LPG Report
Cylinder Valve & Regulator systems.
I have had several calls from members recently with a problem whereby their LPG
appliances are not functioning reliably.
Following questioning the fault has been traced to the Gas Cylinder Valve and
Regulator system that is being used.
The cylinder valve with the course externally threaded outlet and the matching
large black nutted regulator have been used.
This valve and regulator system is known as the QCC or PDQ system.
Members should be warned that this connection system has an excess flow cut-off
valve. built into it. This excess flow cut-off valve is designed to activate at
approx 4 kilowatts of energy draw through the regulator. This has the effect of
shutting down the LPG system if you are operating the Oven, a burner or two on the
cook top, the fridge and maybe the water heater all at once. This is very annoying
and is a very difficult fault to diagnose.
Connecting 2 gas cylinders in parallel will not fix the problem either!!
As the excess flow valve does not shut off the flow of gas completely you may find
that maybe the burner on the cook top is still burning on a very low flame. This can
cause a very serious problem in that you may not even notice the fact that it is still
burning and leave it with a pot on it. The burner could then start burning on high
again unbeknownst to you.
To normalise the system after activation of the excess flow valve, you will need to
shut off all the appliances, turn the gas cylinder off and disconnect the LPG regulator
from the gas cylinder. Then reconnect the regulator and turn the gas cylinder on again.
I recommend that if you have the QCC connection system, to consider changing the gas
cylinders and LPG regulators to the internally threaded type of valve (without the
external thread as well). This type of valve is known as the POL valve, it has been
used on LPG cylinders for in excess of 25 years. Or even better still the Kosan or
Clip On connection system, as used on portable LPG Cabinet heaters up until 10 years ago.
Both the POL and Kosan connection systems are very reliable and do not have the excess
flow valve built into them, so all your appliances will operate correctly, all at once.
I hope this article assist you and makes your Motor Caravanning more enjoyable.
Lex Ward 12673
NZMCA LPG Advisor