Health and Safety Executive/Local Authorities Enforcement Liaison Committee (HELA)

To: Directors of Environmental Health/Chief Environmental Health Officers of London, Metropolitan, District and Unitary Authorities and Chief Executives of County Councils.

For the attention of: Environmental Services/Trading Standards/Fire Authorities/Other

This circular gives advice to local authority enforcement officers

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Garaging of liquefied petroleum gas fuelled vehicles, mechanical handling and maintenance equipment

Introduction

1 LPG has been used as a fuel for internal combustion engines for very many years. In industry LPG fuelled forklift trucks and mechanical handling equipment are widely used as they have greater independence and power than electrically powered equipment and lower carbon monoxide and particulate (smoke) emissions than diesel. Following Government initiatives to improve local air quality and reduce greenhouse gas emissions there is a growing movement towards LPG fuelled road vehicles, particularly cars and light vans.

2 Whilst the UK population of such vehicles is relatively small, the world population exceeds 5 million of which nearly 2 million are in the EU. Over the years robust standards have developed, particularly the UN Economic Commission for Europe Regulation "ECE67" which provides the basis for vehicle and equipment certification throughout the EU and for which the Vehicle Certification Agency is the UK Competent Body.

Background

3 LPG fuelled vehicles for use on the public highway are subject to the requirements of the Road Vehicles (Construction and Use) (Amendment) (No.4) Regulations 2003. Vehicles not used on the highway, i.e. purely for internal transport, are not subject to these Regulations but are subject to the requirements of the Health and Safety at Work Act (HSWA).

Useful advice on standards of construction can be found in:

• LPGA Code of Practice No 11 "Autogas Installations ";
• LPGA Code of Practice No 30 " Gas Installations for Motive Power on Mechanical Handling and Maintenance Equipment."

Garaging

4 The following guidance applies primarily to buildings used to garage significant numbers of vehicles or items of mechanical handling and maintenance equipment on a routine basis. It is not practicable to suggest the number of vehicles that would be considered a significant number. However enforcement officers should use their own judgement when assessing individual sites and should be prepared to prohibit the regular garaging of even a single vehicle if the conditions are clearly unsuitable. The parking of vehicles in warehouses should be discouraged.

5 The guidance does not apply to public car parks.

6 In considering enforcement action clear distinction needs to be made between modern LPG cars, vans and buses constructed or converted in the years since 1997, and older vehicles and mechanical handling and maintenance equipment. Modern road going vehicles are fitted with two electrically operated solenoid valves, one at the LPG tank outlet and one in the engine compartment, which close when the engine is not running and isolate the LPG supply. This greatly reduces the risk of LPG leakage.

7 The connections used on the LPG vessel itself are of types that are widely used in industry and are such that substantial leaks are unlikely. Transient leaks during making and breaking connections will be very small and unlikely to present a significant risk of ignition. The risk of impact of cold droplets on skin and eyes can be reduced by the use of suitable PPE. These vehicles are also fitted with auto stop valves to prevent the overfilling of the LPG tank, and should present no significant risk during filling. Precautions required will be similar to those adopted for petrol-fuelled vehicles.

Note: Some vehicles produced prior to 1997 may also incorporate such safety devices.

8 Older road going vehicles, mechanical handling and maintenance equipment are generally not fitted with such systems but rely on manual isolation at the LPG tank and a mechanical (zero governor) lock off valve in the engine compartment. There is at least one recorded incident of a garaged vehicle of this type causing an explosion following a leak of LPG. The probable source of ignition in this case was an electric switch.

The remainder of this guidance relates to these types of vehicles and equipment

Overnight parking of LPG fuelled vehicles and mechanical handling and maintenance equipment

9 Where practicable LPG fuelled vehicles and mechanical handling and maintenance equipment should be parked in the open air in a well ventilated position. Where this is not reasonably practicable because of lack of space, security, etc, vehicles may be parked inside suitably designed buildings or garages. In all cases LPG tanks should be turned off at the manual valve when the vehicle or equipment is not in use. Procedures for closing the business overnight should include checking that such valves are closed.

10 Where mechanical handling and maintenance equipment use exchangeable cylinders replacement or spare cylinders, both full and empty, should be stored outside in accordance with LPGA Code of Practice 7: "Storage of Full and Empty LPG Cylinders and Cartridges."

11 It is common practice for LPG fuelled vehicles and mechanical handling and maintenance equipment to be parked overnight in a single storey building without any special arrangements for ventilation, and relying on air movement through natural leaks e.g. loose fitting roller doors. Although this practice may be acceptable in some cases, enforcement officers should consider the following matters when asked for advice on this subject.

General design of garages

12 LPG is denser than air and may accumulate in low lying or poorly ventilated areas. Garages for LPG vehicles should not therefore be sited below ground level. The building should be adequately ventilated by providing permanent ventilation openings at high and low level. The building should have at least 2 exterior walls. A good guide for estimating the ventilation standard required would be 2.5% of the area of the roof and walls.

