Whats This- Pipes on a BEST bus??

Revvhead · 28th June 2006, 11:42

Ok, i have noticed that all the CNG BEST buses in bombay have two pipes sticking out of the rear capped with a T. Also has a rubber gland between the pipe and the sheel, so this is definitely an intentional design fit.
The end of the T has a mest siliar to a flame arrestor type mest- but the mesh size seesm to be a bit too large for the purpose of a flame arrestor.

My guess is that it may be part of the safety relief valve system on the CNG cylinders.

I could only snap one (was driving
) but they are always in pairs, side by side. Courtesy the Cab that decided to stop right up to the bus (typical) i could get a full pic of both

any one to shed any ideas on this?

normally_crazy · 28th June 2006, 12:06

could be the CNG filling inlet ?

Revvhead · 28th June 2006, 14:57

Nope no change of that.
There's no evidence of any pressure cap/ quick connect coupling or any high pressure system there.
As i said, the ends have wire mesh on them

I dunno how CNG in cars is filled myself, but am dead sure from the construction its not a filling pipe- that stuff looks like ordinary pipe- altho, if one were to use it as a relief line i figure cryogenice pipes would be neccessary if you construct it properly

naveendhyani · 28th June 2006, 15:48

in delhi also the CNG vehicles have these pipes although they run all the way till the top of the bus. i guess it cud b some leakage preventive measure, though not sure.

sumitkalindi · 28th June 2006, 16:06

Yes it is a release pipe to offload CNG from the tanks incase of some mishap

xtreme power · 28th June 2006, 20:41

i used to think it was for supporting the posters behind..
but i guess im wrong
team bhp...always helps

nitinbhag · 29th June 2006, 17:56

It is the CNG system's pressure relief valve outlet..
The T is so that it doesnt blow off the person/vehicle immediately behind.
The mesh may have a more common-place purpose, to prevent rats and birds getting in

. A flame arrestor is a bit more elaborate than just a mesh.
Why in pairs - Maybe its a dual redundant system ie 2 PRVs or maybe there are 2 CNG tanks in these buses?

Revvhead · 29th June 2006, 18:13

True, but the mesh size is a little wide.
Believe me , in a relief system, a proper mesh is an excellent flame arrestor
and many times thats all there is.

The reason why it could be in pairs is possibly both of two reasons-
The primary one being the redundancy- In the event of malfunctioning/non lift of one relief valve the other will make sure that the pressure is relieved

and/Or

To ensure a sufficient rate and volume of release to prevent any pressure buildup in the line.

28th June 2006, 11:42	#1
Revvhead BHPian Join Date: Apr 2005 Location: Bombay Posts: 450 Thanked: 20 Times View My Garage	Whats This- Pipes on a BEST bus?? Ok, i have noticed that all the CNG BEST buses in bombay have two pipes sticking out of the rear capped with a T. Also has a rubber gland between the pipe and the sheel, so this is definitely an intentional design fit. The end of the T has a mest siliar to a flame arrestor type mest- but the mesh size seesm to be a bit too large for the purpose of a flame arrestor. My guess is that it may be part of the safety relief valve system on the CNG cylinders. I could only snap one (was driving ) but they are always in pairs, side by side. Courtesy the Cab that decided to stop right up to the bus (typical) i could get a full pic of both any one to shed any ideas on this?
	() Thanks

28th June 2006, 12:06	#2
normally_crazy Senior - BHPian Join Date: Feb 2004 Location: Mumbai Posts: 4,369 Thanked: 528 Times View My Garage	could be the CNG filling inlet ?
	() Thanks

28th June 2006, 14:57	#3
Revvhead BHPian Join Date: Apr 2005 Location: Bombay Posts: 450 Thanked: 20 Times View My Garage	Nope no change of that. There's no evidence of any pressure cap/ quick connect coupling or any high pressure system there. As i said, the ends have wire mesh on them I dunno how CNG in cars is filled myself, but am dead sure from the construction its not a filling pipe- that stuff looks like ordinary pipe- altho, if one were to use it as a relief line i figure cryogenice pipes would be neccessary if you construct it properly
	() Thanks

28th June 2006, 15:48	#4
naveendhyani BHPian Join Date: Feb 2006 Location: Melbourne Posts: 542 Thanked: 9 Times	in delhi also the CNG vehicles have these pipes although they run all the way till the top of the bus. i guess it cud b some leakage preventive measure, though not sure.
	() Thanks

28th June 2006, 16:06	#5
sumitkalindi BHPian Join Date: May 2006 Location: Kolkata Posts: 376 Thanked: 17 Times View My Garage	Yes it is a release pipe to offload CNG from the tanks incase of some mishap
	() Thanks

28th June 2006, 20:41	#6
xtreme power BHPian Join Date: Jul 2005 Location: mumbai Posts: 732 Thanked: 75 Times View My Garage	i used to think it was for supporting the posters behind.. but i guess im wrong team bhp...always helps
	() Thanks

29th June 2006, 17:56	#7
nitinbhag BHPian Join Date: Mar 2005 Location: Singapore Posts: 262 Thanked: 2 Times	It is the CNG system's pressure relief valve outlet.. The T is so that it doesnt blow off the person/vehicle immediately behind. The mesh may have a more common-place purpose, to prevent rats and birds getting in . A flame arrestor is a bit more elaborate than just a mesh. Why in pairs - Maybe its a dual redundant system ie 2 PRVs or maybe there are 2 CNG tanks in these buses?
	() Thanks

29th June 2006, 18:13	#8
Revvhead BHPian Join Date: Apr 2005 Location: Bombay Posts: 450 Thanked: 20 Times View My Garage	True, but the mesh size is a little wide. Believe me , in a relief system, a proper mesh is an excellent flame arrestor and many times thats all there is. The reason why it could be in pairs is possibly both of two reasons- The primary one being the redundancy- In the event of malfunctioning/non lift of one relief valve the other will make sure that the pressure is relieved and/Or To ensure a sufficient rate and volume of release to prevent any pressure buildup in the line.
	() Thanks