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	Accessories (Seals, Snubbers,Calibrators, Manifolds) These mechanical components serve to protect the pressure instruments from high or low temperatures, plugging, corrosion, and pulsation, or to provide the means for isolating the instrument for removal or maintenance	0 Posts 0 Topics
	Bellows-Type Pressure Sensors Bellows are formed from seamless tubes that are hydraulically or mechanically roll-formed. Seamless bellows are made of brass beryllium copper, phosphor bronze, Monel, Inconel, and stainless steel.	0 Posts 0 Topics
	Bourdon and Helical Pressure Sensors The C-Bourdon element is made by winding a tubular element circularly to form a segment of a circle, the helical element is made by winding the tube several turns into a helix, and the spiral is formed by winding two or three turns in a spiral around the same axis	0 Posts 0 Topics
	Diaphragm or Capsule-Type Sensors This section is devoted to the description of diaphragm- and capsule-type pressure sensing elements and to the force and motion balance devices that utilize them. As shown in Figure 5.5a, the variety of such pressure detector designs is wide and varied.	0 Posts 0 Topics
	Differential Pressure Instruments The differential pressure (d/p) devices discussed in this section include the various filter status indicators and switches, the various wet and dry d/p indicators, the membrane-type very low differential sensing transmitters, and the regular and smart transmitting d/p cells. Some d/p instruments, such as the manometers, are only briefly mentioned	0 Posts 0 Topics
	Electronic Pressure Sensors The electronic pressure sensor categories discussed in this section include the strain gauge, capacitance, potentiometric, resonant wire, piezoelectric, reluctive, and inductive types and their many subcategories. Most of these devices are available either as basic sensor elements or as part of either a conventional or an intelligent transmitter	0 Posts 0 Topics
	High-Pressure Sensors High pressure can be measured by: 1. Dead-weight testers 2. Pressure repeaters 3. Elastic deformation gauges, such as helical bourdon tubes, strain gauges, or bulk modulus cells 4. Detecting the change in electrical resistance in materials like Manganin	0 Posts 0 Topics
	Manometers Manometers are primary standards of the U.S. National Bureau of Standards and of other standardizing institutions. When so used, their visual reading scales are often replaced by capacitance or sonar devices to provide better precision. In order to achieve primary standard precision, it is necessary to compensate for capillary effects; variations in gravity by location; fluid compressibility; and temperature expansion of the filling fluid, which affects its density and thermal expansion of the readout scale.	0 Posts 0 Topics
	Multiple Pressure Scanners If large numbers of pressures are to be monitored, the sequential scanning of the pressure signals can reduce the total cost of the monitoring system. In aircraft, wind tunnel, and compressor testing or in other applications, where the process materials are air or inert gases, the pressure signals can be connected directly to the scanners	0 Posts 0 Topics
	Pressure Gauges when the gauge movements of the Bourdon-type pressure gauges were discussed. These aspects will not be repeated here. In addition to the type of elastic element used, pressure gauges can also be grouped according to their precision or their dial size. In test gauges the measurement error is held between 0.1 and 0.25% of range, and in order to obtain that level of precision, the dial size tends to be large	0 Posts 0 Topics
	Pressure Repeaters When an instrument air signal is being repeated, the device used is called a booster relay. Its purpose is to provide a higher airflow at the same pressure as the input signal	0 Posts 0 Topics
	Pressure and Differential Pressure Switches Switches are point-sensing safety devices, serving to actuate alarms or initiate safety interlocks. In this section, both pressure switches and differential pressure (d/p) switches are discussed. Pressure switches detect a single process pressure and energize an electric circuit when that pressure has reached its set point	0 Posts 0 Topics
	Vacuum Sensors vacuum measurements are expressed in pressure units that reflect a pressure range and historic preference of the industrial practice. Thus, it is common for vacuum applications that are near atmospheric pressure to be described in inches of water or mercury	0 Posts 0 Topics
	Phosphorus Analyzer Analyzers used in measuring the concentration of phosphorus have already been discussed under chromatographic (Sections 8.12 and 8.13) and colorimetric (Section 8.15) analyzers and will also be discussed under water quality and wet-chemistry analyzers (Sections 8.65 and 8.66). For this reason, the detailed designs of these analyzers are not repeated in this section	0 Posts 0 Topics

This chapter covers a wide range of pressure sensors, which can measure pressures from ultrahigh vacuums, such as 10 − 13 mmHg, to ultrahigh gauge pressures approaching 400,000 PSIG (2,800 MPa).