December 15, 2008. In many sectors of the industrial pressure measurement, measuring instruments have to work reliably and failure-free under severe conditions, for example if the fluid to be measured is aggressive, corrosive, viscous, heterogeneous, toxic, very hot or cold and solidifies or polymerises easily. With the flanged chemical seals series D820, D824 and D825, Baumer offers a reliable protection of the measuring devices against aggressive media. Due to a wide range of diaphragm material and filling liquids, the chemical seals can be used with a lot of difference substances and process temperatures.
Chemical seals are used if the measuring device has to be separated from the medium to be measured due to its physical or chemical properties, but nevertheless a reliable pressure measurement has to be achieved. A chemical seal consists of a flexible diaphragm, clamped or welded between two rigid flanges. The space between the diaphragm and the pressure measuring device contains a filling liquid which transfers the process pressure to the measuring device.The choice of the right chemical seal plays an important role especially in the petrochemical, pharmaceutical and food processing industries. The chemical seal series D820, D824 and D825 with built-in flange are available with the diaphragm materials stainless steel, Uranus, Hastelloy, Tantalum, Titanium and Monel.
The flange facing and the diaphragm are both made of the same material. The wide range of filling liquids allows the use with process temperatures from -60°C up to 400°C. The diaphragm’s low deformation strain rate guarantees long service life. If a manometer’s tube should burst, the chemical seal’s diaphragm is protected against overexpansion, blocking any product leakage.
For corrosive media, the chemical seals can be provided with a diaphragm coating made of PTFE, Halar or gold.To meet the demands of FDA, EHEDG, 3A and prevailing standards in the food and pharmaceutical industries, Baumer pays special attention to the surface condition of diaphragms and welds. The surface roughness of diaphragms is 0.8 µm maximum and is optionally available with only 0.4 µm.
