Siemens FX300 manual Dual seal

	DEVICE DESCRIPTION 2
SITRANS FX300

2.2.6 Dual seal

To cover the requirements of ANSI/ISA-12.27.01-2003 “Requirements for Process Sealing Between Electrical Systems and Flammable or Combustible Process Fluid” Dual seal, a membrane vent is integrated in the neck of the instrument. This vent works in the improbable case of a leakage as an annunciation valve between the primary seal (Process) and secondary seal (electronic compartment).

1Annunciation valve (Membrane vent)

The sealing between the pick-up and the Flow tube is considered as the primary seal. Its construction material is always the same as the Flow tube itself (e.g. Stainless steel 316L or Hastelloy C22). Chemicals used for the process, going through the Flow tube, must be compatible with the designated material.

By using the membrane vent as annunciation valve, all requirements for a dual seal device in accordance to above mentioned standard, are fulfilled.

•It protects the electronic compartment against access by process media, due to possible leakages.

•The leakage of the primary seal is visible.

Regular maintenance should be performed by the customer to ensure this Dual Seal notification system is working properly or that there is no leak.

If a leakage is noticed:

Siemens customer service should be contacted for servicing or replacement of the meter.

06/2009 - SFIDK.PS.050.F2.02 A5E02100423 www.siemens.com/flow 15