The output signal is an AC signal in which its amplitude is a function of the measured quantity. On the other hand, the frequency remains constant. The output signal is an AC signal in which its frequency is a function of the measured quantity. On the other hand, the amplitude remains constant. Pressure transducers are used in almost all, if not all industries that involve pressure monitoring of liquid or gas media inside a vessel, pipe, storage tank, etc.
Some of the industries that use pressure transducers are:. The liquid level inside a tank is one of the most common parameters monitored in every industrial process. The liquid level is directly related to its pressure at the bottom of the tank. While a sight glass directly measures a fluid level, pressure transducers use the applied pressure of the column of liquid and eventually relates this to the liquid level.
A correction factor must be applied to accurately measure the level inside the tank if any of these cases apply:. The pressure transducer is placed way below the tank bottom — for correction on the fluid head in the tubing connected to the sensor and port. The tank contains a liquid other than water — for correction on the specific gravity since pressure transducers are normally calibrated in inches H2O.
The location of a water leak can be detected using pressure transducers. A large, unusual pressure drop across a pipeline might indicate a leak. If there are two pressure transducers placed consecutively in a pipeline and the difference between the pressure measurement is too large even though there are no other obstructions that can cause the pressure drop, then water leakage could be a probable root cause.
Aside from liquid media, pressure transducers are also used for gases like non-combustible, combustible, corrosive, or non-corrosive. Depending on the type of gas, the pressure transducer should be carefully selected. There are pressure transducers that can specifically handle corrosive gases such as ammonia, hydrogen chloride, and methylamine. For combustible gas applications, the pressure transducer should be explosion-proof or has a certification that it is safe to use for this purpose.
The suction pressure and discharge pressure are important pump parameters. For instance, these parameters can be used to calculate the total dynamic head of the pump. In industrial processes, the suction pressure and discharge pressure are normally measured and monitored.
A micro pressure transducer is commonly used for very small pumps while typical pressure transducers can handle larger pumps. For systems with larger pumps, the pressure transducers should be installed a little farther downstream of the pump discharge to prevent the transducer from being damaged due to water hammering.
Some systems involve extremely hot gases or liquids and require pressure measurement. To avoid the high temperature damaging the pressure transducer, a siphon effect should be applied. A siphon is a simple device, usually a metal tube, that allows heat dissipation of the media before it comes into contact with the pressure transducer.
With the help of the siphon effect, a pressure transducer with a low-temperature range can now be possibly used in high-temperature systems. Orifice plates and venturi tubes are simple devices used to measure flow. These devices provide restriction along the pipe that results in pressure drop which is related to flow rate in the pipe. Differential pressure transducers are used to infer the fluid flow rate by measuring the pressure drop.
Differential pressure transducers are also used to measure the pressure drop across a filter. A large pressure drop indicates that the filter is loaded with contaminants therefore it already needs to be replaced. The pressure drop increases as the filter gets dirty because less fluid can pass through the filter, therefore, resulting in a relatively lower pressure downstream of it. Some pressure transducers can withstand temperatures above oC but only within short intervals to allow a cooling-off of the sensors.
These pressure transducers have a piezoelectric core for pressure measurement. Normal-pressure transducers are not suitable for this application because they can be damaged due to the expansion of metal parts. This can also lead to output errors. Different Modes of Pressure Sensor Operation. Different types of pressure sensing elements. Different types of pressure transducers.
Modulation Mods of Electrical Pressure Transducers. Practical Applications of Pressure Transducers. A pressure gauge is a method of measuring fluid, gas, water, or steam intensity in a pressure powered machine to ensure there are no leaks or pressure changes that would affect the performance of the system.
So, in theory which means "to a fairly decent degree in practice, too" , a flexing piezoelectric transducer could be used to power the "deflection detection" circuit i. However, it also means that a piezoelectric transducer under constant pressure will not provide any voltage to the deflection detection circuit.
Really, just say that three times: deflection detection, deflection detection, deflection detection. It just sounds so cool. Piezoresistive transducers, on the other hand, always need power supplied to them, so long-term, constant pressure will not cause problems with measurements.
It's easy to mix the two up. A quick internet search will turn up plenty of conflicting uses and descriptions, sometimes even within a single site. Throw in more general terms, like "strain gauge," or specific configurations, such as "Wheatstone bridge," and it looks like chaos reigns. But remember, that's the internet. Also, "Hello," from the internet! Some careful consideration helps solve most confusion.
