Proportional valve for water, low pressure
Proportional valve for water, low pressure
(OP)
Hi,
We're designing a flow experiment where we need to produce a controlled pulse of water in a pipe. Our current design idea is based on a constant head tank, a flow meter, a proportional valve and a control system as follows:

Image from Gharib et al. J Fluid Mech 1998.
External factors (room size, imaging equipment etc) limits this design to about 1.4 psi pressure in total. Previous researchers have used ASCO 8202, which seems like a perfect fit. However, the 8202 has a too low Cv - 1.1 gpm in the largest configuration - and we need to go to about 6 gpm for the flow rates we need, at this low pressure.
Does the valve forum know of a valve similar to the 8202, but with a higher Cv?
Thanks in advance,
Johannes
We're designing a flow experiment where we need to produce a controlled pulse of water in a pipe. Our current design idea is based on a constant head tank, a flow meter, a proportional valve and a control system as follows:

Image from Gharib et al. J Fluid Mech 1998.
External factors (room size, imaging equipment etc) limits this design to about 1.4 psi pressure in total. Previous researchers have used ASCO 8202, which seems like a perfect fit. However, the 8202 has a too low Cv - 1.1 gpm in the largest configuration - and we need to go to about 6 gpm for the flow rates we need, at this low pressure.
Does the valve forum know of a valve similar to the 8202, but with a higher Cv?
Thanks in advance,
Johannes





RE: Proportional valve for water, low pressure
http://www.thevalveshop.com/menu/auto/burkert/6223...
If there's not a reason to stick with a solenoid valve, there are tons of choices.
Best to you,
Goober Dave
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RE: Proportional valve for water, low pressure
The Cv value is not set in stone - my rough calculations tell me that Cv around 5-6 should be appropriate.
The reason that I want to use a solenoid is that we need a fast reaction speed - we need to open the valve and close it again in about 300 ms.
Do you know of any other type of valve that can be used?
RE: Proportional valve for water, low pressure
So I'm thinking: Will these valve not open at all at lower pressures? Or will they work, but not optimally?
RE: Proportional valve for water, low pressure
Best to you,
Goober Dave
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RE: Proportional valve for water, low pressure
xnuke
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RE: Proportional valve for water, low pressure
RE: Proportional valve for water, low pressure
RE: Proportional valve for water, low pressure
@btrueblood: The plunger idea sounds interesting. We have been discussing putting a piston in a pipe, as in the diagram below, is this what you are thinking of?
This design has some nice advantages, including that we can get very exact and repeatable pulses with the right driver. Our main issues with this design are 1) getting a good seal between the piston and the pipe when pressurized and 2) making it doesn't wear down over the several thousand cycles we need. I'd be very happy to hear what you think.
RE: Proportional valve for water, low pressure
You do not exactly describe your 'controlled' pulse of water. Your flowmeter seems to indicate a controlled amount, variable length, and variable (from pulse to pulse) cv.
Suggestion: If you separate the flow regulation from the opening/closing regulation you might come better out with commercial available components.
In series : a) A standard, but fast, on/off solenoid valve with good repeatability, large enough cv, operating from about zero delta P, and fast opening/closing time (soft opening/closing or not?). See for instance attached data-sheet. http://www.buschjost.com/pdf/E82090.pdf (Kv 8 at 1", available also in NPT). Your problem might then be the abrupt opening/closing, but other direct acting types or brands might give faster opening/closing times.
b) Regulating valve, hand operated valve to give correct combined cv.
An idea?
RE: Proportional valve for water, low pressure
By controlled pulse I mean that I'd like the flow to vary as v = V*sin2(pi*t/T). Here T is the pulse time, about 300 ms and V is the peak flow, about 0.6 m/s.
RE: Proportional valve for water, low pressure
RE: Proportional valve for water, low pressure
The proportional solenoid valves don't work at low pressures as already mentioned.
RE: Proportional valve for water, low pressure
RE: Proportional valve for water, low pressure
I submitted the cylinder/piston idea to the fluid mechanics forum, feel free to chip in there: http://www.eng-tips.com/viewthread.cfm?qid=342215
RE: Proportional valve for water, low pressure
RE: Proportional valve for water, low pressure