6
GAS (METHANE) FEED SYSTEM FROM THE GAS PIPE NETWORK AND AVERAGE PRESSURE
(See BT 8530/1 and BT 8531/1)
When high delivery is required, the Gas Distributing
Companyrequeststhe installation ofaunit comprising a
pressure reducer and a meter, and then connects the
gas feed system to the gas pipe network at average
pressure (a few bar).
This unit can be supplied by the Gas Distributing
Company or by the user, but should be according to the
Gas Company’s precise instructions.
The unit’s pressure reducer should be large enough to
supplythemaximum gas delivery requiredbytheburner
at the rate of pressure normally estimated for it.
Fromexperience,wewouldrecommendutilizingalarge-
sized reducer in order to attenuate the notable increase
in pressure which occurs when the burner comes to a
standstill, with a high delivery.
(Regulations require that the gas valves close in less
than one second).
As an indication, we would advise using a reducer
capableof producing a delivery(m3/h) about doublethat
of the maximum amount estimated for the burner.
If several burners are to be used, each one should have
its own pressure reducer;
thiswill enable thegas feed pressureto the burner tobe
maintained at a constant level even if only one burner is
operating at the time.
Consequently, it is possible to accurately regulate the
deliveryandthereforethecombustion, and thus improve
yield.
The dimension of the gas pipeline should be in function
with the quantity of gas it has to delivery. We advise
maintaining the load loss at a low value, it should be
kept in mind that the load loss is added to the pressure
existing when the burner stops and therefore a
subsequent start up will occur at a pressure that rises in
accordance with an increase in the pipe’s load loss.
Should the gas pressure reach unacceptable values
when the burner stops (rapid closure of the gas valves),
it is necessary to install between the reducer and the
firstvalve of theburner an automaticoverflow valve and
relative conveying pipe, of suitable section, in the open
air.
The end of the conveying pipe in the open air should terminate in a suitable place, be protected from rain and have a
flame trap.
The overflow valve should be regulated in such a way as to completely unload excessive pressure.
See diagram for gas pipeline dimensions.
DIAGRAM FOR CALCULATING THE DIAMETER OF
THE PIPES IN RELATION TO THEIR LENGTH AND
GAS FLOW N° BT 8058
FLOW IN mc/h of METHANE GAS s.a. 0,60
LENGHT OF PIPES IN METERS
DIAMETER OF PIPES IN INCHES
PRESSURE DROP IN mm OF H20
