Small CH leak

I have gate-type isolator valves either side of my circulating pump. These have recently started leaking slightly - not from the gland round the shaft, but from the point where the gate mechanism screws into the body. They have fibre washers which seem to have perished. Tightening helps a bit but there is still a slight drip . . drip.
I intend to replace the valves - probably with ball rather than gate types (any comments?). This will, of course, require the system to the partially drained - so I need to wait for a convenient time - and need a short-term solution.
In a recent post concerning a leaking joint on a radiator valve, someone suggested using a silicon sealant. However, all the tubes of sealant which I have got state that the surfaces must be clean and *dry*. There's no way I can make my surfaces dry - until I fix the leak!
Does anyone have any suggestions of anything I can put on a damp surface, which will still seal?
TIA, Roger
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Try Plumbers Mait. It's made by Evo-Stik Pop it round the joint and it should keep the drip at bay until you can fix it properly.

shaft,
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I
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Roger Mills wrote:

Those small tubes of Fernox leak sealant might do it. It worked for me with a leak on the outlet boss of a very large roof tank, still ok after 4 years.
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Roger,
I had the integral 1/4 turn ball type pump valves to convert from 22mm pipe to the pump flange. The first and only time they were used in anger they promptly started leaking from around the ball handle. I changed to the gate valve type of pump connectors.
My feeling is that these combination flange adaptors/valve are poor quality and suffer from infrequent use. My preference would be a high quality full bore ball valve (1/4 turn) and a separate adaptor flange.
ian
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Thanks for that comment. Unfortunately, I don't have room to install separate flanges and ball valves - it has to be the integral type. Maybe I would be safer sticking with the gate-valve type.
Roger
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On Mon, 3 Nov 2003 12:36:37 -0000, "Roger Mills"

<<snip>>
Roger, I've implemented what Ian describes and it is a better solution than any of the gate valve options.
If you are stuck for space, an alternative is to put flanges at the pump and then a drain cock on the appropriate (lower) side of the pump. Then put the lever ball valves some distance away with a manual air vent if needed on the pump side. Now you can close both valves, open the vent, open the drain and empty the entire section of pipe and pump. OK, so there is a little more loss of water from the system but not a substantial amount.
.andy
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Snap!
I couldn't find any fibre washers of the right size. I temporarily used an O-ring, until I could do a proper repair.

Yes, they are a different length, so you'll need to modify the pipework. I just replaced mine with identical gate valves.
--
Andrew Gabriel

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writes:

These
shaft,
have
there
types
I presume that the ball type are shorter - so I'd have to lengthen one the pipes, which wouldn't be a problem. Someone has suggested that the ball type is more leak prone than the gate type. Does anyone else have a view on this?
Does anyone know whether or not the integral ball type are full bore?
Roger
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On Mon, 3 Nov 2003 12:42:00 -0000, "Roger Mills"

I wouldn't use the integral types at all. The separate lever ball valves are not prone to leaking or sticking at all, IME.
.andy
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Roger Mills wrote:

Two of my close relatives have gate valves on their pumps and I have ball type. None of us have ever had a problem... Never leave a gate valve for a long time in the fully wide open postition or they seem to stick wherever they are fitted; always back off from fully hard open say a 1/4 turn.
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