L.p.gas Gas Supply - Propane / Butane - FULTON VMP Series Installation, Operation And Maintenance Manual

Fulton Ltd
L.P.GAS
2.5.1.3
LPG Boilers should be installed to the requirements of IGE/UP/10 March 2001 and only by
experienced engineers familiar with LPG firing. An L.P. gas boiler is similar in design to a natural
gas boiler, the main differences are important and must be taken into account when installing the
boiler and ordering spare parts.
When installing an L.P. gas boiler, the feed from the bulk tank supply must be fitted with a supply
governor which is set to reduce the supply feed pressure to the boiler governor to between 50
mbar (min.) and 80 mbar (max.).
For PROPANE: The boiler governor must be adjusted to give a firing pressure of 25 mbar at
the test point provided at the elbow on the gas train.
For BUTANE: The boiler governor must be adjusted to give a firing pressure of 20 mbar at the
test point provided at the elbow on the gas train.
Gas Pressure Alarm Indicator Light
For L.P.G. applications the inlet pressure switch is used to protect the system from over
pressure and should be set at 100 mbar.
Further information
Firing LPG fuels in a Fulton Vertical boiler is relatively straightforward, however the nature of the
fuel makes it difficult to ensure that the correct gas flow rate is achieved when commissioning and
servicing the burner.
LPG is stored as a liquid at high pressure, which is vaporised as the pressure reduces through
the pressure regulator at the discharge from the tank. The storage tank pressure regulators
typically reduce the pressure down to 150 - 500 mbar, which is too high for the inlet to the gas
control valve on the Fulton burner. An intermediate or Service Governor is therefore required to
reduce the pressure further to below 80 mbar.
The siting of the LPG storage tank can be crucial particularly in environments where high ambient
temperatures may be experienced. The effect of world wide temperature changes such as caused
by solar gain, can result in significant LPG supply pressure change over a 24 hour period.
The consequences of temperature and pressure changes, is to vary the density of the gas
such that accurate, consistent, and meaningful measurement of the gas flow rate is difficult.
Calibrating, gas flow meters to any degree of practical accuracy is extremely difficult. At best an
LPG gas meter gives an approximation of the gas flow rate, however the installation of a meter is
essential.
Where no metering is available the only available criteria to assess the flow rate is the burner
inlet gas supply pressure at the test nipple on the last elbow prior to the gas entering the burner.
This pressure would normally be established during works testing after manufacture, however
LPG firing is not possible at the Fulton Boiler Works Bristol factory, for both practical and safety
reasons.
The figures given in the Operation and Maintenance Instructions, are calculated figures based
on published data for the Specific Gravity of standard Propane and Butane at 15.6°C. In practice
temperature, pressure and gas constituents variations, are such that the calculated figure should
only be used as a guide.
LPG fuels generally produce higher flame temperatures (Butane being the highest) which makes
it vital that the burners are not over fired, or are operated with any significant levels of Carbon
Monoxide (CO) in the exhaust gas, which could lead to overheating of the boiler pressure vessel.
VMP-IOMM-2018-2
GAS SuPPLy - PrOPANE / BuTANE
INSTALLATION - 2
Page 13