March 809 thread problems

[SliverXZennon]

Hopefully someone can help me here to make sure I'm not insane.

I have this pump. March 809.

It has 1/2" MPT threads on each side. So that means that a 1/2" NPT stainless steel coupling and/or a 1/2" NPT stainless ball valve should thread on correct?

When I go to thread them on it just stops about about a 1/2 a turn. I put tape on the threads and it still looks like I'm starting to get some thread damage. When comparing the MPT to NPT threads, the NPT on the fittings look coarser than the MPTs. Is this right?

I'm getting frustrated because I really want to use this pump!

 

[WalterAtMarchPump]

you may have a fitting with fine or metric threads....try counting the threads on the fitting...ours have a standard 14 threads per inch....on the pump its about 7 threads on it depending on where you count...and its about 1/2" in length....so if you can compare your fitting that way you can see if you may have the wrong threads on the fitting

 

[SliverXZennon]

Thanks Walter, I will check it out. Do you have a link for some fittings that would for sure fit? I will probably need to be ordering them soon.

 

[raouliii]

Where did you get the fittings you already have? A reputable brewing hardware seller or an eBay seller? They may not be NPT (MPT/FPT) fittings.

One method to check Threads per Inch is to use two male fittings, one that fits your SS fittings, one on the pump, and mesh the threads together, side by side. If the threads don't mesh perfectly then they are certainly different thread standards. Another option is to take the SS fittings to Lowes/Depot and validate the question of NPT with pipe nipples there.

 

[processhead]

If the female threads on the SS fittings were not carefully cut, they may not thread cleanly to the pump male threads.

Do you have access to any other 1/2" NPT female pipe fittings?

You could try them as a test to see if you have out of tolerance threads on the SS fittings.

 

[Bobby_M]

It's easy to cross thread a metal fitting onto a plastic fitting and once you start, it's hard to get it started on the right track. Did you wrap some teflon tape on the threads first?

 

[iaefebs]

Take your pump and fittings to the local hardware store and try NPT fittings on both. I bet the hardware guys would enjoy checking out your problem and would want to hear more about what you are using it for. You brew your own beer? what do I need to do this myself? They wont have the SS fitting you need so you won't be obligated to buy anything, but at least you can narrow the problem down, and talk about beer.

 

[WalterAtMarchPump]

Thanks Walter, I will check it out. Do you have a link for some fittings that would for sure fit? I will probably need to be ordering them soon.

We don't deal with any fittings here so i couldn't suggest anyone to go to

 

[SliverXZennon]

First of all, thank you all for helping me disect this issue, being a brand new pump I didn't think I would have this problem!

Where did you get the fittings you already have? A reputable brewing hardware seller or an eBay seller? They may not be NPT (MPT/FPT) fittings.

This is the 1/2" NPT I have been trying to thread. Maybe I'm just crazy and this isn't going to work?

If the female threads on the SS fittings were not carefully cut, they may not thread cleanly to the pump male threads.

Do you have access to any other 1/2" NPT female pipe fittings?

You could try them as a test to see if you have out of tolerance threads on the SS fittings.

I will have to go to HD to see if I can try it out...

It's easy to cross thread a metal fitting onto a plastic fitting and once you start, it's hard to get it started on the right track. Did you wrap some teflon tape on the threads first?

Sure did! Always.

Take your pump and fittings to the local hardware store and try NPT fittings on both. I bet the hardware guys would enjoy checking out your problem and would want to hear more about what you are using it for. You brew your own beer? what do I need to do this myself? They wont have the SS fitting you need so you won't be obligated to buy anything, but at least you can narrow the problem down, and talk about beer.

Narrowing down the problem is priority #1, we'll see where it leads.

We don't deal with any fittings here so i couldn't suggest anyone to go to

Thanks anyway!

 

[SliverXZennon]

Also, just to add... I've been trying to thread on a 1/2" NPT 3-peice ball valve. Do they also not thread on and you need a male fitting?

 

[raouliii]

.....This is the 1/2" NPT I have been trying to thread. Maybe I'm just crazy and this isn't going to work?...

You're attaching a weldless bulkhead fitting directly to the pump?

Or is it just this 1/2" coupling?

If the hardware was purchased from bargainfittings.com, I would trust that it is NPT. How many wraps of Teflon tape did you apply? Too much can be a bigger problem than too little on plastic, especially if it is applied to the first thread.

I suspect you initially cross-threaded the connections and cut new, bad, threads in the plastic. That will be difficult to repair.

... I've been trying to thread on a 1/2" NPT 3-peice ball valve.

A three piece valve tends to be so heavy and bulky that it doesn't easily spin around its axis without a wobble. Which can easily result in a cross-threaded start, especially on plastic. It is best to disassemble it, attach one third of it to whatever it is being attached to and then reassemble.

 

[SliverXZennon]

You're attaching a weldless bulkhead fitting directly to the pump?

Or is it just this 1/2" coupling?

If the hardware was purchased from bargainfittings.com, I would trust that it is NPT. How many wraps of Teflon tape did you apply? Too much can be a bigger problem than too little on plastic, especially if it is applied to the first thread.

I suspect you initially cross-threaded the connections and cut new, bad, threads in the plastic. That will be difficult to repair.

I was threading the fitting from the bulkhead. I put about 2 wraps on the threads also.

 

[LordUlrich]

I have gotten a few fittings with threads that have burrs. I would make sure the threads are clean by screwing it together with a metal fitting, and then try the pump again. I also as a general rule recommend using some kind of disconnect with your pump so you are not wearing down the pump threads.

Sent from my DROID RAZR HD using Home Brew mobile app

 

[SliverXZennon]

I have gotten a few fittings with threads that have burrs. I would make sure the threads are clean by screwing it together with a metal fitting, and then try the pump again. I also as a general rule recommend using some kind of disconnect with your pump so you are not wearing down the pump threads.

Sent from my DROID RAZR HD using Home Brew mobile app

The fitting from the bulkhead came directly off of the bulkhead itself. I did check the threads to see if there were any issues and there were none that I could see. Both the fitting and the ball valve stopped in the same spot on the threads..

 

[SliverXZennon]

Another question for those who know better than I. Could I cut the bad threads off? Being it's plastic I didn't think it would be too hard to make a nice straight cut, especially since only the first thread ring looks bad...

 

[30Bones]

I'd try a real small file to get past the buggered one before I'd try cutting them off

 

[WalterAtMarchPump]

what 30Bones said you may be able to clean up the starting thread enough to get it working before cutting it off

 

[avniharmi458]

I have not knowledge of the pump. I have my own business of service. I am also a house wife.