negative pressure control

[j26]

which valves can we use for the following problem.

up till now we create a negative pressure(-30mbar) in 4 subtanks (+/-10cl, half fluid & half air) with one vacuumpump. So each tank shows -30mbar.

if we want to control the negative pressure in each tank
individually (example tank1 : -28mbar, tank2 : -31mbar,...),
should we work with valves? What kind of valves?

If we use different tube-diameters for each subtank, would the negative pressure be influenced? Maybe the time to create the negative pressure will be extended with smaller diameter but it will reach the wanted value anyway?

Thanks!

 

[hacksaw]

the valves are dictated by the pressure drop and flow requirement, your materials of constructions and how much money you have to spend. it is a routine design issue and has been done many times.

 

[quark]

You can use any quick response actuator valves with pressure transmitters to maintain required vacuum. Vacuum will be acheived irrespective of your pipe size (I am not comparing 1/8" and 2&quot but time is the factor and you are right.If your pump is capable of sucking the rated quantity of air at that vacuum, you won't have any problem.

But don't compare earthworm to anakonda, size does matter

Regards,

 

[Scoob]

Depending on the gas flow rates you are working with will determine the best control valve solution. If the flow rate is small, pilot operated diaphragm valve is a good choice. If the flows are higher, valves like soft seated globe valves with high performance actuators are more appropriate.
The actuator performance will be critical to the solution success. Consider the Emech high speed (~1.3 seconds/90 deg) and high stroke resolution (0.03deg), electric actuator with a built in closed loop controller as a possible 'stand-alone' solution.