Differential pressure gauges

A differential gauge measures differential pressure in two separate pressure systems. They dispose of two connections: one for high (+) and one for low (-) pressure. At EMVO Techniek we have got many different types of differential gauges in stock. They are based on two operating principles:

• With Bourdon tube;
• With diaphragm.

Differential gauge with Bourdon tube

The Bourdon tube of a differential gauge contains a certain liquid. The tube has a “U”-shape and in “rest”, the liquid level is equal on both sides of the U., in balance with atmospheric pressure. One side of the tube is connected to the high pressure measuring point, whilst the other side measures low pressure. The difference in pressure between those two points causes the liquid level in the Bourdon tube to change. The level difference between the two liquid columns in the Bourdon tube indicates the differential pressure.

There is another method that is also quite common: two separate Bourdon tubes are used to set in motion one or two pointers. When there is just one pointer, it will indicate the differential pressure on the scale. In case of two needles, one indicates high pressure, and the other one, low pressure. Therefore, this type can measure pressure in the two separate systems, as well as differential pressure.

Differential gauge with diaphragm

This type of pressure gauge uses a thin, flexible diaphragm that will deform according to the increase or decrease of fluid or gas pressure in a system, which will result in a movement of the pointer in the display. The diaphragm is located between two pressure gauge compartments: one for high pressure, and one for low pressure. Pressure in the high pressure compartment will push the diaphragm towards the low pressure compartment. This deflection is proportionate to the differential pressure.

The functioning of the Bourdon and diaphragm principle in differential gauges is comparable to that of a regular pressure gauge.

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Do you have any questions or do you need any help choosing the right differential gauge? Please feel free to contact us; our experts will be happy to help you.