fork truck hazard

8/12/2019 Fork Truck Hazard

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INDUSTRIAL HEALTH

A GUIDE TO

FORK TRUCK

HAZARD PROTECTION

Published by the DEPARTMENT OF LABOUR - New Zealand

SAFET

Y

WELFARE

ARCHIVE

DIESEL FORK TRUCKS OPERATING WITHINDEFINED HAZARDOUS ZONES


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Published by Explosives and Dangerous Goods

Occupational Safety & Health Service

Department of Labour

Wellington

New Zealand

www.osh.dol.govt.nz

ISBN 0-477-03462-4

Second Edition:1989

Important Note:

All the publications in the Publications Archive

contain the best guidance available at the time of

publishing. However, you should consider the

effect of any changes to the law since then. You

should also check that the Standards referred to

are still current.


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CONTENTS

Section 1 Introduction 4

Section 2 Legislative Requirement 6

Section 3 Approval Procedures 7

Section 4 Modifications 9

Appendix I Maintenance Requirements 12

Appendix II Hazardous Zone Classification 13

Section III T Temperature Rating Testing 14

Section IV List of Approved Units 16

Section V Related Documents 18


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ARCHIVEFLAME PROOF DIESEL POWERED FORK LIFTS FOR USE IN

HAZARDOUS AREAS

SECTION 1

INTRODUCTION

1.1 The mistaken belief that diesel engines, having no electrical spark ignition

system, could be safely used in areas where flammable vapours might be

present, provided that suitable spark arrestors were fitted to the exhaust

system, has been firmly dispelled by various incidents which have

occurred in the petroleum, petrochemical and allied industries.

For instance, an explosion which occurred in recent times in the UnitedKingdom was directly attributable to cyclohexane being ingested by a

diesel engine resulting in wild over-revving, disintegration of the engine

and ignition of the surrounding inflammable gas cloud, which caused

millions of pounds worth of damage.

This, plus a number of similar incidents elsewhere in the world, has

provided some valuable lessons on the behaviour of diesel engines

operating in hazardous zones.

1.2 By drawing in flammable gas through its air intake, a diesel engine cancontinue to run even with its normal fuel supply cut off.

Should such a diesel engine take in sufficient combustible gas to

supplement the normal fuel supply, overspeed can occur to a point where

the engine disintegrates.

1.3 Another risk is that entrained flammable gas in the induction system can

be ignited by a flash over from one or more cylinders at the moment the

inlet valve opens.

Also, after-burning in the exhaust system can cause spark or flame

emission from the exhaust tail pipe, as well as surface temperature rise.

1.4 Diesel exhaust systems frequently operate with surface temperatures of

300C or higher, depending on engine loads. Temperatures of that order

can ignite many inflammable liquids or vapours (auto-ignition

temperature). Standard electrical equipment must also be regarded as a

potential ignition source. Should any form of electrical equipment be

required, it must be of a properly certified flame-proof nature.

1.5 The recommendations in this guide are related to the modifications and

equipment fitted to the vehicle only and are supplementary to existing


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ARCHIVEsafety practices. Training in the use of diesel-powered forklifts in

hazardous zones is outside the scope of this guide.

While it is considered that the implementation of these requirements will

help to reduce to a minimum the risk of accidents associated with the use

of such machines in defined hazardous zones, the modifications as listed

must be regarded as the minimum required to eliminate all possible

sources of ignition associated with standard machines.

Consideration must be given that apart from design aspects, safety in use

is dependent upon the machinery being in a good state of maintenance.

Recommendations relating to maintenance requirements are given in

Appendix I.


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ARCHIVESECTION 2

LEGISLATIVE REQUIREMENT

2.1 The Dangerous Goods Act and associated Regulations prohibit theintroduction of sources of ignition into certain areas where dangerous

goods may be present, or within certain specified distances associated with

such areas.

2.2 Where in the relevant regulations there is any requirement limiting the

presence of sources of ignition, that requirement may be modified in

respect of electrical equipment or machinery liable to be an ignition source

by applying the principle of zoning into regions of differing degrees of

hazard in accordance with such standard specification or code as may be

approved by the Chief Inspector of Explosives, and using within any such

zone equipment, such as modified fork lifts, as may be approved by the

Chief Inspector as being acceptable for the particular zone.

