espressoren wrote:Also used a stainless elbow, 3/8" push fitting on one side and 1/4" NPT on the other.

Oooh.

I'd swap that out for a 1/4" BSPP soonish. NPT will thread in, and will seal with enough thread tape, but the thread count does not match the pump.

Here's what you want:

Either this

Or this:

It is unclear to me which one, as the sizing is 3/8 by 1/4 on one and 1/4 by 3/8 on the other, but I can't tell which one is the tube and which is the thread size! These use a short and tapered thread that fits both NPT and BSPP and seals like the factory fitting does with a flat seal against the pump body. (Given the price difference, I think the second one is the correct one)

In either case, if you ask them via email, they will let you know and if you use Promo code TGIF tomorrow, you'll get free shipping.

Cheers!

- Jake

Really? I looked up the La Marzocco part and it said it was 1/4" NPT. I'll see if I can find it again. Maybe you just mean that it won't go in far enough, which means the teflon tape is doing the work - I noticed the stock fitting had a rubber seal.

https://www.fluidotech.it/site/assets/f ... asheet.pdf

Regardless I think aside from them being brass, your fittings look better and have the rubber seal like the barb fitting did. I'll use what I have until they arrive, will just buy both!

espressoren wrote:Really? I looked up the La Marzocco part and it said it was 1/4" NPT. I'll see if I can find it again. Maybe you just mean that it won't go in far enough, which means the teflon tape is doing the work - I noticed the stock fitting had a rubber seal.

Here's a snip from your datasheet showing G1/4" (BSPP) for the ISO versions and 1/4"NPT for the ASA B2.1 version.

Are you sure they aren't using the ISO spec?
The parts catalogue calls out a G1/4" fitting...

espressoren wrote:https://www.fluidotech.it/site/assets/f ... asheet.pdf

Regardless I think aside from them being brass, your fittings look better and have the rubber seal like the barb fitting did. I'll use what I have until they arrive, will just buy both!

They have Stainless, too!
For a ridiculous amount of money!
https://shop.hoseandfittings.com/catalo ... 06-04.html

No, I'm not sure at all! I don't even know what a GAS fitting is. As you said the threads are NPT compatible and the difference in the doc is only in depth of the inlet (about 2mm maybe?). It's a moot point because we know the original has the rubber seal, so that's the right part. The thing I have is working quite well so I'll leave it be until I get the other. Probably because of liberal Teflon tape.

Glad this forum has knowledgeable members who know about things like these obscure fittings!

Yeah I'm not sure the stainless is worth it. I just think of galvanic corrosion but the nickel plating would probably be fine.

espressoren wrote:As you said the threads are NPT compatible and the difference in the doc is only in depth of the inlet (about 2mm maybe?).

The threads are not compatible. But the fittings I linked to are "universal", so they will work in either NPT or BSP ("G" Parallel or "R" Tapered) threads.

The threads in the pump (G1/4") are parallel and have 19 threads per inch.

1/4" NPT is tapered and has 18 threads per inch.

You were able to get your fitting to thread in because the narrow end on the tapered NTP threads grab hold of the parallel BSPP "G" threads and pull the fitting in. But the threads don't match and either the threads on fitting, the pump, or both will eventually be damaged from long term use.

You've got it sealed up for now, and the new fitting will seal on the seal instead of the threads, so you should be good to go.

Cheers!

- Jake

Yeah I was just reading the difference is so small, 11 threads per inch vs 11.5. The shallowness of this fitting means we bottom out before there's any noticeable lock up. Apparently there's a cylindrical and a conical BSP as well, in addition to tapered or non tapered. Fascinating.

I think this source is wrong about threads per inch of NPT, I guess? At any rate I do think the difference is probably small enough that when the fitting is only 7mm deep, combined with parallel versus tapered, you bottom out before the incompatibility becomes apparent.

https://redfluid.es/en/differences-bspp ... t-threads/

FWIW metal barbed fittings with Oetiker clamps are standard for hooking up taps and running hoses in the brewery/restaurant/bar world and do withstand higher than line pressure (I quick-carbonate at 90 psi). A quick look at McMaster has higher pressure ratings for barbed connectors than quick connectors as well. Quick connectors are certainly more serviceable though (if you want to replace the line without replacing the fitting) and more consistent.