gate valve vs. ball valve?

[FreedR]

Plumbing question. I am setting up a 75g reef upstairs with a basement 30g sump, 20g fuge, and room for later expansion (player to be named later). To build in room to grow, I am planning to get an over-powered pump and throttle it back with a valve. I want to have control over the flow and create some back-pressure, such that the valve will never be totally open nor totally closed, but hold somewhere in between.

I've been reading a lot of reef posts about using gate valves, but I'm a little confused. I've heard about people going to great lengths trying to find PVC gate valves, but from every non-reef person I've heard, gate valves are not to be used for throttling. (For example, McMaster-Carr catalog starting on page 409: "Gate valves are used either fully open or fully closed; they are not recommended for use as throttling valves." http://www.mcmaster.com/ ) Ball valves (or the more expensive butterfly valves, which are used for automobile throttles are generally recommended.

So my question to you all is, why the hype about gate valves? Why not just use a ball valve for this kind of throttling application?

 

[barbra]

People use gate valves instead of ball valves because it gives you greater control over the flow, it is harder to get a ball valve dialed in just right.

Gate valves are not designed for throttling service, I sell valves for a living so I know this well, but since you are not using it in a corrosive environment you don't really need to concern yourself with wearing away the gate. Saltwater is corrosive of course, but not corrosive in the manner that valve manufacturers mean when they discuss the issue. You also do not have enough pressure or flow in an aquarium for it to be an issue. Chances are you will move/upgrade/rethink your plumbing eons before the disk of a gate valve wears to the point where it will no longer create an effective seal.

Ferguson has opened up a host of retail stores lately and many of them have gate valves in stock. They don't all focus on the same segment of industry though so it is good to call in advance to a particular store to determine if they focus on that item.

 

[FreedR]

<a href=showthread.php?s=&postid=10609005#post10609005 target=_blank>Originally posted</a> by barbra
People use gate valves instead of ball valves because it gives you greater control over the flow, it is harder to get a ball valve dialed in just right.

Gate valves are not designed for throttling service, I sell valves for a living so I know this well, but since you are not using it in a corrosive environment you don't really need to concern yourself with wearing away the gate. Saltwater is corrosive of course, but not corrosive in the manner that valve manufacturers mean when they discuss the issue. You also do not have enough pressure or flow in an aquarium for it to be an issue. Chances are you will move/upgrade/rethink your plumbing eons before the disk of a gate valve wears to the point where it will no longer create an effective seal.
<SNIP>

Thanks for the the advice, barbra. I found reasonably priced gate valves at McMaster-Carr, and placed an order. Now, to start drilling some holes in the floor...
:eek1:

 

[AZDesertRat]

The erason gate valves are not recommended for throttling is it eventually wears the seat area out so it will not seal. The kinds of pressure and velocity you are talking about in an aquarium environment is not that big a deal compared to a 5000 GPM 200 HP pump in a water plant. I use ball valves just because they are readily available and cheap but gates are easier to fine tune adjustments with.