Threaded inlet pipe sizing help please

  • We are currently upgrading MFK. thanks! -neo
H

heffesuita

Plecostomus
MFK Member
Jan 16, 2007
149
66
61
windsor v.t
Hello i am needing to order some parts and not sure what to order. I have the bulkhead all ready. Do u go by the inside of the pipe were the threads are or the outside like normal pipe the inside were the threads are is an inch it is a thread x thread bulk head. Need to order the part for the back to screw in to atach hose 2 thanks. Allso the peice that i allready have that screws into the front is an inch on the out side off the threads. I usually use slip x slip so not familiar with these. These came with tank and is allready drilled for these. And is a weird size hole other bulk heads dont seem to fit either to big or to small from what i am finding hole size 1 3/8

20201008_181548.jpg

20201008_181114.jpg

20201008_181109.jpg

20201008_181017.jpg
 
are you trying to just attach a hose to that bulkhead fitting?

i’m not super versed in sump plumbing but want to make sure i understand -

could throw a threaded 90 with a slip fit for kanaplex to run down to output pump
 
The outside diameter of a male pipe thread fitting is just a touch bigger than the comparable outside diameter of the associated PVC pipe which is also the outside diameter of the male slip fitting for the pipe size.

If that return tube you are holding doesn't fit into a standard pipe threaded bulkhead you have a strange thread size... possibly something metric. I can tell by looking at it that it isn't a standard SAE NPT (National Pipe thread) pipe thread on that piece. NPT pipe threads are always tapered. The outside diameter of the thread at the end of the fitting is slightly smaller than the thread 1/2" in from the end of the fitting which forms the taper on NPT threads... the farther you screw the male NPT piece into the female fitting the tighter the threaded joint gets. It is this taper that gives NPT pipe threads their sealing properties.

That piece you are holding is a straight thread... no taper to it.

BSP (British Standard Pipe) threads are straight threads and always seal using a washer or compression ring of some sort... like a garden hose won't seal without a rubber washer. BSP threads are commonly found in the US on plumbing fixtures like faucets and shower valves. The diameter of the thread is very close to NPT but they will not properly seal together due to the missing taper. I have seen many BSP threaded fittings forced to seal with a NPT fitting by a very judicious use of Teflon tape. While this hack will usually work for a low pressure joint it will usually fail eventually (drips) under high pressure.
 
Last edited:
  • Like
Reactions: Backfromthedead, fishhead0103666, TheWolfman and 1 other person
Gotcha thanks for the reply i get what u are saying so i will juat scrap it sadly and start from scratch only reaon i was going tobuse is because there are alot of peices for the water flow direction for the inside and those are not cheap
 
Before scrapping that fitting in the 1st pic, were you planning on installing it inside the aquarium (wet) or outside the tank (dry)?

If you bought that fitting, do you remember where you got it?
 
Just like standard schedule 40 pvc that you would glue. The size of the bulkhead is in relation with the inside diameter of the pvc. I would take the bulkhead to the local hardware store and size up the proper male threaded adaptor for your bulkhead.
 
  • Like
Reactions: Zanzag
heffesuita said:
Gotcha thanks for the reply i get what u are saying so i will juat scrap it sadly and start from scratch only reaon i was going tobuse is because there are alot of peices for the water flow direction for the inside and those are not cheap
Click to expand...

I have come into situations many times where I have spent more on the adapter fittings to make a particular piece "work" than I would have spent just buying a new piece with the proper threads.
 
You must log in or register to reply here.
MonsterFishKeepers.com
Top Bottom