Refer to Appendix II for details relating to hazardous zone classification.

2.3 All suitably modified diesel-powered forklifts intended to be used within

defined hazardous zones are to be approved for such use by the Chief

Inspector of Explosives.

Additionally, the user of any such machine must ensure that it has a formalT temperature rating relevant to the auto-ignition temperature of any

flammable agents that it is likely to come into contact with within a

defined hazardous zone.


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ARCHIVESECTION 3

APPROVAL PROCEDURES

3.1 If it is determined by the user that it may be necessary to operate a diesel-powered forklift unit in a suspected hazardous zone, the first course of

action is to correctly determine the class and extent of the hazardous zone.

The body responsible for determining such an area is the relevant

Dangerous Goods licencing authority for the particular locality.

3.2 Upon confirmation of the existence of an hazardous zone, action may be

taken to modify an existing forklift or to acquire a suitably modified

approved unit for use in such an area.

A list of approved units to date can be found in Appendix IV.

3.3 Any supplier or agent conducting the modification of an existing unit must

comply with the list of minimum requirements as detailed in section 4.

3.4 A further requirement is that such forklifts must have a formal T

temperature rating equal to or less than the auto-ignition temperature of

any dangerous goods that are located within the defined hazardous zone

and which the forklift unit may possibly come into contact with.

3.5 It will be necessary for any such machine to be suitably tested and certified

as to its formal T temperature rating. Such testing is to be carried out by

an approved independent test authority. The rating relates to the maximum

surface temperature during the course of normal operation of any

component subject to heating.

Appendix III details information relating to such testing.

3.6 Upon completion of the relevant testing, a copy of the test report is to be

made available to the Technical Services Officer, Department of Labour,

Dangerous Goods Division. An inspection of the relevant machine will be

conducted for confirmation that the necessary modifications have been

satisfactorily completed.

3.7 Upon the satisfactory completion of the relevant testing and inspection of

the unit concerned, a letter of approval will be issued by the Chief

Inspector of Dangerous Goods.

3.8 Such a letter of approval will detail the particular hazardous zone

classification that the particular machine may operate within. Furthermore,

it will detail the specific T temperature rating of the unit and any

associated operating restrictions that may be imposed upon it.


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ARCHIVE3.9 It has been determined that any similarly modified units of the same make,

model and type, will not require a temperature rating test to be carried out,

on the specific condition that any such similar units are identical in every

respect and in particular have identical modifications and components

fitted as the previously tested and approved unit.

An inspection of such a unit is carried out prior to the issue of a letter of

approval to ensure compliance with the required modifications.

3.10 Should such a unit have any material changes or modifications

incorporated which are a departure from the originally approved unit, then

it may be necessary for a temperature test to be conducted. This aspect will

be determined by the actual changes involved, in particular any changes

which may involve the exhaust system.


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ARCHIVESECTION 4

MODIFICATIONS

4.1 Various modifications are incorporated into approved flame-proof dieselforklifts to eliminate potential sources of ignition which exist on standard

units.

4.2 The various hazards which such modifications are designed to control are

listed below:

(1) Discharge of sparks from electrical equipment.

(2) Discharge of sparks from mechanical causes.

(3) Generation and discharge of static from belt drives.

(4) Discharge of sparks or flames from the exhaust system.

(5) Flash back through the induction system.

(6) Excessive temperature of exhaust gases and excessive surface

temperature of engine and exhaust systems.

(7) Overspeeding and possible destruction of the engine due to induction

of flammable gas or vapour.

(8) Explosion in engine crank case; discharge from crank case and

cylinder head relief valves and breathers.

(9) Explosions in intake or exhaust systems.

(10) Flame transmission to atmosphere by opening of decompression ports.

(11) Reverse running of engine.

4.3 The following list of modifications is considered as the minimum required

to allow use in hazardous zones. Explanatory notes are included.

1. All electrical equipment and apparatus must be removed. See note

3(a).

2. The starter system shall be a non-electric type, either pneumatic.

hydraulic, spring recoil, inertia or manual.

