Isolation Rings can be used with a simple pressure gauge for protection of delicate, expensive instrumentation such as switches, transmitters, recorders, and transducers. Re calibrating gauges are available from Hex.
Hex Valve's Isolation Ring, which fits between customer-supplied piping flanges like many butterfly valves, is available for piping diameters from 2" to 20". It can be used at any pressure within the limitations of ANSI Classes 150 and 300, and even in most vacuum applications.
Several elastomeric materials can be used for the inner flexible cylinder, each with its own temperature limitations and chemical and abrasion-resistant characteristics.