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HVAC Training

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Title:

Chiller Maintenance

Lesson Plan

NMH30C000105

iii) does the machine need to be evacuated

i v) what other work is planned during the outage. (CM work may have been added to the scope)

i) If we are doing minor work then we only need to go to four inches mercury. Sometimes it’s required to pull

down to 4 inches several times on the R – 114 machines.

j) A word of caution, care should be taken to not accidentally open the transfer valve. It’s the only barrier

that prevents hundreds of pounds of refrigerant from re-entering the machine.

Cautions

On EC chillers, isolation valve to automatic metrex head pressure control valve must be closed,

vacuum will invert and damage diaphragm.

k) Refrigerant Transfer Valve

i) When the machine is pumped down take care not to disturb the refrigerant transfer valve.

l) Adding Chiller Oil & Draining Oil from Storage Tank

Note: The following event was covered in HVAC Industry Events class. An optional method of

covering this lessons learned is to ask the trainee to recall the event and challenge them to

recall the why it happened.

Lessons Learned:

OE15289 - Documents an event caused by poor communication and a delay in work that

resulted in freon being sprayed out of a chiller valve.

Abstract: While attempting to re move a chiller jet pump solenoid valve for preventive

maintenance (pm), freon sprayed out of the valve. The causes were determined to be an

inadvertent delay in the work that allowed the freon pressure to increase and

communication between the two maintenance groups involved.

1) What happened? This event occurred at Virgil C. Summer Nuclear Station on 10/01/02

when a routine PM was planned for the chiller jet pump solenoid valve. I&C supervision was

informed by HVAC personnel that freon level and pressure had been sufficiently reduced to

allow solenoid disassembly. The valve is not isolable from the freon flow path, so system

pressure is reduced to a minimum by cooling the chiller down. The I&C technician obtained QC

support and proceeded to the chiller to remove the solenoid. Approximately one hour had

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Carrier 19FA Istruzioni per gli Interventi Pagina 28