chemical inside old pressure sensor?

I am looking at an old Pressure Sensor with a dial display (shows Psi & inch hg gauge) on one end and a membrane type transducer on the other end. On the display there is a label that says "Nr:4" I wonder if this refers to the chemical inside this sealed sensor assembly. Does anyone know what "Nr:4" means? Generally what chemical do they use in these older dial type mechanical pressure sensor?

Reply to
Loading thread data ...

Dear Joseph:

Probably not.

Glycerine is pretty common, to dampen mechanical vibrations in the gauge.

David A. Smith

Reply to
N:dlzc D:aol T:com (dlzc)

Mineral oil is also used.

Reply to

PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.