Different Types of Pressure Measurement Instruments

Posted by TechStar on Nov 11, 2021 10:24:00 AM

Substandard results, as well as any discrepancies in obtaining the correct pressure measurement, can be dangerous. Due to these reasons, it is imperative to choose the best device, including vacuum pressure measurement equipment, according to your needs.

Apart from the manufacturing sector, other industries also need to have accurate pressure measurements to ensure the best production quality.

The simplest definition of a pressure sensor is a device that senses pressure and converts it into an electrical signal. The significance of this equipment is evident in the growing global market share of pressure sensors – a clear indication of its rising and ongoing demand.

With different models and types of pressure sensors available from various manufacturers, you might find it too confusing to choose the most suitable one for your application. Fortunately, it is easy to classify and group these varieties into three main types.

What is the Difference Between Each Pressure Sensor?

The best way to quickly understand the difference between each pressure sensor is to define them. Here are the three major types of pressure sensors:

  • Absolute pressure sensor: With absolute pressure sensors, the reference point is always zero or the closest to the vacuum value.
  • Gauge sensor: Unlike the absolute types, gauge pressure sensors always provide pressure measurements relative to atmospheric pressure.
  • Differential pressure sensor: As the name suggests, the measurement value provided by differential pressure sensors is the difference between pressures from two exposed ports.

When taking barometric pressures or applications not requiring any influence from the air, it usually requires absolute pressure measurements.

On the other hand, the gauge sensor is perfect if you need to consider the ambient conditions. Measuring car tire pressure is an excellent example of this. However, since the sensors get exposed to the atmosphere, humidity can affect the accuracy of the reading.

A differential pressure sensor references neither the internal sensor nor the ambient conditions. This sensor is usually for measuring gas or liquid flow through a pipe or tube – helpful in detecting blockages or seized valves.

How to Know which Pressure Sensor to Choose for Your Application

Pressure sensors have various applications spanning different industries, including general industrial, medical, HVAC, automotive, and energy. Providing a complete list of all its applications is beyond the scope of this article. However, you will discover specific examples here to give you a general idea, helping you narrow down which particular sensor to use for your application.

Below is a non-exhaustive list and quick overview of the most common application examples of each of these pressure sensors:

  • Absolute pressure sensors

    • Barometric
    • Weather stations
    • Meteorological applications
  • Gauge pressure sensors

    • Car tires
    • Chamber pressure
    • Hydraulic applications
    • Water level measurement
  • Differential pressure gauges

    • HVAC
    • Filter and pump monitoring
    • Cleanroom monitoring

Absolute pressure gauges are effective in measuring the vapor pressure of liquids. The measurement they provide can help check tank and circuit leakages, as well as any decrease in pressure of distillation vacuum columns. Meteorologists use this type of pressure sensor in monitoring adiabatic saturation pressure.

Gauge pressure sensors, on the other hand, are the pressure measuring instrument of choice for general industrial purposes. Power grids, refineries, petrochemical, food refrigeration, and sanitation industries have various uses for this device.

You will usually find extensive use of differential pressure gauges in industries related to monitoring liquid flow, liquid level, and filtrations. Refineries, petrochemical, and chemical plants are some examples, as well as power plants.

How Do Each Pressure Sensors Measure Pressure Differently?

Each type of pressure sensor instrument has its unique way of measuring pressure. The working principle behind them can influence its reliability, measurement range, and compatibility with the target environment. There are five ways to convert a mechanical displacement into electrical output, namely:

  • Resistive

  • Capacitive

  • Optical

  • MEMS

  • Piezoelectric

To determine how the sensors achieve their measurements, you must also learn how they connect to their target systems.

How Do These Sensors Attach to Different Systems?

Each pressure sensor has different working principles in measuring pressure.

For the absolute pressure gauge, a diaphragm separates its measuring cell. One side of its sensor gets exposed to the medium it will measure, while the other side connects to the vacuum.

A typical gauge pressure measuring device has one side connected to a pump, like a suction pump, while the other side has a vent hole exposed to the atmosphere. The Bourdon tube pressure gauge is its most common variation, consisting of a C-shaped tube with one end sealed.

Most differential pressure sensors are mechanical, with variations including piston-style, bellows, and diaphragm types. The two pressures requiring measurement must connect to the opposite sides of a single diaphragm – any deflection concerning the diaphragm's resting state determines the pressure difference.

Choose the Right Type of Pressure Measurement for your Application

Now that you know the working principle behind each type of pressure measurement instrument, it will be easier for you to choose which one is suitable for your system. Manufacturers of this instrument generally use the same principles, but further variations help improve the devices, such as remote management and maintenance offered by TechStar.