Can Gas Flow Backwards and Reach Inside a Cylinder in an LPG System?

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Discussion Overview

The discussion revolves around the behavior of gas flow and flame propagation in an LPG system, specifically whether a flame can travel back through a rubber pipe into an LPG cylinder. The scope includes safety considerations related to gas flow dynamics and combustion.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested, Safety-related

Main Points Raised

  • One participant describes a scenario involving an LPG cylinder, a rubber pipe, and a flame at the open end, questioning if the flame can move back into the cylinder.
  • Another participant suggests that the lack of oxygen in the tank and hose may prevent flame propagation, though they caution against taking their word as definitive.
  • A different participant asserts that the flame will not travel back inside the rubber hose but warns that it could potentially burn the hose and shorten it.
  • One participant expresses concern about the safety implications of the flame reaching the gas cylinder.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the behavior of the flame, with differing opinions on whether it can propagate back into the cylinder and the implications for safety.

Contextual Notes

Assumptions about gas flow dynamics, flame propagation, and the conditions within the LPG cylinder and rubber hose are not fully explored or resolved.

Who May Find This Useful

Individuals interested in gas safety, combustion dynamics, and LPG system design may find this discussion relevant.

sgvaibhav
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Consider this case.

An LPG cylinder is used to provide LPG to a rubber pipe (3/8" diameter).
If a regulator is attached to the cylinder, and the rubber pipe is just left open on the other side to let gas out, and a match is kept at the open end.
Will the flame that is created at the open end of rubber pipe move all the way inside the rubber pipe and reached inside the cylinder? Or will the gas flowing at high velocity just not let the flame move back inside?
The pressure regulator is set at 1.2 bar gage pressure, however the pressure gauge after the valve shows 0 reading, since the pipe is just left open to the atmosphere.

The rubber pipe is about 2m long.

A gate valve is used to let the gas out in somewhat controlled quantities.

Schematic attached - i primarily wanted to know if the flame will move backwards and reach the cylinder or not (to know the safety issues)
 

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As far as I know, it's the lack of oxygen in the tank and hose that prevents flame propagation. Don't take my word for it, though.
 
It will not travel back inside the rubber hose. However, it could burn the rubber hose off and continue to make it shorter and shorter...
 
oh that's okay :P...

all i didnt want is the flame going back towards the gas cylinder and blasting the cylinder!
 

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