GTA
All Springer/NP/PCP Air Gun Discussion General => PCP/CO2/HPA Air Gun Gates "The Darkside" => Topic started by: Rimshot on January 03, 2019, 07:57:08 PM
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So doing some cleaning and maintenance on my pcps and shoebox compressor and I am wondering if the membership has found something better than Teflon tape. I have seen a white substance on high pressure fittings that isn't Teflon tape.
Another question when using Teflon tape is how many wraps are preferred?
Thanks
Rim
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Possibly what you've seen is pipe dope. Spreadable teflon, but it's pretty messy for airguns:
https://www.lowes.com/pd/RectorSeal-T-Plus-2-Sealant/1000092785 (https://www.lowes.com/pd/RectorSeal-T-Plus-2-Sealant/1000092785)
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Yellow gas tape, ninja tape is the best
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If you go to a plumbing supply they carry a heavier Teflon tape that is impregnated with the blue thread seal and it works great on pressure fittings
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I use the yellow "Gas-fitters" Teflon tape....
Bob
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On more vote for the yellow gas fitter tape. Seals up every time with two wraps no over tightening like the cheap white stuff required .
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Thanks for the info. I have couple fittings that use PTFE tape and the white stuff is not very good. I'll pick up some of the yellow.
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I use the yellow myslef, holds up good if wrapped right. It's on my fill adaptor for my tanks and any gun that I've repaired.
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Yellow tape,i tried different sealants,but you must clean,degrease and wait hours to pressurize and test,not practical for me.
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Just threaded together some NPT fittings the other day, to make two sets of 90 degree set ups with male and female QD’s on the ends, and used regular white Teflon tape, but also with a light coat of Nylog. Anytime I’ve used this stuff I never, ever, get a leak thereafter. I’ve even used it on the gage threads on what’s on the gun. The PRod’s gage was the last one
.https://images-na.ssl-images-amazon.com/images/I/31F6JYudn6L.jpg
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Looks like good stuff
https://www.youtube.com/watch?time_continue=8&v=sA1WY9oAq7E (https://www.youtube.com/watch?time_continue=8&v=sA1WY9oAq7E)
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Isn't the tape's primary purpose to act as an anti-seize agent and lubricant? The threads should be doing all of the sealing.
The tape is just a band-aid covering poor fit, if it's necessary to seal the fitting.
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I have heard that argument, and yet every time I take apart a tapered pipe fitting I have used Teflon tape on, there is inevitably small pieces of tape crushed into the valleys of the threads on both the male and female sides.... taking up space where there must, therefore, have been a gap....
Parallel threads leak because when tightened they leave a spiral groove on one side of the threads due to clearances.... The THEORY is that tapered threads don't have that, because as you tighten them, the threads fit progressively tighter and tighter and leave no room for air to escape.... That's a great theory, and would be fact, if the PROFILE of the threads, both male and female, fitted precisely together.... However, the reality is, IMO, that there remains a void at the top of each peak / bottom of each valley, caused by non-perfect machining.... It is THAT spiral space that the Teflon tape fills to help prevent leaks....
Bob
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I thought the seal was achieved at the very base of the male fitting when it
bottoms out. Poor choice of words, not bottomed out in the way that a unified burst disk bottoms out and seals against the bottom. I mean bottomed in the sense that the tapers allow no further engagement.
Some of the more detailed manufacturer recommendations say to take care not to apply PTFE tape to the first 2 threads. I presumed that was so it does not contaminate that critical area. When taking apart tapered fittings, I've noticed the very end of the male fitting often has some slight deformation to the thread profile which I why I thought that is where the critical sealing point was achieved...and why they said avoid applying tape to that area. However after reading some more, it seems that recommendation has more to do with preventing tape from breaking away from the end and contaminating the system (e.g. getting stuck in an orifice or valve seat). The subject of sealant vs lubricant is so contentious that I'm having difficulty finding an authoritative source.
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Pipe thread doesn't "bottom out", both male and female threads are tapered.... and the tapers just progressively get less and less clearance until they wedge together and the torque required to tighten them more would break the fitting, or gall the threads.... There is no question that the Teflon tape acts as a lubricant, and allows you to get more "pressure" between the interference fit of the threads than you could without it.... However, I still think it acts as a sealant as well.... or at the very least allows a joint to seal without overtightening it.... Can I prove it?.... no.... Have I ever managed to get a seal without it?.... again, no.... Would I assemble pipe threads "dry" or without Teflon tape?.... not if I ever wanted to take it apart again and expect to be able to reuse the parts....
Bob
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Jason,
Bob hit the nail on the head!
Bring up the point of leaving the first two threads unwrapped or clean of tape. That will help with good thread alignment and not
cross-threading of mating surfaces. It helps with tape not falling into whatever it is the treaded into. I have seen balls of tape the airlines that weren't wrapped with tape properly. Stands of tape can dislodge and become free to clog up whatever is at the end of the path it follows. Air or water fittings should be properly taped the number of turns/wraps depend on thead pitch too, finer threads equals less wraps then course threads.
Tape or sealant depends on types of materials used, SS in SS, SS in Alum can gall up the threads like crazy. Brass on SS/Alum or Brass on Brass is the best IMO and most forgiving. We use the correct tread tape/sealant for the application at work.
For airgun use I use the Yellow Tape designed for gas appilications, it works the best for me. I really like the Black Ninja tape, the only down side is $$ and availability. It can be purchased online or at some paintball shops. Yellow Tape can be picked up anywhere at the local hardware store.
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some people use too much as well as not wrapping tight enough.
so when it is just started threading on, the entire layered up tape gets cut off as one and never makes it inbetween the threads
I discovered this with many jobs by plumbers, I personally find it better to wrap tight and also use finger pressure on the tape to have it compressed well before threading on the female part.
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I agree, also wrapping the tape around the threads in the same direction of threads too.
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I thought the seal was achieved at the very base of the male fitting when it bottoms out. Poor choice of words, not bottomed out in the way that a unified burst disk bottoms out and seals against the bottom. I mean bottomed in the sense that the tapers allow no further engagement.
Some of the more detailed manufacturer recommendations say to take care not to apply PTFE tape to the first 2 threads. I presumed that was so it does not contaminate that critical area. When taking apart tapered fittings, I've noticed the very end of the male fitting often has some slight deformation to the thread profile which I why I thought that is where the critical sealing point was achieved...and why they said avoid applying tape to that area. However after reading some more, it seems that recommendation has more to do with preventing tape from breaking away from the end and contaminating the system (e.g. getting stuck in an orifice or valve seat). The subject of sealant vs lubricant is so contentious that I'm having difficulty finding an authoritative source.
Actually it is recommended to leave the first threads clear of tape to prevent contamination of the working(moving parts) on the inside of gas valves and such due to probable valve failure caused by bits of pipe dope or teflon migrating into the inner workings of the valve.
I know this from being a gas certified HVAC mechanic for 30+ years. Also what Bob S. said the machining is not up to Mil Specs or NASA machining standards.
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When that roll of tape gets wild and tape goes everywhere... What I do is hold the roll as if I were trying to wrap it back on this helps keep the tape tight and allows you to control the feed as you wrap.