Pressure Transducers in Industrial Machinery

Read Time:5 Minute, 9 Second

By USDR

A pressure transducer, also called a pressure sensor or a pressure transmitter, refers to a device that is used for measuring pressure in a fluid. In this regard, a fluid denotes a gas or liquid. Both site managers and engineers often utilize pressure transducers in measuring pressure in various industrial machineries as a way of detecting any potential catastrophe before it occurs. Pressure denotes the force needed to stop the expansion of a fluid. A Pressure sensor on the other hand, is a device that generates an electrical signal corresponding to the pressure exerted on the fluid. Other sensors can also generate auditory signals, visual signals, and/or optic signals instead of electrical signals. While pressure transmitters have multiple uses, most of these uses are automotive or industrial in nature. It is easy to recognize pressure transducers from their shape and colors. They are cylindrical gauges with multiple colors and each of which denotes a certain pressure level. Pressure transmitters resemble other gauges used for industrial purposes.

The Working Mechanism of Pressure Transducers

It is important to note that there are many types of pressure transducers with different working mechanisms. Thus, it is not possible for to explain the working mechanisms of each of these transducers in this article. These devices vary drastically in terms of cost, application suitability, performance, design, and technology. The so-called, strain-gauge base pressure transducer is the most commonly used type of pressure transducer. This pressure transmitter works by converting pressure into its equivalent analogy electrical signal. It converts the pressure in the machinery into its equivalent electrical signal by physically deforming its strain gauges. These strain gauges are embedded in the pressure transducers’ diaphragm and connected to the wheatstone bridge. The pressure exerted on the transmitter causes the diaphragm to deflect and such deflection creates a strain on the gauges. As a result, the strain in turn generates a change in electrical resistance corresponding to the applied pressure. In general, gauge pressure transducers rely on the pressure of a fluid to cause a deflection on a calibrated meter. Other transducers operate in a binary manner in the sense that they can break or complete a given electrical circuit upon application of pressure on them.

Classification of Pressure Sensors

The classification of pressure sensors is based on a number of factors including pressure type, operation temperature ranges, and pressure ranges. Specifically, there are five major categories of pressure sensors based on pressure type.

Absolute pressure sensor: Used for measuring fluid pressure relative to no or vacuum pressure.
Gauge pressure sensor: Used for measuring fluid pressure relative t a given location’s atmospheric pressure.
Vacuum pressure sensor: used for measuring the levels or flow in pressurized vessels.
Differential pressure sensor: Used for measuring the differences between different pressure levels.
Sealed Pressure Sensor: Used for measuring pressure levels relative to the pressure at sea level. It is similar to the so-called gauge pressure transmitter except that its calibration is different from the latter’s calibration.

Industrial Applications of Pressure Sensors

Pressure sensors have many applications in the industrial setting. They are often used in various ways for monitoring as well as controlling various industrial applications. In addition, machine operators also use these transducers to measure numerous variables such as altitude, water level, speed, and gas or fluid flow. Typically, the applications of these transducers fall into two broad categories: pressure sensing and altitude sensing. Pressure sensing is the direct application of the transducers. It is useful in all types of machinery with pressure functionality including cars, crafts, and instrumentation. On the other hand, altitude sensing is useful in various applications such as weather balloons, satellites, rockets, and aircrafts. Some of the applications these transducers include:

Facilitate site managers and engineers to ensure that all the machines exert the correct pressure levels during the production process. In other words, they are used in preventing machines from applying too little or too much pressure during the production process.
Pressure sensors are used to prevent leaks in machinery by measuring pressure loss, fluid flow, altitude, and depth. However, the users must connect these sensors with other devices in order to measure such variables.
Provide warning signals to the machine operators regarding extreme pressure levels in machinery and thus facilitating them to prevent any potential disaster.
Play a key role in the so-called automotive test stands. Automotive test stands is in turn used to perform research and development in various fields including transmission fluid pressure, engine design, fuel pressure analysis, fuel composition, and fuel additives.
Machine operators use pressure transmitters for measuring and controlling pump pressure, lubricant pressure, and hydraulic fluid pressure in hydraulic dynamometers.
Some pressure sensors are specifically designed to measure high velocity changes in pressure including the combustion pressure in gas turbines or engine cylinders.
Some pressure sensors called pressure switches can break or complete electrical circuits upon application of pressure on them.

Advantages of Using Pressure Sensors

The use of pressure sensors provides machine operators with various advantages relative to the use of other gauges. Some of the advantages of using these transducers include:

Assist machine operators to directly measure both pressure differences between and pressure levels inside of machinery
Capable of withstanding any environmental conditions. They can also function while completely submerged.
Can be used to measure various variables when calibrated and connected with other devices.
It is possible to connect pressure sensors to other systems including electrical circuits.
The strain gauge transducer is capable of offering direct current (DC) response
Piezoelectric transducers are highly sensitive and they have a wide operation temperature range.

Disadvantages of Using Pressure Sensors

Despite the various benefits listed above, pressure sensors also present some disadvantages. Some of the disadvantages of these devices include:

They are often costly or expensive. This means that some users cannot afford to purchase these devices.
Some of the transducers such as the strain gauge pressure sensor have limited operation temperature ranges and operation pressure ranges.
Others like piezo-resistive and piezoelectric transducers are temperature sensitive. Piezoelectric transducers have high output impedance and low sensitivity.