Digital solenoid valve technique
While purging, the SVD is activated and a big amount of purge medium flows inside the enclosure through a nozzle with a large cross-section. After purging, the control unit turns off the SVD. The leakage compensation is made by a bypass choke, with a very small adjustable cross-section (diameter 0.3 ...1 mm) inside the valve. The protective medium that flows into the enclosure now is adequate to maintain a pressure of at least 0.8 mbar. The pressure is monitored by the control unit FS850S. The maximum and minimum pressure of the enclosure is programmable.
Proportional solenoid valve technique
Using proportional solenoid valve technique stops wasting protective gas. The internal proportional working sensory equipment and a proportional valve as actuator are combined to a
pressure feedback control system.
Advantages of pressure feedback control are:
- Considerable less consumption of protective gas - additional costs for proportional valve will be amortised soon
- Increased service reliability achieved by constant pressure inside enclosure - increasing leakage caused by e.g. ageing of the enclosure will be balanced and sudden failure will be prevented
- Almost no flow noise and only a small protective gas consumption using a solid enclosure