*mydirectindustry

Catalogs
ASCO
Application Brochure, - Machine safety

Application Brochure, - Machine safety

Product catalog summary

Introduction and Regulatory Framework

This document addresses the safety of machinery with a focus on electro-pneumatics, referencing the European Machinery Directive 2006/42/EC and relevant standards such as EN/IEC 62061 and EN ISO 13849-1. It emphasizes the importance of risk evaluation and compliance with safety requirements to protect personnel involved in machinery operation, adjustment, and maintenance.

Principles of Machinery Safety and Risk Evaluation

Manufacturers must conduct a thorough risk evaluation before designing machinery, incorporating both qualitative and quantitative safety function assessments. Key concepts include:

Risk analysis prior to design
Quantitative assessment of safety functions
Use of Performance Levels (PL) to define safety integrity

The document references standards for functional safety of electrical, electronic, programmable electronic, hydraulic, pneumatic, and mechanical control systems.

Standards and Norms

Key standards cited include:

Machinery Directive 2006/42/EC
EN ISO 13849-1 (Safety-related parts of control systems)
EN/IEC 62061 (Functional safety of electrical/electronic control systems)
EN 60204-1 (Electrical equipment of machines)
EN ISO 14121 and EN ISO 12100 (Risk assessment and basic safety principles)

Reliability Data and Performance Levels

The document provides reliability data for pneumatic components such as valves and actuators, including metrics like MTTF (Mean Time To Failure), MTTFd (Mean Time To Dangerous Failure), B10, and B10d values. These data are essential for calculating Performance Levels (PL) and Safety Integrity Levels (SIL) to ensure compliance with safety requirements.

Actuators are excluded from PL calculations but must be considered in risk evaluations for potential failure modes.

Risk Evaluation Parameters

Risk evaluation considers several factors:

Severity of damage (S)
Frequency and duration of exposure (F)
Probability of occurrence (O)
Probability of avoidance (P)

These parameters combine to determine the required Performance Level (PL) or SIL for safety functions, guiding design and control system architecture.

Design Process for Safety-Related Control Systems

The design process involves:

Selecting system architecture (categories A, B, C, D or B,1,2,3,4)
Deriving achievable safety performance levels (PL or SIL)
Choosing components based on reliability data
Specifying diagnostic coverage (DC) for components
Creating reliability models to support calculations
Addressing common cause failures (CCF), software, and architectural requirements
Documenting the system design and safety functions

Diagnostic Coverage and Reliability Ratings

Diagnostic coverage (DC) is classified as none, low, medium, or high, impacting the achievable PL. MTTFd ratings are categorized as low, medium, or high based on expected operational life. Components must be replaced according to mission time (T10) recommendations to maintain safety integrity.

Examples of Safety Function Architectures

The document presents case studies illustrating safety function implementations for stopping hazardous cylinder movements using different architectures:

Category 1 (PL=c): Basic architecture without diagnostics, relying on component reliability and limited operating time.
Category 2 (PL=c): Incorporates diagnostics with low to medium diagnostic coverage, cross-monitoring of valves and sensors.
Categories 3 and 4 (PL=d): Advanced architectures with cross-checking diagnostics, redundant channels, and high diagnostic coverage to achieve higher safety integrity.

Each example details component reliability data (B10d, MTTFd), diagnostic coverage, and functional descriptions of safety loops, emphasizing the importance of energy isolation, pressure evacuation, and controlled start-up after shutdown.

Good Engineering Practices and Safety Recommendations

Incorporate probabilistic calculations alongside good engineering practices for risk evaluation.
Ensure safety functions cover interruption of energy sources and evacuation of stored energy.
Use diagnostic measures and cross-monitoring to detect failures promptly.
Replace components proactively based on mission time to prevent dangerous failures.
Consider common cause failures and implement measures to mitigate them.

Summary

This technical document provides a comprehensive overview of safety principles, standards, and design methodologies for electro-pneumatic machinery control systems. It highlights the critical role of risk evaluation, reliability data, diagnostic coverage, and system architecture in achieving required safety performance levels. Practical examples demonstrate how to apply these concepts to ensure safe operation and compliance with European safety directives.

Catalog excerpts

Application Brochure, - Machine safety-1

NEW MACHINERY DIRECTIVE 2006/42/EC STANDARDS EN/IEC 62061 - EN ISo 13849-1 EMERSON. Industrial Automation

Open the catalog to page 1

Application Brochure, - Machine safety-2

SAFETY OF MACHINERY Principle of the safety of machinery: To guarantee the safety and health of persons exposed to the installation, operation, adjustment and maintenance of machinery. (published in the Official Journal of the European Union) ALL MACHINERY PLACED ON THE EUROPEAN MARKET (published in the Official Journal of the European Union) ”Functional safety of safetyrelated electrical, electronic and programmable electronic control systems” “Safety-related parts of electrical, electronic, programmable electronic, hydraulic, pneumatic and mechanical control systems” Part 1: General principles...

