acid-resistant, non-skid ceramic floor tiles or an approved acid-resistant epoxy coating applied in

accordance with the manufacturer’s specifications.





iii) The electrolyte used in nickel cadmium batteries is a solution of potassium hydroxide (KOH), in water.In certain cases, small quantities of lithium hydroxide (LiOH) are also included in the solution.

iv) This fluid will not corrode concrete or brickwork, but if left for any length of time in direct contact withthese materials, it will form a white encrustation of potassium carbonate (K2CO3). This encrustationhowever is relatively harmless and can easily be dissolved and removed with cold water.

v) For nickel cadmium battery rooms therefore, corrosion resistance flooring materials are not technicalrequirements and they cannot be justified economically.

5.2.3. Walls

Walls shall be continuous from floor to ceiling and be securely anchored. The walls of lead acid or nickelcadmium battery rooms shall be protected against electrolyte splashes, by applying an approved light-coloured, acid resistant enamel paint.

5.2.4. Windows

Windows shall not be provided in battery rooms. Where windows have been installed in older rooms, theyshall be suitably blanked off to prevent ingress of sunlight

5.2.5. Ceilings

i) The ceilings shall be flat preferably and be at least 2, 5 m above floor-level.

ii) Being considerably lighter than air, the hydrogen given off during battery charging will rise andaccumulate under the high points of ceilings and overhead structures. All such high points shall bevented to the atmosphere. Special attention shall be paid to this ventilation when ceiling beams haveto be used.

iii) Skylights and false ceilings shall not be used.

iv) Ceilings shall be given the same paint treatment as walls (see 5.2.2).

5.2.6. Doors

i) The battery room door shall have the applicable fire and security rating and shall be not less than 800mm wide and 2000 mm high. The door shall have one leaf that opens outwards.

ii) For small substations and small communication stations, a door of 800 mm wide (min) and 2000 mmhigh shall be used.

iii) The inside surfaces of the door shall be protected by an approved light-coloured, acid resistant paint.

iv) All fittings for these doors shall be subject to Eskom’s approval.

5.2.7. Fire Resistance Ratings

5.2.7.1. Battery rooms that are part of attached to or within another building, shall comply with thefollowing:

i) Walls and ceilings shall have a fire resistance rating of not less than one hour.

ii) Floors of battery rooms shall have a fire resistance rating of not less than one hour where such batteryrooms are located above other defined fire zones, for example, rooms, compartments, etc.





5.2.7.2. Exceptions:i) Any exterior wall of a battery room that is more than 15 m from a potential fire zone will not be

required to have a one hour fire resistance rating.

ii) The wall shall however, be of a non-combustible construction.

5.2.7.3. Any duct, pipe, conduit, cable or other equipment that penetrates a wall, floor or ceiling, having afire resistance rating, shall be fire stopped with a fire resistant material such that the fire resistance of thewall, floor or ceiling will not be negatively affected.

5.2.8. Plumbing

i) A laboratory type sink of glazed fire clay shall also be installed at the lower end of the floor, preferablythe door side of the battery room. This sink shall be the large rectangular type preferably withdraining boards on either side, and an acid resistant laboratory receiver beneath.

ii) The sink shall be provided with a supply of suitable running water and controlled by an elbow actionmixer tap. Discharge from the sink and from the laboratory receiver shall be into the white-glazed fire

clay block channel referred to in 5.2.1.1 d).

iii) An industrial safety shower, in addition to eye wash facilities shall be located in the vicinity of thenormal water supply (sink) and shall not obstruct the door exit.

iv) Where there is not enough space for civil extensions to accommodate an industrial emergencyshower, it shall be located outside the battery room next to the door. The shower drain shall beconnected to the battery room drain system.

v) At sites where only low water pressure is available a booster pump shall be installed to achieve3(three) bar water pressure.

