Is retro-fitting a Primus pump possible?

P.s

Re read my post and found some info missing after the edit period had passed

American.....

UNC (Unified National Coarse)
UNF (Unified Natinal Fine)
UNEF (Unified National Extra Fine)
UNS (Unified National Special, which is extra extra fine)

British.......

BSP (British Standard Pipe)
BSPT (British Standard Pipe Tapered)

I'm off to sit in the corner facing the wall

 

Hey Doc,

As mentioned in my earlier and this post https://classiccampstoves.com/threads/is-retro-fitting-a-primus-pump-possible.31101/#post-316135 Nova pump thread is 1/8" 28 tpi. Connector that you have measured is BSPT 1/8" 28 tpi (or R1/8" 28tpi in some sources), like Longilily just mentioned. Here you can see some info that I already earlier posted about those threads: https://en.wikipedia.org/wiki/British_Standard_Pipe

I removed the CEJN connector from my Nova pump and I measured it: Diameter on top end I got 9,65mm. Diameter just next to nut I got 10,15mm. I just have an analog caliper so my measurements are not as accurate as yours. Part number of that connector is 141-1180. Diameter of tapered threads varies depending how deep thread is and how it's made as "Longilily" mentioned. I have a Völkel die which has a text PT1/8X28 (in this web page: http://www.voelkel.com/en/produkte-en/gewindewerkzeuge-en/schneideisen-en.html ) I turned my CEJN connector into it and it went in nicely, but started to cut material from the connector when it got too deep. So I am quite/very sure that you have CEJN connector with same thread BSPT 1/8"x28 tpi.

Best option is always to combine tapered thread with parallel thread. So when you have a tapered thread in the connector it's best option to make parallel thread to the Primus pump. So tap you can get from "Longilily" is perfect solution for you!

From that thread table link you see that around 8,5mm/0.33" (or bit smaller) drill bit would be ok for making the hole before threading.

I hope that these will help you forward & Cheers!

 

Also these are used some places/sources:

• Parallel (straight) threads, British Standard Pipe Parallel thread (BSPP; originally also known as[1] British Standard Pipe Fitting thread/BSPF and British Standard Pipe Mechanical thread/BSPM), which have a constant diameter; denoted by the letter G.
• Taper threads, British Standard Pipe Taper thread (BSPT), whose diameter increases or decreases along the length of the thread; denoted by the letter R.

 

One addition to above... In Nova pump they have used an o-ring on the bottom of the thread that is on pump. I believe that it is an additional measure(for using parallel thread in pump and tapered thread in connector) to make connection/thread fuel tight.

 

Doc,

Did you drop the teeth to that gauge into the valleys of the thread? Trying to match point to point may not yield accurate results. Looking as close as possible it appears like the teeth are aligned to the left on your picture but asque on the right. Does your gauge have 27 tpi?

I'm curious if perhaps 1/8" NPT may be a better fit.

http://www.engineeringtoolbox.com/npt-national-pipe-taper-threads-d_750.html

10.11mm = .397" which is nearly the nominal OD for 1/8" pipe

One other way to verify thread type (BSPT/NPT/ISO) may be the tooth angles.

Hope this helps,

AR

 

Another way to measure the pitch of the thread is to measure point to point along the length of as many threads as you can and divide by the number of threads measured.
10 threads measured 7.50 mm = .75 pitch
10 threads measured. 370" = .037 each = 27 tpi or 0.037037037
10 threads measured. 357" = .0357 each = 28 tpi or 0.0357142857

Ken in NC

 

That is good question. One tpi difference is not so easy to figure out. Maybe Doc has some shop close by where he could find 1/8" BSP and/or 1/8" NPT pipe fitting and to check which one fits better to his CEJN connector.

 

Does the CEJN 141 range do an NPT option then

 

And 1/8" BSPT?

 

Looks that Doc's CEJN connector is with tapered thread so maybe 1/8" BSP(P) would be enough.

 

Looks that CEJN has also NPT version from 141 connectors: http://www.cejn.com/products/fluids/couplings-nipples/series-141-fluids/

 

I was going by this. Is the BSPP tapered?
NPT nominal size looks too big, based on what Doc measured.

 

Nope, not tapered



Docs pic with the gauge looks good for BSP rather than NPT to me, only my opinion though


I use that very same chart Ken, it's one of my icons on my iPad

 

Any reasonable hardware store on the left coast would have a pipe nipple in 1/8" NPT on hand. Simply dropping tooth into valley will tell the story. They'll either mesh or not.

