A Differential Pressure Switch, just like a regular pressure switch, is a simple electro-mechanical device that operates on the basic principles of levers and opposite forces. Mainly, they are used for sensing a difference between two points in a process. Three key elements are used in various combinations to manufacture different kinds of differential and standard pressure switches to suit unique industrial needs. These elements are:

A sensing element made either of bellows or diaphragm, metallic or elastomeric
A hardened spring to determine the range set point
A snap-acting micro switch available in a wide variety, SPDT, DPDT, etc.
 
The Working Principle
The purpose of the Differential Pressure Switch is to sense a difference in pressure between two pressure sources in a control process. When the pressure from two different sources is connected across a sensing diaphragm, the pressure difference creates a force which then acts upon the pre-tensioned spring. This action moves a balancing arm or mechanism to effect the minimal movement required to activate the micro switch.

High and low pressures are applied on either side of the specially contoured sensing diaphragm. This feature helps to eliminate errors due to a difference in area which is commonly a problem present in twin element Differential Pressure Switches.

Pressure ports for high-process pressure, as well as low-pressure are separated by an elastic diaphragm. The difference in pressure between the two ports causes axial movement, otherwise known as measuring travel, of the diaphragm against a measure range spring. The differential pressure, which is proportional to the measuring level, is transmitted through a connecting rod with little friction to the plungers of the micro switch.

The micro switch contains the electrical contacts of the switch, and electrical contacts will actuate based on the switch points and set points. Overpressure is protected by contoured metal bolsters for the elastic diaphragm. 

Adjustments for Setpoints

The adjustment of the switch point or setpoint can be accomplished by setpoint screws accessible from the front of a Differential Pressure Switch. The graduated scales allow a relatively accurate adjustment of the switch points, and indicate the setpoint has been changed.

As a manufacturer and trader of pressure transmitter,YUNYI can supply series products in this field, such as pressure transmitter, temperature transmitter, level transmitter, sensors, flowmeters, flow transmitter.The brands we can provide include Rosemount, Yokogawa, ABB, Siemens, Honeywell, etc. We also have our factory to produce our transmitters and flowmeters, if you want to know more information about our transmitter, please contact us immidiately.