b. If utility vessel has been evacuated — Crack
open valve 4 to gradually equalize pressure
between unishell and utility vessel. Ensure
that unishell pressure does not drop below 35
psig to prevent tube freeze-up.
6. Open valve 4 fully.
7. Open valve (29) to equalize the liquid refrig
erant levels between vessels.
8. Close valves 1,2, 3, 4, 5, 6, 7 and 8.
9. Open isolation valves (27), (28) and (30) and
service valve 9.
10. Close drain valve (26).
MACHINE DEHYDRATION — It is recommended
that the machine be dehydrated only if it has been
open for a considerable period of time, or if there
has been a complete loss of unishell holding charge
or utility vessel refrigerant charge.
WARNING; Do not staxt compressor ot oil
puH^ even, for a rotation check wliile machine
is under dehydration vacunm.
NOTE: Dehydration is readily accomplished at
normal room temperature. If room temperature is
high, dehydration takes place more quickly. At low
room temperatures, dehydration is extremely
difficult and special techniques must be applied.
Contact your Carrier representative for further
information.
Perform dehydration as follows:
1. Connect a dehydration pump to the refrigerant
charging valve (6) Fig. 1.
2. Connect a mercury manometer (absolute
pressure-type) to the dehydrator discharge hand
valve, (35) Fig. 1, and then open the valve. If
only the utility vessel is to be dehydrated, a tee
for the manometer must be provided between
the refrigerant charging valve and a valve on the
vacuum or dehydration pump.
3. Open the proper pumpout system valves to
evacuate the desired vessel(s).
4. Operate the dehydration pump until the
manometer reads 0.20 in. Hg abs (29.80 in. Hg,
ref 30-in. bar.); continue to operate pump for 2
more hours.
5. Close refrigerant charging valve; stop dehydra
tion pump; record manometer reading.
6. After a 2-hour wait, take another manometer
reading. If reading has not increased, dehydra
tion is complete. If reading has increased,
repeat steps 4 and 5.
7. If reading continues to rise after several dehy
dration attempts, suspect a machine leak. If this
is the case, pressurize the unit to approximately
8 to 10 psi with dry air or nitrogen. Locate and
repair leak. Then repeat dehydration procedure.
Inspect Piping — Refer to piping diagrams in job
data and inspect chilled water, condenser water,
and oil cooler water piping. Ensure that flow direc
tion is correct in all cases and that all specified
piping requirements are met.
CHECK WATER FLOW RATE - Ensure that
cooler and condenser water loop is full, with air
vented from high points. Water flow thru cooler
and condenser must meet job requirements.
Measure water pressure drop across the cooler and
condenser or across the pumps. Check to see that
water flow rates agree with design flow.
Oil cooler water supply should meet the follow
ing specifications:
Clean water
Max water temperature 85 F
Max inlet working pressure 100 psi
Water velocity in tube, ft/sec 10 max ~ 6 min
Water flow, gal./min 7 max -- 4 min
Water press, drop, psi diff 5 max — 2 min
Valves and/or controls Field supplied
Field Wiring — Prior to starting equipment, refer to
wiring diagrams in job data and check power
supply as follows:
1. Connect a voltmeter across power wires to
compressor motor starter and measure voltage.
Compare this reading with voltage rating on
compressor and starter nameplates.
add
WARNING: Do not attempt to check high
voltage supply without proper equipment.
Serious personal injury can result.
2. Compare ampere rating on starter nameplate
with ampere rating on.inotor nameplate.
3. Check voltage to the following components and
compare to nameplate values: oil pump starter,
pumpout compressor motor starter.
4. Check 120 volt supply to oil heater.
5. Test motor and its power lead insulation
resistance using a 500-volt insulation tester such
as a megohmmeter. Proceed as follows:
a. Open starter main disconnect switch.
b. Test the three phases of compressor motor,
phase to phase, and phase to ground, with
tester connected on the motor side of the
starter contactor in the starter. Take resist
ance readings at 10-second and 60-second
intervals for each phase.
c. Divide the 60-second resistance reading by
the 10-second reading. This gives polariza
tion ratio. The polarization ratio must be
1.15:1 or higher. The 10-second and
60-second resistance readings must be 5.0
megohms or higher.
If the readings are unsatisfactory, repeat the
tests at motor terminals with motor power leads
disconnected. This will indicate whether fault is in
motor or in motor power leads.
Check Starter — Before starting the 19EA, open
the main disconnect and then check starter:
1. Remove contactor arc chutes. Be sure con
tactors move freely, and that shipping string is
removed. Replace arc chutes.
2. If starter has been on jobsite for a considerable
period, check contactors for dirt and rust.
Clean contact magnet surfaces lightly with
sandpaper. Apply a very thin coat of vaseline to ^
magnet surfaces, then wipe it off. If starter haf
been in a dusty atmosphere, vacuum clean
starter cabinet and wipe with a lint-free cloth.
3. Remove fluid cups from magnetic overload
relays. Add dashpot oil to cups per instructions
