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SERVOTOUGH Laser 3 Plus Functional Safety Manual 07931006B_3

SERVOTOUGH Laser 3 Plus Functional Safety Manual 07931006B_3
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SERVOTOUGH Laser 3 Plus Functional Safety Manual 07931006B_3

Product catalog summary
Introduction
The SERVOTOUGH Laser 3 Plus is a sophisticated gas monitor designed for safety instrumented systems, comprising a Transmitter Unit (TU) and a Receiver Unit (RU), with optional power supply and ancillary equipment. This document provides functional safety information for the product.
Safety Information
  • Demand Mode: Operates in Low Demand mode according to IEC 61508 standards.
  • Safety Functions: Certified for hardware safety integrity, indicating gas concentration via a 4-20mA output. Diagnosed failures are shown by out-of-range mA output values.
  • Boundary of Safety System: Includes gas concentration measurement, optional ambient pressure and temperature compensation, and mA output, excluding display, Ethernet communications, and external sensors.
Product Configurations
The product can be enhanced with an Additional Input/Output board for extended capabilities, such as additional mA output and external measurement compensation.
Failure Rate Data
Failure rates are expressed in failures per million hours (fpmh) based on FMEDA analysis, covering configurations for various gas measurements like O2, CO, NH3, and CH4.
Safety Instructions
  • Installation: Must follow product manuals, ensuring lenses are clean and peak tracking is active.
  • mA Output: Connected equipment should treat out-of-range currents as fault indicators.
Proof Tests
Routine checks and maintenance are essential to maintain system integrity, especially with additional boards or pressure compensation features.
Definitions and Descriptions
Includes definitions for terms like Average Probability of Failure on Demand (PFDAVG), Dangerous Failure, and Safety Integrity Level (SIL).
Fault Indication and Relay Settings
Faults are indicated by out-of-range input currents (0mA or >20.5mA). The fault relay should not be the sole fault indicator and should de-energize under fault conditions.
Settings for Safety Functions
Post-installation, specific settings must support safety functions. mA outputs should indicate out-of-range currents under fault conditions, with the range set to 4-20mA. mA inputs must raise a fault status for out-of-range currents, with typical values between 4mA and 20mA. Clipping should be disabled or set outside necessary measurement ranges.
Protection and Safety Checks
Passwords should be changed from default values to prevent unauthorized changes. Regular safety checks should follow IEC 61508 guidelines, with a recommended proof test interval of one year. Fault conditions must be resolved before tests.
Proof Tests and Routine Checks
Proof tests aim to detect undiagnosed dangerous faults. Routine checks ensure spurious analyzer outputs do not compromise safety, verify mA output currents, and ensure purged spaces are correctly purged. Additional checks are needed if the Additional Input/Output board or internal pressure compensation is enabled.
Definitions and Descriptions
Provides definitions for terms such as Average Probability of Failure on Demand (PFDAVG), Dangerous Failure, Failure Mode Effects and Diagnostic Analysis (FMEDA), Hardware Fault Tolerance (HFT), and Safety Integrity Level (SIL). It explains the relationship between hardware fault tolerance, safe failure fraction, and SIL, and distinguishes between Type A and Type B subsystems based on complexity and understanding.
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Catalog excerpts

SERVOTOUGH Laser 3 Plus Functional Safety Manual 07931006B_3-1

SERVOTOUGH Laser 3 Plus FUNCTIONAL SAFETY MANUAL OPERATOR MANUAL Part Number: Revision: Language:

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SERVOTOUGH Laser 3 Plus Functional Safety Manual 07931006B_3-3

IMPORTANT INFORMATION Continued safe and reliable operation of this equipment is conditional on all installation, operation and maintenance procedures being carried out in accordance with the appropriate manuals, by personnel having appropriate qualifications, experience and training. Failure to observe the requirements of the manual may result in the user being held responsible for the consequences and may invalidate any warranty. Servomex will accept no liability for unauthorized modifications to Servomex supplied equipment. This manual should be read in conjunction with the other product manuals...

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SERVOTOUGH Laser 3 Plus Functional Safety Manual 07931006B_3-4

© Servomex Group Limited 2019

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SERVOTOUGH Laser 3 Plus Functional Safety Manual 07931006B_3-5

© Servomex Group Limited 2019

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SERVOTOUGH Laser 3 Plus Functional Safety Manual 07931006B_3-6

© Servomex Group Limited 2019

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SERVOTOUGH Laser 3 Plus Functional Safety Manual 07931006B_3-7

About this manual Safety information Sections of this manual contain supplementary installation and configuration instructions. These should always be read in conjunction with the other manuals listed below which provide more detailed instructions and contain important safety information. Scope of the manual This manual provides information and instructions that will be needed in order to use the 07931-Series Laser in safety instrumented systems. It is aimed at those responsible for planning, designing, installing, commissioning and maintaining safety instrumented systems using the 07931-Series...

