Throttle valves for raw water 1

[workingweekends]

Hey guys,

Looking for a thread (or any reference really) which discusses different options for flow control valves; particularly those which are well suited for turbid water and can easily be throttled.

Thank you in advance for your recommendations.

 

[bimr]

Here is general description:

Valves

 

[LittleInch]

First you need to define what you actually mean by "turbid". My understanding is that this is a vague description meaning "dirty" or cloudy containing particles.

also the control range, pressure, velocity, valve CV required have a big impact on what is and isn't possible.

Control valves are designed to be throttled so I'm not sure what you mean by "easily throttled"

Once you have fluid with dirt or particles, your choices of control valve start to reduce. You then either need very hard seals or disc edges in something like a butterfly valve, or you need slurry pinch valves like this

http://www.flowrox.com/Products/3_1_pinch_valves

In general most types of valve designed for isolation (gate, ball, plug and butterfly to a certain extent, are not good at control and either have a poor control range or suffer wear very rapidly when trying to control with any substantial pressure drop.

Standard globe valves need very hard seats and discs to cope with dirt.

You would be advised to search and look up what they do for slurry as this is probably closer to your requirements.

Try and find a way to not need control valves - use of multiple pumps or VFDs or batch pumping - all much better in the long run.


Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[workingweekends]

More details: Max velocity of 1.5 ft/s, max pressure 20 psi, max of 185 ntu, average pH 8.5.

VFD was ruled out by the powers that be. Looks like I'll need a robust butterfly valve of the sort.

 

[bimr]

Based on what you have detailed so far, the diaphragm would be the best selection.

http://www.globalspec.com/learnmore/flow_control_flow_transfer/valves/diaphragm_valves

 

[LittleInch]

Similar in many ways to the pinch valve, but diaphragm looks good to me. You won't be getting much of a pressure drop before you have no flow so a butterfly might be Ok - all depends on what level of pressure drop and accuracy of flow control you want across this valve. Also size could be critical.

I have no idea what 185 ntu means in practice wrt particles, but sure looks pretty murky...

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[bimr]

185 turbidity would be equivalent to a murky river quality. The water velocity should be maintained above 3 ft/sec to keep suspended solids from dropping out.