York Screw Chiller YCIV0287VA46

This procedure must be performed at the specified time by an industry certified technician who has been trained and qualified to work on this type of equipment.

A record of this procedure being successfully carried out should be maintained on file by the equipment owner should proof of adequate maintenance be required at a later date for warranty purposes.

Sample compressor oil, check for acid, and replace if necessary.

Disconnect power source and lock out and check tightness of power wiring connections.

Check glycol concentration on low temperature or other applications where freezing may be a problem.

Check programmable operating setpoints and safety cutouts and ensure they are correct for the application

Check compressor and evaporator heater operation

Check for dirt in the control panel and check door gasket sealing integrity

Warning: Ensure the vapor portion of the refrigerant container or cylinder has not been contaminated with other gases that are not R-134a, including air.

Is the appropriate saturation property for the correct refrigerant used?

Refer to Table 55 on page 314 for R-134a to determine if the saturation pressure and ambient temperature of the refrigerant in the container coincide.

Is only refrigerant vapor from the top of the drum or cylinder admitted to the system until system pressure is raised above the corresponding saturation pressure at the freezing point of the chilled liquids?

For all other liquids, establish the freeze point temperature and vapor charge to a pressure that is 5°F (2.78°C) higher than that freeze point.

Enter the pressure for water with R-134a at 32°F.

Before charging, establish the starting weight for the refrigerant cylinder.

Is a refrigerant pump used to draw vapor from the chiller and discharge it to the vapor connection of the refrigerant cylinder?

Is air prevented from entering the system during charging?

Connect a high-capacity vacuum pump with indicator to the charging valves as shown in Figure 147 on page 306 and Figure 148 on page 306. Start the pump.

Ensure all the system valves including manual valves and EEVs are 100% open. Ensure that all valves to the atmosphere are closed with flare caps in place, if applicable.

Operate the vacuum pump until a pressure of 5,000 μm is reached. To avoid freezing any trapped moisture in the system, see Table 54 on page 310 for corresponding pressure and temperature values.

To start the 8-hour vacuum hold test, close the system charging valve connection to the vacuum pump. Note the time and pressure.

Hold the vacuum obtained in Step 4 in the system for 8 hours. Even a slight rise in pressure can indicate a leak, the presence of moisture, or both. Check for pressure change with the chiller at the same temperature. Pressure changes proportional to temperature and can affect results.

To determine if it is moisture or a leak, conduct a pressure rise test. Evacuate the system to 5,000 μm again and perform another hold test. If the pressure rise goes to 0 psig, it indicates that a leak is present. If moisture is present, the pressure stabilizes at some level below atmosphere and should correspond to the room ambient temperature or the heat being applied to the vessel. See Table 54 on page 310 for values.

An acceptable vacuum pressure rise is 150 μm for the first 60 minutes.

If the vacuum does not hold within the limits defined in Step 6, find and repair the leak. If leaks cannot be identified while pressurized but vacuum hold tests indicate a leak, this may be due to an elastomeric or O-ring sealing issue.

Result: When the 5,000 μm vacuum hold test is successful, perform a final evacuation.

Warning: This procedure should only be performed by a qualified technician.

Pressure test and evacuation performed at the factory?

Enter the leak rate (acceptable limit is 0.1 oz/year at DWP)

If leaks are indicated, they must be repaired immediately.

Leaks stopped by ensuring face seal nuts and flange bolts are correctly torqued?

For any major repair, the refrigerant charge must be removed and the system leak checked using reliable methods like a pressure test.