/ Dual Fuel
LP standby systems use propane, butane or a blend of the two as a substitute or
supplement for the primary natural gas supply.
Gas -- At a Glance:
Colorless, odorless vapor at room temperature & pressure. Odorants added for
- Heating Value:
Propane -- 91,300 Btu/gallon (2500 Btu/cu ft)
Butane -- 100,000 Btu/gallon (3200 Btu/cu ft)
& Storage: As a liquid by pressurizing it. At 70°F propane can be
liquified by subjecting it to a pressure of about 175 psig. Butane requries only
Generally available in most areas of North America. Supplies may become tight
during harvest season in agricultural areas due to heavy demand by crop dryers.
butane both have higher heating values than natural gas, so the same amount of
heat can be generated from smaller flows of these fuels.
gas, propane and butane are heavier than air. This higher density, combined with
the difference in Btu value, requires different pressure and flow control settings
when switching from natural gas.
butane actually have lower ignition temperatures than natural gas. However, this
doesn't usually have any noticeable effect on the operation of industrial burners.
LP standby system consists of a storage tank, vaporizer, if needed, and regulators
and valves to control the flow of LP to the burner systems. This is a parallel
system to the natural gas supply system. Because of its simplicity and low cost,
it's popular for small installations with only a few pieces of burning equipment.
One inconvenience of these systems is that switchovers between fuels is often