The fitting of a diaphragm seal unit to a pressure gauge is recommended where the medium to be measured is highly viscous or contains suspended solids or is potentially corrosive to the Bourdon Tube. Seal units are normally connected directly to the gauge, but connection may be made by flexible capillary, which makes them ideal for remote pressure indication.

 

Flexible capillary can be used to facilitate the fitting of a gauge in a surface or panel mounting location. Maximum capillary length is 5 metres.

 

Pressure is transmitted from the diaphragm seal unit to the bourdon tube by a suitable filling medium, the selection of which will ensure compatibility with the process and process temperature. Where it is known that the instrument will be used on processes subject to extremes of temperature, the temperature at the tapping point should be advised at the time of ordering.

 

Diaphragm seal units can be directly for remotely fitted to Rototherm gauge types: SPG, RPG, DMC, SPGA, DP3 and Turret gauges.

 

Diaphragm Seal Arrangements

 

Type A - Welded Construction

 

Type A seals are of fully welded construction and are hence most suited to applications that do not involve viscous fluids, suspended solids or crystallising liquids.

 

Maximum Working Pressure:

5000 psi

Process Connections

Male screwed: 3/8”, 1/2” BSP, 1/2” BSPT, 1/2” NPT, 1” BSP and 1” BSPT. Other screwed connections on request.

Flanged connections: Any standard flange size - see table

Diaphragm Materials

316 Stainless steel - standard

Monel, Hastelloy, Tantalum and PTFE coatings are available on request

Materials of Construction

304 stainless steel top housing

316 stainles steel bottom housing

(316 stainless steel top housing option)

 

Type B - Bolted Construction

 

Type B seals are of a bolted construction with the diaphragm welded

to the top section enabling the seal to be easily disassembled and are

particularly suited for applications in which periodic cleaning of the seal

may be required.

 

Maximum Working Pressure

3000 psi

Process Connections

Male screwed: 3/8”, 1/2” BSP, 1/2” BSPT, 1/2” NPT, 1” BSP and 1” BSPT. Other screwed connections on request.

Flanged connections: Any standard flange size - see table

Diaphragm Materials

316 Stainless steel - standard

Monel, Hastelloy, Tantalum and PTFE coatings are available on request

Materials of Construction

304 stainless steel top housing

316 stainles steel bottom housing

(316 stainless steel top housing option)

 

Type C - Welded Diaphragm Bolted to Flange Construction

 

Type C seals use similar construction to the Type B, but are flange mounted and are most suitable for viscous product applications.

 

Type C seals require a flange with a nominal bore of at least 2”; for applications requiring smaller bore flanges please refer to details on Rototherm extended flange seals Types 4 and 6.

 

Maximum Working Pressure

Refer to flange maximum pressure rating table in data sheet

Process Connections

Flange mounted seals - see table in data sheet

Diaphragm Materials

Stainless steel - standard, Monel, Hastelloy and Tantalum

PTFE coatings are available on most models

Materials of Construction

316 stainless steel tops - bases are available

in 316 stainless steel, PTFE lined, Monel and

Hastelloy - others are available on request.