REPLACING REFRIGERANT CONTROLS WITHOUT REMOVING CHARGE

[VTP99]

I was looking at a Manitowic service manual today and found this " This is a required in-warranty repair procedure " using a pinch-off tool. I have one but never use it. Anyone out there using one ?

[icemeister]

Manitowoc recommends a pinch-off & re-rounding tool for replacing stuff like the fan cycle or high pressure control. I've used one for years, more often to add service access valves to True units and such.

Here's a past post on that tool:

http://hvac-talk.com/vbb/showpost.ph...32&postcount=5

(The Ritchie P/N is #60665)

[Phase Loss]

I have a pinch off tool, but have never used it on a live system. Just scrap copper in my Van and when I re-round it, it never resumes it's original round shape...it definitively re-opens the pinch off, just not round.

You able to make them round again Ice?

[icemeister]

I have a pinch off tool, but have never used it on a live system. Just scrap copper in my Van and when I re-round it, it never resumes it's original round shape...it definitively re-opens the pinch off, just not round.

You able to make them round again Ice?

Mine come out maybe "75% round" which is fine for a pressure control or access valve. The trouble I've seen is the pinch point is weakened and so it may fail due to vibration. I've had good luck with building up the pinch point with a little silphos to stiffen it a bit.

[VTP99]

The first and last time i used my i was trying to remove a condensing unit. On the 1/4" liquid line it would not seal it off. When i cut the line it keep spewing out. I tried to pinch it down more and it ended up cutting it.
Also are you even a little concerned about welding a charged system ?

[Texas-Tech]

If you have the room I pinch it twice about an inch apart. They never come out round but it can save you a lot of time.

[icemeister]

The first and last time i used my i was trying to remove a condensing unit. On the 1/4" liquid line it would not seal it off. When i cut the line it keep spewing out. I tried to pinch it down more and it ended up cutting it.
Also are you even a little concerned about welding a charged system ?

When you braze on an access valve, it's not on the charged side of your pinch-off point...so it's not a problem.

As for adding some braze to build up the re-rounded portion, I don't see that as a particular problem.

I've never cut one off with the pinch-off/re-rounding tool, but I know I've come close...hence the buildup of brazing material suggestion.

If you have the room I pinch it twice about an inch apart. They never come out round but it can save you a lot of time.

I've done that a couple of times when I can't get the first one to hold for whatever reason. Good tip.

[mizzterclean]

I use pinch off tools regularly. Lots of tools out there but not all are good for service. I always look for a aset that doesn't touch in the pinch area. Mine round well and have never had a problem. Imperials.

[trippintl0]

I actually saw a Manitowoc CVD unit that some hack had replaced the headmaster by using 3 pinch off tools... lame! It wasn't flowing enough during harvest, maybe because pipe only re-rounded 50% or maybe because he used an off the shelf part with 180# set point... Either way that was pretty interesting to see!

I have used pinch off tools a lot for sealed system access. But I don't like to use them on discharge lines like for a rooftop condensing unit because I've been on at least 3 calls where a discharge line access valve broke at the pinched off section.

Anytime I pinch off for a sealed system, once I recover, I cut out the pinch-off section.

[Kelly T]

I have used one for years , never had a problem with them, but mainly use them for true boxs and manitiwocs as others have mentioned.

3 pinch off tools to change a headmaster? why didnt' I think of that

[VTP99]

O.K. after seeing your commits here next opportunity i'll give it another go. One more thing comes to mind. Are we not worried about trapped AIR ?

[VTP99]

If you have the room I pinch it twice about an inch apart. They never come out round but it can save you a lot of time.

I don't know why i didn't think of doing that.

[icemeister]

O.K. after seeing your commits here next opportunity i'll give it another go. One more thing comes to mind. Are we not worried about trapped AIR ?

If Manitowoc wants you to replace in-warranty controls this way, let them worry about the trapped air.

For access valves, I just do a little purge after re-rounding.

[VTP99]

If Manitowoc wants you to replace in-warranty controls this way, let them worry about the trapped air.

For access valves, I just do a little purge after re-rounding.

Good point icemeister. No problem on the purge if you forget to put to core back in.

[yoyohat]

When you braze in access ports on a true or other unit that is full of refrigerant, is there any worry about brazing a part without being able to use nitrogen? Does this cause any problems down the road with "scaling" perhaps clogging a metering device?

[bob_scheel]

When you braze in access ports on a true or other unit that is full of refrigerant, is there any worry about brazing a part without being able to use nitrogen? Does this cause any problems down the road with "scaling" perhaps clogging a metering device?

You can squirt some nitrogen into the fittings before you braze. Even though it is not flowing it will still prevent oxidation. Also the small amount of oxidation created would be blown out by a purge after you opened the pinch. Usually you are talking about less gas than would be in a charging hose. I do question applying heat to the pinch off to dab some braze on it. That would likely produce some acid by breaking down the refrigerant.

[yoyohat]

Thanks for your reply bob_scheel.

[MicahWes]

Wouldn't applying heat to brazing temperature weaken the copper so that in the end the added brazing alloy gets your strength back to where it would have been if you had just left it alone?

[VTP99]

Wouldn't applying heat to brazing temperature weaken the copper so that in the end the added brazing alloy gets your strength back to where it would have been if you had just left it alone?

If I was to fold a 1/4" copper tube and open it back up it would be quit weak at the kink. Pretty much what you get with the pinch-off tool. Now if you just welded the kink I would agree with you. Personally I would weld beyond that point. It would be much stronger and no different then any other weld you make.