Open the catalog to page 2

Application Brochure, - Machine safety-3

reliability dATA The products’ reliability data (MTTF, MTTFd, B10, B10d…) gained from reliability tests under standard conditions can be downloaded in the SISTEMA format from our website www.asconumatics.eu Distribution function Stainless steel spool and sleeve valve series L1/L2 Spool valve series 551 552-553 Shut-off valve and slow start-up Fluid control solenoid valves Compact series Pilot valve series 302-190-192 Actuator control Position detector Series 541-542-543 Stopper cylinder series 346 or NCPPG Actuators (pneumatic cylinders) are not taken into consideration in the calculation of...

Open the catalog to page 3

Application Brochure, - Machine safety-4

• Functional description: Construction and risk evaluation of machines Functional and safety-relevant requirements for safety-related control systems EN ISO 12100 Safety of machinery Basic concepts, general principles for design Electrical safety aspect EN 60204-1 Safety of machinery. electrical equipment of machines - Part 1: General requirements Design and construction of safety-related control systems for machines EN ISO 13849-1 Risk related to the hazardous event Frequency and/or duration of exposure F Probability of occurrence O Probability of avoidance P Safety integrity levels SIL...

Open the catalog to page 4

Application Brochure, - Machine safety-5

Survey of the safety functions of a machine: • Functional specifications to determine dangerous malfunction • Safety-related specifications Specify the diagnostic means for each component to ensure the required DC (Diagnostic Coverage) Select a system architecture among types: • A, B, C • Category or D B, 1, 2, 3 or 4 Select the system components involved in the safety functions taking their reliability data into account • MTTF MTT^ Bw B,0tf etc. Specify the other requirements: • CCF (Common Cause Failure) • Software • Architectural requirements • System integrity Create a reliability model...

Open the catalog to page 5

Application Brochure, - Machine safety-6

FOR YOUR SAFETY Only the pneumatic part is described in the form of a subsystem in these examples. Other safety-related components (e.g. protective devices, electrical logic elements) must be added to ensure the safety function is complete. The examples shown here only relate to the stopping of hazardous movements. In pneumatics, safety measures concerning the interruption of energy sources, the evacuation of potential energy (pressure contained in a part of the circuit), and a “progressive” start-up after an unexpected shutdown should not be omitted. To attain a PL = c, category 1 architecture...

Open the catalog to page 6

Application Brochure, - Machine safety-7

Safety function: Stopping of the potentially hazardous movement of cylinder 1A. Functional description: Input 'I': not represented, movable guard or light barrier, etc. Logic element 'L': not represented, PLC B10d (valve 1V1B - series 542) = 44 912 670 cycles, i.e. an operating time of 16.2 ans, MTTFd = 162 years "high" MTTFd (sensors 1S1) = 45 000 000 h, i.e. 11 718 years "high" The case study shows: DC (Diagnostic Coverage) = 60% "low". PL Performance levels I | MTTFd rating for each channel = low I I MTTFd rating for each channel = medium I I MTTFd rating...

Open the catalog to page 7

Application Brochure, - Machine safety-8

Safety function: Stopping of the potentially hazardous movement of cylinder 1A. Functional description: Output signal Input signal Output signal Inputs 'I1' and 'I2': not represented, movable guard or light barrier, etc. Logic elements 'L1' and 'L2': not represented, PLC B10d (valve 1V1B - series 542) = 44 912 670 cycles, i.e. an operating time of 32.4 years, MTTFd = 324 years "high" B10d (valve 2V1 - series 520) = 20 000 000 cycles, i.e. an operating time of 14.5 years, MTTFd = 145 years "high" B10d (pressure switch 2S1, dynamic rod lock 2Z1) = 4 000 000 cycles, i.e. a mission time of T10 =...

Open the catalog to page 8

Application Brochure, - Machine safety-9

• Safety function: Stopping of the potentially hazardous movement of cylinder 1A. • Functional description: Output signal Input Output signal signal Inputs 'I1' and 'I2': not represented, movable guard or light barrier, etc. Logic elements 'L1' and 'L2': not represented, PLC Stop of cylinder ensured by: 0V1B: Energy isolating valve: ensures the system is exhausted. Calculation of the probability of dangerous failure: B10d (valve 1V1B - series 542) = 44 912 670 cycles, i.e. an operating time of 32.4 years, MTTFd = 324 years "high" B10d (valve 2V1 - series 520) = 20 000 000 cycles, i.e. an...

Open the catalog to page 9