SAFETY IN FOCUS BASIC GUIDE TO SAFETY PNEUMATIC CIRCUITS FOR ISO YOUR AUTOMATION PARTNER

Transcription

1 SAFETY IN FOCUS BASIC GUIDE TO SAFETY PNEUMATIC CIRCUITS FOR ISO YOUR AUTOMATION PARTNER

2 TABLE OF CONTENTS On the safe side with SMC 3 Residual pressure venting 26 Basic guide to safety with SMC 4 SMC products 28 Typical safety functions in pneumatics 6 Framework conditions 32 Performance levels and categories in pneumatics 9 Legal information 34 ISO pneumatic circuits 10 2

3 ON THE SAFE SIDE WITH SMC We think in optimal systems Trust us for safety. SMC is a powerful and reliable partner for factory automation, offering pneumatic and electrical solutions. From concept to end of life, we support our customers to achieve and maintain the required levels of functional safety when using our products. Achieving the required level of functional safety is a detailed task that can only be undertaken by qualified engineers. Our global network of customer service teams are there support this process by providing the advice and information needed to design the optimum solution for you application. No matter how small or large the project we have solutions to meet your requirements for flexible, productive, safe machinery and systems. For more details about SMC and machinery safety, please refer to our catalogues! We offer a range of CE marked safety products compliant with the Machinery Directive to provide the necessary levels of risk reduction to provide a safe working environment for the operating personnel. W Safety in Focus Machinery directive and ISO in practice (MA15VK-373c) W Safety in Focus Pneumatic circuits for ISO (MA15VK-372) ON THE SAFE SIDE WITH SMC 3

4 BASIC GUIDE TO SAFETY WITH SMC The machine maker has to provide a machine that complies with the EU Machinery Directive. This is achieved by designing in accordance with the harmonised standards, documenting in the technical file, making a Declaration of Conformity and attaching the CE mark to the equipment. This document provides ideas that the responsible designer can evaluate in the context of his application. It suggests solutions for typical pneumatic safety functions that may be used to comply with the requirements of ISO The table on page 10 guides the user from the applications of pneumatic actuators to selecting the safety function and the Performance Level / category. In principle the machine maker has to go through the following steps: Risk assessment (ISO 12100:2010 clause 5) The machine maker has to determine the limits and the intended use of the machine, to identify the hazards and to estimate the risks. By evaluating the risks he has to decide whether the risks have adequately reduced. Risk reduction (ISO 12100:2010 clause 6) If the risks have not been adequately reduced he has to consider risk reduction in the following three steps in the order of: W Inherent safe design measures (clause 6.2) W Safeguarding and complementary protective measures (clause 6.3) W Information for use (clause 6.4) As an example a movement of a pneumatic actuator in the machine can be a hazard. Inherent safe design measures Safe guarding and complementary protective measures Information for use The hazard shall be reduced by design measures. As an example the velocity of an actuator can be limited by a fixed orifice in the flowpath of the pressurized air. The residual hazard shall be protected by safe guarding or complemetary protective measures. In case of pneumatics ISO is a suitable standard to design a safety related part of a control system (SRP/CS). As an example the movement of an actuator can be reduced by venting the pressurized air or stopping and preventing unexpected movement by adequate valves and structure of the pneumatic system. Residual risks shall be informed to the user and maintenance persons. As an example residual risk can exist by trapped air in a cylinder chamber. Before maintenance the trapped air shall be vented by a residual pressure relief valve. A label on the machine shows the risk of trapped air. A method to confirm that there is no residual pressure before disassembly must be provided. 4

