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    Pressure Sensor FAQs

    Frequently asked pressure sensor questions

    How to clean a pressure sensor

    If process media deposits are building up in your sensor’s pressure port then regular cleaning is important to maintain the accuracy of your pressure sensor.  We would always advise you to speak to the manufacturer or supplier for specific cleaning instructions as it may invalidate your warranty or, in a worst-case scenario, damage the sensor if the process is not performed correctly.
    Always cover the contacts or the pressure port before carrying out any cleaning and do not touch the contacts or the pressure port when cleaning.
    Exterior cleaning of the pressure sensor can be done by using a cotton swab that has been immersed in an alcoholic cleaning solution.  Cleaning should be carried out in a downward direction away from the pressure port opening.
    For pressure measurement in viscous or pasty media, we suggest using our flush-diaphragm type pressure sensors which little or no recess at the measurement end of the pressure sensor allowing fluid to flow across the sensor without clogging the pressure port.

    How to repair a pressure transducer

    We would always recommend that you contact the manufacturer or supplier of your pressure transducer and do not attempt to carry out any repairs yourself as this may invalidate the warranty or cause further damage.
    We have an expert repair team here at Applied Measurements who would be happy to discuss repairing your pressure transducer. Contact us at info@appmeas.co.uk

    Can I buy a pressure sensor online?

    Yes, we have a pressure sensor online shop. Several of our pressure sensors are available ex-stock.

    What instrumentation works with a pressure sensor?

    We sell various pressure sensor instrumentation that will accept a current or voltage input from a pressure sensor. Our intuitive4-P universal process input digital indicator is a 6-digit LED panel display and works seamlessly with current or voltage pressure sensors.

    How many wires does a pressure sensor have?

    A pressure sensor can have 2 wires, 3-wires or 4-wires, dependent on their output signal.

    Our 4-20mA pressure sensor current output pressure sensor offers a 2-wire loop-powered circuit, where the 2-wires provide the supply and also output the signal.

    Our voltage output 3-wire pressure sensors use 2 wires to carry the +ve and -ve supply and 1 wire to deliver the output.

    Our 4-wire pressure sensors have a mV/V output and use 2 wires to carry the excitation and 2 wires to carry the output.

    Details of their wiring will be on the accompanying calibration certificate delivered with the pressure sensor when shipped to you.

    What are the benefits of an I2C pressure sensor?

    I2C pressure sensors are easy to install into an existing I2C bus with easy clipping on and off, simple 2-wire data transfer and low power consumption. For an in-depth article on the benefits of I2C, please read….

    Where are pressure sensors used?

    Pressure sensors are in a wide range of industries from ranging from medical, automotive and HVAC to geotechnical, meteorology and all manner of industrial process measurement and control applications.

    What applications can pressure sensors be used in?

    Pressure sensors can be used in weather forecasting, process applications, water level monitoring, sewage level monitoring, materials testing and car safety testing, amongst many thousands of other applications.

    What do pressure sensors detect?

    Pressure sensors detect changes in the pressure of liquids and gases.

    Which pressure sensor is best?

    There is no one size fits all. The better question would be which pressure sensor is best for your specific application. You need to consider the media, environment, pressure range, accuracy and output.

    How to choose a pressure sensor

    The following application requirements are important to consider when choosing a pressure sensor:
    1) Pressure media & temperature
    2) Operating environment
    3) Pressure range to be measured
    4) Accuracy level
    5) Electrical output signal
    6) Process connection type
    7) Electrical connection type
    For a more detailed explanation please see article…

    What are the main types of pressure sensors?

    The main types of pressure sensors are gauge, absolute, sealed and differential.
    Gauge is referenced to atmospheric pressure, sealed is referenced to a sealed chamber, absolute is referenced to a vacuum and differential measures the difference between two pressure ports.

    For more details about each please see our Different Types of Pressure Measurement article.

    What is a flush diaphragm pressure sensor?

    There are 2 different types of flush diaphragm pressure sensors; oil filled and non-oil filled. Oil-filled pressure sensors have an external diaphragm on the front and the cavity behind, which contains the sensing element, is filled with oil. A non-oil-filled flush diaphragm pressure sensor has the strain gauge bridge bonded directly to the rear of the sensing diaphragm.

    For an in-depth look at both please read article.

    Are pressure sensors analogue or digital?

    A pressure sensor can be either digital or analogue and is determined by the output signal transmitted. An analogue pressure sensor transmits its signal as an analogue current or voltage output for example 4mA to 20mA, or 0V to 10V. A digital pressure sensor converts the analogue input and transmits it as a digital output such as ASCII, Modbus and CANopen via RS232, RS485 or USB interfaces. We sell both analogue and digital pressure sensors.

    Which is more accurate, an analogue or digital pressure sensor?

    Both analogue and digital pressure sensors can be accurate, but the accuracy of each type of sensor depends on various factors.