3. All electrically actuated gauges are removed. They may be replaced

by alternative mechanical types such as mechanical load indicators,

capillary tube dash board gauges etc.

(a) Note that if any electrical equipment is required though operational

necessity, than such equipment is to be of a suitably certified

flameproof type approved for use in the relevant hazardous zone.


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ARCHIVE4. The unit shall comply with the maximum surface temperature

requirements as laid down in Australian Standard 1915:1976.

The temperature class of the unit shall be at or below the ignition

temperature of the gases or vapours to which the unit is liable to be

exposed in actual operation. See Appendix III for further information.

5. Light alloy metals, and paints based on light alloy powders, shall not be

used unless the components concerned are suitably protected against

possible mechanical impact or rubbing that could produce incendive

sparking.

6. Blades of the cooling fan shall be made from non-metallic materials.

7. All driving belts shall be of anti-static type.

8. Static discharge. All wheels shall be tyred with rubber or non-metallic

material. At least two tyres and wheels shall be constructed of antistaticmaterial in accordance with B.S. 2050, or some other approved effective

static discharge device shall be provided.

9. Adequate flame paths to be provided on all inlet and exhaust connections.

All such joints, including the attachment of the inlet and exhaust manifold

to the block, shall have a flame path of not less than 13 mm through or

across the joint. This may require spiggotting into the block and manifold

to obtain the required distance. In any case, all such joints shall generally

comply with the requirements for appropriate group enclosures in

accordance with A.S. C98.

10. Suitable metal-clad or other acceptable jointing material gaskets shall be

interposed between all joint faces to ensure that leakage does not occur.

11. Where valve spindles pass through the walls of any component of the

induction system, the diametrical clearance shall not exceed 0.13 mm for

an axial length of not less than 25 mm, unless end caps are fitted. No

screw, stud or bolt hole shall pass through the wall of any component of

the exhaust or induction system.

12. An approved flame arrestor is to be fitted on the air intake between the air

cleaner and intake manifold. This is to counteract flashback through the

induction system.

It is preferable that such a unit is manufactured from stainless steel.

13. An overspeed shutdown device is to be fitted. This may take the form of

(i) a strangler valve unit fitted to the induction system to close the air

intake; or (ii) a system to inject an inert gas into the air intake. Such a

device, which is designed to stop the engine in the event of flammable gasor vapour in the atmosphere causing the engine to overspeed, may be

operated either manually or automatically. It is desirable that any


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ARCHIVEautomatic system has, in addition, provision for manual operation. This

manual facility must be readily accessible.

14 Relative to the pre-determined T temperature rating requirement of any

particular machine, it may prove necessary to provide a water-cooled

exhaust manifold. Many standard machines may meet the necessary limit,

but may require additional cooling when operated under full load

conditions. The relevant testing will determine this aspect. It is preferable

that such manifolds are manufactured from stainless steel.

Appendix III relates to T temperature rating requirements and testing.

15. A suitable exhaust flame trap and spark arrestor unit is to be fitted. This is

to consist of a water scrubber unit, preferably fabricated from non-

corrodible materials, in which the exhaust gases are passed through water.

The unit is to be fitted with baffles to prevent water carry over and should

be designed to minimise back pressure on the engine.

The unit shall contain sufficient water to allow 8 hours of normal

operation without refilling.

Under certain conditions, consideration may possibly be given for the use

of a suitably certified spark arrestor unit (Dry Cyclone Type) combined

with a flame trap (Spaced Plate Type). Such an arrangement would

probably require the use of an exhaust aftercooler unit.

16. An air-operated (may be aerosol) horn unit to be fitted as an audible

warning device.

17. The fuel tank shall be constructed of metal at least 1.6 mm thick and shall

be fitted with a drain plug and a non-spill vent to maintain atmospheric

internal pressure.

18. An engine having a crankcase volume of over 0.5m3shall be provided

with relief devices. Relief valves or breather units on engines shall be

suitable explosion proof types or else fitted with flame traps.

Alternatively, they may discharge into the induction system downstream ofthe flame trap and upstream of the shut off valve.

Dipsticks and/or filler caps should be screwed or effectively secured by

other means.

19. The fuel injection pump and governor where fitted shall be so designed

that reverse running of the engine is not possible.

