non pvc standard bulkhead fittings?

[sharkdude]

Here is my dilema:

a friend bought a used tank where the prior owner has permanently glued an over complex drain plumbing straight from a 1 inch bulkhead through the back wall.

we are two weeks out from moving this tank and we thought we would use the opportunity to simplify the drain plumbing.

On my tank, I modified a built in wet dry to function as an overflow but I installed a bulkhead through the back wall instead of bottom. Rather than use a fitting that fit inside the bulkhead, I found a female to 1 1/2 barb fitting that fit the outside of the bulkhead. This way there is little reduction and drain flow is not impeded.

I wish to do something similar for my friends tank but a 1 inch lifeguard bulkhead fitting has an o.d. of 1 3/4 inches and a 1 1/4 female fitting doesn't quite fit!

I've tried aquatic ecosystems and savko and a few lfs but to no avail.

does this make sense? any suggestions?

thanks in advance,
sharkdude

 

[Anonymous]

You are having difficulty because you aren't using the bulkhead as it was designed. The threads on the oustide of the bulkhead are not there for you to attach plumbing to. They are there for the nut and nut only. The fact that you found a fitting that would work on a different bulkhead is just a fluke, I assure you the manufacturer of the bulkhead never intended for you to do this.

Thus there is nothing non-standard about the bulkhead fitting, your intended use is non-standard.

My suggestion would be for you to use the plumbing part as originally designed, otherwise you run the risk of cross threading stripping the bulkhead and not having a water tight seal.

 

[MattM]

<BLOCKQUOTE><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><HR>Originally posted by sharkdude:
<STRONG>I see no logical reason that a bulkhead fitting could not be used the way I have on my sytem.</STRONG><HR></BLOCKQUOTE>

The reason is because the outside thread is a mechanical thread, not a pipe thread.

Pipe threads are sized to fit plumbing parts. More importantly, they have a slight taper, so the parts get tighter as you thread them together, forming a water-tight seal.

Mechanical threads are sized to fit bolts and nuts. They do not have a taper so that you can thread them all the way together and tighten the nut down against the surface. Because they don't get tighter as you thread them, they aren't designed to be water-tight.

[ August 10, 2001: Message edited by: MattM ]

 

[sharkdude]

Thanks Tom for your insightful reply.

here is reply from my friend in need of assistance,

"Obviously he missed the entire point of the question. Looking to maximize water flow. What is the point of using the inside fitting which restricts flow massively.It would be like installing 1" exhaust on a 454 CI motor, just does not make sense. "

I see no logical reason that a bulkhead fitting could not be used the way I have on my sytem.

[ August 10, 2001: Message edited by: sharkdude ]

 

[FishHead1]

Sharkdude - Tell your friend Tom is right. If you want to maximize water flow, use the proper parts. Remove the bulkhead, drill a larger hole and install a larger bulkhead fitting. If you try to Mickey Mouse it you will have much larger problems in a year or two!