Fisher IM Supplement: Safety manual for Fisher 4660 High Low Pressure Pilot for Safety Instrumented System (SIS) Solutions Manuals & Guides

Instruction Manual Supplement

D103776X012

4660 Pressure Pilot

April 2018

Safety manual for Fisher™ 4660 HighLow
Pressure Pilot for Safety Instrumented System
(SIS) Solutions

When the Fisher 4660 highlow pressure pilot is used in a Safety Instrumented System (SIS) the design process should
follow a safety lifecycle as described in several international standards (IEC61508, ANSI/ISA 84.01, etc.) The following
must be thoroughly reviewed and implemented as part of the safety lifecycle. This is in addition to regular installation
procedures and warnings listed in the latest version of the Fisher 4660 highlow pressure pilot instruction manual
(D200163X012

WARNING

This instruction manual supplement is not intended to be used as a stand-alone document. It must be used in conjunction
with the following manual:
Fisher 4660 HighLow Pressure Pilot Instruction Manual (D200163X012

Failure to use this instruction manual supplement in conjunction with above referenced manual could result in personal
injury or property damage. If you have any questions regarding these instructions or need assistance in obtaining this
document, contact your Emerson sale office

).

).

or Local Business Partner.

A. Definitions, Acronyms and Abbreviations

1. FIT  Failure In Time (1x109 failures per hour)

2. FMEDA 

3. Low Demand Mode  Mode, where the demand interval for operation mode on a safetyrelated system is greater
than twice the proof test interval.

4. PFD

5. SIF  Safety Instrumented Function

6. SIL  Safety Integrity Level

7. SIS  Safety Instrumented System

Failure Modes, Effects, and Diagnostics Analysis

 average Probability of Failure on Demand

AVG

B. Related Literature

1. D200163X012  Fisher 4660 HighLow Pressure Pilot (Instruction Manual)

2. Exida FMEDA Report for Fisher 4660 HighLow Pressure Pilot  Report no. EPM 12/06089 R001

C. Product/ System Properties

1. The product is a highlow pressure pilot that activates emergency shutdown systems. It can be used with either a
single or dual set point capability to maintain full output pressure when the process is operating within the set point
range.

www.Fisher.com

4660 Pressure Pilot

April 2018

Instruction Manual Supplement

D103776X012

2. The fail safe state for the 4660 pressure pilot is with zero output pressure.

3. The 4660 pressure pilot is a Type A device having a hardware fault tolerance of 0 (HFT = 0). The 4660 pressure pilot
is limited to a Low Demand Mode of the SIS applications.

4. The 4660 pressure pilot is suitable for use in application to a maximum Safety Integrity Level of 3 (SIL3).

5. The failure rates for the 4660 pressure pilot are listed below. Consult the exida FMEDA report no. EPM12/06089
R001, available from your Emerson sale office

or Local Business Partner, for a detailed list of the assumptions used in

the analysis.

Failure Rate (FIT)

Failure Category

Low Trip High Trip High-Low Trip

Fail Safe Detected 0 0 0

Fail Safe Undetected 307 278 290

Fail Dangerous Detected 0 0 0

Fail Dangerous Undetected 115 143 139

No Effect 482 482 502

Configurations

6. A decrease in process pressure below the Low Set Point, or an increase in process pressure above the High Set Point
trips the 4660 pressure pilot, i.e. vent the output pressure to zero.

7. When the process pressure returns to a value between the Low Set Point and the High Set Point, the 4660 pressure
pilot resets to full output pressure. However, full output is not instantaneous. The difference between the set point
and reset to full output is the triptoreset zone.

8. Safety Instrumented Function (SIF) design verification must be done for all components in the SIF including the
4660 highlow pressure pilot. The SIF must fulfill the requirements according to the Safety Integrity Level (SIL). Each
subsystem must be checked to assure compliance with minimum hardware fault tolerance (HFT) requirements.

9. When using a 4660 pressure pilot in a redundant configuration, a common cause factor of at least 5% should be
included in safety integrity calculations.

D. Installation/ Configuration/ Commissioning

1. The 4660 pressure pilot complies with the requirements of ATEX Group II Category 2 Gas and Dust.

2. The ambient temperature limit is 59 to 71_C (75 to 160_F).

3. The supply pressure will be maintained within 1.4 to 4.5 bar (20 to 65 psig); too low supply pressure may not be
sufficient to energize the pressure pilot properly. The supply medium must be clean, dry air that meets the
requirements of ISA 7.0.01. A maximum 40 micrometer particle size in the air system is acceptable.

4. Normal installation is with the 4660 pressure pilot mounted vertically and with process, supply and output
connections facing downward per 4660 instruction manual.

5. Preliminary to the high or low set point adjustment, make sure the bourdon tube contains no pressure, install either
a pressure gauge or an optional indicator in the output pressure line, remove the cover screws and the cover,
unlock the lock disk, turn the High Set knob clockwise and/or the Low Set knob counterclockwise until it has
reached the travel end, and turn on supply pressure.

6. Connect an external pressure source to the process pressure connection. Adjust to the desired high or low set point
pressure and turn the high or low knob. The high or low set point is obtained when the output pressure of the 4660
pressure pilot has changed from full output to zero. Lock the locking disk.

7. The safety function of the SIF must be tested after installation.

E. Operations, Maintenance and Decommissioning

1. Personnel operating the 4660 pressure pilot and performing maintenance must be competent to do so.

2. Use lockout procedures and select the appropriate maintenance procedures as defined in instruction manual. The
blockandbleed relay assembly and some other assemblies are offered as repair kits.

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