Retrofit of R404A/R507A systems

1.

Data protocol at stable operation with present refrigerant.

2.

Switch off system.

3.

Reclaim the refrigerant with appropriate reclaim unit, down to ambient pressure:

• Open or bypass the shut off, check, solenoid and control valves.

4.

If necessary, adjust high and low pressure switches.

5.

Close the compressor shut off valves.

6.

If necessary, change elastomer gaskets in the compressor (Compatibility of BITZER products):

• on reciprocating compressors at oil pump and sight glass.
• on screw compressors maybe further gaskets.

7.

On open type compressors change the shaft seal.

8.

Drain compressor and (if applicable) separator oil and charge new polyolester oil:

• Leave the oil heater switched off.
• Measure oil volume and recharge with same amount.
• Oil type according to compressor manufacturers specification.

9.

Change filter drier.

10.

Change insert of suction line filter, if existing. Install suction line filter, if dirt appears or chemical stability of the system is questionable.

11.

Adjust or replace the expansion valves:

• on 2-stage compressors resp. economiser operation (screw compressors), also the valves for the liquid injection.

12.

Change elastomer gaskets of valves, control apparatus aso. or replace these components.

13.

Further remove refrigerant with reclaim unit and subsequently evacuate down to 3 to 5 mbar standing vacuum.

14.

Tightness test:

• Set all shut off valves, solenoid valves, control valves and check valves to open position or bypass.

15.

Charge new refrigerant into the liquid reciever:

• Charge refrigerant blends only from liquid phase to avoid change of concentration.
• Charge amount of 80% of original charge at start, or according to refrigerant manufacturer's information.

16.

Commissioning according to the operating instructions of the system:

• Check operating conditions.
• Evaluate suction gas superheat using the dew point vapour pressure table of the new refrigerant (Vapour pressure tables) resp. BITZER Refrigerant App.
• Evaluate charge amount using the liquid sight glass.

17.

If necessary, add refrigerant via the suction line:

• Charge very carefully from the liquid phase to avoid wet operation.
• Check the charge via the sight glass.
• Evaluate liquid subcooling using the bubble point vapour pressure table of the new refrigerant (Vapour pressure tables) resp. BITZER Refrigerant App.

18.

If necessary, adjust the control apparatus.

19.

Data protocol at stable operation with the new refrigerant.

20.

Mark the system with stickers with the new refrigerant denomination.

21.

Record the changes in the system log book.

22.

Check the oil level at stable operation.

23.

Dispose of or recycle the reclaimed refrigerant.

24.

Dispose of the used oil.

25.

Check the operating conditions and oil level after 10 to 24 hours:

• Wet operation can cause low oil level.
• If necessary, adjust control apparatus.

26.

Check the tightness of the system and the elastomer gaskets in the months following the re-commissioning.