What type of valve will create this pneumatic system

[drivefast]

I would like to use the vacuum from an engine to actuate a vacuum canister. However an engine can experience pressures of 10-20 kPa on engine deceleration, up to 101 kPa at WOT. I need to create a pneumatic circuit that will meet these criteria:

1. At 60 kPa and below the vacuum of the engine is
caped and the vacuum canister does not actuate.

2. At 80 kPa and above the vacuum of the engine is
caped and the vacuum canister does not actuate.

3. From 60 kPa to 80 kPa the vacuum canister is
activated by the engines vacuum signal.

I know how to accomplish this if I would use electromechanical solenoid valves but I don't want the cost of sensors and microcomputers. Is there a cheap and easy way to accomplish this?

Thank you.

 

[Navin A S]

Yes, you can use a pneumatic circuit to accomplish this. The circuit would involve two pressure-sensitive valves connected in series. The first valve would be set to open at a pressure of 60 kPa and close at 80 kPa, while the second valve would be set to open at 80 kPa and close at 60 kPa. This way, when the pressure is between 60 and 80 kPa, both valves will be open, allowing the vacuum signal from the engine to actuate the vacuum canister. When the pressure is above 80 kPa or below 60 kPa, both valves will be closed, blocking the vacuum signal from reaching the canister.