Some help with HK style bulkheads please.

[Stealthy Ninja]

Hi, I live in Hong Kong and have recently decided to replace my old freshwater tank with a new tank with a built in overflow thingy (not sure the exact name, it is inside the tank and has two holes cut in the bottom).

Anyway, according to the guy in the shop they will provide the following "bulkhead" style connectors. Since they aren't the normal bulkheads I see on forums, I have a couple of questions:

My question is, for this sort of thing should I put a gasket on the water side and the dry side or just the water side? Also, should I add teflon tape and/or silicone to the thread?

Option 1 or 2 (gaskets):

 

[Stealthy Ninja]

Sorry, I mean the two holes are in the bottom of the TANK and the pipes go down into the sump.

Basically all I want to know is should I add two gaskets or one?

Also for this type should I add silicone near the gasket and/or teflon tape to the thread?

 

[ca1ore]

Those don't look like bulkheads to me - they just look like male and female PVC fittings. Doesn't look like enough overhang on either part to provide a good seal. I'd insist on the proper thing.

 

[thegrun]

...but if they do have enough surface area the gasket goes on the wet side only.

 

[woodnaquanut]

...but if they do have enough surface area the gasket goes on the wet side only.

That's correct.

The principle is to keep the water from getting to the threads that connect the wet side to the dry side. That is not possible from the dry side.

If you put gaskets on both sides (or just dry side), you'll have a hard time turning the dry side nut because it will stick to the gasket and not slip on the glass.

I agree with the other comments. The pics do not look like standard US bulkheads. It does look like, if they work, there would be less space taken up by the big flange used on US bulkheads.

 

[hllywd]

Wet side/dry side... Doesn't matter for our purposes if one orientation is more advantageous, a bulkhead may be mounted in either orientation. The big rule is that the gasket always goes under the flange, not under the nut. An additional gasket shouldn't be placed under the nut either, it will prevent proper tightening of the assembly leading to leaks. No tape, and no silicone should be used since they may actually cause further issues.

Now for the pieces you're being supplied. They are simply male, and female adapters, not a bulkhead assembly. There is no flange area to apply pressure to the gasket to make a seal. While you might be able to achieve a seal initially using these pieces, I would not trust them to keep water off the floor.

Here is what a bulkhead fitting looks like: http://www.drsfostersmith.com/product/prod_display.cfm?c=3578+10090+4013&pcatid=4013

You should insist on, or order the proper fitting. Here they are cheap. I can't say what your availability could be, but I can't imagine they're rare. Do this right!

 

[Stealthy Ninja]

Thanks everyone for you advice and words.

What is shown there isn't the actual thing. It's a picture I found online of something similar that I photoshopped to show you the idea. I'll go ask the guy next week about getting proper bulkheads.

 

[JoelA7]

Gasket under flange on the water side so you can conveniently tighten/loosen the dry side. +1 to order a true bulkhead. The flange is much larger.

 

[Stealthy Ninja]

OK it seems my memory was slightly wrong.

Turns out they're like this:

or this (this one has no gasket):

The flange is a lot bigger than I first though. Also the guy confirmed you only put the gasket on the water side.

I asked the guy about the other type and he said that the standard type of "bulkhead" isn't for putting pipes into.

BTW these go in a hole at the BOTTOM of the tank (if that makes a difference) with pipes going up and down from them.

 

[Stealthy Ninja]

The flange side has grooves cut into it (I assume to let the rubber grip better). The female/nut side is smooth.

 

[ca1ore]

OK it seems my memory was slightly wrong.

Turns out they're like this:

or this (this one has no gasket):

The flange is a lot bigger than I first though. Also the guy confirmed you only put the gasket on the water side.

I asked the guy about the other type and he said that the standard type of "bulkhead" isn't for putting pipes into.

BTW these go in a hole at the BOTTOM of the tank (if that makes a difference) with pipes going up and down from them.

I think the chap selling you this doesn't know what he's talking about. I'm also not sure that this thing won't leak as the threads will be exposed to the flowing water regardless of how you place the gasket. If you must use it, I'd suggest the gasket go on the wetside and you put thread sealant on the threads. Either that or actually put the gasket on the dry side.

 

[Stealthy Ninja]

I think the chap selling you this doesn't know what he's talking about. I'm also not sure that this thing won't leak as the threads will be exposed to the flowing water regardless of how you place the gasket. If you must use it, I'd suggest the gasket go on the wetside and you put thread sealant on the threads. Either that or actually put the gasket on the dry side.

Yes after reading what you wrote I remember the guy saying to put on silicone and thread sealant of some kind. Would it be a good idea to add the gasket on both sides then?

 

[hllywd]

Again... wet side/dry side doesn't matter a bit, flange on the wet side is usually preferred, but not always. One gasket has to go on the male side which is always the flange side, this is how water is prevented from getting to the threads of the fitting causing it to leak. A gasket should never be placed under the nut as it will prevent proper tightening. The shoulder, or flange with those fittings is still very narrow, and the gasket must prevent water from getting to the threads in the first place making thread sealant irrelevant. If the tolerance between that fitting, and the hole are tight it may work, but it's still not a typical bulkhead.

I'm not going to say your vendor doesn't know what he's talking about, but the standard bulkhead is most definitely designed to accept pipe. That's why they come threaded, or slip fit. IMO a real bulkhead fitting is still the best, safest application. Thread sealant, or silicone should not be used in a proper bulkhead installation, nor should it be needed.

 

[ca1ore]

If you must use these, given that there is no distinct flange side per se (only hard and fast rule is that gasket stays with the flange, regardless of which side of the aquarium), what I would do would be to install the male fitting with the gasket on the outside of the tank and screw the female fitting down from the inside. That way the gasket is sealing the internal threads along with water inside the tank. Given the relatively shallow shoulder on the fitting, it may still leak, but I see no other way to do it.

 

[Stealthy Ninja]

Thanks for the words of advice.

I'm looking into alternatives, though I guess the holes will be cut for these fittings. I'm going to duck over to a local hardware/plumbing supply store nearby my work to see if they have anything resembling a proper bulkhead. If I can buy some to try out I might just do it, otherwise I will probably be stuck with these fittings.

I'm thinking this is the "Hong Kong style" of doing these things. Sometimes Asia is like that, they don't do things the "right" way but somehow it still works.

I'm thinking if I'm forced to use these, I'll add some silicone and/or teflon tape to prevent the water flowing along the threads, causing a leak. Not ideal, but if I do it right it shouldn't leak. I mean apparently the fish tank shop does it this way all the time and they don't get leaks, so I'm hoping for the best.

I'll update these threads again in a few weeks when the tank is delivered and I have a chance to have a good look at them.

 

[Stealthy Ninja]

I went to the local shop and they didn't have a clue about bulkheads... I'll keep searching but assuming I can't find an alternative:

Since this sort of connection (unlike a standard bulkhead) doesn't have a nut side (and a flange side) instead it seems to have two flange sides (male and female) that will pull towards each other when tightened. Is there any reason why I couldn't put a gasket on both sides of the aquarium glass so that the fixture will seal on both sides?

Please correct me if I'm wrong, but I'm thinking this design pulls evenly both ways so the gaskets on both sides will seal, stopping the water flowing out either from the tank or through the threads.

As suggested by this having two rubber gaskets:

 

[Stealthy Ninja]

Everything turned out fine.