Strain gauge really is a more general term than either piezoelectric or piezoresistive, but is usually used as shorthand only for piezoresistive transducers. For example, some people use piezoelectric for piezoelectric transducers, and strain gauge for all others, including piezoresistive ones.
A Wheatstone bridge is a specific configuration of the bridge electric circuit that is usually used on pressure transducers. We touched on part of how a pressure transducer works above: an electrical circuit usually a bridge is attached to the backside of a diaphragm, a small piece of flexible material.
As the pressure that the diaphragm is exposed to changes, the diaphragm flexes, changing the characteristics of the circuit. That's the transducing part of a pressure transducer. However, in order for the measurement to be of much use, it has to be transmitted somewhere: to a display , or a control system, etc.
There are some instances when it is advantageous to denote a pressure transducer as separate from a pressure transmitter, i. In reality, neither can be used without the other. A pressure transducer without a pressure transmitter generates a signal far too weak to be communicated to a controller, and a transmitter without a transducer has no message to communicate.
An integral part of how a pressure transducer works is how it is built to measure pressure. Some are linear enough over the desired range and does not deviate from the straight line theoretical , but some sensors require more complex calculations to linearize the output. So, pressure sensor non-linearity is the maximum deviation of the actual calibration curve from an ideal straight line drawn between the no-pressure and rated pressure outputs, expressed as a percentage of the rated output.
Hysteresis: The maximum difference between transducer output readings for the same applied pressure; one reading is obtained by increasing the pressure from zero and the other by decreasing the pressure from the rated output. It usually measured at half rated output and expressed as a percentage of the rated output.
Measurements should be taken as rapidly as possible to minimize creep. Repeatability or non-repeatability : The maximum difference between transducer output readings for repeated inputs under identical pressure and environmental conditions.
It translates into the sensor's ability to maintain consistent output when identical pressure are repeatedly applied. Temperature Shift Span and Zero: The change in output and zero balance, respectively, due to a change in transducer temperature. Each pressure sensor has a "characteristic curve" or a "calibration curve", which defines the sensor's response to an input. During a regular calibration using the sensor calibration machine, we check the sensor's zero offset and linearity by comparing the sensor output under reference weights and adjusting the sensor response to an ideal linear output.
The pressure sensor calibration equipment also check hysteresis, repeatability and temperature shift when customers request it for some critical pressure measurement applications. If you have further questions about calibration terms and definitions, please refer to our Sensor Calibration Terms Glossary. Contact us to learn more! As strain gauge pressure transducer sensor are exposed to continuous usage, aging, output drift, overload and improper handling, FUTEK highly recommends a yearly recalibration interval.
Frequent recalibration helps confirm whether the sensor maintained its accuracy over time and provides a load cell calibration certificate to show that the sensor still meets specifications. However, when the sensor is used in critical applications and harsh environments, pressure sensors may require even more frequent calibrations.
Please consult appropriate calibration intervals with our Technical Support team, who will help you evaluate the most economical calibration service interval for your sensor. Store Service Applications Support Contact. Product Questions Application Questions. Technical Support More ways to contact us.
Recalibration Returns RMA. Your cart contains 0 packages. Store Service Applications Support search Get in touch. How does a Pressure Transducer work? Fig 1: Metal Foil Strain gage. Fig 2: Pressure Measurement Transducer Circuit. How to measure Pressure? What are the types of pressure transducers and measurement methods? Fig 3: How does a differential pressure sensor work? Tank Level Measurement using differential pressure measurement sensor.
Fig 4: Pressure measurement using a pressure sensor in a water pumping system Types of pressure-sensing technologies or working principles There are a variety of pressure-sensing technologies or sensing principles capable of transducing pressure into a measurable and standardized electrical signal.
But with several different types of available models and many uses, it may be challenging to know how to choose the right model for your purposes. This guide will take you through what transducers are, how they work, the different types and potential applications.
A pressure transducer, sometimes referred to as a transmitter, is a device that turns pressure into an equally proportional electrical signal. Transducers use variable pressure sensors to measure deflection and resistance. The produced signal will be either a voltage, current or frequency, based on the applied pressure.
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