INTRODUCTION
Bi-fuelled vehicles using Liquefied Petroleum Gas (LPG)/Petrol as a means of propulsion are becoming commonplace as manufacturers begin to offer them as an alternative to the traditional petrol or diesel only options.
The basic system retains the mechanical components of a petrol engined vehicle, but with minor alterations, mainly to the engine’s fuel intake system. The LPG system, whether it is a factory or an aftermarket fitment, will usually consist of a filler valve, LPG tank, injection system and components to distribute and control the LPG. The system should also incorporate operating controls/gauges mounted on or built into the vehicle dashboard.
SAFETY PRECAUTIONS WHEN WORKING ON LPGIPETROL BI-FUEL VEHICLES
The safety precautions have been categorised and are listed in two sections:
Section 1 - lists general safety precautions related to repairs on a vehicle that does not necessarily involve work directly on or to the LPG system.
Section 2 - lists safety precautions specifically related to repairs on a vehicle that does involve work on or to the LPG system.
These precautions are intended to be used as a guide and in conjunction with vehicle manufacturers/converters specific repair procedures and safety instructions. Most of the precautions for LPG are similar to those for petrol vehicles.
SECTION 1: GENERAL SAFETY PRECAUTIONS
An LPG equipped vehicle can often be recognised by its markings, i.e. badges and decals. It will also have an additional LPG filler valve, probably located on the rear wing, behind the fuel filler flap, and an additional LPG tank under the vehicle or in the spare wheel well. Where the wheel well is used, a tyre puncture repair kit may be supplied instead of the spare wheel/tyre. If an LPG equipped vehicle enters a workshop without obvious markings but the repairer is aware it is a bi-fuelled vehicle, it should be identified in order that personnel are able to take appropriate precautions.
- It should never be assumed that a vehicle does not have any LPG leaks.
- All sources of ignition, such as naked flames and cigarettes should be kept well away from the work area.
- The use of non-neon type inspection lamps should be prohibited.
- The work area should be well ventilated.
LPG in its gaseous form is heavier than air, therefore working on the system below ground level, e.g. in a basement should be prohibited. For the same reasons working over a pit should also be discouraged, however, if this is absolutely necessary the following should be observed:
- The pit must be adequately ventilated.
- All electrical equipment installed or used (including lighting) should be suitable for a zone 2 hazardous area.
- Gas detectors should be fitted to the bottom of the pit. These should be checked daily.
- Where the vehicle is undergoing repairs involving heat, welding or painting, there are specific precautions that are listed in more detail in the next section of this newsletter.
SECTION 2: SPECIFIC SAFETY PRECAUTIONS
When working on any part of the LPG system which contains or is thought to contain liquid LPG, the repairer should wear the appropriate PPE (Personal Protective Equipment). This would include:
- Non-Acrylic Clothing - The static electricity created by the acrylic is a potential ignition risk.
- Safety Gloves - LPG can cause frostbite if it comes into contact with the skin.
- Eye Protection - Escaping liquid can cause eye damage.
Components of the LPG system should only be repaired or replaced by following the vehicle manufacturers/converters instructions and using materials approved by them.
When working on the LPG circuit it is possible to isolate the tank from the rest of the system by following the vehicle manufacturers/converters isolation procedures. The following are general procedures:
- Switching off the ignition or switching over to petrol will only shut off the LPG supply at the engine, there will still be LPG in the supply lines.
- The lines from the filler valve to the tank can be emptied by partially opening the union close to the valve and allowing the slow release of LPG to the atmosphere. THIS OPERATION SHOULD BE CARRIED OUT IN THE OPEN AIR AWAY FROM SOURCES OF IGNITION AND WITH THE OPERATOR WEARING THE APPROPRIATE PPE. The union should not be completely undone until it is sure that the LPG has stopped escaping, it should only take a short period of time to empty. If LPG continues to escape it may indicate a fault elsewhere in the system.
- The lines from the LPG tank to the engine can be emptied by disconnecting/isolating the outlet solenoid valve at the tank and running the engine in LPG mode until it stops "out of gas". By performing this operation, the components down stream of the tank can be safely worked on.
- Performing the above procedures will isolate the tank and will allow it to be removed from the vehicle.
- The vehicle battery should be disconnected prior to carrying out further work on the LPG system.
- The vehicle manufacturer/converters instructions regarding the disconnection of ECU’S should be followed.
- Where the vehicle is to be welded or heat is to be applied within close proximity to the LPG tank and/or lines, the tank or lines must be removed. The LP Gas Association (LPGA) recommend a "clear" distance of 1 metre between the heated area and LPG tanks or lines.
- If the vehicle is to be subjected to high temperatures, i.e placed in a spray booth, the LPG lines must be emptied and the LPG tank removed. The LP Gas Association (LPGA) give a guideline safe maximum temperature of 400C, however, this may vary for specific manufacturers/converters.
- The above will also apply where infra red equipment is used for localised heating of panels/paint around the filler valve area.
- When working on the LPG tank the vehicle must be earthed via its earth cable.
- It should be noted that a tank containing LPG can be very heavy, approximately 80kg, and therefore assistance may be required for its removal.
- Where a tank has been removed it should be stored in accordance with the The LP Gas Association (LPGA) Code of Practice No 7. This is means storage outside, if possible, in a well ventilated area, away from sources of ignition. It should not be stored below ground level and should be separate from other flammable/combustible materials. Suitable notices should indicate the LPG storage area. If there are any doubts about the safe storage of tanks, repairers should carry out a risk assessment and liaise with their local authorities.
- Workshops should only empty an LPG tank if they have the necessary equipment and specifically qualified personnel.
- No LPG tank valves, or components which render the tank "open", should be removed without the tank being fully drained beforehand.
Note: A tank would only normally require emptying in the event of it being scrapped.
- If a substantial LPG leak is detected from the system the vehicle should be moved into the open air so that the gas can disperse. This should only be done if it is safe to do so and if it can be positioned far enough away from other vehicles and buildings so as not to further increase risk of ignition.
- If there are signs that the leakage is uncontrollable, or there are any doubts about safety, then the emergency services should be called.
- Components of the LPG system should be periodically inspected for wear and damage. If found to be unserviceable or damaged they should be renewed. Where damage has occurred to, or in close proximity to, any component of the LPG system, these areas should be checked thoroughly and any damage rectified accordingly.