5.2.9. Cable Entry Facilities

5.2.9.1. Where the cable entry is through the floor, the following shall be adhered to:

i) The cable opening shall be adjacent to the wall and stands where applicable.

ii) PVC or cement cable pipes curved to the bending radius of the cable shall be cast into the floor insuch a way that the entry of the cables into the battery room is perpendicular to the floor.

iii) To prevent fluids or foreign matter from entering the pipe, its upper end shall project at least 50mmabove the finished floor surface.

5.2.9.2 For any other form of cable entry, the following shall be adhered to:

i) These cable entries shall be either vertically from the floor above, if applicable or horizontally (at asatisfactory height) through one of the battery room walls.

ii) A separate entry, as near as possible to the battery terminals, shall be provided for each batterybank.

iii) These entries shall be kept sealed with vermiculite or equivalent material, to prevent hydrogentransfer before and after installation of the cables.





5.2.10 Ventilation

5.2.10.1. General

i) Battery rooms shall be so positioned and designed that they are subjected to only very slight changes

in temperature.

ii) The nominal temperature in the battery room shall be 25 °C and the temperature shall be kept asclose to this as possible. If the temperature exceeds 35 °C, special consideration shall be given tocontrolling the air temperature. Air used for ventilating battery rooms shall not exceed 25 °C. Batte ryrooms shall be positioned on the coolest side of the complex.

iii) Where a powered room ventilator cannot be used, a wall mounted axial type extract fan with backdraught dampers shall be used. The fan shall be mounted as high as possible in the wall, but notbelow the level of the light fittings.

iv) In very large battery rooms with deep roof beams, especially where cross flow between inlets andoutlets is difficult to achieve (for example, when inlets and outlets must be in the same wall), the

extract system shall include a duct with several intake points made available at high level.

v) Hydrogen gas from battery rooms shall be extracted or ventilated to a safe area, i.e. outdoors or toan area where the gas will always dissipate into the atmosphere without possible danger of the gasaccumulating in any part of that area.

vi) Where it is necessary to provide ventilation ducts to discharge hydrogen gas to a safe area, suchducting shall comply with the above requirements.

vii) The ducting shall be protected with a one-hour fire rated material or plaster. Fire rating however willonly be required if the ducting passes through intermediate rooms or potential fire zones.

viii) In applications where there is complete dependence on forced ventilation, it is recommended that

redundancy be provided in the extract fans, with suitable non-return dampers and a means ofmonitoring operation so that, in the event of failure of the operating fan, the stand-by unit can beswitched on.

ix) Where both supply and extract powered systems are provided, they shall be selected to ensure thatthere will, under normal conditions, be a slight negative pressure in the battery room.

x) Fans shall be selected to provide the required performance even when operating against normalsystem resistance, including dust-laden filters, as well as considering prevailing wind and any otherdetrimental effects. Generally speaking, axial or centrifugal fans are required in applications wherethe fans have to overcome filter resistance. Each application shall be checked to ensure that fannoise will not be a negative factor to the adjacent environment.

xi) Air inlets, through which the necessary replacement air would enter the battery room, shall be fittedinto one of the longitudinal walls and / or in the door, opposite the air outlets, in such a way that theyare evenly distributed along the section of wall opposite the battery cells, to ensure that there is across ventilation system . They shall also be located as close to the floor as possible to ensure thatthe incoming fresh air passes around and over the battery cells.

xii) Air-bricks for ventilation are not recommended as they have shown that, unless a great number areused, the resulting ventilation will be negligible. Air-bricks, moreover, readily permit the entry of dust.

xiii) The size of natural roof-ventilator required for each application depends on the height of the ventilatorabove the air-intake points, the effective difference between internal and external air temperatures,and the rate at which the air is to be extracted.





xiv) For a very small battery room, the ventilator-louvre combination shall be selected and installed so thatit will be capable of removing the air-hydrogen mixture from the room at a rate not less than, 250 x10

-7 P m

3 /s, for example.

xv) All battery rooms shall be naturally or forced ventilated by ensuring that the minimum amount of airexchanges takes place thereby rendering the battery room safe. This can be done by determining theamount of hydrogen given off by the cells during the end-of-charge phase where gassing is causedby overcharging. See annex B for the calculations.

xvi) Battery rooms shall be provided with the following options wired to a central point:

• A remote operated facility for ventilation. . Some battery chargers have the facility to do thiswhen they are switched to a higher charging rate. This option will not be used where the fanis required to function permanently.

