Carrier 17EX specifications Return Chiller to Normal Operating Conditions, General Maintenance

Transferring Refrigerant into the Cooler/ Condenser/Compressor Section Ð These steps de- scribe how to transfer refrigerant from the economizer/ storage vessel into the cooler/condenser/compressor section. This is normally done to prepare for service work on the economizer/storage vessel.

1. Isolate and push refrigerant into the cooler/condenser/ compressor section:

a. Valve positions:

VALVE	1	2	3	4	5	6	7	8	9	10	11
CONDITION		C			C			C	C	C	C

b. Turn off chiller water pumps and pumpout condenser water.

c. Turn on the pumpout compressor to push refrigerant out of the economizer/storage vessel.

d. When all liquid refrigerant is out of the economizer/ storage vessel, close the cooler isolation valve 7.

e. Turn off the pumpout compressor.

2. Evacuate refrigerant from the economizer/storage vessel. a. Access the CONTROL TEST table on the LID. Select the PUMPDOWN LOCKOUT screen. From this screen, turn on the chiller water pumps and monitor vessel

pressures.

b. Valve positions: Close valves 3 and 4, open valves 2 and 5.

VALVE	1	2	3	4	5	6	7	8	9	10	11
CONDITION			C	C			C	C	C	C	C

c. Turn on the pumpout condenser water.

d. Run the pumpout compressor until the suction reaches 15 in. Hg (50 kPa abs). Monitor pressures on the LID and on refrigerant gages.

e. Close valve 6.

f. Turn off the pumpout compressor.

g. Close valves 1, 2, and 5 (all valves are now closed). h. Turn off the pumpout condenser water.

i. From the CONTROL TEST table on the LID, turn off the chiller water pumps and lock out the chiller com- pressor from operation.

Return Chiller to Normal Operating Conditions

1.	Be sure that the vessel that was opened has been evacu-
	ated and dehydrated.
2.	Access the CONTROL TEST table. From this table, se-
	lect the TERMINATE LOCKOUT function to view the
	vessel pressures and to turn on chiller water pumps.
3.	Open valves 1, 3, and 6.
		VALVE	1	2		3	4	5		6		7	8	9	10	11
		CONDITION		C			C		C			C	C	C	C	C
4.	Slowly open valve 5, gradually increasing pressure
	in the evacuated				vessel				to	35		psig		(141		kPa)
	for HFC-134a. Feed refrigerant slowly to prevent
	freeze-up.
5.	Perform a leak test at 35 psig (141 kPa).
6.	Open valve 5 fully. Let the vessel pressures equalize.
		VALVE	1	2		3	4	5		6		7	8	9	10	11
		CONDITION		C			C					C	C	C	C	C
7.	Open valves 9 and 10.
8.	Open valve 7 to equalize liquid refrigerant levels.
9.	Close valves 1, 3, 5, and 6.
		VALVE	1	2		3	4		5		6	7	8	9	10	11
		CONDITION	C	C		C	C		C		C		C			C

10.Continue to use the TERMINATE/LOCKOUT function on the LID to turn off water pumps and enable the com- pressor to operate.

GENERAL MAINTENANCE

Refrigerant Properties Ð Refrigerant HFC-134a is the standard refrigerant in the 17EX. At normal atmospheric pressure, HFC-134a boils at −14 F (−25 C) and must, there- fore, be kept in pressurized containers or storage tanks. The refrigerant is practically odorless when mixed with air. This refrigerant is non-combustible at atmospheric pressure. Read the Material Safety Data Sheet (MSDS) and the latest ASHRAE Safety Guide for Mechanical Refrigeration to learn more about safe handling of this refrigerant.

Refrigerant HFC-134a will dissolve oil and some non- metallic materials, dry the skin, and, in heavy concen- trations, may displace enough oxygen to cause asphyxi- ation. When handling this refrigerant, protect the hands and eyes and avoid breathing fumes.

Adding Refrigerant Ð Follow the procedures de- scribed in Charge Refrigerant into Chiller section, page 57.

Use the PUMPDOWN LOCKOUT function on the CON- TROL TEST table to turn on the chiller water pumps and lock out the compressor when transferring refrig- erant. Liquid refrigerant may ¯ash into a gas and cause possible freeze-up when the chiller pressure is below 30 psig (207 kPa) for HFC-134a. If the water pumps are not controlled by the PIC, they must be controlled manually.

Removing Refrigerant Ð When the optional pump- out system is used, the 17EX refrigerant charge may be trans- ferred into the economizer/storage vessel or another storage vessel. Follow procedures in the Pumpout and Refrigerant Transfer Procedures section when removing or transferring refrigerant.

Adjusting the Refrigerant Charge Ð If it is nec- essary to add or remove refrigerant to improve chiller per- formance, follow the procedures under the Trimming Refrigerant Charge section.

Refrigerant Leak Testing Ð Because HFC-134a is above atmospheric pressure at room temperature, leak test- ing can be performed with refrigerant in the chiller. Use an electronic detector, soap bubble solution, or ultra-sonic leak detector. To keep false readings to a minimum, be sure that the room is well ventilated and free from concentration of refrigerant. Before making any necessary repairs to a leak, transfer all refrigerant from the leaking vessel.

Leak Rate Ð The ASHRAE recommendation is that chill- ers should be immediately taken off line and repaired if the refrigerant leak rate for the entire chiller is more than 10% of the operating refrigerant charge per year.

Additionally, Carrier recommends that leaks totalling less than the above rate but more than a rate of 1 lb (0.5 kg) per year should be repaired during annual maintenance or when- ever the refrigerant is pumped over for other service work.

Test After Service, Repair, or Major Leak Ð If all refrigerant has been lost or if the chiller has been opened for service, the chiller or the affected vessels must be pres- sure and leak tested. Refer to the Leak Test Chiller section (page 46) to perform a leak test.

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