Dp-MAG differential pressure indicators monitor a changeable pressure difference using a visual display and electrical contacts of up to two points.
Negative pressures deviations from a default position case a hermetically sealed plunger to move against the force of a calibrated measuring spring.
The plunger position relative to the pressure drop is transmitted via a permanent magnet, i.e. at low friction, to a display field and, if required, to reed contacts for electrical signaling.