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Thread: Slide Valves
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26-07-2021, 10:01 AM #1
Slide Valves
Hi all,
My new Koi pond build is coming along nicely and I am now waiting to get the fibreglassing done (shortage of 12/15mm insulation boards). However, the filter house still needs to be completely fitted out which leads me to my question. In line with my previous post feedback I have gone on the aggressive side with filtration and gone for a Profidrum CombiBio 30 which has left me a little tight on space at either end to get the valves/pipes/pumps etc. fitted. I have beed advised by dealers and read articles stating that ball valves are the way to go because slide valves are leaky, however, ball valves take up a lot of space and slide valves would make installation a lot easier. My main use for the slide valves would be on the 4" gravity feeds and would only be closed for maintenance or opened for bottom drain purging. My question in a nutshell is, are slide valves to be avoided at all costs or is the bad press unjustified?
Thanks
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26-07-2021, 11:24 AM #2
ball valves are much better for dirty pond water, i'd really try and shoehorn one in if you can.
and the valterra do leak, especially when left in the open position.
as they are really just sluice valves for draining, so would normally remain closed.
or for use in clean water where grit and dirt doesn't foul the rubber seals.
due to the construction if you have an issue with particals getting jammed in the blade seals,
you can't easily remove them to repair without splitting the whole body of the valve.
if space is tight but you want a high quality slide valve that can be repaired without removing the whole valve body.
you can use a VDL (Van De Lande) slide valve they are much better quality and can have the blade removed from the top without removing the body.
though you would still need to drain or isolate water below the level of the valve to repair.
but they are generally more expensive than most 4" ball valves, and mostly used in metric sizes in europe so not so easy to get over here.
they do make 4 inch imperial valves but may have to special order with a company like Bosta.
https://www.bosta.co.uk/all-products...e-12149?c=3135
https://www.vandelande.com/en/products/pvc-u-inch/681-slide-valve/
Last edited by davethefish1; 26-07-2021 at 11:26 AM.
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26-07-2021, 11:30 AM #3
No very ones cup of tea but I love my standpipe valve I robbed the idea off @zerouk member on here
Freddyboy the legend
"we are water keepers first"
Johnathan
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davethefish1 Thanked / Liked this Post
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26-07-2021, 11:56 AM #4
Hi DTF1 and thanks for the info.
When the slide valves leak can I assume that they don't leak on the floor but allow a small amount of water to pass through to the other side when closed? That being the case it should be ok on my BD purge as a few drips to waste will just act as a micro trickle out? I will have a ball valve on the BD inlet so I would just need to empty the filter if the slide valve ever needed replacing etc. That being said, can they be replaced easily or does the solvent weld connectivity make it difficult?
I will still try to incorporate ball valves where possible but just thinking of the worse case. A proper filter installer could probably figure it all out but I was planning on giving it a go myself.
Cheers
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davethefish1, Ajm Thanked / Liked this Post
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26-07-2021, 11:57 AM #5
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Ajm Thanked / Liked this Post
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26-07-2021, 12:16 PM #6
they leak past the slide as the rubber seal gets particles jammed in it preventing it closing properly.
but also from the gland at the top, as it isn't a very good seal either.
i've seen numerous posts of people on here having a difficult repair job to remove them and then re install ball valves...
it's your choice,
but imagine how difficult it will be to retro fit ball valves a year or so down the line, with a pond full of fish....
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Ajm Thanked / Liked this Post
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26-07-2021, 12:30 PM #7
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davethefish1 Thanked / Liked this Post
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26-07-2021, 02:01 PM #8
not quite sure what youy mean there, about pipes up and down again...
if you want to bring a gravity feed up put a ball valve on it and then turn it down again to feed the filters, to give you the room to fit it.
it would collect some air in the top portion, water would still get through under gravity but it would have restricted flow at the highest point due to the air locked in that section.
and reduce the ability to purge the bottom drain which needs doing regularly.
if you were to do that, i'd recommend continuing the verticle pipe up with a 4" tee piece above the water line, and use the side conncetion to continue to the filter to allow any air to escape.
this one also has an over flow attached to the side with a uniseal.
this has the added advantage if you get any blockage in the bottom drain you can rod it without removing pipework or draining down.
but be aware that suddenly opening/shutting the ball valve can cause a plume of water to shoot over the top
so maybe you could reduce it down to 1" and feed it back into the filters.
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Mannh85 Thanked / Liked this Post
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26-07-2021, 03:44 PM #9
Hi Dave,
You have described what I meant very well and I get what you mean about an air lock in the horizontal up and over section before it drops down to the filter inlet. The option to rod the BD can't be a bad thing either as long as I prevent the tsunami when opening valves
Very much appreciate the advice and comments. I will take a fresh look at it.
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Ajm, davethefish1 Thanked / Liked this Post
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28-07-2021, 09:56 PM #10
for an idea,
i just found this site while looking for some 3" fittings.
yorkshire based...
https://www.epco-plastics.com/produc...al-slide-valve
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28-07-2021, 10:42 PM #11
My slide valve leaks on my BD. Crap things.
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davethefish1, Scamp Thanked / Liked this Post
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28-07-2021, 10:57 PM #12
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samp09 Thanked / Liked this Post
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28-07-2021, 11:39 PM #13
Thanks for the info Dave. I'm guessing these ones are better in some way?
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davethefish1 Thanked / Liked this Post
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28-07-2021, 11:43 PM #14
the epco ones are top entry like the VDL,
they'll still leak.... but it's easier to remove the guts fix them
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28-07-2021, 11:50 PM #15
Ok I’ll bear them in mind if I can’t cram in the massive ball valves. I have 3 4” gravity feeds to my filter so very busy at the drum feed end.
Cheers Dave
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29-07-2021, 08:14 PM #16
I have two 4” slides on my bd. Originally I bought ball valves but screwed up my design, and didn’t allow enough space to fit along with everything else. So a slide to isolate nexus, and a slide to purge.Every single slide I have had leaked, and has been replaced with balls, except these two. So the purge is normally closed, leaked constantly a bit to waste, lowering pond level. So have sealed with a rubber cap, and purge through the nexus/ Draco now. The slide isolating the nexus is closed only for occasional maintenance, so I can live with the leak when I do have too close it. My advice ball valves, otherwise you will regret it…cheers
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29-07-2021, 10:44 PM #17
Hi Scamp
Much appreciate the advice and it sounds like my issue is very similar. All advice points away from slide valves so I will endeavour to incorporate the ball valves. My filter pad has yet to be built so still time to do the pipe work crypton factor!
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