Diaphragm pressure sensors
process pressure changes. Disk is held firmly all around the
outer edge. The process pressure pushes on one side of the disk. Central
portion of the disk moves in or out as the process pressure changes. Two types
of diaphragms are used.
Single diaphragm: uses only one flexible element.
Capsule diaphragm: uses two flexible elements.
Diaphragm capsule may be made of phosphor bronze, stainless
steel or other metal alloys. Two diaphragms are welded together around the edge
to make the capsule. The inside of the diaphragm is then connected to the
process pressure and outside pressure is the reference. Outside of the capsule
is exposed to the atmosphere (for measuring gauge pressure). Capsule can be enclosed
in sealed container so that reference can be either a vacuum or one side of a
process pressure.
