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FPT thread

Here is the link Brad referred to. I'm tooting my own horn, I went on to give lengthy answers in my post, but there was lots of good stuff in the whole thread.

You'll notice how your 1 inch fitting falls between the 11 thread per inch you have in Europe and the 11.5 pitch we have on this side.

I don't know how easy it is to find an adaptor outside of the US, I think most of the world happily ignores our quirky measurement methods. We're the ones adapting - not the other way around.

The grave difficulty with going to a machine shop in Europe to get an 11.5 pitch is that most engine lathes there are not equipped for that oddity. It will call for the extra work of calculating a gear ratio. 11.5 is an incredibly stupid number, so is 11 by the way. Easy to divide 12 would have been so nice.

Identify the thread first before forcing anything.


Thread gauges in Europe often don't even contain the 11.5 leaf. If anyone is interested in getting the thread gauge I mention, I have found a good source. Let me know. I'm in OH.


  • Jimmy Gillies
    Jimmy Gillies Member Posts: 250
    1'' FPT threads

    We are trying to install Heat Pumps and I have very limited information from site, can you please help.
    Our Plumber on site has 1''FPT threads(female)on the Heat Pump and I think?? they may a US thread type, does anyone know where we can get any connections to take us back to 1''BSP.
    Thanks very much.
    Jimmy Gillies.
  • Brad White_9
    Brad White_9 Member Posts: 2,440
    No pun intended, but

    there was an excellent thread on this site a couple of months ago, maybe longer, on BSP versus US standard threads. In one standard the pitch lined up enough but without taper to make it workable with wick and dope as I recall.

    Viessmann gives adapters for their 3/4" (19mm) connections so I am sure that they are commercially available. Not sure where, but I suspect the Italian brass companies are doing a brisk business these days.

    Sorry not a full usable answer but perhaps a drop of hope?
  • Bill_17
    Bill_17 Member Posts: 68
    BSP to NPT

    Most hydraulic equipment suppliers carry adapters for BSP to NPT and vice versa. Good luck.
  • Brad White_115
    Brad White_115 Member Posts: 4
    How could I forget the author?

    Thanks, Christian, for the link and as always, for the erudition.
This discussion has been closed.