Ashcroft A Series - N4 Pressure Switch - Manual (Page 7)

A-S ERIES S WITCH S AFETY M ANUAL
I&M009-10210
REV A - 4/19/2013
4 INSTALLATION AND COMMISSIONING
4.1 Installation
The A-Series pressure switch must be installed per standard practices outlined in
the Installation Manual.
The environment must be checked to verify that environmental conditions do not
exceed the ratings.
The A-Series pressure switch must be accessible for physical inspection.
4.2 Physical Location and Placement
The A-Series pressure switch shall be accessible with sufficient room for pressure
and electrical connections and shall allow manual proof testing.
The A-Series pressure switch shall be mounted in a low vibration environment. If
excessive vibration can be expected special precautions shall be taken to ensure
the integrity of pneumatic connectors or the vibration should be reduced using
appropriate damping mounts.
4.3 Pressure Connections
It is the responsibility of the designer of the SIF to ensure that the pressure tubing
and connections used when installing the switch are rated for the operating
pressure of the system, and do not restrict the pressure to the switch.
5 OPERATION AND MAINTENANCE
5.1 Proof test without automatic testing
The objective of proof testing is to detect failures within an Ashcroft Switch that are
not detected by any automatic diagnostics of the system. Of main concern are
undetected failures that prevent the safety instrumented function from performing
its intended function.
The frequency of proof testing, or the proof test interval, is to be determined in
reliability calculations for the safety instrumented functions for which an Ashcroft
Switch is applied. The proof tests must be performed more frequently than or as
frequently as specified in the calculation in order to maintain the required safety
integrity of the safety instrumented function.
The following proof test is recommended. The results of the proof test should be
recorded and any failures that are detected and that compromise functional safety
should be reported to Ashcroft.