Transducer

Pressure Transducer

Pressure transducers, when connected to an appropriate electrical source and exposed to a pressure source, will produce an electrical output signal (voltage, current, or frequency) proportional to the pressure. Most transducers are designed to produce output that is linear with the applied pressure and independent of other system variables — the most important of these being temperatures. Most outputs are mV, V, mA, and, sometimes, as a frequency.

Pressure transducers have a sensing element of the constant area and respond to force applied to this area by the fluid pressure. This force deflects a diaphragm, bellows, or Bourdon tube. In turn, these deflections, strains, or tensions are converted to electrical outputs through a variety of different transduction methods. Figures illustrate three of them.

To operate, most pressure transducers require an electrical input (usually called excitation). Many operate from a 5- to 10-Vdc input and produce full-scale outputs from, say, 0 to 20 mV and 0 to 100 mV. Transducers that produce high-level voltage outputs operate from voltage sources. Typical outputs are 0 to 5, 1 to 5, 1 to 6, and 1 to 11 Vdc. Digital control circuits can be interfaced by routing transducer output through an analog-to-digital (A/D) converter or by using a transducer with frequency output. This allows pressure to be monitored by microprocessors, programmable controllers, computers, and similar electronic instruments.

Pressure transducers that generate a current output usually are called transmitters. By definition, they are variable-current devices and produce 4- to 20-mA outputs with supplies of widely varying voltage.

Outputs are chosen with the following factors in mind:

• the type of device that will receive the transducer's output signal (programmable controller, panel meter, signal conditioner, etc.)
• the distance between the transducer and its receiving device
• presence of electromagnetic interference (EMI) in the environment, which can come from sources such as power lines, welding equipment, solenoid valves, motors, 2-way radios, etc., and
• cost as it relates to the entire installed system (not just the transducer).

Pressure Transducer is available through Quick Time Engineering Inc.

Quick Time Engineering Inc is an international company with offices and distribution networks in the USA, Hong Kong, Europe and Malaysia.

In its 20 years of operation since 1998, Quick Time Engineering Inc had emerged from a local engineering company with a single staff that provided solutions in factory automation to become nowadays a company that serves the Oil & Gas industries, EPC contractors, System Integrators and other industrial automation and process control companies worldwide. Customers from over 50 countries worldwide trust us with their need for process control instruments and industrial automation products.

For more information about Quick Time Engineering Inc, visit www.quicktimeonline.com or email enquiry@quicktimeonline.com