    Analogue pressure sensors provide continuous output signals that vary proportionally with the applied pressure. Analogue sensors have a fast response time and are easy to set up. They typically have a lower resolution and accuracy compared to digital sensors. The accuracy of an analogue sensor can also be affected more readily by external factors such as temperature changes, noise, and signal drift over time.

    Digital pressure sensors generally have low power consumption, offer better diagnostic data and can even offer multiple output signals in some cases. They offer higher resolution and accuracy, which makes them more suitable for applications that require highly precise pressure measurements. Digital sensors are also less affected by external factors and feature integral monitoring and compensation to improve their accuracy.

    Generally, digital pressure sensors offer higher accuracy and precision compared to analogue sensors, but the choice of which to use ultimately depends on the specific requirements of your application.

    Pressure Sensor vs Pressure Switch

    A pressure sensor and pressure switch are both devices used to measure or detect changes in pressure. A pressure sensor is designed for continuous monitoring and a pressure switch is an electronic device that triggers when a certain pressure level is reached. They have different functions, outputs, applications, and internal designs.

    A pressure sensor is designed to measure and monitor pressure continuously and provide an output signal proportional to the measured pressure.

    Whereas, a pressure switch is an electronic device to monitor pressure that triggers when the pressure reaches a certain set point or level. A pressure switch could be used as a safety mechanism as part of an automatic shut-off system.

    The output of a pressure sensor is typically an analogue signal (such as 4-20mA or 0-10V) that represents the measured pressure.

    In contrast, the output of a pressure switch is typically a contact closure (such as a relay) that closes or opens when the pressure reaches a pre-determined pressure level.

    Pressure sensors are often used in applications where precise and continuous monitoring of pressure is required, such as in industrial processes, HVAC systems, and medical equipment.

    Pressure switches are often used in applications where the pressure needs to be controlled, such as in pumps, compressors, and safety systems.

    Pressure sensors and pressure switches have different internal designs. Pressure sensors typically use a sensing element (such as a diaphragm used in conjunction with piezoelectric crystal or strain gauge bridge) to detect changes in pressure and convert them into an electrical signal.

    Pressure switches, on the other hand, typically use either a mechanical switch or an electronic sensor to detect changes in pressure and trigger the output accordingly.

    Flush mounted vs non-flush sensor

    Flush-mounted pressure sensors and non-flush pressure sensors differ in both design and installation.

    A flush-mounted sensor is designed to be mounted flush with the surface of the material it is measuring. This means that the sensing element’s face is flat at the end of the pressure sensor. They are often used in food processing environments and pharmaceutical applications, where it is important to have a clean, smooth surface. The flush mounting design also helps to prevent damage to the sensor and reduces the likelihood of contamination. It can be used in viscous media where a non-flush port is liable to clog.

    A non-flush sensor has a protruding, threaded port with a central hole that leads to the sensing diaphragm. They are screwed into a mating thread on a pipe, valve, T-piece connector vessel wall. These types of sensor are suitable for the measurement of gases and low-viscosity fluids. Non-flush pressure sensors are commonly used in industrial automation, robotics, hydraulics and machine control applications.

    Pressure Sensor vs Load Cell

    Both a load cell and a pressure sensor measure force.  The main difference between a pressure sensor and a load cell is the way they measure force.  A load cell measures the force directly and a pressure sensor measures the force indirectly as it is measuring the pressure from the changes in media (oil, liquid or gas) pressure.

    A load cell is a transducer that converts force into an electrical signal. Load cells typically have strain gauges attached to a metal or alloy sensing element that deforms in direct response to the applied force. The strain gauges measure the direct deformation and convert it into an electrical signal that can be measured and analysed. They are typically used to measure the weight or force of an object, such as in industrial weighing scales, material testing machines, and other force measurement applications.

    A pressure sensor is designed to measure the pressure of a fluid or gas. They work by measuring the force exerted by a fluid or gas on a sensing element with a known surface area such as a diaphragm or piezoelectric crystal. Pressure is defined as force per unit area, with the equation P = FA. The change in force on the media is converted into an electrical signal that can be measured and analysed. Pressure sensors are commonly used in industrial and automotive applications, as well as in medical devices and environmental monitoring.

    What is the difference between a pressure transducer and a pressure transmitter?

    Normally when people talk about pressure transducers and pressure transmitters these terms can become interchangeable but technically speaking they are not the same devices. The difference between a pressure transducer and a pressure transmitter is the type of output the device sends.

    A pressure transducer usually provides a raw output signal. It converts the force it is measuring into a proportional voltage output i.e. volts or millivolts, whereas a pressure transmitter outputs a processed current signal i.e 4-20mA which can be directly connected to a control system. A pressure transmitter contains additional built-in circuitry.

    Pressure transducers are commonly used in research and development applications, where a high degree of accuracy is required and the signal processing can be customised to suit the demands of the user. Pressure transmitters are more commonly used in industrial applications, where a standardised output signal is required for interfacing with control systems.

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