pressure transducer


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Pressure transducer

An instrument component which detects a fluid pressure and produces an electrical, mechanical, or pneumatic signal related to the pressure.

In general, the complete instrument system comprises a pressure-sensing element such as a bourdon tube, bellows, or diaphragm element; a device which converts motion or force produced by the sensing element to a change of an electrical, mechanical, or pneumatic parameter; and an indicating or recording instrument. Frequently the instrument is used in an autocontrol loop to maintain a desired pressure.

Although pneumatic and mechanical transducers are commonly used, electrical measurement of pressure is often preferred because of a need for long-distance transmission, higher accuracy requirements, more favorable economics, or quicker response. Electrical pressure transducers may be classified by the operating principle as resistive transducers, strain gages, magnetic transducers, crystal transducers, capacitive transducers, and resonant transducers.

In resistive pressure transducers, pressure is measured by an element that changes its electrical resistance as a function of pressure. Many types of resistive pressure transducers use a movable contact, positioned by the pressure-sensing element. One form is a contact sliding along a continuous resistor, which may be straight-wire, wire-wound, or nonmetallic such as carbon.

Strain-gage pressure transducers might be considered to be resistive transducers, but are usually classified separately, They convert a physical displacement into an electrical signal. When a wire is placed in tension, its electrical resistance increases. The change in resistance is a measure of the displacement, hence of the pressure. Another variety of strain gage transducer uses integrated circuit technology. Resistors are diffused onto the surface of a silicon crystal within the boundaries of an area which is etched to form a thin diaphragm.

In magnetic pressure transducers, a change of pressure is converted into change of magnetic reluctance or inductance when one part of a magnetic circuit is moved by a pressure-sensing element—bourdon tube, bellows, or diaphragm.

Piezoelectric crystals produce an electric potential when placed under stress by a pressure-sensing element. Crystal transducers offer a high speed of response and are widely used for dynamic pressure measurements in such applications as ballistics and engine pressures. See Piezoelectricity

Capacitive pressure transducers almost invariably sense pressure by means of a metallic diaphragm, which is also used as one plate of a capacitor.

The resonant transducer consists of a wire or tube fixed at one end and attached at the other (under tension) to a pressure-sensing element. The wire is placed in a magnetic field and allowed to oscillate. As the pressure is increased, the element increases the tension in the wire or tube, thus raising its resonant frequency. See Pressure measurement

pressure transducer

[′presh·ər tranz‚dü·sər]
(engineering)
An instrument component that detects a fluid pressure and produces an electrical signal related to the pressure. Also known as electrical pressure transducer.

Pressure transducer

An instrument component which detects a fluid pressure and produces an electrical, mechanical, or pneumatic signal related to the pressure. See Transducer

In general, the complete instrument system comprises a pressure-sensing element such as a bourdon tube, bellows, or diaphragm element; a device which converts motion or force produced by the sensing element to a change of an electrical, mechanical, or pneumatic parameter; and an indicating or recording instrument. Frequently the instrument is used in an autocontrol loop to maintain a desired pressure. See Process control

Although pneumatic and mechanical transducers are commonly used, electrical measurement of pressure is often preferred because of a need for long-distance transmission, higher accuracy requirements, more favorable economics, or quicker response. Electrical pressure transducers may be classified by the operating principle as resistive transducers, strain gages, magnetic transducers, crystal transducers, capacitive transducers, and resonant transducers.

In resistive pressure transducers, pressure is measured by an element that changes its electrical resistance as a function of pressure. Many types of resistive pressure transducers use a movable contact, positioned by the pressure-sensing element. One form is a contact sliding along a continuous resistor, which may be straight-wire, wire- wound, or nonmetallic such as carbon.

Strain-gage pressure transducers might be considered to be resistive transducers, but are usually classified separately, They convert a physical displacement into an electrical signal. When a wire is placed in tension, its electrical resistance increases. The change in resistance is a measure of the displacement, hence of the pressure. Another variety of strain gage transducer uses integrated circuit technology. Resistors are diffused onto the surface of a silicon crystal within the boundaries of an area which is etched to form a thin diaphragm. See Integrated circuits, Strain gage

In magnetic pressure transducers, a change of pressure is converted into change of magnetic reluctance or inductance when one part of a magnetic circuit is moved by a pressure-sensing element—bourdon tube, bellows, or diaphragm.

Piezoelectric crystals produce an electric potential when placed under stress by a pressure-sensing element. Crystal transducers offer a high speed of response and are widely used for dynamic pressure measurements in such applications as ballistics and engine pressures.

Capacitive pressure transducers almost invariably sense pressure by means of a metallic diaphragm, which is also used as one plate of a capacitor.

The resonant transducer consists of a wire or tube fixed at one end and attached at the other (under tension) to a pressure-sensing element. The wire is placed in a magnetic field and allowed to oscillate. As the pressure is increased, the element increases the tension in the wire or tube, thus raising its resonant frequency. See Pressure measurement

References in periodicals archive ?
By locating several pressure transducers along the length of the barrel, the progress of melting along the length of the extruder can be analyzed.
The 1390 accepts direct input from 350-ohm strain-gauge pressure transducers, while the 1391 accepts voltage and current inputs.
The snubber would screw on to the front end of the transducer and then thread into the piping system, The snubber is located between the piping under pressure and the pressure transducer. The following equation determines the maximum pressure change that occurs during a fluid hammer.
Pressure Transducer Accuracy Pressure transducers are the most delicate of on-line rheometer components.
Machine advantages are said to include a rigid base with structural steel construction, a wear-resistant bimetallic barrel designed for 10,000 psi operating pressure with removable barrel flange, rupture disc and pressure transducer behind the front flange, an inverted-L style control panel with a modular design for improved accessibility, and a gear drive reducer with a heavy-wall, two-piece iron housing and single helical gearing.
"Setra's pressure transducer has an amplified output as opposed to a millivolt output, so we don't have to amplify the signal output of the transducer;' explained Bergst.
Measuring pressure transducer (intelligent) ars-2000alw-pd / 0 .
Whitney's engineers found an off-the-shelf solution from Setra Systems Inc., its Model 235 differential pressure transducer. Setra, based in Boxborough, Mass., says the Model 235 is designed to be used with liquids or gases at line pressures up to 2,500 psig and is accurate within a fraction of a percent over a wide range of pressures and temperatures.
introduces the Model 201 Pressure Transducer. Its rugged design, wide operating temperature range and high 45-psi overpressure capability are said to make it ideal for the most demanding applications, including vapor recovery systems, exhaust gas control systems and industrial scrubbers.
Machine advantages are said to include a rigid base with structural steel construction, a wear-resistant bimetallic barrel designed for 10,000 psi operating pressure with removable barrel flange, rupture disc and pressure transducer behind the front flange, an inverted L style control panel with a modular design for improved accessibility, and a gear drive reducer with heavy-wall, two-piece iron housing and single helical gearing.
Sensortechnics' PS9000 pressure transducer offers pressure measurment for aggressive and corrosive liquids and gases.
Part of PSI's 9000 Series line, the Ethernet Model 9021 uses an internal 32-bit microprocessor to correct for pressure transducer zero, span and nonlinearity errors.