Knife valve question

[lastlight]

I have heard many times that there is metal parts inside the valve exposed to the water. Also have read they aren't as fine-tunable as a gate valve. They're cheaper but I'd personally go with the gate valve rather than take the chance.

[Delphinus]

It's more the space requirements and that I just need an open or close, that has me thinking of it. A ball valve is already too big to fit where it needs to go.

When I looked at one I checked for metal and didn't find any but that slimey residue makes me think its petroleum based and I guess that makes it a no go. Still want to know what it actually is though!

[lastlight]

If this is the one from western pump tony the guy told me he wouldn't use it in an aquarium. Can't justify that but it's what I was told.

[Delphinus]

That's what I thought, ok thanks..

[Funky_Fish14]

Tony... I use a number of(3?) PVC knife valves on a couple tanks, including my SW. Everything is doing just perfect? Just figured i'd toss that out there. The knife valves arent exactly the best though. and when you do 'close' them, they have the potential to leak.

[StirCrazy]

Tony, a knife valve is a gate valve. all a gate velave is, is a valve that a "gate" slides over the opening. the name Gate valve applies to several different types and is the name for a catagory of valves. the gate doesn't have to operate from the side, but can come from the top or bottom.

the main divisions of valves are gate, Ball, butterfly, and diaphram and most valve out there are one of these. there are a few that we use that don't fit into these groups which would be needle valves.

as for your original question, it is usaly a food grade silicon lubracant, but I would wipe it off and put it on your self so you know. and they adjust flow just fine. as for the metal in them.. hmm that might be a bit of a concern, if it is exposed and not stainless. what size are you looking for?

Steve

[Delphinus]

Thanks Steve, I understand the division of valves, in this case though at least for us guys with fish tanks, a gate valve is usually one used for fine control and we usually don't bother with the "knife" style gate valves.

What I thought I needed was something just to divert a flow path. But I had about 8" to work with on 2" pipe so a ball valve and a T would simply not fit. A gate valve or a knife valve would, however, and the reason I was asking is that it's easy for me to pick up a "up down gate valve" and not so easy to pick up a "turny-turny-turny gate valve" (there, is that better if I call them THAT??? ) and besides, I didn't WANT a turny-turny-turny gate valve when all I wanted was a "wooshy grunty single sweep push action" gate valve.

After all is said and done though, I think I'm going in a different direction with the piping after all. I'll probably buy your dead pump instead. Let me have a payday here and I'll be in touch..