Home>>Guidelines >>Safety Code Of Practice For CNG Buses >>Bus Body Building
Precautions to be taken before/during Body building of CNG bus
Individual valve provided on each cylinder should be closed completely during
the entire Body building stage and should be opened for moving the finished
bus. Cylinder valves should also be closed while working on engine and fuel
In case of a gas leak at cylinder connections, use Teflon tape over the thread
and tighten to arrest the leak.
Wood or any other material, which is likely to catch fire soon, should not be
used for Body building on CNG vehicle. Flame retardant, treated wood and other
material is acceptable.
CNG cylinder mounting and the piping should not be disturbed during body
building under any circumstances. This is liable to make the warranty for the
chassis null and void by the chassis manufacturers and it is dangerous as it
may lead to erroneous gas connections.
Welding should not be done over the gas cylinders or anywhere near them.
Proper shielding of gas cylinder should be done so as to isolate from welding
sparks. Shielding and ducting of gas pipelines and cylinders to be as per AIS
028 D1, during Body building.
Radiator should be properly covered to prevent it from any damage from welding
Do not use damaged cylinders (with welding splatters). Do not weld / repair
damaged cylinders. Replace them with new CCOE approved cylinders with valid
Ducts/conduit (other than the protective sheath if provided) carrying the CNG
fuel pipes and hoses should withstand the internal pressure of 30 kpa and
should withstand a static force of 60 kg without permitting leakage as per AIS
Battery isolator switch should be cut off.
After completion of body construction, the battery cut off switch is to be
compulsorily fitted on the right hand side of the driver's seat.
Battery removed from the chassis should be properly stored and put on charge.
Battery cable should be routed in such a way that cables are not in contact
with any metal parts/metal cutout openings. For metal cut out openings suitable
rubber grommet to be provided. Suitable clipping for battery cables to be
All electronic components/wiring harness should be properly shielded/earthed in
order to prevent damages during Body building.
Provide louvers on the body skirt up to the bottom of the floor level on both
sides and also in the rear; flap doors suitable for accessing the cylinder hand
valves quickly. It should have quick closing and opening arrangement to prevent
tampering by unauthorized persons
Height of the skirt should be kept to the minimum.
Provide opening to gas filling points (size 250 mm x 250 mm)
Adequate venting arrangement to be made by the body builder to vent the
entrapped gas if any to the atmosphere.
Trap door in floor with rubber sealing to provide access to tighten the
cylinder straps nut on either side.
Removable shielding guard below cylinder valve and piping and connection points
for safety against flying stones to be provided.
Shielding of exhaust silencer from cylinders and piping.
The four gas cylinder mounting Xbearers have to be integrated with the bus
Drilling of holes or welding on frame side of members is not allowed.
The doors of the bus should have quick opening mechanism for the exit of
passengers and also the driver/codriver in the case of an emergency. (In case
of pneumatic door operating mechanism, the emergency opening arrangement should
Emergency exit door to be provided on the opposite side of the service door or
at any easily approachable location as allowed by the bus body code.
The structural members on which the side panels and rear side panels are
supported, should be sufficiently strong to protect the cylinders/valves in
case of minor collisions.
Weather proof connectors shall be used for external areas to avoid
water/moisture ingress during use.
Front and rear bumpers of the vehicle shall be sufficiently strong and the
requirements prescribed in a relevant standard as and when notified
Refueling valve shall be accessed only from exterior of the vehicle.
Body building structure material should not carry leaked gas through pipe hatch
section in the passenger compartment. Proper sealing at the entry point to be
At least one "Dry Chemical Powder" Fire Extinguisher is to be provided in the
driver's compartment for use in case of emergency.
Smoking on CNG Bus - Prohibited or 'No Smoking' symbol can be painted on
the outside and inside of the bus
First aid kits containing items notified under Rule 138 (4) (d) of CMVR 1989
shall be provided.