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SERVOTOUGH Laser 3 Plus Functional Safety Manual 07931006B_3-8

Introduction Product description The 07931-Series Laser is an advanced gas monitor. It comprises a Transmitter Unit (TU) and a Receiver Unit (RU), with an optional AC to DC power supply and ancillary equipment, and sample cell for an extractive system. For continuous in-situ applications, the 07931-Series Laser is installed directly across stacks, ducts and reactors. This manual provides detailed functional safety information for the SERVOTOUGH Laser 3 Plus product. The applicability of this information to the various product configurations is given in the appropriate sections. © Servomex Group...

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SERVOTOUGH Laser 3 Plus Functional Safety Manual 07931006B_3-9

Safety information Demand Mode The safety integrity level claimed for this product is based on usage in a Low Demand mode of operation in a 1oo1 (simplex) architecture, as defined in IEC 61508 Edition 2.0 2010-01. Safety functions The SERVOTOUGH Laser 3 plus is certified suitable for use in safety instrumented systems in respect of hardware safety integrity ONLY, according to IEC 61508 Edition 2.0 2010-04. The usable safety function is defined as: The indication of gas concentration by means of a 4-20mA output to the level of performance specified in the appropriate Functional Safety Product...

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SERVOTOUGH Laser 3 Plus Functional Safety Manual 07931006B_3-10

Boundary of safety system The following aspects of the analyzer are considered to be within the boundary of the safety system covered in this manual: • • • • • • Measurement of the specified gas concentration(s) Optional measurement of ambient pressure as a compensation parameter. Optional measurement of ambient temperature as a compensation parameter. Optional measurement compensation by external current inputs to the Additional Input/Output board. Central processing and control. mA output. The following are considered to be outside the safety boundary and are not covered in this manual: • •...

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SERVOTOUGH Laser 3 Plus Functional Safety Manual 07931006B_3-11

Product configurations The capabilities of the standard product may be extended with the optional Additional Input/Output board. This adds a mA output to support a second measurement, and two analogue input channels that are able to support measurement compensation by external temperature and/or pressure measurements. It is also possible to configure, through the user interface, pressure compensation by the built-in sensor. This gives rise to the following configurations: Configuration Internal pressure compensation enabled External pressure compensation enabled ✓ ✓ External temperature compensation...

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SERVOTOUGH Laser 3 Plus Functional Safety Manual 07931006B_3-12

Failure data. Safety function 1 - This table contains the functional safety data that applies when the safety function is achieved through mA output 1 as fitted to the standard analyzer. Configuration Safety Related Characteristic Device type Hardware fault tolerance Safety integrity level Dangerous detected failure rate Dangerous undetected failure rate Safe failure rate Diagnostic coverage % Safe failure fraction Total failure rate Average probability of failure on demand Safety function 2 - This table contains the functional safety data that applies when the safety function is achieved through...

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SERVOTOUGH Laser 3 Plus Functional Safety Manual 07931006B_3-13

Safety instructions General observations The 07931-Series Laser must be installed and operated as described in the product manuals and any supporting documentation. Suitable precautions must be taken to ensure that the lens on the analyser are kept clean, such as use of purged gas as described in the product manuals. It is recognised that this analyzer will be used in a variety of applications. It is the user's responsibility to ensure that it is suitable for any particular application and that it is operated within its specification. In particular, any specific conditions laid down in the appropriate...

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SERVOTOUGH Laser 3 Plus Functional Safety Manual 07931006B_3-14

Settings After installation and commissioning according to the instructions in the product manuals, the following settings MUST be set to support the safety function. Please refer to the Operator Manual for step by step instructions on these settings. Note also that a password will typically be required in this process. mA output settings Any mA output used in a safety function MUST be set to indicate an out-of-range current under fault conditions. This is achieved as follows. Set the mA output range to the 4-20mA option. Ensure that the Underrange current is set to a non-zero value. Set the...

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Other Settings For the safety assessment to be valid all settings referenced in the appropriate Functional Safety Product Specification MUST be set as specified. In addition, the following general settings must be set as shown: Purge Compensation: Baseline Subtraction: Baseline subtraction will remove the measurement from the output for validation purposes. Operator MUST ensure that this feature is disabled before returning equipment into service. Protection of settings The 07931-Series Laser is supplied with all passwords set to default values. After configuration these MUST be altered to provide...

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