A remote seal system consists of the following components.

• Pressure transmitter
• One or two remote seals
• Filling liquid
• Connection between pressure transmitter and remote seal (direct mounting or by means of capillary)

The volume in contact with the measured medium is terminated by a flat embedded elastic diaphragm. Between the diaphragm and the pressure transmitter is the filling liquid.

In many cases, a capillary has to be connected between the remote seal and the pressure transmitter in order e.g. to minimize temperature effects on the latter when hot media are involved.

However, the capillary influences the response time and the temperature response of the complete remote seal system. Two capillaries of equal length must always be used to connect a remote seal to a pressure transmitter for differential pressure.

The remote seal can be optionally equipped with a projecting diaphragm (tube).

Remote seals of sandwich design are fitted with a dummy flange.

Designs

Diaphragm seal

With diaphragm seals, the pressure is measured by means of a flat diaphragm which rests in a bed.

The following types of diaphragm seals exist:

Diaphragm seal of sandwich design without (left) and with a projecting diaphragm (tube)

• Sandwich design
• Sandwich design with projecting diaphragm (tube) to DIN or ASME which are secured using a dummy flange.

Diaphragm seal of flange design without (left) and with a projecting diaphragm (tube)

• Flange design
• Flange design with projecting diaphragm (tube) to DIN or ASME, secured using holes in the flange.

Quick-release diaphragm seal

• Quick-release remote seals, e.g. to DIN 11 851, SMS standard, IDF standard, APV RJT standard, clamp connection, etc.
  • Miniature diaphragm seal with male thread for screwing into tapped holes
  • Remote seals with customer-specific process connections

Miniature diaphragm seal with diaphragm flush with front

• Miniature diaphragm seals

The quick-release remote seals are primarily used in the food industry. Their design means that the measured medium cannot accumulate in dead volumes. The quick-release clamp present on the remote seal means that quick dismounting is possible for cleaning.

Clamp-on seal

Clamp-on seal with quick-release design (left) and for flange mounting

With clamp-on seals, the pressure is first measured using a cylindrical diaphragm positioned in a pipe, and then transmitted to the pressure transmitter by means of the filling liquid.

The clamp-on seal is a special design for flowing media. It consists of a cylindrical pipe in which a cylindrical diaphragm is embedded. Since it is completely integrated in the process line, no turbulences, dead volumes or other obstructions to the flow occur. Furthermore, the clamp-on seal can be cleaned by a pig.

The following types of clamp-on seals exist:

• Quick-release clamp-on seals, e.g. to DIN 11 851, SMS, IDF, APV/RJT standard, clamp connection etc. The quick-release facility attached to the remote seal enables the seal to be removed quickly for cleaning purposes.
• Clamp-on seals for flanging to EN or ASME.
• Clamp-on seals with customer-specific process connections.

Note:

The pressure data on the transmitter and the remote seal must be observed with regard to pressure/temperature behavior.