Vogt P-34AL-15, Руководство по обслуживанию

Страница: 109 / 159

P34AL-15 & P34ALOF-15 Service Manual
SERVICING OPERATIONS
9/22/05
9-21
If excessive water is in the ammonia, it will cause frost on the suction line to the compressor, and
dilution of the oil. This condition should not go uncorrected and the water needs to be removed.
1. Perform a total pumpdown of the freezer. See “PUMPDOWN”.
2. A total pumpdown is accomplished when there is no frost or ice on the freezer or oil trap and the
freezer pressure is below that pressure relative to the surrounding temperature. Refer to the
Temperature-Pressure chart for ammonia.
3. With the freezer pressure below 25 PSIG, attach a hose to the oil trap drain valve, #61 and
extend the other end into a container (5 gallon bucket, etc.).
4. Open the hot gas check valve (101).
5. Open the drain valve a little and drain out the oil and water that is present.
6. Continue to drain oil/water, and purge the freezer and compressor to 0 PSIG.
7. Close the compressor discharge stop valve and the oil return valve. Make sure the power is
disconnected and locked-out.
8. Drain the compressor oil, remove the compressor side cover and clean the inside of all oil and
foreign matter, and reinstall the side cover.
9. Connect a vacuum pump, or pumps to the freezer and compressor, and evacuate them to 2000
microns or below while maintaining 60°F (10°c) or higher room temperature. A 5 CFM or
larger vacuum pump is best.
10. During evacuation, add new oil to the compressor. Also purge the receiver for non-
condensables.
11. After evacuation, break the vacuum by manually opening the liquid line solenoid valve and
gradually opening the liquid line stop valve (29 or at the receiver), letting liquid ammonia enter
the freezer and raise the pressure.
12. When the freezer (suction) pressure is up to at least 60 PSI, manually close the liquid line
solenoid valve and restore power to the machine.
13. Open the compressor discharge valve, oil return valve, and all other valves that should be opened
for normal operation.
14. Turn the “HAND/AUTO” switch to “HAND”. When the receiver liquid level is near its normal
operating level or the pressures are near equal and the compressor crankcase has warmed, the
compressor can be started and ice production resumed.
15. After several cycles, check the system for symptoms of excessive water, and if necessary, repeat
the pumpdown and evacuation procedure.
Note: whenever excessive water is present in the system, the source should be identified and
corrections made prior to further operation.
Circulating Water Pump Motor . The motor bearings are prelubricated and sealed. They require
no further lubrication. The pump should operate with the water level above the impeller housing.
The pump is equipped with a mechanical seal, which is self-adjusting and requires no lubrication.
However, the pump should not be operated unless circulating water. The pump manufacturer