Greetings Ammonia Gents:

Say, I have performed a leak test and have discovered a PRV that is leaking in one of our small plants (750 lbs flooded chiller). The PRV is on a de-superheater. The de-superheater has an isolation valve on the high side HP gas inlet. And, it has an isolation valve on the condensate outlet. The condensate drain line leads from there to a float drain that allows high pressure condensate through to the low-side so it can return to the flooded chiller through 8 feet of 1/2" tubing. There is an isolation valve where the liquid enters the chiller to valve of the drain tubing. A bench test on an identical float drain indicates that approximately 10 psi will be all that is needed to allow the liquid in the tubing to boil off and back into the de-superheater if it were depressurized.

Unfortunately, there is no service valve on this assembly. Due to the physical location of the de-superheater, the only place to install a service valve is on the bottom of the desuperheater and this would require moving the float down about 4 inches, and that requires opening the tubing.

Our main tech is unavailable to help with this, and while the rest of us have training in the use of safety equipment, PPG and the like, I would appreciate your thoughts on how best to vent this assembly so I can install a new PRV and a service valve and then vac the unit down. One idea is to turn on the pump and fan to the evaporative condensor and then to valve off the liquid return lines so as to pump out the chiller and therefore this little return tubing. Another thought would be to gear up and unscrew a fitting at the top of the de-superheater enough to allow gas to vent - after isolating the tubing from the chiller of course.

If any of you can share your techniques and safety tips, warnings, encouragement... with a newbie, I would greatly appreciate it.

Kind regards,

JB