Carrier 17DA - Manual (Page 6)

WARNING: No brine over l O O F must be
allowed to flow thru the cooler.
7. Ensure that there is water in the cooling tower.
8. If the auxiliary equipment such as chilled
water pump, condenser water pump, and
cooling tower fan are not wired into control
console circuit, start these items manually
before starting the compressor.
9. Start oil pump.
10. Close bleed valve on inboard side of the
compressor.
1 1 . 1 7 D A compressors are equipped with an
AUTO-MANUAL control station. The initial
start should be on manual control from this
station.
12. Start compressor.
a. Bump electric motors by pushing the
START and STOP buttons in quick
succession. Compressor rotation must be
counterclockwise when viewed from drive
end.
b. Run turbine or engine drives at slow
speed.
13. Listen carefully for unusual mechanical noise
while coasting down.
14. Shut down.
Charge Refrigerant
WARNING: When liquid Refrigerant-12 is in­
jected into a low vacuum of 29.48 in. mercury
it will unmediately flash to a gas at a tempera­
ture lower than minus 100 F. It is for this
reason that water must be circulating before
charging liquid refrigerant. Non circulating
water would quickly freeze and damage the
machine. If an auxiUaiy' refrigerant storage tank
(receiver) is furnished, liquid refrigerant may be
charged directly into this evacuated receiver
without danger.
Large machines run with liquid refrigerant in
the cooler so refrigerant is charged into the cooler
or low-pressure side of the machine. For general
instructions on how to handle refrigerant refer to
Carrier Standard Service Techniques, Form SM-1.
Use the Charging by Weight method, cross check­
ing with the machine’s refrigerant sight glass pro­
vided on the back of the cooler shell, and the
suction pressure gage.
Charge refrigerant as follows:
1. Start Cooler and Condenser water circulating
pumps.
2. Charge the first refrigerant in the vapor state,
continuing until the machine pressure exceeds
35 psig. The refrigerant temperature corre­
sponding to this pressure is high enough to
prevent water freezing damage and will also
satisfy the refrigerant low-pressure cutout
safety switch setting (31.5 psig). Now turn the
refrigerant bottles or drums over and begin
charging the refrigerant in the liquid phase.
Continue charging liquid refrigerant until about
2/3 of the estimated full load charge is in the
machine.
3. Adjust control station to operate at MANUAL.
Ensure that the guide vanes are closed as
indicated on the main guide vane indicator.
4. Set Subcooler Level Controller as follows:
a. Set Proportional Band at 35%.
b. Set Level-Set adjustment at 50%.
When stable operation is achieved, readjust
Level-Set to maintain the Hquid level at the
midpoint of the sight glass on the Level
Controller. Recheck this level when full load is
reached and reset if necessary.
5. Start the compressor. Observe the machine’s
operation for 1 5 - 2 0 min before increasing the
load. During this period, make the following
checks and adjustments :
a. Check oil pressure.
b. Adjust water flow thru oü cooler so that
bearing temperatures stay between 150 F
and 170 F approximately.
c. Watch bearing temperatures carefully. This
is the first time that the machine has been
run under refrigeration load. Bearing tem­
peratures may level off at some temperature
slightly higher than 170 F hsted above. This
may be the normal stable condition for this
bearing. High thrust bearing temperature
will shut the machine down at 180 F.
6. Slowly open the guide vanes, by manual con­
trol, thus increasing the load. Do not exceed
the current rating of the electric motor. Watch
for other signs of overloading a turbine or
engine drive.
7. Add Uquid refrigerant, trimming the charge off
at the point where the machine reaches design
operating temperature and pressure conditions.
WARNING: Excessive overcharge may cause
liquid refrigerant carry-over into the com­
pressor, causing severe overload and possible
compressor damage.
8. Shut the machine off. When the refrigerant
level settles down, mark this optimum level on
the sight glass. Maintain this shutdown level. To
determine the approximate refrigerant charge
for your machine, add the cooler charge to the
applicable condenser charge as listed in Table 5.