Switzer instrument ltd providesa new series of electronic pressure transmitters. These transmitters provide the latest thin film technology combined with high stability electronics. Transmitters are available in a variety of enclosures made of cast ss or aluminium which are weather-proof and flame-proof for use in hazardous industrial environments. Following are some hardware features of these transmitters which include:are rugged in design and offer an economical alternative to conventional transmitters. Gauge pressure of liquids, gases, vapours and fluids of most corrosive nature can be measured to provide linear 4-20 ma output signal. Process industries generally require different types of hardware for measurement, transmission, indication and alarm generation. These new transmitters have an option to provide indication and alarm function besides transmission in any combination or all features in a single instrument. Following are some of the salient features of these pressure transmitters which include:any other design such as a very high direct line accuracy, high turndown ratio capability , full temperature compensation, low mechanical drift with ambient and process temperature changes-all achieved through highly stable electronic circuit design; transmitters also incorporate excellent rfi immunity as well as protection against accidental voltage reversal; accuracy is overall ±0.2% of adjusted span throughout its turndown capability. A silicon wafer is used for the detection of the primary pressure sensing element, on which ion implanted piezo-resistive elements are configured in a bridge form. The bridge elements are laser trimmed to unity ratio of corresponding arms. The sensing wafer is suitable, protected by 316-ss or monel or hastelloy diaphragms. When the diaphragm is subjected to pressure, the stress on silicon wafer produces a strain flexing the bridge to give an electrical output which is sensed by an excitation dc source of constant current. The sensor is temperature compensated to ensure minimal drift with ambient and process temperature changes. Following are some of the electrical features of these pressure transmitters which include: mv output signal of the sensor is suitably conditioned by the electronics using the latest integrated circuits; output is 420 ma proportional to pressure; minimum voltage compliance is 12 v;highly stable electronics facilitate excellent external load characteristics at different supply voltages. Pressure ranges are available from a lowest value of 10 mbar to as high as 1,000 bar.
