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HVAC Training

Page : 29 of 42

Title:

Chiller Maintenance

Lesson Plan

NMH30C000105

elapsed from the time of notification by the HVAC group to the actual start of disassembly.

Based on the information received from the HVAC mechanic, the I&C technician did not check

the freon pressure gage. The technician was loosening the bonnet bolts for the jet pump

solenoid valve on "C" Chiller when freon started spraying from the opening. The technician and

the chiller w ere sprayed before he managed to reassemble the solenoid valve sufficiently to

stop the leak. The HVAC group was informed and they reduced freon level and pressure to

allow work to continue. A small amount of freon was expelled during subsequent disassembly

but the technicians were prepared for it and consequently it was not a problem.

2) Why did it happen? The causes identified in the OE

1. The I&C technician did not perform the task immediately upon isolation of the system.

When the HVAC mechanic notified I&C, he did not communicate that the internal pressure

would increase with time. The technician did not know the internal pressure would increase

with time as the chiller heats up from the initial cool down.

2. This critical information was not covered in the pre-job briefing. The I&C technician did not

communicate with the HVAC mechanic just prior to removing the solenoid and was not

expecting freon to spray out when the solenoid w as removed.

3) Could this type event happen at PV? What scheduling problems can the group identify

that may be applicable?

Corrective actions identified in the OE.

The I&C and Mechanical HVAC maintenance groups have discussed communication protocol

and awareness of possible changing conditions on plant equipment when delays in work

activities occur or time is of the essence. In the future HVAC and I&C will work together on this

task until the solenoid is removed. Additional means to isolate the system or a way to note the

potential for freon leakage during task performance is being investigated by maintenance.

4) What could you do to prevent this from happening?

Explanation

Have the students look at the Essential PM as you cover the lesson.

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Carrier 19FA Istruzioni per gli Interventi Pagina 29