Why are people using gate valves for flow control?

[TylerS]

I see this a lot and it bothers me. Gate valves mechanically are designed for full open or full close operation, they aren't meant for flow control. If a gate is used for flow control the flat plate that makes up the gate will erode away from the bottom due to the water rushing through. This changes the flow rate over time, and eventually make it so the gate won't fully close. Ball valves are usually a much better option.

Are people not seeing gate erosion in their setups? I noticed that sellers of gate valves are marketing them for flow control, which is also odd.

I guess it could be a price issue, I would think a gate valve is cheaper to make? Any thoughts?

 

[Waters]

I believe it is a price and availability issue. They can be purchased at any home improvement store while the ball valves are sometimes harder to find (and are usually more expensive).

 

[AZDesertRat]

Gates are much harder to find and more expensive.
You are correct in that gates are not normally used for flow control but in the case of an aquarium they are more precise than a ball valve as far as fine adjustment. In aquaria our pressures and velocities are so low they last a long time. In my real life as a municipal water system operator and operations and maintenance consultant you would never see one being used for this purpose.

 

[Cleo642]

Globe valves are best used for throttling service, but they are very pricey. They can be to tuned to a percentage of flow. Ball valves can be used for throttling service, but they are a part the 1/4 turn family and are really meant for on/off service.

 

[Drauka99]

I only use a gate valve because it is much easier to tune the flow rate. Ball valves just are not fine tunable enough. Yes globe valves should be used but they are hard to find and prohibitly expensive. I'm a use what works guy and gate valves work.

 

[Ligershark]

I use a gate valve for my drain near my sump on my herbie overflow. It is not under high pressure and is the only valve that requires precision to make a small trickle for my emergency overflow (the gate valve is actually on the syphon line but adjusts the level of water in the overflow). Gate valves are a lot more expensive and harder to find (i've always had to order them) than ball valves. I use ball valves on all my other applications.

 

[TylerS]

I only use a gate valve because it is much easier to tune the flow rate. Ball valves just are not fine tunable enough. Yes globe valves should be used but they are hard to find and prohibitly expensive. I'm a use what works guy and gate valves work.

So I guess you aren't seeing undesired flow rate changes or erosion of the gate? How long have you been using them?

 

[AZDesertRat]

PVC gate valves will last for decades in a reef tank installation. Again the pressure is minimal as is the velocity which is what scours out a gate in larger municipal, commercial and industrial installations.

 

[Drauka99]

Had tanks up for 5 years with one and never saw anything detrimental to the valve.

 

[klesel]

Had two on my tank for 8 years never had any problems one was 2/3 open and other 3/4 open never showed any sign of problems and had them after a 1800 gph pump Think need a hell of Flo to have that kinda problems

 

[Rjramos]

These ball valves were fine adjusted years ago to drain my overflow, and marked exactly where the flow is right(in red marker). Periodically, I open and close the valves all the way to clear anything that might have attached. In 20+ years, never had a problem.

 

[ReeferBob]

hmm.... I don't think you are correct with the PVC gate valves used in our applications. I think you could run them for 100 years and never see a bit of erosion of any part of the valve. Gate valves are always the valve of choice for flow control in aquariums. Most people use ball valves for on/off only installations (maintenance breaks).

And aren't most valves used for flow control in other-than-aquarium use also gate valves? Like all of the faucets in your house?

 

[AZDesertRat]

No, gates are not used for throttling flows in other than aquarium situations. Faucets in your house are more like globe valves in older faucets and cartridge type valves similar to ball valves in newer faucets. You may have a gate valve on the incoming water line from your water meter but it is intended to be fully open or fully closed only for maintenance.
When you are under house or boosted pressure and throttle with a gate you are causing cavitation across the gate and seat areas due to the velocity and pressure drop. Say you have 60 psi on one side and an open pipe or hose on the other, the velocity across the small cross surface area that is open is sonic velocity and causes tremendous wear plus vibration between the gate and the threaded shaft which leads to more wear. In an aquarium we may have 4 feet of head (1.7 psi) to dissipate across one side to the other so wear is negligible. Its rare to find an aquarium pump that pumps more than say 15-16 feet of head or less than 7 psi and most are in the 11-12 feet of head range or about 5 psi, you can put your finger over the end of the pipe and stop the flow.

 

[Salty1962]

I like to be able to control my overflow with more precision and control. Ball valves are difficult to move it they haven't be opened or closed for a while. Just my preference. I had a return break off while trying to close it a while back.

 

[ReeferBob]

I did a little research on valves. Both ball and gate valves are not recommended for flow control. Globe valves are but yes, they are very expensive. For our purposes, gate valves work best in the "affordable" range of valves. Price being no object, PVC globe valves do exist and would be a better choice.