Tag: nylog


Service valves are so basic and we see them with such regularity that we can miss them altogether.

Before I give the tips I want to address the tech who tells the customer it was “probably the service valve” or “the caps were loose” as a plausible reason for a leak without actually doing a proper diagnosis. Don’t make excuses, find the leak.

Now some tips.

#1 – Look before you connect

Look for oil around ports BEFORE you connect your gauges every time. If you have a leaking schrader and cap you want to know that before you connect your gauges and eliminate that leak. Keep in mind that a service cap is NEVER meant to be the seal from a leak, it does act as an insurance policy against a tiny leak in a schrader. If you find a leaking schrader, replace it.

#2 – Be Gentle With the Heat 

No matter the valve make sure you protect it from heat when brazing or soldering (Here’s looking at you Staybrite #8 techs).

The schraders should be out when brazing anyway, but the internals of the valve are also sensitive to heat. Ever see a valve leaking from the stem? Odds are it was overheated at some point.

When opening and closing the valve DON’T CRANK DOWN so hard. We all know you are strong, but when you crank it open and closed like that you can over-compress and damage the seals and mating surfaces. Snug is good, if you need to “put your back into it” it’s probably too much.

#3 – Check Your Seals

A 1/4″ service port is actually just a 1/4″ flare fitting. Technically they don’t NEED a seal if the cap is a flare cap (think Trane brass caps). The only trouble with the brass flare caps is they do need to be on pretty snug to seal.

Most manufacturers have gone to caps with a rubber O-ring seal inside, they seal better and they only need to be finger tight. Before installing these caps get in the habit of checking the seal EVERY TIME. Make sure it’s there and that it’s in flat.

I have seen many leaks caused by an O-ring that got put in cockeyed and depressed the schrader slightly when the cap was installed.

#4 – Try the New Fangled Technology

We used to always advise using a bit of refrigerant oil when making flares and even when reinstalling the top caps on service valves. The oil doesn’t really “seal” anything but it helps you get a snug fit without twisting or damaging anything (the technical term is “galling”).

Trouble is, we are going away from mineral oil and toward POE and POE fouls if it is exposed to the air (humidity) for too long. Granted, a drop of mineral oil on a flare isn’t going to hurt a POE system but IT’S THE PRINCIPLE DANGIT!

I have raged against the use of thread sealants like leak lock in refrigerant circuits for years. I’ve seen teflon tape and leak lock on flare fittings and Chatleff fittings… Teflon tape and leak lock do not belong on refrigerant circuit components folks. They aren’t designed for that purpose and if they get in the system they are gonna cause issues. In many gases gumming up the threads and mating surfaces with these products can inhibit a good seal by getting between the flare mating surfaces.

A product I like is called Nylog it’s a very thick but constantly viscous product (never gets hard) and it won’t hurt the system if a little gets inside because it’s made of refrigerant oil.

You can put a drop on the threads and mating surfaces of all your flares, chatleff connections (the valve connections with the teflon seals), top caps on your service valves, pipe threaded ports…. everywhere.. but just a drop

You can also use it on your hose connections to get a better seal when pulling a vacuum.

Just use a small amount otherwise dirt will stick all over everything.

#5 – Using the Right Wrench and Back it Up 

For those systems that still use flare hex caps its best to use a 9/16 box end wrench or flare wrench (shown above) and use a backing wrench when removing the cap. All it takes is ONE TIME of breaking it off to regret using a big ‘ol adjustable wrench.

— Bryan

 

First off we need to clarify that very few unitary manufacturers use flares anymore. You will most often find flares on ductless and VRF / VRV systems and in refrigeration. A flare uses a flared female cone formed into tubing (usually copper) that is pressed onto a male cone (usually brass) by a threaded flare nut. A flare shouldn’t be confused with a chatleff fitting that uses a threaded nut and seals with teflon or nylon seal.

This is not a full lesson on how to make a flare, this will give you some best practices to make a flare that doesn’t leak.

  • Use proper depth, the old school method is to bring the copper up a dimes width above the block but modern flaring blocks usually have built in gauges that work well.
  • Don’t trust factory flares. In many cases factory line-set flares are made poorly, often it’s better to just cut them off and start over
  • Ream the copper before flaring to remove the burr but don’t OVEREAM and thin out the copper edge.
  • Use a good, modern flaring tool designed for refrigeration. This is a great one
  • When making the flare use a bit of refrigerant oil, or even a better a bit of Nylog. You only need a drop or two, one drop on the flare while making it to prevent binding and create a smoother flare surface with a bit on the back of the flare as well to allow the nut to slide easily. I also like one small drop on the threads and spread to the mating surfaces. Some manufacturers disagree with this due to the effect it has on torque specs so always follow their recommendations when in doubt. In my experience a bit of assembly lubricant really helps.
  • Use a flare wrench instead of an adjustable wrench and tighten with a torque wrench.  I understand that very few techs do this… but it is a great practice if you want to get it right the first time with no leaks and no damage. This can be done easily be done with a set of SAE crowsfoot flare nut wrenches and a 3/8″ torque wrench. As always use manufacturers torque specs if available. If not you may use the chart below. Make sure to keep the crowsfoot at 90 degrees to the wrench (perpendicular) and place your hand on the end grip of the wrench. If you have lubricant on the threads stay on the low side of the torque rating.

Some things NOT to do that I’ve seen –

  • Don’t use leak lock or teflon tape on flares
  • Don’t Over Tighten flares to try and get them to stop leaking. If they are properly torqued and still leak they are made wrong
  • Don’t use too much oil or nylog, a drop or two will do
  • Don’t try and jam a teflon seal from a chatleff on a flare

Using these practices we have VERY FEW leaks on flare fittings.

Some other things to note –

There is a company called Spin that uses a flaring tool that goes on a drill. Their tool actually heats and anneals the copper. They claim they don’t need to get the flare to 45 degrees because the annealing makes the copper soft enough that the nut itself with finish the flare. We have used it a few times with good results.

There are now companies that make nylon / teflon (I’m actually not sure what they are made of) gasket inserts that go into a flare. Some techs swear by them, I really don’t see the necessity but I don’t have any experience with them.

Finally, make sure when your system has flares to pressure test to the rated test pressure and bubble test the joints. Then perform a vacuum to below 500 microns and decay test. This will help ensure that you got it right. If it leaks, cut it off and remake it.

  • Use a good tool
  • Get depth correct
  • Ream properly
  • Use a good assembly lubricant
  • Torque properly
  • Pressure test to 300+ PSIG (in most cases) and bubble test carefully

— Bryan

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