5 Safe pneumatic circuit as complementary protective measures (ISO 12100:2010 clause 6.3) If the risk is not adequately reduced by an inherent safe design the pneumatic circuit must be suitable to reduce the residual risk in an appropriate way. Safety functions of pneumatic circuits (ISO 12100:2010 clause 6) Part of the risk reduction is to define safety functions. Typical safety functions of pneumatic circuits are described on pages 6-8. The safety function is not an operational function. Failure of the safety function may lead to a dangerous situation. Required Performance Level (PL r ) (ISO :2015 clause 4) For each safety function the required Performance Level shall be specified by the risk graph. The determination of the required performance level is the result of the risk assessment and refers to the amount of the risk reduction to be carried out by the safety-related parts of the control system. Evaluating the achieved Performance Level (PL) (ISO :2015 clause 4) For the evaluation of the selected safety system, the Performance Level is determined based on the following values: W Structure (category) W MTTF D : Mean time to dangerous failure W DC (Diagnostic coverage): Diagnostic coverage of the known failure modes. W CCF (Common cause failure): Failure of different items caused by single event Verification that achieved PL meets PL r (ISO 13849:2015 clause 4.7) For each individual safety function the PL of the related SRP/CS shall match the required performance level (PL r ). Testing and checking is required to verify that the SRP/CS meets the PL r requirement. BASIC GUIDE TO SAFETY WITH SMC 5

6 TYPICAL SAFETY FUNCTIONS IN PNEUMATICS With the safety functions Safe venting of the system and Safe venting of actuator, the compressed air is released from the pneumatic subsystem to the atmosphere. On the following two pages the difference between the two safety functions is explained. In addition further safety functions are described on page 8. Safe venting of the system This is defined as a safety function that guarantees safe venting of a specific part of the system. The extent of the circuit safely vented with this safety function depends on the design of the pneumatic circuit and must be re-evaluated by the machine manufacturer on a case-by-case basis. Generally, the pneumatic cylinders are not vented safely with this safety function. Safely vented range of the pneumatic system 6

7 Safe venting of actuator This is defined as a safety function that guarantees safe venting of the pneumatic actuators. If the pressure chambers of a linear or rotary actuator are vented the force or the torque is safely reduced. Safely deactivated force / torque TYPICAL SAFETY FUNCTIONS IN PNEUMATICS 7

8 Safe stopping This safety function provides a safe stopping of the actuator movement. The movement has to be stopped in a certain time or a certain stopping distance to avoid a hazard to the machine operator or the maintenance personnel, who may enter the hazardeous area. The cylinder is pressurized during this safety function. If necessary, additional measures such as safe venting of the air pressure has to be taken. Safely reduced speed In case of installation and maintenance the speed of a movement by an actuator shall be reduced below a specified speed. The safely reduced speeds are specified in machinery standards to avoid dangerous situations during installation and maintenance. Prevention of unexpected start-up This safety function prevents the unexpected start-up of all downstream actuators. The safe state is obtained through energy isolation (closed-circuit principle). Safely reduced force / torque In case of installation and maintenance the force or torque of a movement by an actuator shall be reduced below a specified force or torque. These safely reduced force or torque are specified in machinery standards to avoid dangerous situations during installation and maintenance. Safe position This safety function ensures the pneumatic actuator moves to a safe position. The safe postition is defined by the machine maker depending on his risk assessment. Safe pressure monitoring This safety function provides a safe monitoring of a pneumatic pressure. The monitoring is only allowed for diagnostic reasons. Based on the diagnostic input the safety PLC will carry out the required safety function eg. venting a system. Safe hold-up This safety function provides a safe hold-up of a load to avoid an injury inside the hazardous area. The load shall not fall down by gravity to trap any part of a person. 8

9 PERFORMANCE LEVELS AND CATEGORIES IN PNEUMATICS To fully understand the definitions of the categories you must refer to the current version of ISO The information here gives a basic overview. In the following pages PL c / Cat 1 and PL e / Cat 4 pneumatic circuits are explained. Category B This category is used for the lowest PL. As a onechannel system a single component failure may lead immediately to a hazardous situation. Failures are not detected as there are no diagnostics. Category 1 This is still a one-channel system without diagnostics covering generally PL c. The components and the system must fulfill the basic and well-tried safety principles and be well-tried components. Category 2 Category 2 requires a checking system which can generate an output to initiate appropriate control system action. In such cases machine makers often decide to use category 3 systems with redundancy. Category 3 This category is a two-channel system with diagnostics covering generally PL d. The diagnostics must be periodically executed to recognize dangerous failures which have not caused a loss of safety function due to the dual channel architecture of the system. Category 4 This category is required to achieve the highest PL levels. It is a two-channel system with diagnostics covering generally PL e. The diagnostics must be executed at suitable intervals to ensure the availability of the safety function when demanded. RESPONSIBILITIES The machine manufacturer is responsible for the specification, construction, implementation, validation and maintenance of the safety control (SRP/ CS). In this regard, the behaviour of the safety control system in the event of power loss and power restoration must be observed. The component manufacturer is responsible for component validation based on component-related, basic and well-tried safety principles. In addition, a component which is intended for category 1 usage must be approved as a well-tried component for a specific application. However it is the responsibility of the machine manufacturer to confirm the suitability of a component for the function that it has to perform. PERFORMANCE LEVELS AND CATEGORIES IN PNEUMATICS 9

