New Differential Pressure Sensor Incorporates LVDT Technology to Create More Environmentally-Resistant, Dependable and Economical Pressure Sensing Solution

Overview:

Differential pressure (dP) sensors with electronic signal processing are increasing being used to monitor flow, filter condition and level. Since these devices offer linear and accurate output, they are also replacing the differential pressure switch that only support on-off condition and useless for closed loop control system. These dPs are often configured with expensive valves and fluid filled remote seals for added protection against corrosive media, radiation and/or extreme media temperature ranges when operating in demanding environments. In cold ambient environment specially operating in temperatures below -4 deg F (-20 deg C), the sensor need to be heated either by trace heater or within a heated enclosure to maintain the operation of the dP sensor. In addition to being expensive, these valves and seals tend to be bulky and require time to install and maintain. In many critical applications such as food and pharmaceuticals, filled fluids are a serious concern due to process contamination. In gaseous systems such as hydrogen and oxygen and semiconductor applications, fluid filled sensors are being banned since the leakage of fluid into the process could lead to an explosion and serious safety issues.

A new series of LVDT (linear variable differential transformer) based oil-less dP sensor with dual channel ASIC (applications specific integrated circuit) have been developed that can operate in a wide range of corrosive materials, radiation and temperature without any oil filling and bulky sealing systems. By encapsulating LVDT proven technology with digital compensation, the pressure sensors combine the benefits of friction-free operation, environmental robustness and unlimited mechanical life. By selecting the diaphragm thickness and material properties, Table 1 show the dP ranges that can be produced using the LVDT technology.