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  • Need help identifying odd fitting

    OK, time to check with the Galactic Compendeum of All Knowledge in the Universe... You guys!

    I have been tasked with identifying an odd hose barb fitting for work.



    This is a black plastic (possibly nylon) fitting that supplies DI cooling water to the aluminum buss on the secondary of a 90 MVA transformer. It was damaged during an arc flash and fire. We currently have no leaks, but MANY (i.e. >60) need replacement.

    The barb is easy enough, but I'm having real trouble id'ing the thread.



    NOTE: Being a softer plastic, measurements may be off +/- a few thou.

    It is a straight thread with an o-ring seal.

    I have checked and rechecked the thread and I keep getting 25 tpi.

    I do not have thread gages, but I counted 10 threads and measured 0.400".

    I have compared the threads to a 5/16 x 24 bolt - too coarse.

    1/4" x 28 bolt - too fine.

    Overall size is very close to 1/8" x 27 npt, but the threads not still not quite right.

    I have been all over the net and have achieved nothing but confusion.

    Any insight will be greatly appreciated.

    Suitable replacement parts would need to be (in order of desireability) plastic, stainless, or brass. Absolutely nothing magnetic.

    Thanks
    Last edited by kyfho; 06-25-2012, 02:55 PM.

  • #2
    Originally posted by kyfho
    I have checked and rechecked the thread and I keep getting 25 tpi.


    Any chance that it is a Metric thread, (10X1.0 for example)?


    Rex

    Comment


    • #3
      Looks like BSPP to me...

      That would be British Standard Pipe Parallel. Check out McMaster-Carr, I think they may have what you need. Later.

      Dave

      Comment


      • #4
        Looks to be a NST National straight thread (no taper). On some of the Ille whirlpools one of the fittings was an 11/16 straight pipe thread. Finally bought a tap and die set, as the factory replacements were really stupidly expensive for replacing.
        Try here they have an extensive lines of fittings. www.usplastic.com
        Glen
        Been there, probably broke it, doing that!
        I am not a lawyer, and never played one on TV!
        All the usual and standard disclaimers apply. Do not try this at home, use only as directed, No warranties express or implied, for the intended use or the suggested uses, Wear safety glasses, closed course, professionals only

        Comment


        • #5
          I think daved20319 may have called it. Try a 1/8-28 bspp

          Comment


          • #6
            With the seal on the O-ring, it't not likely to be a pipe thread. You could compare the thread pitch against an M6x1 metric screw. As Rex suggests, it could be an M10x1 special pitch. I can't find any British or American thread with 25tpi.

            Dave Cameron

            Comment


            • #7
              Lot of special thread stuff at 1.00 mm pitch.
              In fact just run 80 unions off on the little CNC tonight at M12 x 1.0 for some Japanese air brushes.

              Repeat job and they come thru in 40's up to 100 at a time, must have done 700 to 800 now over two years
              .

              Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.



              Comment


              • #8
                I've found several things in the past with a 25 TPI thread, and these things had imperial threads elsewhere, so a metric thread is unlikely.

                That said, unless the mating nut is long, and close fitting, there's very little difference between 1.00 mm pitch and 25 TPI.

                So, I;m saying that TPI is quite possible as a special, but if you;re replacing it with something off-the-shelf, go with 1.00 mm, or even 26TPI at a pinch, if it'll fit.
                Richard - SW London, UK, EU.

                Comment


                • #9
                  Although it is certainly not a "standard" thread, it could very well be 3/8" X 1.0 MM. Mixed imperial and metric dimensions are not common but I have run across a few. Most US lathes will not cut 25 TPI but will cut 26 TPI. Neither is a common thread but 13 TPI is common for 1/2" so 26 TPI is on the gearbox.
                  Don Young

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                  • #10
                    If the manufacturer of the equipment is still in business, why not ask them?

                    Comment


                    • #11
                      I know it's plastic but 3/8" x 26 BSB [ Brit Standard Brass - virtually same as Cycle thread ] is a standard.

                      BSB is as it's name implies is used for brass fittings over here.

                      The other semi standard are Enotts fittings which are all 24 thread regardless of size. These were very common for screwed air line fitting in the days before push in's

                      One thing about standards is that there are plenty of them.
                      .

                      Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.



                      Comment


                      • #12
                        M10 by 1.0 is not uncommon in braking systems. I have a tap to that spec for cleaning up caliper threads.
                        Paul Compton
                        www.morini-mania.co.uk
                        http://www.youtube.com/user/EVguru

                        Comment


                        • #13
                          Originally posted by Don Young
                          Although it is certainly not a "standard" thread, it could very well be 3/8" X 1.0 MM. Mixed imperial and metric dimensions are not common but I have run across a few. Most US lathes will not cut 25 TPI but will cut 26 TPI. Neither is a common thread but 13 TPI is common for 1/2" so 26 TPI is on the gearbox.
                          I've come across 10mm x 26 tpi before, so the reverse is just as possible.

                          Tim

                          Comment


                          • #14
                            A 3/8" UNF is 24 TPI.

                            Nev
                            Nev.

                            Comment


                            • #15
                              This seems to be the Mother of all Identification Charts. I bookmarked it.

                              Comment

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