Perkins 4012TESI Series, User Handbook Manual, Page: 23 / 57

GAS SPECIFICATION
4012/16 Gas, February 1998 19
DERATING
SETTING ENGINE POWER TO SUIT
ACTUAL SITE CONDITIONS
Derating means reducing the power output
of an engine from its normal rating at normal
temperature and pressure conditions to
allow for adverse effects of site conditions
e.g. altitude and ambient temperature.
Perkins Engines (Stafford) Ltd. may be
unaware of the final destination of an engine
at the time of despatch from the works. The
engine will be set to give the power output at
normal temperature and pressure under ISO
3046
standard conditions, using gas
conforming to British Natural Gas
Specification, having a lower calorific value
of 34.71 MJ/Nm³ (930 BTU/Sft³), which when
operating under the actual site conditions,
could result in severe damage to the engine
(refer to page 18 ) .
Providing that the actual gas being used
meets with the above conditions, then the
engine need only be derated for altitude and
ambient temperature conditions.
Any engine so supplied must be derated in
accordance with the published percentage
derate figure as shown in the
Product
Information manual , by the Equipment
Manufacturer on his premises, or even on
site.
To derate, calculate, (using the above
percentage derate figure) the new reduced
power output of the engine, and run the
engine or generating set on this load.
Where possible this maximum load limit
should be set and locked in the engine
control panel.
IT IS ESSENTIAL
THAT FULL
ACCOUNT IS TAKEN OF ALL DERATING
INFLUENCES WHETHER GAS
SPECIFICATION, ALTITUDE, AMBIENT
TEMPERATURE OR HUMIDITY. WHERE
ANY OF THESE DEVIATE FROM THE
STANDARD SPECIFIED IN THIS
MANUAL THE RATING OF THE GAS
ENGINE MUST BE ADJUSTED AS
INSTRUCTED BELOW.
WARNING