Pressure Gauge Types and Working Principle | Simple Science

Summary

This video explores the different types of pressure gauges and their working principles. It covers Bourdon tube gauges, including C-type, spiral, and helical types, explaining how they measure medium to high pressures. The video also delves into diaphragm pressure gauges, known for their insensitivity to vibrations, and bellows-type gauges, used for absolute, gauge, and differential pressure measurements. Each type is suited for specific applications based on the pressure range and media characteristics, offering viewers a comprehensive understanding of pressure measurement technologies.

Takeaways

• 😀 Pressure gauges are instruments used for measuring applied pressure by detecting the deformation of pressure-sensing elements.
• 😀 There are three main types of pressure gauges: Bourdon tube, diaphragm, and bellows, based on the pressure sensing elements.
• 😀 Bourdon tube pressure gauges are used for medium to high pressures and come in three forms: C type, spiral type, and helical type.
• 😀 The C type Bourdon tube has a flattened circular cross-section that straightens when pressure is applied, creating nonlinear motion converted to pointer movement.
• 😀 Spiral type Bourdon tubes provide higher sensitivity and accuracy by uncoiling when pressure is applied, eliminating mechanical amplification.
• 😀 Helical Bourdon tubes provide even greater motion, reducing the need for mechanical amplification and allowing high-pressure measurements with high over-range protection.
• 😀 Diaphragm-type pressure gauges use circular, corrugated membranes that elongate under pressure, transmitting small deflections to the pointer for more accurate readings.
• 😀 Diaphragm elements are insensitive to vibration and suitable for measuring highly viscous, impure, or crystallizing media, with a range from 0 to 40 bar.
• 😀 Capsule-type diaphragm pressure gauges use two corrugated diaphragms welded together to form a sealed capsule, with pressure introduced into the first diaphragm.
• 😀 Bellows-type pressure gauges are used for vacuum, absolute, and differential pressure measurements, with a dual-bellows setup for differential pressure sensing.

Q & A

What is the primary function of a pressure gauge?

A pressure gauge is an instrument used to measure the applied pressure of a medium, using pressure-sensing elements that deform elastically under pressure to help determine the pressure.

What are the three main types of pressure gauges based on pressure-sensing elements?

The three main types of pressure gauges are Bourdon tube, diaphragm, and bellows, each designed for different pressure measurement applications.

How does a Bourdon tube pressure gauge work?

A Bourdon tube gauge uses a circular-shaped tube that flattens under no pressure. When pressure is applied, the tube becomes more circular, causing it to straighten, which moves a pointer mechanically through gears to indicate the pressure.

What is the difference between C-type, spiral-type, and helical-type Bourdon tubes?

C-type Bourdon tubes have an arc of 270 degrees and are used for various pressure ranges, spiral-type Bourdon tubes provide greater movement for improved sensitivity and accuracy, and helical-type Bourdon tubes offer even greater motion and high-pressure capabilities with high over-range protection.

Why are spiral-type Bourdon tubes preferred for some applications?

Spiral-type Bourdon tubes are preferred because they provide more sensitive motion and increased accuracy due to the uncoiling of the spiral without introducing mechanical friction or lost motion.

What are the applications for diaphragm-type pressure gauges?

Diaphragm-type pressure gauges are often used in applications involving highly viscous, impure, or crystallizing media, and they can measure pressures within the ranges of 0 to 16 mbar and 0 to 40 bar.

What is the role of the capsule in a diaphragm-type pressure gauge?

The capsule in a diaphragm-type pressure gauge consists of two welded diaphragms that measure low pressure. The deflection of the diaphragms is transmitted to a pointer to indicate pressure.

What distinguishes bellows-type pressure gauges from other types?

Bellows-type pressure gauges use an expanding or contracting bellow element based on pressure differences. They are typically used for intermediate pressure measurement and are suitable for absolute, gauge, and differential pressure measurement applications.

How do absolute bellows pressure gauges work?

In an absolute bellows pressure gauge, one bellow is used to measure the process pressure, while the other is evacuated and sealed to serve as a reference. The pressure of the medium is compared against the reference, and any change in the process pressure causes the bellows to extend, resulting in a pointer movement.

What is the difference between a differential pressure gauge and an absolute pressure gauge?

A differential pressure gauge measures the difference between two pressures, while an absolute pressure gauge measures pressure relative to absolute zero. The differential pressure gauge will show a reading when the pressures on either side of the sensing element differ.