AR

 

Morning, Guys,

I must admit, that my mutton head is spinning with all these numbers!! YIKES!! Math has never been my strong suit, but I also have to laugh. I've had to learn certain aspects of math for two separate hobbies that I've long enjoyed: Competitive shooting, and building loudspeakers!!! I feel quite comfortable thinking about, and discussing ballistics, and likewise, the mechanical, electrical, and magnetic theories necessary for quantifying speaker enclosure/transducer matching. But, reading what you all have so kindly shared in this discussion, has my head swirling with numbers that simply do not "click" with my limited mentality!!!

This morning, I'll head down to the Village, and check out our local Ace Hardware. I do believe that they have NPT fittings, as I once checked that out on a fuel tank that I am trying to mate with an old Coleman #7/8 cabin range. With Winter quickly coming on, that Coleman project has been put on hold, for now. In any case, I'll take the CEJN connectors that I have, to Ace, and see if I can match them up to the 1/8" NPT. Actually, knowing that the fuel tank that I'd purchased for that Coleman project has several NPT holes threaded into it, in a couple of sizes, I did try to fit the CEJN connector to those holes, and found two that allow it to be screwed in a ways. Without using a tool to screw it in further, the fitting stops a bit past the half away point. And, both connectors screw in a bit differently, with one going in a bit further than the other. I've snapped more photos, and will post them after returning from my ramble down to Ace Hardware.

I sincerely thank you all for your help on this project, and for your grasp of the knowledge that is needed for such things. My hat is off to you, one and all, for sharing your knowledge with me!!! Talk soon, and God Bless@!

Every Good Wish,
Doc (fuzzy-headed fool that he sometimes is!!)

 

If you have access to such a store, I'd be inclined to go with AR and physically check with a male NPT thread as AR suggests, (Put a male NPT nipple against your male CEJN fitting and see if they mesh) rather than trying to screw it into, what you know to be, an NPT female thread. I say this because they are very close in TPI and even if it is an NPT female thread and your fitting is BSP, it will still screw in to a certain degree which may mislead you

Good luck Doc

P.s threads are a headache for a lot of people Doc, not just you

 

In school math, physics and chemistry were my favorite subjects. On those I was quite ok but with other subjects I was struggling. Later on I have been happy that I put effort to those my favorite subjects, they have helped me a lot in different areas. Maybe without those I would have had a lots of trouble. Languages were not my strong points but I got work where I needed to use them so I got trained to them while I was working. Now I can use my English a bit with my hobbies and some times I am able to express myself to others in English.

Let us know the results of your Ace Hardware visit. Have a successful visit there!!!

 

Hi, Guys,

Just got back from Ace. The "tool guy" there took on look at the connector, and without measuring it, said, "that's a 1/8" U.S. Pipe thread, 28tpi". They have what he said was the proper tap, but no drill, as it appears that what I need is an "R" size. However, why does the gauge I have, show that this connector only fits into a 3/8" threaded hole????!!!! I'm more confused than ever, and in truth, for now, I'm throwing in the towel on this project. I simply cannot afford to give it any more time, right now. I'll keep studying, and learning, and when I have more free time, will tackle this again. Until then. I'm calling it quits, Mates!! Thanks, again, for all your help, and sorry I'm so daft about understanding more of it. Take care, and God Bless!

Every Good Wish,
Doc (frustrated, and at his "dim-wits" end!!)

 

Doc, cool down!

What is U.S pipe thread? Is it national pipe thread(NPT): https://en.wikipedia.org/wiki/National_pipe_thread

There is no 1/8"x28tpi on that list it should be 1/8"x27tpi. On shop you should have tried your connector to 1/8" female thread connector to see if it fits into NPT 1/8"x27tpi female thread ok. I have found out that quite many guys in hardware shops don't fully know the area for what they are selling goods&tools. So it is better to find needed information myself before going into shop or use the shop just to see&measure parts there.

 

Oh dear Doc

You must be pulling your hair out !!!

Ok

Bit confused here as 'US pipe' is NPT which is 27TPI not 28TPI

28tpi is BSP !

Don't throw the towel in ! I'm posting to you very soon, so take a risk on me and let me post an appropriate size tapping drill along with a BSP (28TPI tap), (BTW size 'R' is not the be all and end all, there are many equivelant size drills both metric and imperial very very close to that size Doc especially bearing in mind were talking about a tapered thread here )

ill post both drill an tap as planned

Rest easy Doc

Edit, crossed with Kari (afterburner)