Why does everyone use couplers on their bulkheads?

[JayMac]

I have been wondering this for some time now, and it has started to bug me that I haven't been able to come up with a legitimate answer!

For my weldless bulkhead assemblies, I have always used the short nipple+silicone O-ring+ desired FTP fitting. For example: on my MLT I have a 1/2" FPT compression fitting which screws on to the nipple and pushes the silicone O-ring against the wall to create a seal. The compression fitting is then connected to cPVC piping which connects to my manifold.

However, every time I look online and see complete bulkhead assemblies offered by various suppliers, I see that a locknut threads on to the nipple to create the seal with the O-ring, then a coupling is screwed on to provide a connection to the dip tube or whatever may be present. Why is the coupling used at all? Why not piece together a diptube that has FTP threads (which is what I have done) ?

I'm only asking this because I am making changes to my equipment, and if there is any benefit to this setup, I would gladly conform to this way of assembly... but I have failed to see why!

Thanks for your help,
Jay

 

[acidrain]

How did you make a dip tube with FPT? Most "off the shelf" pipes are MPT.

 

[JayMac]

1/2" FTP that connects to a 90 degree street elbow is what I use for my brewpot.

Otherwise, it could be a FTP compression fitting to tubing bent to 90 degrees.

Seems a lot easier than a coupling, then a MTP compression to tubing in my eyes... How is tubing MPT?

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[BargainFittings]

The short answer is the male threaded adapter fittings are generally cheaper.

 

[acidrain]

This is a MPT (male pipe thread):


This is a coupler:

 

[acidrain]

What you have created is perfectly fine... probably what I would do. I was confused by your description, and honestly, I don't use weldless fittings.

 

[Sideways]

I think so you can use a false bottom. Plus they are easier to remove for cleaning and dont require teflon tape

 

[JayMac]

This is a MPT (male pipe thread):


This is a coupler:

That is not a MPT tube, what it appears to be is a MPT x FTP coupling. MPT designates a threaded tube which can be inserted to a tube with threaded inserts (FTP). My point is that the coupler acts as an extra piece of hardware that is not generally required.

I would yield to the previous post which states male fittings are cheaper, but are they when you include another $4-5 for the coupling?

I guess what I'm fishing for is a concrete answer for why couplings are (nearly) ALWAYS included with bulkhead kits, when FTP connections generally reduce the amount of hardware by a piece?


Do you use a coupler? Why? Do you see benefits? Or would a female threaded fitting simplify your design?

Thanksjay

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[acidrain]

You have your terminology wrong...
FTP = female T pipe
FPT = female pipe thread
MPT = male pipe thread
What you have is a weldless bulkhead (assuming), a FPT to sweat coupler, and a sweat/sweat street elbow.
I'm not really understanding your question... do you wish that somebody would manufacture a threaded elbow to eliminate the coupler? There are FPT/ hose barb elbows.
In this case there is a half dozen ways to skin a cat. Do what works for you. Personally I use weld-in bungs and all SS fittings. My mash tun is bottom draining with FB.

 

[JayMac]

In short:

Virtually all fittings come in MPT and FPT forms. Why use a coupler + MPT fitting combo when a FPT fitting is all that is required?

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[big_len]

For me, I just like the idea that the valve was independant from whatever was fitted inside. So the valve is tightened up good and solid, in the right orientation, with a good seal on the o-ring, by the coupler - regardless of what I then plan to do on the inside, be it a hose barb or a dip tube or what-have-you.

P.S. I will refrain from mentioned BSP/T for the sanity of the thread

 

[LordUlrich]

My best guess is it is mostly from a historical rather than a practical reason.
It is my guess that the welded connectors were developed first. Most welded connectors are made with a coupler as it is way easier to make a clean weld with a coupler than a nipple. Weldless fittings were created to emulate the welded fittings without welding, so it makes sense to try and have the same fitting on the inside.

 

[Bobby_M]

In short:

Virtually all fittings come in MPT and FPT forms. Why use a coupler + MPT fitting combo when a FPT fitting is all that is required?

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I provide several bulkhead options and only one of them has a female coupler as the innermost fitting. You'd get that version if you want to thread in a bazooka screen. You can also get it with a plain elbow or a barbed elbow to act as a compact diptube.

I think people buy the version with the coupling because it seems like it offers flexibility and an ultimate decision doesn't have to be made right away.

In some (very poorly designed) WL bulkheads, the coupling is there because something had to hold the SS washer and oring from slipping off the pipe nipple.

You can also get our custom bulkhead with integrated diptubes which eliminates the separate thread in compression fitting. In other words, we took your question even further. Why thread a separate compression fitting in at all? Let it BE the bulkhead.

Anyway, this:

Definitely looks better and is easier to clean than this:

 

[JayMac]

I provide several bulkhead options and only one of them has a female coupler as the innermost fitting. You'd get that version if you want to thread in a bazooka screen. You can also get it with a plain elbow or a barbed elbow to act as a compact diptube.

I think people buy the version with the coupling because it seems like it offers flexibility and an ultimate decision doesn't have to be made right away.

In some (very poorly designed) WL bulkheads, the coupling is there because something had to hold the SS washer and oring from slipping off the pipe nipple.

You can also get our custom bulkhead with integrated diptubes which eliminates the separate thread in compression fitting. In other words, we took your question even further. Why thread a separate compression fitting in at all? Let it BE the bulkhead.

Anyway, this:

Definitely looks better and is easier to clean than this:

Thanks for the explanation Bobby.

I'm planning to make my false bottom connect using a QD, and I was planning on just buying a female FPT QD to thread on to the nipple ... but I wanted to make sure I wasn't making a stupid decision by buying the FPT version instead of MPT+coupling.

From what you posted, it seems that there is nothing wrong with assembling it the way I have, so I'll just go ahead and buy it

..that is, unless you say so haha

 

[Bobby_M]

I think you understand it just fine.