tap valves

[tarz]

What is the best method to tap systems under pressure without creating a future leak? Such as taking a pressure reading at the evap outlet,etc not equipped with pressure tap.

[Dad]

A bullet valve is the only way that I know but it is a leak waiting to happen.

Why some companies do not put pressure taps on their systems I will never know. Maybe they don't want every technician in town to install gauges and lower the preset charge. They should have their heads examined and trust a professional. They want you to check cap tube systems by subcooling.

Wish I could help but we run into them everyday.

[smilies]

On small systems I use these Vise-grip pliers with a piercing tap at the jaws. This way you can't leave the bullet valves on. They are a leak just kicking back waiting until that weekend.

Be sure it's a gas problem first.

[R12rules]

Check out this old thread.

http://hvac-talk.com/vbb/showthread.php?threadid=34132

or

http://hvac-talk.com/vbb/showthread....9&pagenumber=2

[Edited by R12rules on 06-01-2004 at 11:39 PM]

[R12rules]

In my opinion, these are a must have tool on your truck. I have never had any trouble with them.

I put them on systems which were charged and running.

I always sweat them on using either Stay Brite #8 or 45% silver brase.

They are great!

[Dad]

Thanks R12...

I have tried them but I was not very comfortable heating a liquid line. Saw one of my techs try one for the first time and paid the price. He started using a pinch off tool on the processing tubes. Added an access fitting and reopened the tube.

My way is this. I check all other possible causes and cures, only then do I get into a preset charge system. I let the customer know up front what I have to do. I am confident when I leave that the box is good to go and not a recall waiting for next Saturday. I just don't like recalls. Makes me feel stupid.

[tarz]

I tried the C&D M series valve yesterday and I soaped it up and it leaked, even with the cap on. Was it just me, what the trick?

[R12rules]

Originally posted by tarz
I tried the C&D M series valve yesterday and I soaped it up and it leaked, even with the cap on. Was it just me, what the trick?

Okay ... here goes.


First I select the spot I want the tap to be mounted.

I choose a location far as I can from any other soldered joint. The reason I use Stay Brite solder for this type of work is the melting range. It is so low. around 450 degrees farenheight.
Whereas silverbrase is around eleven hundred and fifteen percent is around four hundred degrees ABOVE that!
So ... in MOST CASES, the tap your installing and the solder you'll be using are NOT going to be disturbing any other soldered or brased joint on your sealed system!


Next I choose the location to be free from being out of round on the tubing I am about to join this tap onto.

Next I super clean the tube to a luster. Next I super clean the tap inside and out where I am going to be soldering.

Then I apply a small amount of flux to the place where the tap will mount.

Then I set the tap in place. I hold it with one hand while I take a pair of pliers or a tiny hammer and fold, mold the sides of the saddle tap onto the tubing.
I actually tap, tap, tap ... on the line tap saddle sides themselves in order to conform them, to mold them into a perfect fit onto the contour of the tube itself.

Then I apply a tiny bit more fulx paste to the joint ....finally I being applying heat to the underside of the joint. I then add the Stay Brite #8 silver bearing solder to the heated joint.
This solder is $30 a pount. It is sold in one pound rolls.

I apply just the bare minimum amount of sodler to the joint.


Then I shut down the torch, take a cool rag and take the heat out of the joint, then I apply a charging hose to the tap and apply either refrigerant pressure or nitrogen pressure.
Note, I have NOT yet pierced the line! I have not gone beyond the oint of no return!

If I have a bad solder joint, there is yet time to resolder and make it 100% leak free!

Also, with the tap being installed in this manner, I am able to freely inspect the inside of the soldered joint for excess solder to any inperfections there may be.

And all of this preliminary work is performed to the joint BEFORE the line has ever been pierced and possibly compromised.

Then and only then ... when I am 100% satisfied that I have a 100% leak free joint, do I install the piercing bullet. And ebfore I insert this bullet into the tap, I first set the white nylon "O" ring onto the sharp end of the piercing bullet.
Then, using a back up wrench on the tap at it's soldered base ... I tighten down the special brass cap onto the tap. This drived the bullet down into piercing the tubing joint itself.

Located inside the bullet is the schraeder valve core assembly.
The valve core in these taps is removeable, but of course .....


And anybody whose a technician and doesnt use these tps, or cant find a good reason to use4 them ... well, they are probably not able to stand on their heads and recite the emancepation proclamation, in it's entirety, neither!!!



Hope this helps.


[Edited by R12rules on 06-03-2004 at 01:09 AM]

[mccool]

Of Course if your in a market all the above does'nt apply!

[tarz]

Thanks R12 for the very detailed explanation. I will try your method next time.

[R12rules]

Originally posted by mccool
Of Course if your in a market all the above does'nt apply!

Hell, in a market, if and when I need to read a pressure or install a schraeder where there was none, I'd jus take out my alignment awl and a hammer .... punch a hole in the line and stick in a schraeder on a tube stub. Then sweat it in place.

Of course .... I'd have the core outa there first ... that would allow the fosgene to vent off and not hinder my welding process.


And then on a liguid line, I'd probably have to step up the heat quite a bit due to the cooling affect caused by the liquid freon squirtin' out the hole!

Doing it like this would save on pumping down the system with those leaky ball valves. Plus it would surely save time on evacuation too.












Jus kidding guys.

[NedFlanders]

.

Originally posted by R12rules
And then on a liguid line, I'd probably have to step up the heat quite a bit due to the cooling affect caused by the liquid freon squirtin' out the hole! [/B]

I've actually heard stories about some old cranky Hussmann construction foreman doing this.

It does seem possible.
But I would've not wanted to be around when it was attempted.

Back then though , they were real men...smokin' Camels , greasy pompadores ,sleaves rolled up with battleship tatoos on their arms.

How 'bout it Dave , was it really like that?