• A facility that can detect when the ventilation system fails or the filters are blocked. This shallbe done by means of a pair of potential free contacts that would indicate when the system isabnormal, and can be used to inhibit the battery charger from switching to the higher charge

mode or initiate an alarm on the charger.

5.2.10.2. Small battery rooms

Small battery rooms are defined as those in which the sum of the products obtained by multiplying thenominal ampere hour capacity of each battery in the room by its number of cells is less than 6000.Whenever possible, such rooms shall be naturally ventilated with roof ventilators and louvred air inletswith filters in outside walls. In cases where such rooms have no outside walls and/or it is not practical toprovide roof ventilation, a forced ventilation system shall be provided.

5.2.10.3. Large battery rooms

i) Large battery rooms are those containing battery installations having a total capacity, exceeding the

limit imposed in item 5.2.9.2. All such rooms shall be force ventilated.

ii) Where a central ventilation system is not supplied, the ventilation fan shall be powered from the samesource as the battery charging equipment and controlled in such a way that maximum availableventilation is assured when batteries are on charge and gassing is likely.

iii) Where roof ventilation is fitted, the fans shall only be operational when a battery charger is selected toa higher charge mode, a feature fitted to all modern chargers. All fans shall be fitted with a “Fan fail”alarm and a normally open or normally closed potential free contact, to provide an alarm when thefan fails.

iv) Depending on building configuration and prevailing ambient conditions, any of the following systemsare acceptable. For reasons of cost and overall reliability, the simplest system that meets basic

requirements shall always be preferred.

• Powered roof ventilator with panel filters at the air inlets in at least one outside wall. This is alow cost system that provides filtration of replacement air. Filtered openings for replacementair shall be provided as remotely as possible from the extraction point, to encourage a throughdraught at high level. Disposable filters 600 x 600 x 50mm of 95% gravimetric efficiency orminimum dust holding capacity of 1 300 g/m

2 are recommended. Maximum velocity through

panels 2 m/s. Doors shall be close fitting, and cable entry pipes and other openings (to otherrooms or the outside) properly sealed to prevent ingress of unfiltered air that could also causedust ingress.

• Dust collector type fan-filter units may be used. Such units are relatively expensive butvirtually maintenance free and can usually be justified where dust conditions are particularlysevere as, for example, in the boiler house of coal-fired power station.





• Fan filter units as above with naturally ventilated roof ventilation. This system shall only beused when the battery room door exits to the outside of the building, i.e. the hydrogen shallnot be forced into adjacent rooms.

5.3 Electrical Requirements

5.3.1. Fan Motors

5.3.1.1. When a special ventilation system is used to comply with 5.2.8 of this standard, the extraction fanshall comply with the relevant safety regulations and shall be subject to Eskom’s approval.

5.3.1.2. The preferred motors for these extraction fans shall be the single-phase squirrel-cage inductiontype and shall be suitable for direct-on-line starting.

5.3.1.3. They shall, moreover, be of the “increased safety” design commonly known as Class I Division II‘non-sparking’ motors. ‘Non-sparking’ motors are acceptable for battery room applications as specified inSABS 0108- and are available in South Africa. A certificate is issued with each motor or batch of motors.

5.3.2. Artificial Lighting

5.3.2.1. General

i) The entire lighting installation within the battery room shall consist exclusively of type ‘e’ apparatusand luminaires.

ii) The basic difference between the type ‘e’ protection now required and the traditional type of protectionusing flameproof or explosion-proof enclosures that has been in use for many years, is as follows:

• In the traditional method of protection, it is assumed that an explosion may occur inside theenclosure, and the enclosure is therefore designed so that such an internal explosion cannotdamage it or cause the ignition of the gas or vapour surrounding it.

