Asco 552 Series User Manual

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©ASCO, L.P. 160 Park Avenue, Florham Park, New Jersey 07932 www.asco.com
I&M No V 9629 R9
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3.2 Response Time
The response time of a solenoid pilot valve will vary by design. The factors that affect response time are pilot
valve orifice size, operating pressure, size of actuator, torque required to open and close process valve, and
distance between pilot valve and actuator. It is the responsibility of the end user to use a pilot valve that
delivers the correct opening and closing time of the process valve required for the application.
4 Operation and Maintenance
4.1 Proof test without automatic testing
The objective of proof testing is to detect failures within an ASCO Solenoid 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 ASCO Solenoid 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. Any failures that are detected and that compromise functional safety
should be reported to ASCO .
Table 1
Step Action
1 Bypass the safety PLC or take other appropriate action to avoid a false trip, following company
Management of Change (MOC)
procedures
2
Inspect the external parts of the solenoid valve for dirty or clogged ports and other physical
damage. Do not attempt disassembly of the valve.
3 De-energize the solenoid coil and observe that the actuator and valve move. Energize the
solenoid after a small movement of the valve.
4
Inspect the solenoid for dirt, corrosion or excessive moisture. Clean if necessary and take
corrective action to properly clean the air supply. This is done to avoid incipient failures due to
dirty air.
5
Record any failures in your company’s SIF inspection database. Restore the loop
to full
operation.
6 Remove the bypass from the safety PLC or otherwise restore normal operation
This test will detect approximately 99% of possible DU failures in the solenoid (Proof Test Coverage).
The person(s) performing the proof test of an ASCO Solenoid should be trained in SIS operations, including
bypass procedures, solenoid maintenance and company Management of Change procedures. No special tools
are required.
4.2 Proof test with automatic partial valve stroke testing
4.2.1 Testing of the Product
An automatic partial valve stroke testing scheme that performs a full stroke of the solenoid valve and
measures valve movement timing will detect most potentially dangerous failure modes.
4.2.2 Physical Inspection
It is recommended that a physical inspection (Step 2 from Table 1) be performed on a periodic basis with
the time
interval determined by plant conditions. Maximum inspection interval is five years but an annual
inspection
is recommended.

Asco 552 Series Specifications

General

Brand	Asco
Model	552 Series
Category	Control Unit
Language	English