10 ISO PNEUMATIC CIRCUITS PL c CATEGORY 1 PL d/e CATEGORY 3/4 Safety function Application Clamping device / rotary actuator Horizontal actuator Vertical actuator Clamping device / rotary actuator Horizontal actuator Vertical actuator Safe venting of the system Safely deactivated force / torque Page 11 Page 11 Page 11 Page 19 Page 19 Page 19 Page 12 Page 12 Page 20 Page 20 Safe stopping Page 13 Page 13 Page 13 Page 21 Page 21 Page 21 Prevention of unexpected start-up Pages 11, 12, 13 Pages 11, 12, 13 Pages 11, 13 Pages 19, 20, 21 Pages 19, 20, 21 Pages 19, 21 Safe position Page 14 Page 14 Page 14 Page 22 Page 22 Page 22 Safe hold-up Page 15 Page 23 Safely reduced speed Safely reduced force / torque Safe pressure monitoring Page 16 Page 16 Page 24 Page 24 Page 17 Page 17 Page 17 Page 25 Page 25 Page 25 Page 18 Page 18 Page 18 Page 18 Page 18 Page 18 If the risk assessment demands measures for safe venting between the cylinder chamber and the pilot check valves, it can be realized through the circuit variations beginning from pages The pneumatically or electrically controlled residual pressure valves allow the two piston sides of the actuator to be vented from outside the hazard zone by trained personnel. This is one of the safe working practices and should be documented in the instruction manual by the machine builder. The machine operator must be trained accordingly. The circuits on the following pages show only the pneumatic subsystem. It is the sole responsibility of the machine maker to decide the suitability of these circuits and to complete the safetyrelated part of the control system (SRP/CS) e.g. the electrical control and the diagnostics. The use of any of the example circuits to provide a safety function is only allowed if the legal conditions on page 34 are fully complied with. For further product support please contact SMC. SMC offers validated products for you to determine their suitability for use as a safety-related part of control systems (SRP/CS) for ISO applications including all necessary documentation and SISTEMA library. Please ask for the SISTEMA-Package. 10

11 SAFETY FUNCTION CIRCUIT 1 Safe venting and prevention of unexpected pressure accumulation in the system Application Performance Level Category Pneumatic system up to PL c (pneumatic subsystem) 1 (single-channel) Circuit description The area of the pneumatic actuator to be vented is vented by safety-related valve 1V1. The area of the pneumatic system that can be vented safely depends on the customer's pneumatic setup. This means the area of the pneumatic system vented safely with this safety function can only be determined by the machine manufacturer. Safety-related valve 1V1 is used both to safely vent the pneumatic system determined by the machine manufacturer and to safely prevent the introduction of pneumatic energy to the overall downstream pneumatic system. For more descriptions of the safety functions, see pages 6-8. Safety-related block diagram Channel 1 1V1 Once the safe state at the machine is ensured, the solenoid of safety-related valve 1V1 is supplied with power through the safe outputs of logic O1, and the valve switches to its service position. Here it is not necessary to evaluate the valve spool position monitoring as diagnostics are not required for category 1 systems. Compressed air supply System to be protected Inputs Safety-related logic Safe outputs For suitable products please see pages The framework conditions on page 32 must always be considered. ISO PNEUMATIC CIRCUITS 11