20. All fuel or lubricating oil lines are to be routed clear of any likely hot

spots, in particular the exhaust system. All such lines are to be well

supported and clear of any possible chafe points.


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ARCHIVEAPPENDIX I

MAINTENANCE REQUIREMENTS

As indicated in Section 1, continued safety in use of an approved unit is dependent

upon the unit being in a good state of maintenance at all times that it is utilised in a

hazardous zone.

In association with ongoing maintenance of such units, any replacement parts fitted

to such units which may affect flame-proofing of the unit must be suitably

approved items, manufactured in accordance with the requirements to which the

machine has been originally approved.

The following aspects should be checked at intervals of not longer than three

months, or as indicated by the manufacturer, and a maintenance record kept

covering these items. It should be noted that local conditions and operationalrequirements may require shorter intervals to be considered for such servicing.

This servicing is required in addition to normal mechanical service checks.

(1) Exhaust system including muffler unit and spark arrestor unit if fitted

for carbon build-up, corrosion and damage.

(2) Rotating mechanical equipment

for security and freedom from contact with stationary parts.

(3) Antistatic fan belts for condition and tightness.

(4) Certified electrical equipment (if fitted)

for damage or deterioration, correct operation.

(5) Pressure/temperature alarms and other shutdown devices

for operability at set conditions.

(6) Overspeed shutdown devices

for freedom of operation, correctly filled cylinder for inert gas system if

fitted.

(7) Relief valves and breathers

or operability and cleanliness.

(8) Fasteners and Joints

for tightness and security particularly on induction, exhaust and fuel

systems.

It should be noted that specific maintenance schedules as specified by the relevant

manufacturers should be adhered to. In particular, this will relate to the care and

correct usage of water baffled exhaust scrubber systems, and spark arrestor

elements.


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ARCHIVEAPPENDIX II

HAZARDOUS ZONE CLASSIFICATION

Hazardous areas may be regarded as those areas where dangerous goods of aflammable nature are present, or may be expected to be present in quantities such

as to require special precautions with respect to the use of items of equipment

liable to be a source of ignition. Within such areas where by regulation there is any

requirement limiting the presence of sources of ignition, that requirement may be

modified in respect of mechanical equipment utilised in the area by applying the

principle of zoning into regions of hazard in accordance with such standard

specifications or codes as may be approved by the Chief Inspector of Explosives.

The classification and delineation of hazardous areas requires, in each case, a

careful review of all the relevant factors. The quantity of flammable substance that

may possibly be liberated, its physical characteristics, the natural tendency of

vapours to disperse into the atmosphere, the location and general ventilation of the

area, and the standards of maintenance or housekeeping that may affect the nature

and extent of the hazard, are factors that must be recognised in determining the

degree and extent of danger.

In all instances, the local dangerous goods licencing authority is responsible for

determining the existence and extent of any hazardous zone.


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ARCHIVEAPPENDIX III

T TEMPERATURE RATING TESTING

The normal operating temperature of any vehicle component, either electrical or

mechanical to which surrounding atmosphere has access shall not exceed that

stated in Table 1, according to the temperature class for which the vehicle is

intended.

Compliance with the specified temperature limits shall be determined by the

temperature test based upon the requirements of A.S. 1915-1976. The specific

temperature class required for any particular machine is determined by the ignition

temperature of the gas or vapour that the machine is liable to come into contact

with, as determined by A.S. 1896.

TABLE 1

Operating Temperature Limits

Class Max. Surface Temp. oC

T1 450

T2 300

T3 200

T4 135

T5 100

T6 85

A distinction should be drawn between flashpoint and ignition temperature. The

former is the lowest temperature at which an explosive gas/air mixture can exist

under normal atmospheric conditions, whereas the latter is a higher temperature at

which the most ignitable mixture will ignite spontaneously on account of the

environmental temperature.

Test Procedure

(1) The test course shall be 60m long and shall include a gradient of 5 percentwith a total rise of l m.

(2) The test course shall be negotiated at a rate of not less than six complete

cycles per hour and the test shall be conducted in such a manner that the

vehicle is in operation for not less than 50 percent of the total time.

