Accuracy high pressure sensors

An example of this problem is shown in Fig. 5.27, where the transitionmode closed-loop control of central oxygen partial pressure is performed by adjusting the discharge power. The graph shows that the central oxygen partial pressure is kept constant with high accuracy. Additional A-sensors have been used to monitor the top and the bottom O2 partial pressure. These pressures vary for the two consecutive runs by several millipascal. As a consequence, the films are neither homogeneous nor reproducible. 

The high pressure-high temperature adsorption isotherms have been measured using a RUBOTHERM magnetic suspension balance The adsorption isotherms and the detail of the experimental procedure are presented elsewhere [11,12] Considering the measurement accuracy of each sensor (mass, temperature and pressure), the relative errors on the adsorbed mass and on the pressure are estimated respectively to 0 3 and 0 5 % the temperature is measured with an accuracy of 0 1 K The main cause of experimental error is not the lack of accuracy of the sensors but rather the buoyancy effect on the adsorbent sample on the one hand and on the adsorbed phase on the other hand The first contibution is taken into account by... 

These measures allow reduction in the effect of mechanical strain on the sensing element, resulting in a pressure sensor with a high accuracy of 2% FSD at 5 kPa. 

Hydraulic sensor selects CYAT type pressure sensor, which has high measuring accuracy, stable and reliable performance, good sealing performance. 

Meanwhile a variety of high-pressure pH electrodes using different modes of pressure compensation have been reported, see, e.g., Dexter and Perkins-Rohrbach (1986) or Queck and Auras (1985). Some commercial CTD probes e.g., Aquatrace by Chelsea Instruments, 55 Central Avenue, West Molesey, Surrey KT8 2QZ, UK) are provided with pH sensors which can operate down to 4000 m and provide accuracies of < 0.05 pH units. 

Differential pressure sensors are special pressure sensors with two chambers separated by a membrane. The pressure difference between those two chambers is detected. This setup allows determination of pressure differences significantly smaller than either one of the applied pressures with high accuracy. Fields of application are the pressure losses over certain unit operations such as separation columns or the use of differential pressure to monitor two other process parameters flow and level. The latter applications are discussed in the subsequent chapter. In high-pressure technology, two aspects have to be observed closely. First, the maximum allowable differential pressure of the transducer can easily be exceeded due to high system pressures, thus destroying or offsetting the sensor. Second, fluid... 

Outlet Volumetric Flow The nominal volumetric flow of 0.15 m /sec (corresponding to a mass flow of 3.08 kg/sec) for the four loop non-optimized Brayton system of Section 6 is assumed. The range 0.01-1 m /sec has been selected to cover a sufficiently wide range of operation to provide for plant startup at reduced flows, full power operation, and casualty performance. The accuracy of 0.0025 m /sec typifies the accuracy of 0.25% of point found in gas industry ultrasonic flow metering equipment The time constant of 1 second typifies high precision pressure sensor with digital instrumentation. 

As has been indicated, the sensor can be adapted to almost any process application. The sensor is designed to withstand pressures to 300 psi and can be designed to withstand process temperatures as high as 450° C using sapphire window materials. Accuracies between 0.01 an 0.5 % are typical. Sensitivities to 0.01% have been obtained and are primarily limited by the sophistication of the network analyzer utilized. 

Measurement and control of low-flow rates are a requirement in such applications as fuel cells, purging, bioreactors, leak testing, and controlling the reference gas flow in chromatographs or in plasma-emission spectrometers. The most traditional and least expensive low-flow sensor is the variable-area flowmeter. It has a high rangeability (10 1) and requires little pressure drop. Due to its relatively low accuracy, it is limited to purge and leak-detection applications. 

Since the sensor is intended to detect very low pressures of 5 kPa, reduction in the sensing element error is important to achieve high accuracy. We therefore put some ideas into designing the sensing element glass base and the package [2]. 

Carbon Monoxide (a) 1-100 ppm reformate pre-stack sensor Operational tern perature <150°C Response time 0.1-1 sec Gas environment high-humidity reformer/partial oxidation gas H23O-75%, CO2, CO, N2, H2O at 1-3 atm total pressure Accuracy 1-10% full scale... 

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