The Definitive List of Pressure Measuring Instruments

Pressure measuring instruments come in various types, each designed to meet specific requirements for measuring pressure under different conditions.  

Since pressure is one of the most variable parameters, accurate measurement is essential for industries dealing with gases, water, and other liquids. This is why pressure measurement equipment, including absolute pressure transmitters, plays a crucial role in monitoring and controlling these substances.  

The right instrument depends on your industry and specific processing needs. Some devices offer both absolute and relative readings, while others factor in environmental conditions to provide more precise measurements. Having a diverse selection allows you to choose the most efficient solution for your application.

Piezometer  

A piezometer is used to measure the static pressure head of a flowing liquid at a specific section of a pipe. It consists of a tube with one end exposed to the atmosphere, while the other end is mounted flush with the inner wall of the pipe.  

Limitations of a Piezometer:  

- Not suitable for measuring high pressures  

- Cannot measure negative gauge pressure  

- Ineffective for rapid pressure changes  

Manometer  

A manometer is a pressure measurement instrument that uses liquid columns to gauge pressure in gases and liquids. It comes in various designs, including U-shaped, single-column, and inclined tubes.  

- When one limb is open to the atmosphere, the device measures the pressure of the connected source.  

- When both limbs are connected to different sources, it records the pressure difference between them.

Bourdon Gauge  

The Bourdon gauge is a reliable instrument for measuring high pressures, as well as negative or vacuum pressures. To ensure accuracy, it must be calibrated using known pressure values.  

This device features a closed metallic tube with an elliptical shape at one end, while the other end is connected to the gauge point for pressure measurement. When fluid enters the tube, it tends to straighten, causing movement that is translated into a pressure reading.  

Diaphragm Pressure Gauge  

The diaphragm pressure gauge operates similarly to the Bourdon gauge but is better suited for measuring low pressures. Instead of a Bourdon tube, it uses a corrugated diaphragm that deforms elastically when exposed to pressure.  

Once deformation occurs, the gauge transmits a signal to a pointer on a graded scale, displaying the measured pressure. This mechanism is similar to how an aneroid barometer functions, making it a practical tool for sensitive pressure measurements.

Barometer  

A barometer is an essential device used for measuring local atmospheric pressure. It plays a crucial role in weather prediction and forecasting, making it a fundamental tool for meteorological organizations. Additionally, some home and business owners use barometers to monitor air pressure fluctuations in their properties.  

A mercury barometer typically consists of a one-meter-long glass tube, sealed at one end and filled with mercury. When a portion of the mercury flows into a bowl, a vacuum forms at the top of the tube. The atmospheric pressure acting on the mercury in the bowl supports the mercury column inside the tube, allowing for accurate pressure measurements.  

Types of Barometers:  

- Aneroid Barometer – This instrument contains a partially evacuated, corrugated metal box supported by a strong spring to prevent collapse. Changes in atmospheric pressure cause the box to deform, which is then translated into a pressure reading.  

- Siphon Barometer – Also known as a household barometer, this device features a U-shaped glass tube with a wider open end that functions similarly to a traditional mercury barometer.

Micro Manometer  

A micro manometer operates on the same principles as a standard manometer but is designed to reduce capillary effects and meniscus reading errors, ensuring greater accuracy.  

Its centrifugal design makes it ideal for applications requiring high-precision pressure measurements, with calibration ranging from 10 mbar down to 3 mbar. This instrument determines the null position when oil droplets sprayed into its glass chamber come to a complete stop, allowing for precise pressure detection.

Why Use Pressure Measuring Instruments?  

No matter the type of device, the reasons for using pressure measuring instruments are largely the same:  

- Maintaining Product Quality – Ensures consistency in production by regulating pressure levels.  

- Enhancing Safety – Prevents equipment failures and potential hazards.  

- Optimizing Machine Efficiency – Helps systems operate at peak performance, reducing downtime and wear.  

These instruments are essential for preventing dangerous pressure build-ups, which could lead to explosions or equipment damage. Even when extreme consequences are unlikely, proper pressure monitoring extends the lifespan of machinery and improves overall performance.  

Choosing the Right Pressure Measuring Instrument  

While pressure measurement devices vary in design, their fundamental working principles remain the same. Selecting the right type depends on how pressure is gauged—whether through direct or indirect measurement methods—and the specific application requirements.