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Bellows pressure sensing element

Pressure-sensing elements (a) flat diaphragm (b) corrugated diaphragm (c) capsule (d) bellows (e) straight tube (f) Cshaped Bourdon tube (g) twisted Bourdon tube (h) helical Bourdon tube (i) spiral Bourdon tube. (From Norton, H.N., Handbook of Transducers, Englewood Cliffe, NI Prentice-Hall, 1989, 294-330. Reprinted with permission.) Previously published in Chau, K.H.L., Pressure and sound measurement, in The Measurement, Instrumentation, and Sensors Handbook, Webster, I.G., Ed., CRC Press, Boca Raton, FL, 1999, p. 26-3.)... [Pg.185]

Figures 29-19 and 29-20 illustrate two different mecbanical-hydraulic systems. Figure 29-19 is a bar-lift steam chest with a heavy-duty hydraulic seivo. The speed-sensing element is a flyball assembly attached to a rotating pilot. This rotating pilot sends a control-pressure signal that is proportional to speed to a bellows on the seivo. A change in control pressure initiated through the rotating pilot by either speed or speed changer deflects the bellows and seivo pilot valve. The seivopiston position is proportional to the control pressure. Figures 29-19 and 29-20 illustrate two different mecbanical-hydraulic systems. Figure 29-19 is a bar-lift steam chest with a heavy-duty hydraulic seivo. The speed-sensing element is a flyball assembly attached to a rotating pilot. This rotating pilot sends a control-pressure signal that is proportional to speed to a bellows on the seivo. A change in control pressure initiated through the rotating pilot by either speed or speed changer deflects the bellows and seivo pilot valve. The seivopiston position is proportional to the control pressure.
Another type of pressure transmitter utilizes a bellow s-sealed differential transformer. The sensing element of this transmitter is similar to that of the previous unit and consists of a metallic bellows. The very slight movement of the bellow s during a pressure change is transmitted to a differential transformer by a rod with a secondary bellows seal. A matching transformer installed in a bridge circuit allow S a calibrated instrument to indicate or record the actual pressure in the system. [Pg.860]

Since the oil pump inlet is at sump (suction) pressure, a pressure gauge on the pump discharge will indicate the total pressure at that point above atmospheric, i.e. suction (gauge) plus pump head. Any detection element for true oil pump pressure must sense both suction and pump outlet pressures and transduce the difference. Oil safety cut-outs have pipe connections to both sides of the oil pump and two internal bellows are opposed to measure the difference. [Pg.107]

One important application of pneumatic transmission is in the operation of diaphragm actuators. These are the elements generally employed to drive the spindles of control valves (Section 7.22.3) and, if hard-wired transmission systems are employed, require devices which convert electric current into air pressure or air flowrate, i.e. electropneumatic (E/P) converters. The basic construction of a typical E/P converter is illustrated in Fig. 6.77. A coil is suspended in a magnetic field in such a way that when a current is passed through the coil it rotates. This rotation is sensed by a flapper/nozzle system (Section 7.22.1). The nozzle is supplied with air via a restrictor and its back pressure actuates a pneumatic relay. The output from the latter is applied to the feedback bellows and also acts as output from the E/P converter. Electropneumatic valve positioners employ the same principle of operation. [Pg.551]


See other pages where Bellows pressure sensing element is mentioned: [Pg.43]    [Pg.43]    [Pg.1136]    [Pg.959]    [Pg.1305]    [Pg.1306]    [Pg.1140]    [Pg.109]    [Pg.20]    [Pg.24]    [Pg.479]    [Pg.650]    [Pg.170]    [Pg.408]    [Pg.153]    [Pg.860]    [Pg.474]    [Pg.454]    [Pg.125]    [Pg.672]   
See also in sourсe #XX -- [ Pg.453 , Pg.454 ]




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