Diaphragm seals are partitions in pressure measuring instruments which prevent the measured medium from entering the measuring system.
The designs can vary greatly depending on the measurement task. Particularly important for the protective function of the device is the diaphragm, a thin film that shields the gauge from pressure in the process vessel or pipe. To transfer the process pressure „caught“ by the diaphragm to the measurement element, a pressure transmission fluid is used. Depending on design and process conditions, this fluid can affect the measurement accuracy disadvantageously.
The LTC (Low Temperature Coefficient) diaphragm compensates this temperature-dependent volume expansion of the pressure transmission fluid with a stainless-steel diaphragm. Using a special manufacturing process the mechanically robust stainless-steel diaphragm with a thickness of at least 0.1 millimetres is put into a position between two zero positions and operates in this range with almost no deflection. This allows the diaphragm to absorb volume changes to the fluid due to the influence of temperature so that these fluctuations have practically no effect. Compared to conventional sinusoidal diaphragms, an LTC diaphragm can deliver up to 70 per cent greater measurement accuracy.