What is the Difference Between A Capsule Pressure Gauge and Diaphragm Pressure Gauge

Pressure gauges are commonly used in industrial control and measurement processes. Pressure gauges can be divided into mechanical and electronic pressure gauges. Users favor mechanical pressure gauges because of their flexible components and high mechanical strength. They are widely used in industrial production.

pressure gauge

We follow the needs of the different working conditions on-site. The design of the diaphragm pressure gauge is widely used, which has led to the multiplication of the diaphragm box pressure gauge. The two methods are nearly identical and use the same diaphragm pressure-taking principle. Still, the way the diaphragm is designed distinguishes the two, and we describe the two types of pressure gauges below.

1. The diaphragm pressure gauges 

stainless steel corrosion-resistant diaphragm pressure gauge has a stainless steel pressure guide system, housing, etc. It has strong corrosion resistance. It is mainly used in the chemical, petroleum, and textile industries to measure small pressures of gases and liquids. It is especially suitable for the size of small forces of corrosive, viscous media (non-consolidated non-crystalline).

1.1 Features of diaphragm pressure gauges

Diaphragm pressure gauges are corrosion and vibration-resistant diaphragms.

Diaphragm pressure gauges

1.1.1 Corrosion resistance

Diaphragm pressure gauges are suitable for measuring the pressure or negative pressure of various fluid media that are corrosive, non-solidifying, or non-crystalline. Corrosion resistance depends on the diaphragm material.

1.1.2 Vibration resistance

The vibration-resistant diaphragm pressure gauge is filled with a damping fluid and a cushioning device. It has good vibration resistance. It will have essential pulse changes or pressure shocks when we measure the pressure of the medium. It will be able to measure stably on occasions where there is often sudden unloading in the production process and places with high environmental vibrations.

1.2 Working principle of diaphragm pressure gauge

The gauge consists of a measuring system (including flange joints, corrugated diaphragm), a transmission mechanism (including linkage, gear transmission mechanism, pointer, and dial), and a casing (including case and cover ring). The instrument’s case is a splash-proof construction, which has good airtightness to protect its internal mechanism from dirt immersion.

The principle of action of the instrument is based on the deformation of the elastic element (the diaphragm on the measuring system). Under the pressure of the measured medium, the diaphragm is forced to produce a corresponding elastic deformation – displacement – which is amplified by the drive of the connecting rod set. The measured value is indicated on the dial by a fixed pointer to the gear.

Diaphragm pressure gauges

1.3 Advantages of diaphragm pressure gauge

1.3.1. Good overload performance.

1.3.2. Linearity.

1.3.3. Suitable for measuring absolute and differential pressures.

1.3.4. small size and moderate price.

1.3.5. Can be used for the measurement of viscous and slurry materials.

1.4 Disadvantages of diaphragm pressure gauge

1.4.1. Poor vibration and shock resistance.

1.4.2. Difficult to maintain.

1.4.3. Low measuring pressure.

2. The diaphragm Box Pressure Gauges

The diaphragm box pressure gauge is also known as a micro-pressure gauge. They measure micro-pressures and opposing forces of gases that do not have a corrosive effect on copper alloys and are not dangerous for explosions. They are widely used in boiler ventilation, gas piping, combustion installations, and similar equipment.

2.1 The features of the diaphragm box pressure gauge

2.1.1 It is suitable for measuring low micro-pressures of liquids, gases, or vapors that are not explosive, do not crystallize, do not solidify, and have no corrosive effect on copper and copper alloys.

2.1.2 The stainless steel diaphragm-type pressure gauge is suitable for processes with high requirements for corrosion resistance. It can measure the micro and negative pressures of various gaseous media. Its pressure guiding system and housing are made of stainless steel.

2.1.3 Stainless steel of diaphragm box pressure gauge concerning the structural characteristics of the original diaphragm box pressure gauge and developed with the corrosion-resistant effect of the micro-pressure meter. It is used in equipment such as boiler ventilation and gas pipelines. It can measure the micro-pressure and negative pressure of various gas media in processes with high requirements for corrosion resistance. Accuracy class: 2.5

2.2 Principle of Capsule Pressure Gauge 

The instrument consists of a measuring system (including fittings, corrugated diaphragm, etc.), a drive mechanism (including lever mechanism, gear mechanism), indicating parts (including pointer and dial), and a housing (including case, liner, and glass).

diaphragm box pressure gauge

The instrument works on being under the pressure of the measured medium. The free end of the corrugated diaphragm will be deformed elastically and then amplified by the drive of the gear mechanism. The measured value is indicated on the dial by a pointer fixed to the gear shaft. There is also a zeroing device, which allows easy adjustment of the zero position.

The measuring range of the capsule pressure gauge is from -80 to 60000 Pa, but we have to choose different capsule pressure gauges according to the other pressure ranges. For example, if the pressure is between -1000Pa and 60000Pa, we recommend using a disc-type diaphragm pressure gauge. On the other hand, if the pressure is between -80Pa, we recommend using a rectangular diaphragm pressure gauge.

3. Difference

3.1 Diaphragm pressure gauge

The Diaphragm pressure gauge has a diaphragm. The Diaphragm pressure gauge diaphragm plays the role of the elastic element.

3.2 Capsule pressure gauge

It increases the diaphragm’s displacement and improves the pressure gauge’s sensitivity. The two concentric diaphragms are welded together, made into a hollow membrane box, and used as an elastic sensitive element to measure a tiny pressure gauge called the membrane box pressure gauge.

4. Conclusion

Pressure gauges have become part of the applications in various industries. For example, they are used in the mechanical and chemical industries and the medical industry. A pressure gauge is simply an instrument used to measure pressures less than or greater than atmospheric pressure as a reference.

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