According to the principle of operation, differential pressure regulators can be divided into two large groups:

1. Regulators, closing with increasing pressure drop. In these regulators, a spring holds the valve in the open position and more pressure is applied to the sensing element to close the valve.
2. regulators, opening with increasing pressure drop. In these, a spring holds the valve in the closed position, and more pressure acts on the sensing element, opening the valve.

Some regulators require the use of two or more impulse tubes to operate. They are necessary to transmit an impulse of regulated pressure to the sensitive element of the valve (diaphragm, piston or bellows), as well as to transmit a power impulse to moving elements.

The need for impulse piping is indicated in the description of the valves. Impulse piping is connected at the differential pressure points.