On Sunday, 18 October 2020 10:18:29 UTC+1, wrote:
NY explained :
Are there ever cases where water gets into a gas main and the pressure of gas
forces it out of appliances - eg out of the burners of your gas hob or
boiler? ;-)

Well not a full flow, but I have heard of some water being mixed in
with gas at the burner, which can be very dangerous when the flame goes
out - especially so where the appliance has no flame failure system.

Our old living room gas fire lacks flame failure, but it was only
fitted decades ago as a back-up for those (very) rare occaisions when
our CH fails. It has only seen any use for a couple of days, since it
was installed.

When I was at school it was not unusual for the gas and water taps
to get connected together in one of the chemistry labs.
The short term effect was that all the bunsen burners went out. Later,
the rusted gas pipe under the central "island" bench fractured and
the gas ignited in the void under the bench. The bench relocated
itself by around a metre after having become airborne.

John