Anyone come across a source for a *leak proof* bulkhead fitting for standard 68mm rainwater pipe?
I am fitting out and old galvanised tank for rainwater harvesting (first job, glass fibre the inside to hide the rust) and want to arrange an overflow using a diverter coupler which means the fill pipe will be below water level before the overflow level is reached.
Water gathered from a 55' x 18' roof so I need the full 68mm size!
Failing finding anything suitable off the shelf and if you are fibreglassing inside the tank anyway (and a good use for it btw <g>) I might be tempted to fibreglass a suitable stub of 68mm pipe though at the same time then you can be fairly sure it will be sealed.
I'd cut several 100 mm long strips of CSM about 20mm wide and with the stub held securely in place, glass the strips round the pipe like 'L brackets' and flower petals and do the same again, overlapping the first layer and then a circular collar over that with the middle cut like a star (out to the 68mm diameter) and then a band round the stub, to just pin down any lose ends (woven roving / bandage better than CSM for that last bit. I probably have some here you can have (stick in the post etc)).
Cheers, T i m
Or, for less effort, you could use a 3 inch bulkhead fitting or tank connector (same thing, two different names) connected with flexible hose. You might get away with a 2 inch.
I made an interesting discover the other day. I needed to fit some of this stuff (two inch, actually) over the threads of another fitting that was just too big. I popped the end of the hose in boiling water for a minute or two and it became soft enough to push straight on. I secured it in that case with a few layers of PVC tape as it does not see much pressure, and small leaks wouldn't matter. I suspect if you used a jubilee clip, especially when it was warm, it would be very effective.
I think Tim was quite specific in his requirements (if not directly mateable to 68mm stuff). ;-)
Also, if he does line this tank with fibreglass he might need to glass in a smooth collar of some sort if using a bulkhead / flanged fitting, or use some additional sealant to ensure it seals against the back of fibreglass?
Was the 'discover' doing that on that large a profile or in general?
Or a few turns of galvanised garden wire twisted up at the end?
Yeah, that sort of construction pipe is often used on boats and in caravans (for waste / bilge pumps, where I have sometime used the warming trick).
Cheers, T i m
Is the fibreglass tank circular or does it have a flat side?
Can you uses a access connector, with the 'plate' on the inside of the tank. You would need to cut the access hatch plate to make a suitable hole.
I would have thought, with some silicone sealant, and using the plate with longer screws, ideally stainless designed for constant immersion, this would solve your need.
Hmm.. That might do!
The tank is an ancient rectangular 4' x 3'6 x 3'6 riveted galvanised steel construction I have been using as a secure chemical store after fitting a hinged lid. The exterior is sound but the inside had some rusting hence the glass fibre.
The fill pipe could be a sliding fit in the lid and your *hatch plate* outlet extended and insect proofed above planned water level.
So far, I have not found a bulkhead or tank connector adaptable to 68mm although I take the point that the plastic can be stretched with the application of heat.
Well the short answer to that, AFAIK, is that the only official fittings you will get for drain pipe are for gutters, spouts, and tees. And I agree that the petal approach should work if the penetration has to be
67mm pipe.
There's a choice there, if the tank is good he can seal against the tank, and then fibreglass over it. Alternatively try to get a smooth layer of fibreglass that the standard washer will seal against, or perhaps use a thick washer made from closed cell foam.
Well, it was on two inch MM pipe that was definitely not going on to the threaded boss "cold". I've often used the hot water trick on garden hoses, and on various nylon or PVC "fuel pipe". But I was interested to find that the reinforcing "spring" in the Machine Mart hose, which is a very tough thermoplastic, does in fact soften very satisfactorily in boiling water while still retaining enough strength to grip when pushed on to the threads. I just thought others might find that information useful. The pipe looks and feels superficially as though the "spring" could be metal, in which case of course the approach would not work.
I've done various other sorts of bodge on that type of hose before, on the previous connection I needed to attach it to something like domestic sink waste pipe, and I did that by wrapping the pipe with Sylglas/Denso Tape and twisting that inside the MM hose. Followed up with my favourite wrapping with PVC electrical tape under tension.
IBCs (Intermediate Bulk Container Tank) are cheap and don't rust, plus if translucent you can see the water level. Just a thought.
Can you insect-proof the top of the drain pipe?
Snippage.
Indeed. 1000L and there are numerous adapters available for piping the threaded outlet. However, I already have an almost suitable, larger tank:-) Left over glass fibre kit and the potential satisfaction of re-purposing a large lump of otherwise scrap steel. Currently the collected rainwater goes to a soakaway.
I have lots of fine mesh plastic netting bought to protect garden produce for tank vents. Gutter and down pipe not practical but I assume insects lay their eggs in standing water.
And he's in there fibreglassing 'anyway' etc. ;-)
I'm not sure I'd like that as you are sorta then relying on getting a good seal 'outside' the actual water container (now a fibreglass box inside a galv tank). ;-)
I would finish the glassing with a couple of layers of fibreglass tissue and then lightly clamp a flat object on top with a layer of something non-stick in between.
Yes, or a thicker / softer rubber etc.
Ok.
Agreed. It look far less likely that it might all (as you say, inc the anti-crush reinforcement) respond to heat but seems to.
The trick with all that sort of thing is understanding the mechanics of what is going on. I've seen people try to join / fix fuel hose with insulation tape and seem surprised when it more or less melts or un-glues in front of them or things that instantly burst off out though because of pressure.
<snip>Cheers, T i m
Oh indeed. Pressure, temperature, chemistry. But I do find you can make surprisingly effective and also neat-looking connections with tape. For one of my sink drains, I had to couple solvent weld and compression pipe where there was no room for a compression coupling. But telescoping the tubes together and wrapping with stretched PVC tape has worked fine for
25 years. Also, it would be easy to dismantle if I need to.
And mechanics ... the chances of being able to get access / sufficient material on the job to stand a chance.
And you are likely to be able to cover all the requirements of course. ;-)
Yeah. I have similar in place that have been there on years (not on any plumbing as it happens) even when often it was only going to be temporary. ;-)
Generally yes. I'm not sure if the adhesives used in 'the old days' were chemically better (even if not for the environment etc) but you do also get those where you try to un-peel something and it all flies undone because the adhesive has failed / dried throughout or it's all bonded together (like self amalgamating tape).
Cheers, T i m
A film of oil tends to stop that! It does mean the overflow must dip below the surface and have a anti-syphon feature
snip
Yes. I had forgotten that. Reduced surface tension so the wrigglies can't hang there to breathe?
The plan is to use the water for garden/greenhouse irrigation so it may empty in long dry spells.
Paraffin is more usual than lubricating oil. Diesel would do equally well. Not so much that it prevents egg laying, it stops mosquito larvae from breathing through their snorkels when they hatch.
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