Pressure Gauges:

Pressure gauges are instruments used to measure the pressure of gases or liquids in various systems. There are several types of pressure gauges, including:

1. Bourdon Tube Gauge: This is the most common type of pressure gauge, which uses a curved tube that expands or contracts based on the pressure applied. As the tube moves, it drives a pointer to indicate the pressure on a scale.

2. Diaphragm Gauge: These gauges use a flexible diaphragm that deforms with pressure changes. The movement of the diaphragm is converted into a measurement using a mechanical linkage.

3. Capsule Gauge: Similar to diaphragm gauges, capsule gauges use two diaphragms welded together to measure pressure. The pressure difference between the diaphragms creates a movement to indicate the pressure.

4. Manometer: Manometers are simple pressure gauges that use a liquid-filled tube to measure pressure. The pressure causes the liquid level to rise or fall, indicating the pressure value on a graduated scale.

Differential Pressure Gauges:

Differential pressure gauges, on the other hand, measure the difference in pressure between two points in a system. They are particularly useful for monitoring flow rates, filter conditions, or level variations in vessels. Some common types of differential pressure gauges include:

1. U-tube Manometer: This basic differential pressure gauge uses a U-shaped tube with liquid inside to measure the pressure difference between two points.

2. Piston-type Differential Pressure Gauge: These gauges use a piston to measure the pressure difference. As the pressure changes, the piston moves, indicating the differential pressure on a scale.

3. Bellows Differential Pressure Gauge: Bellows gauges use flexible metal bellows to measure the pressure difference. The bellows expand or contract, causing a pointer to move on a calibrated scale.

4. Orifice Plate: Although not a gauge itself, an orifice plate is often used with differential pressure gauges to create a pressure drop that can be measured. This setup is commonly used for flow measurement.

Each type of pressure gauge and differential pressure gauge has its specific applications and advantages, and the choice depends on the requirements of the system being monitored.