RSL

Refrigerant Solutions Limited

Appendix 8 

# RS-50 (R442A)

RETROFIT PROCEDURE TO REPLACE R404A OR R507

Replacing R404A or R507 with RS-50 essentially will follow the procedure specified by the equipment manufacturer for a refrigerant ch ange. Since RS-50 is ze otropic it is very important that liquid, not vapour, refri gerant be added to the system.

1. Ensure the right equipment is available, eg recovery unit and cylinders, container for recovered lubricant, vacuum pump, wei ghing scales, replacement drier etc.

2. Before removing the R404A or R507A, ope rate the unit under standard operating conditions and record the pressures, temper atures and any other relevant measurable data to establish unit performance. Typical ly, the appropriate standard conditions for setting up the unit will have already been specified by the equipment supplier.

3. Recover and weigh the R404A or R507A from the unit. The weight should be within the range specified by e quipment manufacturer.

4. Replace the filter/drier a nd evacuate the system.

5. As in the case of R404A and R507, RS- 50 should be used with a polyol ester

lubricant.

6. Before operating the unit , charge the unit with liquid RS-50. The weight added at this stage should be approximately 10% lower than the R404A or R 507 charge specified by the equipment manufacturer.

7. Operate the unit under conditions similar to those used in Step 2, closely watching the liquid line sight glass, the co mpressor oil level sight glass and the suction superheat.

8. RS-50 has a lower liquid flow rate than R 404A and R507, so that it may be necessary to close the expansion device relativ e to its setting for R404A or R507.

9. The evaporator superheat should be checked and changed as necessary by adjusting

the TX valve.RSL

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10. If liquid is observed in the suction line si gh t glass or the suction superheat is lower than required, close the TX valve further. If the equipment manu facturer recommends charging R404A or R507 by evaporator superheat or liquid sub-cooling, use the same amount of superheat or sub-cooling for RS-50

11. If a liquid line sight-glass is fitted, charge to a full glass gradually adding more liquid RS-50 until only liquid is passing through the expansion valve. Do not overcharge the system.

12. Adjust the expansion device s uperheat setting as required.

13. Check system thoroughly for leaks.

14. Remove all R404A or R507A labels and clearly label system RS-50.

Warning: It is highly recommended that the th ermostatic expansion valve be checked and adjusted to compensate for small differen ces in the pressure temperature relationship of the replacement refrigerant wh en compared to the original refrigerant. Failure to check and adjust the valve could allow liquid refrigerant to enter the compressor and damage bearings and other compressor components

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RS SERIES OF REFRIGERANTS PRESSURE/TEMPERATURE CHARTS

RS Series Pressure/Temperature charts indi cate both liquid bubble point and vapour dew point of the RS Series Refrigerant.

Liquid Bubble Point: this is the temperature which the liquid refrigerant will begin tovaporize at the given pressure. Below this temperature the liquid refrigerant will be subcooled.

Vapour Dew Point: this is the temperature at whic h refrigerant vapour will begin to condense at the given pressure. Above this temperature the refrigerant vapour will be superheated.

EvaporatorVapour Superheat:

To determine evaporator superheat, measur e the suction line temperature at the outlet pipe of the evaporator and measure the su ction pressure at th e outlet pipe of the evaporator. Using the Pressure/Temperature chart, determine the vapour dew point for the measured suction pressure. Subtract the determined dew point from the actual temperature and this difference is the evaporator superheat.RSL

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Condenser Liquid Sub-Cooling:

To determine condenser sub-cooling, measure the temperature of the outlet pipe of the condenser and measure the condenser pressure at the outlet pipe of the condenser. Using the Pressure/Temperature chart, determine the liquid bubbl e point for the measured condenser pressure. Subtract the measured temperature from the determined bubble point

and this difference is the condenser liquid sub-cooling.