PTFE Tape

[malcopate]

Hi Guys new to the forum at present having a few issues with my boss over the use of PTFE Tape on R134a refrigerants/oils .I have explained to him that this is not suitable for these applications as it leaks thru time due to a chemical breakdown,however my opinion is not being recognised as yet. Is there anyone out there who can give me some hard facts(preferably in the form of scientific proof or Defra/fgas origins).As at present i only have opinions from other fridge engineers and opinions dont count with him.The sooner the better thanx guys.

[NB12]

I dont have any specific data but I have been led to believe that you can no longer use ptfe tape for any refrigerant aplication, and are now meant to use a thread paste of some sort. Loctite or some sort, we used a paste from wurth that was refered to as blue gunk.

[hyperion]

There is an alternative version of PTFE which is supposed to be gas suitable. This looks the same but is supplied in a Yellow outer cover. Have successfully used this on a R134A installation when the thread sealant had failed. As this is primarily a plumbing product, I have no data as to its suitability for refrigerants.

[monkey spanners]

Found this,

http://www.allchemi.com/eng/refregerants/compatibility.html

Seems like ptfe is only just compatible with all refrigerants, maybe is the combination with POE oil that causes leaks.

[Quality]

PTFE is almost bullet proof but loctite 577 is indestructible

[stufus]

I'm with Quality on this one !!
Loctite 577 ,there is no substitute..
Cheers
Stu

[Grizzly]

Malco
Yours is an interesting post.
I posed a similar question nearly 3 yrs ago.
http://www.refrigeration-engineer.com/forums/showthread.php?19185-Sealing-Threaded-joints-with-P.T.F.E.&highlight=PTFE

The interesting thing is I recently visited that particular site and discovered a leak on one of the actual PRV'S I was talking about.
Only it was not one of the ones that I had installed with PTFE but One of the special loctite ones.

Basically I was one of the ones that believed the E stood for Ethylene as the E in POE oils.
Therefore the theory about the tape "breaking down" would make sense.
The problem is that I have been monitoring these and other joints for quite a while now and yet to find a PTFE one leaking.
One point is that a leaking thread sealed with PTFE can be "Nipped up" IE the joint can be moved and the seal regained. However a loctite joint cannot as they cure dry, there is a green one that allegedly the joint can be disturbed.
Some of the green one I have done did not like being disturbed!
I too like MS and Quality have read elsewhere about PTFE's Virtually impervious to all chemicals.
So although Loctite is very specialist it is less forgiving than PTFE. The one that comes with the yellow top is stated as Gas tape, because it is thicker and is designed to be wrapped around the thread ONCE.
I seem to remember the term single wrap being used somewhere?
And yes it is primarily used by Plumbers / Gas Fitters.

In summary Malcopate, I to had the same belief with regard to PTFE but have since changed my mind.
In defence of those that do not like its use. More care is required to obtain a proper leak free joint when using the tape but as I say it is more forgiving in the long run.
Grizzly

[Magoo]

I'm with Quality on this one !!
Loctite 577 ,there is no substitute..
Cheers
Stu
Totally agree Stufus, in the past had lots of nasty experiences with PTFE and R22, loctite 577 is a god send

[malcopate]

thanx lads great feed back did a little research myself and yes its niether here nor there,however a-gas came back with a similar chart to monkey spanner....marginal but lock tite seems to be the stuff of preference but a wee bit costly but if it saves the world then so be it lol.

[Grizzly]

I knew I had read something somewhere!
Grizzly

P.T.F.E. POLYTETRAFLUORETHYLENE
TEMP RANGE -195°c to +250°c
P.T.F.E. is an extremely inert material and is unaffected by virtually every known chemical including almost all acids, alkalis and solvents.
These exceptional properties make P.T.F.E. an ideal material for O-ring Back up Rings. It's cold flow characteristics under permanent strain are usually a disadvantage in P.T.F.E. O-Rings, e.g. It has little memory to return to its original form.

[AlexG]

Agree with Grizzly. PTFE is known like teflon with high chemical resistance.

[stufus]

There's also Slic Tite (LA-CO)which is a liquid PTFE suitable for fluids ,gas, refrigerants and oil's .
Have used it on heavy oil installations but not for refrigerant applications so can't vouch for it ,but if you believe what you read , should be suitable.
Cheers
Stu

[monkey spanners]

Been using this stuff for 10+ years, not had any leaks with it. This is mostly on R22 R404A R437A and R134a.
Its cheaper that locktite. Available at FSW (RPW as was)

http://www.toolstation.com/shop/Plumbing/Consumables/Tru+Blu+50g/d20/sd2711/p40236

Not to be confused with that leak lock $hite!

Also used on mains an chilled water too with good results!

(have got some of that LA CO slicktite stuff too and its great on water etc but seems a bit gritty for ref systems (though have seen it used on gaskets...))