Conflicting Info on gasket placement

[waterbeing]

I recently ordered some bulkheads for a tank I'm reinstalling and was surprised when they came in their own plastic bag with a sticker note prominently covering the bulkhead hole that stated:

Since these are drain line bulkheads (1"), it made sense to install in that order as the gasket will be on the wet side of the bulkhead. In another type of application (when using these same 1" bulkheads for sumps,etc), it could be desireable to have the flange side of the bulkhead on the outside (dry side) and that would leave the gasket to be placed on the wet side (nut side) of the unit. Most of the advise I've seen says to install the gasket on the wet size always; however, I question that now after reading the manufacturers suggestion.
I would appreciate thoughts concerning both ways of installation, and in particular if someone has experience with the gasket being on the 'nut' side of the tank/sump instead of the flange side. When used with the flange side to the outside/dry side, I think it still makes sense to put the gasket under the flange even though it's now on the 'dry side' instead of the commonly suggested 'wet side". I'll be trying one both ways for a sump I'm plumbing today...so I guess I'll find out a little bit via actual experience. Hope this makes sense.

 

[disbjohn]

it is best to put the gasket on the wet side.

 

[melev]

Correct. I try to always have the flange inside the tank.

 

[waterbeing]

Marc, Disjohn
I'd like to put the flange inside the sump also, but due to some space restrictions outside the sump, I need to reverse the direction. So I was planning on putting the gasket on the outside (along with the flange). I can't convince myself that either way is going to work well and to make matters worse, I will not be able to get to the bulkhead to make any change when the tank is in place, as the sump will only fit through the back and is too large to move inside the stand even if I emptied the sump..:sad:
I'm having trouble with the thought of the gasket on the 'nut' side the most too. :?
Other thoughts, ideas?

Doug

 

[melev]

You might consider two gaskets perhaps. Usually the problem is the nut can't turn against the rubber gasket due to friction. Some auto parts have the rubber gasket then one made of cardboard-like material that allows the nut to slide/tighten more easily.

 

[quangtam7]

Imo, gasket on wet side because it is easier to re-tight the nut if there is a leak, if it is outside and you were trying to unscrew a pipe, the bulkhead itself could get unscrewed too, then you will have to stick your hand inside the sump to tight it (this is hard if you tight space). For sump, I personally prefer gasket on the dry (out)side to save space. Gaskets on both sides is bad, imo.
In this pic, it is pretty hard to re-tight the nut, this is why many makers glue it to box permanently.

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[waterbeing]

Thanks for the input. I finally put the gasket on the flange (in this case the dry side) and I asked one of the LFS's today and they advised putting it under the flange also. So my large bulkhead (1 1/2") is plumbed with the flange and gasket on the outside and a smaller bulkhead (1") is plumbed with the gasket on the wet side (with the nut), so maybe by tomorrow, I'll get to put water in it and see which (if either) leaks. :sad:

Thanks for the discussion and picture.

Doug

 

[quangtam7]

@waterbeing wrote:

I see something's wrong here, gasket should always be on the flange side just like you have with 1.5". Remember, gasket on dry (flange) side, the pipe thread and bulkhead's outside (male) thread have same turning direction, that is if you unscrew the pipe (ccw), the bulkhead could turn ccw and get loose, where as the gasket on wet (flange) side, they have opposite direction, if you uncrew (ccw) the pipe, the bulkhead will turn opposit direction (cw) which will make it tighter so less chance of getting leak, also it's easier to tight the nut since it is outside. This is why manufaturers recommend gasket on wet side.

 

[waterbeing]

Ken,
I agree with the gasket under the flange configuration. The one that I installed with the gasket on the wet/nut side did indeed leak. The one with the gasket on the dry side (under the flange) has not leaked yet. Your point about the pipe and bulkhead threading was enlightening as I had not considered that as part of the consideration. That is normally yet another good reason for installing bulkheads with the flange to the wet side and the gasket on the wet side also. I would like to have done it that way, but I didn't have the space in my case. As far as bulkhead installation is concerned it appears:
1. Try to install the bulkhead with the flange AND gasket on the wet side, but if not possible then
2. In any case install the gasket on the same side as the flange (as stated by the manufacturer of the one I got) regardless of wheather the flange is on the dry or wet side.
Thanks,
Doug