3/8in brass unions

[DavidThompson]

Having replaced the fuel pump in my car I need to fit a pressure regulator, but am struggling to find a supplier of brass fittings for the 3/8in copper fuel pipe.
I want to avoid rubber tube and push on fittings, which would be an easy option.
Anyone any ideas where I might get them?

[John Murch]

https://www.vintagecarparts.co.uk/categories/vintage-car-parts-taps-pipe-and-fittings-fittings

Not sure if anything here would be what you are after.

[DavidThompson]

Thanks John, I had spoken to VS but strangely without a positive result.
The mysteries of thread sizes and descriptions unfold as I try and find the bits I need. My quest would probably be easier if I knew what I was talking about, but sadly that is not the case.
Am I correct in thinking that 3/8 BSP relates to the internal diameter of the fitting? i.e. the OD of the pipe which is to be joined?, and that the OD of the male thread is 16.6mm? the internal female thread being 15.2mm ID?
Anyone know what the female thread ID is of 1/8 NPT?

[John Murch]

I hope someone wiser than I can answer your question.
I have always found pipe fittings and sizing a nightmare.

[Christopher Carnley]

David,

Which fitting are you looking for, is it the compression type, and more to the point, what does the pipe attach to, and what are its threads?

BSP refers to the external diameter of the pipe that the fitting is intended to fit.

[Nicholas Simons]

David
Unlike Metric, BSF and Whitworth threads, the ruling dimension for BSP is not the outside nominal diameter of the male thread. See
https://en.wikipedia.org/wiki/British_Standard_Pipe
for details.

[DavidThompson]

Christopher & Nicolas,
Thank you for your useful replies.
I am now minded that I need 3/8 BSP unions, preferably compression for ease, and 3/8 BSP to 1/8 NPT adaptors to allow connection to a Petrol King regulator.