Dual Seal - Siemens SITRANS FX330 Operating Instructions Manual

DEVICE DESCRIPTION
2

2.2.10 Dual seal

To comply with the requirements of ANSI/ISA 12.27.01 "Requirements for Process Sealing
Between Electrical Systems and Flammable or Combustible Process Fluids", a membrane vent
is integrated in the neck of the device. This vent is located between the primary seal (process)
and the secondary seal (electronics compartment) and works to prevent pressure build-up in the
device neck, thus preventing product from penetrating the electronics compartment in the
unlikely event of a leak in the primary seal.
Figure 2-7: Dual Seal
1 Membrane vent
The seal between the pick-up and the measuring tube is considered as the primary seal. The
material used for this is always the same as that used for the measuring tube itself (e.g.
1.4435/316L for measuring tube made of stainless steel 1.4404/316L or Hastelloy
measuring tube made of Hastelloy
depending on process parameters (product, temperature) must be taken into account.
By using the membrane vent, all requirements for a "DUAL SEAL" version in terms of the above
mentioned standards are met.
• It protects the electronics from the process media.
• Any leak in the primary seal can be detected.
Even though there is no reason to expect the seal to fail, regular visual checks should still be
carried out to detect any possible leak as early as possible.
In the event of a leak, contact the manufacturer's service department to service or replace the
device.
20
®
C22). When selecting the material, corrosion resistance
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SITRANS FX330
®
C276 for
05/2016 - A5E36751269-AA