SET PS-2 AND PS-3 TO OPERATE
It is sufficient to confirm that both compressor pumps
have an off cycle and are not running continuously.
Switch over the manual alternation system or bleed air
from tank on automatic alternation system to confirm
startup and off cycle of both pumps.
Measure the cut-in pressure, pump-up time, cut-out
pressure, and off time under normal operating conditions.
Pump-up time should be below 50 percent operation
(less on time than off time) and operate between 70 to
90 lb/in2 (480 to 620 kPa) pressure. Check operation of
pump using manual switch over if necessary.
figures for reference (a card attached to
the unit is handy). Decreasing off periods
in pressure range) indicate an increase in air consumption
with an increasing pump-up time. This could be due to
6 0 H Z -1
S W I T C H
A L T E R N A T O R
S W I T C H
f - - - - - - - _ - i - --L--L-.
S T A R T E R
5-10 LB/IN2 (35-70 kPa)
added devices or leaks. Increasing pump-up time with no
change in pressure range
compressor pump and may warrant closer observation as
it is usually followed by
Check backup operation by operating the safety relief
valve (see SAFETY RELIEF VALVE paragraph).
second pump should cut in after the tank pressure has
dropped 5 to 10 lb/in2 (35 to 70 kPa) below cut-in
pressure for the first unit.
wear is suspected, check the dead-ended pump-up
time (pumping up tank with the system off) against the
value given in Table 3. If this time differs from the table
by more than 10 percent, troubleshoot according to
instructions given under WON'T PUMP AIR paragraph,
and take proper action.
off time indicates wear in the
increase in oil consumption.