Maintenance of theElectronic
( EPC ) PressureControllers onSRI GCs
If theEPCActual reading is very high
( higher than the gas cylinder pressure
for instance ), then the pressure sensor
may be broken or contaminated ( fre-
quentlywithwater from old gas line tub-
ing ).
You canmove the bad sensor from the
jack on oneEPC board to the corre-
sponding jack on another EPC board to
determine if the sensor reading is the
same on both boards. For example, if
the carrier gasActual reading is 991,
you canmove the carrier gas sensor to
theAir sensor jack on another EPC
board. TheAir Actual readingwill now
show theCarrier gas sensor. If theAir
Actual now reads 991 then it means the
sensor itself is probably the problem, not
the rest of the circuit. If theCarrier gas
sensor reads normallywhen connected
to the jack on theAir EPC board then
thismeans theCarrier EPC boardmay
be the problem.
It is also possible that the phone cable
going from theEPC board to the jack on
the display board is loose or discon-
nected. It wouldmake sense to return
the badCarrier gas sensor to the carrier
EPCboard, verify the readingwas still
991 and then switch the cable from the
carrier gasEPC board to the display
boardwith theAir jack on the display
board. If the bad reading of 991moved
to theAir Actual when the cablewas
moved then it mean the display board is
OK.
October 2009
Page4
TheActual
pressure can
NOT really be
this high
Move the bad sensor to a jack
on a different EPC board
Switch the ca-
ble to a different
display board
phone jack to
rule out a bad
connection
