Pressure triggered alternating value

[jetstreamcloud]

I need a value that closes when pressure
is less than -3 Hg and releases once
it has achieved -15 Hg until it again
reaches -3 Hg. continuously.
Any suggestions on where and what I
should be looking for ? or even, if need
be - who I would need ?

Dennis

 

[quark]

Jetstream!

You ought to be more specific in that. Eventhough the unit of pressure is irrelevant to my answer but it is better to specify always. what I understood from your post is you have to cutoff a vacuum line valve when some level of vacuum is created and then to hold until it drops to a certain level. In that case you have to install a vacuum switch in the line and that indication (control signal) will be given to a control valve. If the line size is more you have to use a pneumatically actuated valve.

Regards,

Truth: Even the hardest of the problems will have atleast one simple solution. Mine may not be one.