Carrier almost killed me today

[Coolie]

I had just finished replacing a discharge gas thermistor on a carrier chiller.
You know the one...1/2" brass fitting with two wires coming out the moulded end.

I had pumped it down, reclaimed remaining refrigerant in the 3 compressors on the circuit into the liquid side and replaced the sensor as well as the oil switch. Done the pressure test and vacced her down to 500 micron and openend the valves.
Watched everything start up beautifully and run for 10 minutes.
Went back to visually inspect the sensor and oil switch and all seemed ok. As I bent down to start clearing my tools, the moulded end of the sensor blew out while the comp was running and discharged 62 kg of R409a into the plant room.
I had just enough time to turn the machine off and get out before I popped my clogs. If I was standing in fron of the sensor when it blew off, i would have copped all the force and the gas in the face and probably would not be here writing this story!

This warm beer i am drinking is going down very well.....and i hate warm beer. The cold ones are just about ready.......aaahhhhhhhh.......

[GHAZ]

Hello coolie i always thought the head thermister which is 1/2 inch npt. is a sensor pocket and thread all in one and the sensor is behind it and therefore it should,nt blow out, unless the threads had a crack in them.wish you a speedy recovery from the trauma

[Coolie]

Well

No sensor pocket at all, so watch out for that....straight onto the head pressure. Bad design, but somehow they get away with it.

I just had may fourth beer for the night.....so nerves are settling back down....

It'd be interesting to hear what carrier have to say for themselves.

[Coolie]

Ok.....so replaced the dodgy sensor and the faulty one was pretty faulty.

The whole housing is cast from a solid brass body and the klixon is glued to the bottom....
well the body tore away from the thread, reslting in a total loss of refrigerant.
I only realised after I got home that I was working with R409a, which consists of 60% R22....not good. This means about 32kg of R22 was released into the atmosphere....strangely enough the next few days were quite warm...
Lol

Just glad I am still about to tell the story

[chillin out]

Glad to see you are still Ok.
You will be watching out for that next time...llol

Chillin:):)

[star882]

A few years ago, a friend of mine (Tiffany Houck) had a valve core blow out just after testing a system. She was testing a prototype of a CPU cooler for a Britney CPU. The system used R410a. According to her, the valve core blew out right after she disconnected the gauges. The high side was at about 400PSI (just after high ambient test). I don't know how it happened but I think the core was loose or the threads were damaged.

[Coolie]

It just goes to show that one can not be too carefull. Anything can happen...and you just dont know what it will be.

It is good to see the fairer sex involved within the trade. Not many about.
So go get 'em

[chillin out]

A few years ago, a friend of mine (Tiffany Houck) had a valve core blow out just after testing a system. She was testing a prototype of a CPU cooler for a Britney CPU. The system used R410a. According to her, the valve core blew out right after she disconnected the gauges. The high side was at about 400PSI (just after high ambient test). I don't know how it happened but I think the core was loose or the threads were damaged.
I have nearly done this as well.

When she was attaching her gauges I think that they were put in at a slight angle and then straightened when she tightened them. This causes the valve core to go to the side and when she released the gauge line it would have caught it and because of the pressure pushing the line off it would have pulled the core out.

p.s. if that's really you in the picture, is she as good looking as you?
(and NO, that's not me in my picture...lol)

Chillin:):)

[Tycho]

http://www.refrigeration-engineer.com/forums/showthread.php?t=4041

[star882]

I have nearly done this as well.

When she was attaching her gauges I think that they were put in at a slight angle and then straightened when she tightened them. This causes the valve core to go to the side and when she released the gauge line it would have caught it and because of the pressure pushing the line off it would have pulled the core out.

p.s. if that's really you in the picture, is she as good looking as you?
(and NO, that's not me in my picture...lol)

Chillin:):)
That might have been how it happened.

Yeah, I'm one of the prettiest HVAC technicians out there... Tiffany is pretty good competition, though. Hannah (of the "HVAC couple") is my main competitor, however.

BTW, the "HVAC couple" told me that there's also a "chiller couple" out there. (They told me to google "amanda carrier" "stan mcquay". I think that's a HVAC easter egg!)