In certain applications, venting of the actuator has to be avoided in case of pressure failure. For this purpose Hafner has developed the so-called pressure holding valve.
From a technical perspective the pressure holding valve is a double non-return valve which is blocking the air-flow when neither at port P1 nor port P2 any pressure is applied.
These kind of valves are often used in combination with double acting pneumatic grippers. The grippers may not lose the load when the pressure cut-off for any reaons (e.g. pull off of tubing).
But also for all other kind of pneumatic clamping applications, this function can be very helpful.
Imagine: A workpiece is being clamped pneumatically in order to machine it with an electrical spindle. A pressure failure while machining process may lead to serious consequences: tool breakage, machine damages, personal injuries. This can only be avoided by using a pressure holding valve which is installed at the clamping device.
The valves are generally available with G 1/8-in. (type DSV-1/8) or G 1/4-in. (DSV-1/4) ports.
They are also available with a manual exhaust function. The user can exhaust the actuator manually by pushing the manual exhaust buttons. If for instance a pneumatic gripper is holding the load in case of pressure failure, the user can manually exhaust the gripper and thereby unload the load safely. Please ask for our valves type DSVH-1/8 (G 1/8-in.) or DSVH-1/4 (G 1/4-in.).
For the automation of pneumatic rotary actuators, Hafner can offer the valve also with NAMUR-interface. The DSVN-5 can be mounted between the NAMUR pilot valve and actuator. The actuator will be blocked in case of pressure failure and remain in the last position.
Filed Under: Pneumatic Tips