• In the type ‘e’ system however, flameproof and explosion-proof enclosures are not requiredbecause the equipment is instead designed in such a way that all possible sources of ignition,such as arcs, sparks and excessive surface temperatures, can be closely controlled. As a resultof this, the statistical probability of an explosion occurring is reduced to an acceptably low level.

5.3.2.2. Main lighting installation

i) The main lighting installation in the battery room shall be supplied from the station’s 230/400 V a.c.auxiliary supply.

ii) The installation shall consist of fluorescent luminaires only, type Ex’e’ class 1 Div 1 (T1 – T4). Thisform of lighting is favoured over mercury-vapour lighting for the reason that the latter, when subjected

to dips in supply voltage, may go out and remain out for periods of up to ten minutes. Incandescentlighting is also considered unsuitable because of its relatively low lumen output and short service life,both of which factors give rise to excessive maintenance costs.

iii) The fluorescent fittings chosen shall preferably be installed on the ceiling, and shall provide sufficientlight output to illuminate the tops of the batteries to a level not less than a maintained 100 lux, inaccordance with the OHS Act for battery and charging equipment rooms.

5.3.2.3. Emergency lighting installation

i) The emergency lighting installation shall consist of incandescent luminaires type Ex’e’ (T1 – T4), witha standard two pin bayonet or screw type socket or fluorescent luminaires as in 5.3.2.2 and fitted withD.C. to A.C. converters. These units shall be supplied from the station battery using the normal d.c.

distribution system.

ii) These luminaires shall be mounted on the ceiling only.





iii) The maintained level of emergency lighting required in this area shall be not less than 20 lux at floorlevel to enable employees to evacuate the workplace safely, in accordance with the OHS Act.

5.3.2.4. Luminaire positioning

i) The luminaires shall not be mounted directly over the battery stands.

ii) The luminaires shall be positioned in parallel with the battery stands. This precaution will facilitatemaintenance on the fittings, and will also minimize the obvious dangers of working over the cells.

iii) No battery baks shall be installed directly under the luminarie.

5.3.3. Other Electrical Equipment

5.3.3.1. All light switches, power outlets, distribution boards, telephones and fan contactors (item 5.2.8.3),shall be mounted outside but still in close proximity to the battery room door.

5.3.3.2. These devices are not required to be explosion-proof, flameproof, or type ‘e’.

5.4. Safety and Maintenance

5.4.1. Maintenance and Protective Equipment

All maintenance and protective equipment as specified in TST41-643 shall be provided.

5.4.2 Safety Signs

The required safety signs are specified in table 1.





Table 1 – Safety signs required for battery rooms

Description of safety signRequired location of safety

signEskom code and drawing

number

a. A notice identifying theroom as being a batteryroom.

b. It clearly sets out theelementary first aidprocedures in the case ofeye and / or skin contactwith an acid or alkali.

c. A no-smoking prohibitivesign and corrosivesubstance warning sign

are also posted on thenotice.d. The notice also displays

that unauthorized entry tothe battery room isprohibited.

At the designated entrance tothe battery room.

TG 1: 0.52/20380 Sheet 1

(See Annexure C.1)

a. This notice shows thatopen flames are prohibitedinside the battery room.

b. It also shows that anapron, eye protection andgloves shall be worn.

On wall directly opposite theentrance to the battery room.

TG 2: 0.52/20380 Sheet 3

(See Annexure C.2)

A notice indicating the locationof the emergency shower.

Next to the emergency shower. GA 20: 0.52/20381 Sheet 1

(See Annexure C.3)

A notice indicating the locationof the eyewash equipment.

Next to the eyewashequipment.

GA 19: 0.52/20381 Sheet 2

(See Annexure C.4)

A notice showing that thedrinking of water is prohibited(when applicable)

On wall above battery roomsink or water container.

