Flowserve 3200MD User Manual download pdf (Page 30)

User Instructions - Digital Positioner 3200MD LGENIM0059-09 12/13

10 Requirements for Safety

Integrity

This section provides information and additional user responsibilities

in order to meet Safety Integrity Level 2 (SIL 2) per IEC 61508 Parts

1-3.

10.1 Fail Safe State

The fail safe state for the Logix 3200MD positioner:

• Fail Safe State 1: The spool valve is at less than 5% of full

stroke such that Output (Port) 1 is venting and Output (Port) 2

is open to supply pressure.

• Fail Safe State 2: The spool valve is at greater than 95% of full

stroke such that Output (Port) 1 is supply pressure and Output

(Port) 2 is open to venting.

• ! NOTE that these represent the fail safe state of the positioner.

The valve fail safe state may be different depending on spring

conﬁ guration and tubing. Ensure the valve fail-safe state is

appropriate for your application.

10.2 Safety Function

The Logix 3200MD positioner moves to fail-safe state upon the fol-

lowing conditions:

• Loss of supply pressure (less than approximately 7 psi).

• Fail Safe State 1

• Removal of analog input power (less than 4.0 mA)

• Fail Safe State 1

• Disconnection of feedback arm mechanism.

• Fail Safe State 1 or 2 (conﬁ guration dependent).

The Logix 3200MD positioner detects and annunciates the following

safety related conditions:

• Analog input less than approximately 2.0 mA.

• Analog output power less than approximately 12.5 V.

• Pilot Relay Response Alarm (user adjustable settings)

• Position Deviation Alarm (user adjustable settings)

• Pilot Relay Position Limit Alarm

For a detailed description of these alarms, See section 7.10 Logix

3200MD Status Conditions.

10.3 Fail Safe State Response Time

A typical response time for the spool to move to a fail safe state

due to a complete and sudden loss of supply pressure or a sudden

command change is less than 50 ms*. The response time may be

slower, possibly up to 1 second with subzero (F) temperatures.

A typical response time for the spool to move to a fail safe state due

to linkage pin failure is less than 200 ms*. The response time may

be slower with stroke lengths longer than 8 inches.

A typical response time for a valve to move to a fail safe state due

to a complete and sudden loss of supply pressure or a sudden

command change can be less than 150 ms*. However, the response

time will vary widely with actuator size, stroke length, starting posi-

tion, fail safe direction, tubing size, supply pressure, and tempera-

ture. The positioner air ﬂ ow capacity affects the speed of the valve

moving to a fail-safe position. See section 4.1 for air ﬂ ow capacity.

Test the ﬁ nal valve assembly response time to ensure it meets your

requirements.

*Tests were with a 25 inch double acting actuator, ambient tempera-

ture 74°F (23.3 °C), 60 PSI (4.1 bar) supply, quarter inch tubing,

starting at 50% open, moving to close, .75 inch stroke, 1.5 inch

feedback arm.

10.4 Diagnostic Annunciation and

Response Time

The Flowserve 3200MD Positioner will report the conditions below

within 1.0 second of occurrence by transition of the Analog Output

to less than or equal to 3.6 mA for as long as the condition exists.

• Analog input less than approximately 2.0 mA.

• Analog output power less than approximately 12.5 V.

• Detection of one of the following safety related alarms.

• Pilot Relay Response Alarm (user adjustable settings)

• Position Deviation Alarm (user adjustable settings)

• Pilot Relay Position Limit Alarm

Upon detection of the alarms, the Analog Output will remain at less

than or equal to 3.6 mA for at least 5 seconds or as long as the

alarm persists.

Should any of the safety related alarms arise, the positioner will

continue to attempt to control to the analog input signal.

The settings of the Pilot Relay Response Alarm and the Position

Deviation Alarm affect the time between the occurrence of a physical

problem and the generation of the alarm. Ensure these settings are

adjusted to an acceptable level. The Pilot Relay Position Limit Alarm

can take up to 8 seconds to generate if the spool sticks suddenly.

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Flowserve 3200MD User Manual Page 30

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