VN-A-PCPF

Function and Description

The PROTEGO^® Type VN-A-PCPF pilot-controlled diaphragm valve is a newly developed valve for pressure and vacuum relief. It is primarily used as a device for out-breathing in tanks, containers, and process equipment. It provides protection against vacuum and overpressure and prevents the intake of air and unallowable product vapor loss up to the set pressure. The valve can also be used as an in-breathing valve where the main valve is directly controlled when it is exposed to a vacuum, i.e., it functions as a weight-loaded diaphragm valve.

The main valve is controlled by a pilot valve which is controlled by the tank pressure. A small amount of vapor is released into the atmosphere by the pilot valve when the valve opens. The set pressure is adjusted by increasing or decreasing the tension on the spring on the pilot valve.

As the pressure increases, the closing force on the main valve increases, i.e., the valve becomes tighter with increasing tank pressure until the set pressure is reached. Once the valve has started to lift, it opens fully within a 10% of the pressure increase or opening pressure difference, and the nominal volume flow is released through a fully open valve. If and when this level is exceeded, the pressure increase will follow the performance curve (Δp/V. curve). From set pressure to full capacity (fully open valve), the pressure increase is 100% in case of vacuum venting/in-breathing function.

The tank pressure is maintained up to the set pressure with a tightness that is above the normal standards due to our highly developed manufacturing technology. This feature is ensured by valve seats made of high quality stainless steel with precisely lapped valve discs. After the overpressure is released or the vacuum is balanced, the valve re-seats and provides a tight seal.