TG 3: 0.52/20381 Sheet 3

(See Annexure C.5)





6. Revision Information

Rev Notes Date

0 Original document NWG 7014- (Design for battery rooms)Leon Drotche

1990

0 Renumbering, old number TRMASACN1 July 2007

7. Authorization

This document has been seen and accepted by:

Name Designation

Tony Sheerin M&C Applications Manager

Piet Jooste Transmission Grids

Chico Ramgovind Secondary Plant Manager(Central Grid)

Krish Govender Secondary Plant Manager (Eastern Grid)

Rhulani Matshidza Secondary Plant Manager(North East Grid)

Noxolo Sipunzi Secondary Plant Manager(Western Grid)

Paul Grobler Secondary Plant Manager (Northern Grid)

Johan Pieterse Secondary Plant Manager (North West Grid)

Ian Worthington Secondary Plant Manager (South Grid)

DC Work Group Transmission National DC Working Group/Committee





Annexure A(Informative)

Hydrogen Removal

A1. Basic Principles

When batteries are on charge, hydrogen bubbles are released and, due to the buoyancy, these bubblesrise rapidly in the air until they meet an obstruction such as the ceiling where they tend to accumulate.

Compared with heavier gases, the hydrogen diffuses relatively quickly so that in due course it becomesevenly distributed under any obstruction. This process of molecular diffusion is greatly accelerated underconditions of air turbulence.

The main purpose of ventilation is to keep the hydrogen concentration within safe limits. Ridge ventilatorsare particularly effective because they release some hydrogen to the outside before it is able to diffuse inthe room. It should also be borne in mind that lightweight building elements such as ceiling tiles do not

provide an effective barrier to hydrogen. Battery room walls shall therefore, be extended to roof sheetingheight where there is a pitched roof over the battery room and the roof is provided with a ridge ventilator.

The ventilation system is based on the assumption that the air that enters the battery room through thefilters will mix with and adequately dilute the hydrogen gas discharged by the cells. The resulting air-hydrogen mixture discharged by the cells will then be extracted from the room by the fans at a rate notless than that recommended in the tables (A3).

A2. Determination of Basic Ventilation Rate (BVR)

If a battery in the room is on charge, such room will be considered sufficiently ventilated if its air -hydrogen mixture is being extracted from it at a rate not less than that given by the following formula:

BVR = q x t x d x s x P

where

q = volume of hydrogen in litres produced per second per ampere per cell

q = 126,7 x 10-6

l/s rated at 25 °C at sea level

t = “thinning factor” = 100 / 3.8 % = 26,3

An air - hydrogen mixture can explode if the volume of hydrogen contained in the mixture equals orexceeds 3,8% of the total volume.

d = “diffusion factor” that normally has a factor of 3,0.

This factor provides against the possibility of the hydrogen being non-uniformly dispersed throughout theair in the room

s = a general safety factor that, for stationary installations, is normally 2,5





Annexure A(Continued)

P = the sum of the product obtained by multiplying the number of cells in the largest battery in the room bythe output current rating, in amperes, of the battery’s particular charger plus (+) the corresponding

product obtained in respect of the second largest battery in the room.

NOTE: When designing the ventilation system, the worst possible charging conditions (normally duringcommissioning) should be assumed. Such conditions would occur if, due to a charger fault, maximumrated charger current is forced through a fully charged battery. Basic ventilation rate (BVR) should beachieved at any prevailing conditions (i.e. blocked filters).

Combining the above values into the original equation, it follows that the basic ventilation rate required forthe battery room is:

BVR = q x t x d x s x P = 126.7 x 10-6

x 26.3 x 3 x 2.5

= 250 x 10-4

P litres/sec

= 250 x 10-7

P m3 /sec

BVR is sufficient for safety purposes. However, to increase life expectancy of the cells, considerationshould be given to ventilating the room to limit temperature rise to 5 °C above ambient. In a well-in sulatedroom, this can be achieved by supplying 10 to 15 air changes per hour.

A3. Recommended Ventilation Rates (RVR) for South African conditions

Obviously the formula derived in A2 can apply only to battery rooms located in temperate regions at sealevel.

