The Diaphragm Pressure Gage uses the elastic deformation of a diaphragm (i.e. membrane) instead of a liquid level to measure the difference between an unknown pressure and a reference pressure.

A typical Diaphragm pressure gage contains a capsule divided by a diaphragm, as shown in the schematic below. One side of the diaphragm is open to the external targeted pressure, P_Ext, and the other side is connected to a known pressure, P_Ref,. The pressure difference, P_Ext - P_Ref, mechanically deflects the diaphragm.

The membrane deflection can be measured in any number of ways. For example, it can be detected via a mechanically-coupled indicating needle, an attached strain gage, a linear variable differential transformer (LVDT; see the schematic below), or with many other displacement/velocity sensors. Once known, the deflection can be converted to a pressure loading using plate theory.

•	Pros:
	-	Much faster frequency response than U tubes.
	-	Accuracy up to ±0.5% of full scale.
	-	Good linearity when the deflection is no larger than the order of the diaphragm thickness.
•	Cons:
	-	More expensive then other pressure sensors.