13 The garage or building should be provided with explosion relief by using some lightweight roof or wall panels for construction. The design of existing buildings may preclude this but consideration should be given to this aspect when designing a new garage.

14 The provision of doors at both ends of the building, particularly in large buildings, will give alternative means of access for normal use and for emergency purposes. Such doors can also be opened when required to provide additional ventilation.

15 There should be no pits or drains etc in the floor of the garage within 3m of the parking area.

16 Any building or garage in which LPG fuelled vehicles and mechanical handling and maintenance equipment are regularly parked should carry a cautionary warning sign stating this fact.

Sources of ignition

17 Fixed sources of ignition should be excluded from that part of the building where LPG vehicles are garaged, and smoking should be prohibited.

18 The garage area should be heated by indirect fixed heaters with combustion air taken from outside the building. Inlets to recirculating air heaters, which have high temperature elements, should be positioned at least 1m above floor level.

19 Other sources of ignition, e.g. electrical sockets, should be positioned at least 1.5 m away from parked LPG fuelled vehicles and mechanical handling and maintenance equipment and be at least 1m above floor level.

20 Where LPG vehicles or items of mechanical handling and maintenance equipment with manual isolation valves are parked in buildings they should be separated from adjacent vehicles or other large objects by a distance of at least 1 m in all directions to assist with the normal ventilation process. Suitable floor markings should be provided for this purpose.

Overfilling of vehicle fuel tanks

21 It is common practice in large fleet operations to fill the LPG fuelled vehicle or mechanical handling and maintenance equipment in the evening ready for use the following morning. If the LPG tank in a vehicle is "overfilled" and parked overnight in a warm environment, the liquid LPG will expand and may result in vapours being discharged through the pressure relief valve. If auto-fill stop devices are not fitted particular care is required to ensure that overfilling does not take place. This will require the provision of good supervision and safe systems of work, which should include the double-checking of tank levels.

Note: Cars, vans and buses are normally fitted with a device to automatically limit the fill to 80% of its water capacity.

22 Any vehicle or mechanical handling and maintenance equipment that is accidentally overfilled should be kept in the open air in a well-ventilated place until the error has been corrected. If the overfilling has not produced a leak, the engine should be started immediately and run until the excess fuel has been used.

Overnight leaks

23 It is important that the person responsible for opening-up the building where LPG fuelled vehicles or mechanical handling and maintenance equipment have been parked overnight, has been instructed to be particularly vigilant in checking that no leakage of LPG has occurred before introducing any source of ignition, e.g. starting a vehicle or mechanical handling and maintenance equipment. During the night even a small leak can lead to the formation of a dangerous concentration of gas at floor level which, if not detected, may on ignition have serious consequences.

Action in the event of a suspected leak

24 Where a leak is suspected, the alarm should be raised and the building evacuated. When it is safe to do so all nearby sources of ignition should be extinguished, including the switching-off of all vehicle engines until the leak has been stopped and any dangerous concentrations of LPG air dispersed. Ventilation will be assisted by the opening of all windows and external doors.

25 Any vehicle with a suspected LPG leak should not be parked in a building but should be kept in a safe place in the open air until the leak has been found and corrected.

26 Where a parked vehicle cannot be moved safely into the open air people in the building should be immediately evacuated until the emergency has passed.

Vehicle maintenance

27 For repair work that does not involve the LPG system, vehicles can be repaired inside buildings providing the work will not present a risk of fire or ignition of the LPG. In this case the general workshop conditions should meet the standards set out in "Health and Safety in Motor Vehicle Repair", HSG 67. Where work involves breaking into or removing LPG components it should be carried out in the open air, away from drains and sources of ignition.

28 It is possible for gas to be released whilst work is being undertaken on the LPG system of these vehicles. It is therefore essential that such work should only be undertaken by skilled mechanics who are conversant with LPG automotive systems. The work should not be carried out over or adjacent to pits unless they are fitted with appropriate ventilation systems, gas detectors and lighting appropriate for a "Zone 2" area.

Training

29 All personnel involved in the operation of LPG fuelled vehicles and mechanical handling and maintenance equipment, e.g. drivers, maintenance fitters, warehouse personnel, etc should be conversant with the properties and hazards of LPG. They should also be trained in suitable fire fighting techniques.

Fire precautions

30 Every building where LPG fuelled vehicles and mechanical handling and maintenance equipment are parked should be provided with a sufficient number of dry powder extinguishers, i.e. at least two 9 kg extinguishers per garage (up to 200 m2 floor area), plus further 9 kg for each additional 200 m2 - BS 5306: part 3 2003 "Portable Fire Extinguishers" will provide further details.

31 The occupier of the building or garage should advise the local fire brigade of the presence of LPG on the premises, and consult them on the appropriate action to be taken in the event of fire.

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