As standard, our schaffer type diaphragm gauges are constructed in stainless steel (this includes the case, movement and top/bottom flanges. Other materials are also available.
All diaphragms up to and including 250kPa are made of 316 StSt., above this range they are cold galvanised spring steel (C 70 W 1) protected as standard with self adhesive 0.005" thick PTFE sheet (Teflon). Other protection materials are also available for the diaphragms and/or bottom chamber process connections.
To deliver a more positive drive from the diaphragm to the movement, we utilise a large (160mm diameter) diaphragm for all ranges from 2.5 to 40kPa inclusive. This feature also makes these gauges much more sensitive to better measure small pressure changes (than can smaller diaphragms) and positively operate accessories such as electrical contacts, maximum pointers etc.
The modular design of these gauges enables us to supply them with a broad choice of process connection materials and sizes, either threaded or flanged. These gauges will more readily handle viscous fluids, rugged and chemically aggressive environments, low pressures, and relatively high overloads than bourdon tube systems.
Models 250 and 253 are specially made for chlorine applications, having a silver plated diaphragm and a nickel plated bottom chamber/process connection. See chart below.