There is a loose convention across manufacturers for designating the type of reference that a pressure sensing device has, which can be confusing if you are unfamiliar with specifying this often overlooked but critical specification parameter.
To help identify the reference of a particular pressure range found on a product label or technical data sheet a list of abbreviated suffixes is provided below.
Gauge – Measuring pressure with reference to atmospheric pressure, also referred to as Relative and Vented Gauge:
Sealed Gauge – Not vented to atmospheric pressure, but instead the reference is fixed to 1 bar.
Absolute – Zero reference pressure or absolute vacuum
Differential – The difference in pressure at point B compared to the pressure at point A.
On product marking labels or any document that includes a description of the pressure range, the reference type is included after the pressure unit type e.g. 15 psi abs or 15 psia.