In order to provide ventilation data that can be used readily under typical South African conditions, theabove formula has been expanded to produce the following table A1.

Table A1 – Ventilation data for South African conditions

Altitude abovesealevel

Atmosphericpressure

Recommended ventilation rate (RVR)

metres m barBattery room

temperature °°°°Clitres per sec cumecs m

3/s

0 1013 0 229.P.10 229.P.100 1013 25 250.P.10 250.P.10

305 977 25 259.P.10 259.P.10610 942 25 369.P.10 269.P.10914 908 25 279.P.10 279.P.10

1219 875 25 290.P.10 290.P.101524 843 25 301.P.10 301.P.101829 812 25 312.P.10 312.P.102134 781 25 324.P.10 324.P.102438 752 25 337.P.10 337.P.10





Annexure B(Informative)

Ventilation to avoid hydrogen concentration in battery rooms

NOTE: The following is an extract from BS 6133:1985 – Safe operation of lead-acid stationary cells andbatteries.

In order to be certain that the ventilation of the battery room is adequate to keep the averageconcentration of hydrogen gas in the room within safe limits, it is necessary to be able to calculate the rateof evolution of hydrogen. Hydrogen is evolved during a recharge or freshening charge of the battery whenthe voltage rises above 2.30V per cell. During this period when the cells are gassing freely, it isrecommended that the concentration of hydrogen gas within the battery room is limited to an average of1%, except in the immediate vicinity of the cell tops. This is only one quarter of the normally accepted safelimit of 4% hydrogen, but in view of the potential hazard with stationary batteries, this additional safetymargin is fully justified.

The following method may be used to calculate the ventilation requirements of a battery room.

26,8Ah input to a fully charged cell will liberate 8 g of oxygen and 1 g of hydrogen.1 g of hydrogen occupies a volume of 12 l at 20 °C and at a pressure of one standard atmosphere.Therefore 26,8Ah input will evolve 12 l of hydrogen. Therefore the volume of hydrogen evolved from abattery per hour:

300045.0arg

45.0arg

8.26

12arg

mcurrent echcellsof no

lcurrent echcellsof no

lcurrent echcellsof no

××=

××=

××=

The volume of hydrogen found by the above calculation can be expressed as a percentage of the totalvolume of the battery room, and from this, the number of changes of air per hour to keep theconcentration of hydrogen below 1% can be calculated.

Example

Consider a battery of 100 cells, using a double tier, double row terraced arrangement, in a room withdimensions 4 m x 2 m x 3 m.Charge current = 17 A (finishing rate of charge for cell type used).Volume of hydrogen evolved per hour = 120 x 17 x 0,00045 = 0,92m

3.

Total volume of room = 4 x 2 x 3 = 24 m3.

Approximate value of battery and stand (i.e. volume of battery + 20 % for volume of stand) = 3 m3.

Therefore volume of free air in room = 21 m3.

Therefore concentration of hydrogen gas after charging for 1h above 2,3V per cell (gassing potential) at17 A with no ventilation would be:

%4.4%10021

92.0=×=

Therefore to keep the concentration of hydrogen gas at a maximum of 1%, the air in the room will need

changing 4.41

4.4= times per hour, or about five times per hour.

To allow for variations from the assumed values and contingencies, ventilation shall be arranged tochange the air in the room six times per hour.

NOTE: The effectiveness of a ventilation system can only be assessed by sampling gas concentrationsunder operational conditions.





Annexure C.1

Unauthorized entry prohibition

No smoking allowed

Warning of corrosive substances

First aid procedure in case of burns, due to eye or skin contact with acid or alkali





Annexure C.2No open flames allowed

Hand and eye protection to be worn





Annexure C.4Eyewash




Note: Concerns queries and comments on this document should be referred to the compilerWhen downloaded from Transmission database, this document is uncontrolled, responsibility lies with the

Annexure C.5Drinking of water is prohibited

04 battery room standard 41-644

Documents