Vent valve instead of vent hole: With this option, the model PG43SA-S hygienic diaphragm pressure gauge is even suitable for pharmaceutical cleaning from the outside with particularly aggressive agents. The closed valve seals the inside of the pressure gauge relative to IP68 ingress protection. In this manner, it prevents the penetration of cleaning media.
In the pharmaceutical industry, protecting substances and medicines from contamination is a priority. Therefore, thorough cleaning of the equipment after each batch is indispensable. However, its effectiveness depends critically on the concentration of the substances used and the level of the temperatures.
Hygienic diaphragm pressure gauges like the WIKA model PG43SA-S are ideal for monitoring the pressure of mobile tanks in the pharmaceutical industry.
Cleaning: Caustic soda and nitric acid
In various cases, the equipment not only undergoes cleaning on the process side (CIP, SIP), but also cleaning from the exterior. This also pertains to a pharmaceutical company that uses the WIKA model PG43SA-S for pressure monitoring in mobile tanks. Here, the cleaning process is completed from the exterior at high temperatures and with chemicals that have a significantly higher concentration. The media include, for instance, 30 percent30 % caustic soda and 60 percent60 % nitric acid ? both in diluted form. With these substances, the measuring instrument is cleaned from all sides in a cleaning system using nozzles.
During this operation, chemicals can enter the case of the pressure gauge through the vent hole. The materials of the measuring instrument can withstand the typical soap concentrations and temperatures. However, extremely aggressive substances, as in the application described, and/or very high temperatures attack the inside of the pressure gauge as time passes. The consequence: The measuring instrument should be replaced.
WIKA diaphragm pressure gauge model PG43SA-S in the new version with vent valve: The sectional view shows the valve in open position. The safety ring is marked in red.
Pressure measurement with open valve
WIKA therefore addressed the question: How do the service life of the PG43SA-S be extended, even when cleaned from the outside under extreme conditions? The solution: by using a version with a vent valve. Sizzling closed valve (IP68) seals off the inside of the instrument from cleaning substances. However, during its actual function, pressure monitoring, it should be open. Otherwise, correct measurement of the gauge pressure is impossible. This is because internal pressure builds up in a closed case, which leads to a falsified measurement result.
Easy operability
The new vent valve is actually visible and installed on the surface of the case for quick access. It might be opened or closed without tools via a wing nut. The direction of rotation, and open and closed positions, are clearly marked on the case. The nut and the valve seal come in hygienic design. A safety ring prevents the valve from being unscrewed.
Sterilisation within an autoclave
Before each external cleaning, the vent valve is closed. The pressure gauge then comes with an ingress protection of IP68. If the cleaning process is accompanied by sterilisation in an autoclave, the valve must be opened again. As a result of the saturated steam conditions that occur there, internal pressure would otherwise also build up ? with negative consequences for the measuring instrument.
Conclusion
The model PG43SA-S diaphragm pressure gauge has been specifically designed for a wide selection of sanitary applications. The new variant with vent valve and IP68 ingress protection has further extended the range of applications for the pressure gauge.
Note
More info on the model PG43SA-S hygienic pressure gauge and other types of the PG43SA series can be found on the WIKA website. Would you like to buy hygienic pressure gauges? In our WIKA online-shop you will find some o our standard designs. Assuming you have any questions on pressure gauges with the IP68 ingress protection option, your contact will gladly help you.
See also our post
Pressure gauges for pharmaceutical processes: Flush-mounted ?dry measurement?