In closed systems, the transmitter location is

restricted by the maximum allowable distance

above the lower tap. In pressurized systems, this is

the same as the 1 atmosphere equivalent seen

previously. In sub-atmospheric systems (vacuum

systems), the transmitter should be mounted at or

below the lower tap. This ensures the transmitter

always sees a positive pressure on both the

measurement and the reference sides.

In two seal systems, the distance between the taps

becomes the reference offset from zero. The

calculations are the same regardless of where the

transmitter is mounted.