BogMonster Posted January 9, 2010 Share Posted January 9, 2010 A few weeks ago I got a Britpart double-pump compressor like this http://www.britpart.com/Accessory.asp?PageRef=4&AccessoryRef=2144 it's a good bit of kit (basically the same as all the other double pump units) but the other day I managed to bust the clear window on the pressure gauge in the process of trying to pull it back out my thumb slipped and I managed to fk up the guts of the gauge as well Haven't found any gauges with a thread this small in any of the shops here but I am confused as to what thread it might be. It is almost exactly 8mm according to my calipers: but it definitely isn't 8mm metric as it is a finer thread than a standard M8 bolt, and it would seem to be slightly tapered as well. The other thing I am confused about is that in a shop, I found a similar gauge (50mm face diameter, rear entry) but with a thread about twice the size however the manufacturers label said this was being sold as a 1/4" BSP fitting despite the fitting being about 1/2" in diameter! (I didn't measure it, as it was obviously no good for what I needed). Almost all the gauges seem to be BSP or NPT threads, so what size might it be? If the gauge fitting that was a bit over half an inch in diameter was supposed to be a 1/4 BSP (which I don't understand) then I guess mine might be a "1/8 BSP" but I don't understand the sizing if a thread 8mm in diameter can be a 1/8" size - can anybody clarify this? There are also some sold as "G1/4" and "G1/8" e.g. the ones here http://www.bearingboys.co.uk/Gauge_-_Back_Entry-1593-c not sure if these are BSP or NPT or Wibblymetroimperial or what Help! Quote Link to comment Share on other sites More sharing options...
errol209 Posted January 9, 2010 Share Posted January 9, 2010 Help! I could be 1/8 BSPT (British Standard Pipe Taper(ed)), as the 1/8 bit refers to the ID of the pipe you use, not the OD of the fitting (1/2 BSP fittings are about an inch across!) Try this page Edit: However 8mm doesn't make an appearance! Edit again: but 1/16 NPT is bang on. Quote Link to comment Share on other sites More sharing options...
Jon White Posted January 9, 2010 Share Posted January 9, 2010 1/8 BSP, 1/8 NPT and M10x1 are all very, very similar and infact will all more or less screw into each other as the threads are that close. All are more or less 10mm major diameter so its none of them. 1/16 BSP is the most likely but is a fairly uncommon size as that is 7.723mm major diameter and 28tpi. Alternately it could just be M8 fine. Whats the pitch of the thread? HTH Jon Quote Link to comment Share on other sites More sharing options...
BogMonster Posted January 10, 2010 Author Share Posted January 10, 2010 Thanks, 1/16 NPT seems like a possibility then, will get calipers and try measuring the thread pitch. Any of the possibilities look like they will need to come from the rocking horse poo shop Quote Link to comment Share on other sites More sharing options...
zim Posted January 10, 2010 Share Posted January 10, 2010 1/8 bsp or bspt. can't see 100% take out a breather from your landrover axle, and try screw it it - they're 1/8 bsp. i think the ports on the older ARB compressor (the ones where the solenoids screw in) are 1/8 bspt. G Quote Link to comment Share on other sites More sharing options...
Jon White Posted January 10, 2010 Share Posted January 10, 2010 Zim - it cant be 1/8BSP as the OD is too small! Either 1/16 BSPT or 1/16NPT are the most likely. BSP is 28tpi, NPT is 27tpi. You really need to get a set of thread pitch gauges on it to work out which one it is! Only other possibility is M8x1 or M8x0.75 but these wouldnt be tapered. HTH Jon Quote Link to comment Share on other sites More sharing options...
Jon White Posted January 10, 2010 Share Posted January 10, 2010 Oh I should add in answer to your first question, G1/8 and G1/4 refer to 1/8 and 1/4 BSP parrallel i.e. not tapered. You can read all about it here http://en.wikipedia.org/wiki/British_standard_pipe_thread Jon Quote Link to comment Share on other sites More sharing options...
BogMonster Posted January 10, 2010 Author Share Posted January 10, 2010 27 into 28 sounds like a good self-sealing locking thread if one is wound into the other and it happens to be wrong Thanks, I will have to continue the hunt, looks like the 1/8 BSP gauge that I identified is not going to be any use Quote Link to comment Share on other sites More sharing options...
Jon White Posted January 10, 2010 Share Posted January 10, 2010 Just bear in mind the od's are slightly different, but they're all so close that they can be bastardised into each other! Jon Quote Link to comment Share on other sites More sharing options...
BogMonster Posted January 10, 2010 Author Share Posted January 10, 2010 So far the bastardising was mostly verbal when I broke it but that may be the way forwards The snag is there is not much room to lash up adaptors if I still want to fit it in the plastic carry case that the compressor lives in, so it needs to be small and easy to stow. Quote Link to comment Share on other sites More sharing options...
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