(3) The vehicle shall be operated at normal speed over this course, hauling

full-rated load. Mast tilt should be fully to the rear against the stops with

the relief valve in full operation.

(4) At the end of the course the vehicle shall be stopped and the load moved

through the full lifting cycle.


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ARCHIVE(5) The vehicle with the load shall then return to the starting point where the

load is again moved through the full lifting cycle and then deposited

beside the test course.

(6) The vehicle shall then be operated with no load over the same course, at

the end of which the forks shall be raised to full height and lowered.

(7) The vehicle shall then be returned to the starting point and the load picked

up.

(8) These runs shall be repeated, laden and unladen trips alternating.

(9) The test shall be continued until constant surface temperatures have been

reached.

(10) During the test, the temperature of any surface exposed to the surrounding

atmosphere shall not exceed the value specified in Table 1 for the

temperature class assigned to the unit.

Brake Temperature Test

(1) Immediately following the above temperature test, the unit, while carrying

its rated load at maximum possible speed, shall be operated over the

course and shall be brought to a complete stop every 15m by application of

the brakes.

(2) The test shall be continued until constant surface temperatures are reached

on the brakes

(3) During the test, the brake temperature shall not exceed the value specified

in Table 1 for the temperature class assigned to the unit.

The relevant testing is to be carried out by an independent testing agency approved

by the Chief Inspector of Explosives. A report of the test is to be provided to the

dangerous goods division.


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ARCHIVEAPPENDIX IV

LIST OF APPROVED UNITS

The list on the following page details the various diesel powered forklifts whichhave been approved to date as being suitably modified for use as flameproof units

for use in designated hazardous zones.


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APPRO

VEDFLAMEPROOFDIESEL

POWEREDFORKLIFTS

Manufa

cturer

Supplier

Model

SerialNo.

TestingAuthority

T

emp.Class

HazardZone

DateApproved

Hyster/

Baldwin

Gough,Gough

H50H

ED72/009

Exp.Div.NSW

-

C1.1ZN1

10.6.1910

&Hammer

BelcherEquip./

Belcher

2115E

WakefieldLab.

T6

C1.1ZN11

0.1.1984

FordSp

ecial

Equipment

TowTruck

Clark

Andrews&

C500-Y560

11212-30

Materials&Testing

T2

C1.1ZN1

24.4.1981

Beavan

11213-30

Lab.Ltd

11194-29

Datsun

LoadLift

QF02A2FU

5345

Materials&Testing

T3

C1.1ZN-l

23.1.1980

Datsun

LoadLift

QF02A25U

25315

LabLtd.

T3

C1.1ZN1

21.12.1983

Datsun

LoadLift

QF02A25U

22815

T3

C1.1ZN1

17.10.1983

Datsun

LoadLift

QF02A2FU

22125

S.G.S.NZLtd

T3

C1.1ZN1

1.5.1984

Nissan

LoadLift

QF02A25U

25325

S.G.S.NZLtd

T3

C1.1ZN1

7.1.1985

Nissan

LoadLift

QF02A25U

25925

T3

C1.1ZN1

24.9.1985

Toyota

Andrews&

F025

11993/19

DSIRCH.CH

T4

C1.1ZN1

5.1984

Beavan


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RELATED DOCUMENTS

Dangerous Goods Act 1974.

The Dangerous Goods (Class 2 - Gases) Regulations 1980

The Dangerous Goods (Class 3 - Flammable Liquids) Regulations 1985

Dangerous Goods (Labelling) Regulations 1978.

M.P. 6105: 1976 Electrical Wiring in Hazardous Locations.

Australian Standard 1896:1976 Method of Test for Ignition Temperature of Gases

and Vapours.

Australian Standard 1915:1976 Electrical Equipment for Explosive Atmospheres.Battery Operated Vehicles.

Australian Standard C98:1970 Electrical Equipment for Explosive Atmospheres.

Flameproof Enclosure.

British Standard 2050:1978 Electrical Resistance of Conducting and Antistatic

Products made from Flexible Polymeric Material.

NFPA 505 Fire Safety Standard for Powered Industrial Trucks.

Exploded view of a typical modification of a diesel engine for use in defined

hazardous zones.

(not included)