12 SAFETY FUNCTION CIRCUIT 2 Safe venting of actuator and prevention of unexpected start-up Application Performance Level Category Clamping device rotary actuator horizontal actuator up to PL c (pneumatic subsystem) 1 (single-channel) Circuit description The pressure chambers of the pneumatic actuator (linear cylinder and rotary actuator) are vented by means of safety-related valve 1V1. To do this, the valve must have switched to its open centre position (safety-related position). Safety-related valve 1V1 is used both to safely vent the pressure chambers of the pneumatic actuator and to safely prevent the introduction of pneumatic energy to the actuator. The consequences of venting must be evaluated for safety in the actual application. For more descriptions of the safety functions, see pages 6-8. Safety-related block diagram 1V1 potentially hazardous movement For suitable products please see pages The framework conditions on page 32 must always be considered. 12

13 SAFETY FUNCTION CIRCUIT 3 Safe stopping and prevention of unexpected start-up Application Performance Level Category Clamping device rotary actuator horizontal actuator vertical actuator up to PL c (pneumatic subsystem) 1 (single-channel) Circuit description circuits I and II: The pneumatic actuator to be stopped (linear cylinder or rotary actuator) is stopped by safety-related valve 1V1. To do this, the valve must switch to its closed centre position (safety-related position). In Circuits I and II the trapped compressed air is used between the valve 1V1 and the pneumatic actuator to prevent movement. Circuit III: The pneumatic actuator to be stopped (linear cylinder or rotary actuator) is stopped by safety-related check valves 1V2 and 1V3. To do this, valve 1V1 must have switched to its open centre position (safety-related position). This causes the two pilot check valves 1V2 and 1V3 to close. In Circuit III the trapped compressed air is used between the two pilot check valves 1V2 and 1V3 and the pneumatic actuator. This circuit can be used to shorten the stopping time in the case of long hose lines (large volume) by reducing the volume. All three circuit variations can be used not only to stop pneumatic actuators safely but also to prevent pneumatic energy from being introduced into the pressure chambers of the pneumatic actuators. For suitable products please see pages The framework conditions on page 32 must always be considered. Safety-related block diagram 1V1 1V1 1V1 1V2 1V3 Circuit I Circuit II Circuit III potentially hazardous movement potentially hazardous movement potentially hazardous movement ISO PNEUMATIC CIRCUITS 13

14 SAFETY FUNCTION CIRCUIT 4 Safe position and prevention of unexpected start-up Application Performance Level Category Clamping device rotary actuator horizontal actuator vertical actuator up to PL c (pneumatic subsystem) 1 (single-channel) Circuit description The pneumatic actuator is retracted by safety-related valve 1V1. To do this, the valve must have switched to its safe position. The appropriate pressure chamber of the actuator must be used for the reversing motion. This safety function can only be used when the reversing movement does not represent a potentially hazardous movement. Safety-related block diagram 1V1 potentially hazardous movement potentially hazardous movement For suitable products please see pages The framework conditions on page 32 must always be considered. 14

15 SAFETY FUNCTION CIRCUIT 5 Safe hold-up Application Performance Level Category Vertical actuator up to PL c (pneumatic subsystem) 1 (single-channel) Circuit description The cylinder movement is blocked by safety-related valve 1V2. To do this, the pilot line of valve 1V2 must be safely vented. This is done by switching safety-related valve 1V1 to its open centre position. Safety-related block diagram 1V1 1V2 potentially hazardous movement For suitable products please see pages The framework conditions on page 32 must always be considered. ISO PNEUMATIC CIRCUITS 15

16 SAFETY FUNCTION CIRCUIT 6 Safely reduced speed Application Performance Level Category Horizontal actuator - vertical actuator up to PL c (pneumatic subsystem) 1 (single-channel) Circuit description The pneumatic actuator is controlled by safety-related valves 1V1 and 1V2 at a safely reduced speed. For this purpose, the exhaust air is vented from the cylinder chambers through the inherently safe throttles 1D1 and 1D2, which are screwed into the exhaust of the safetyrelated valves 1V1 and 1V2. Valves 1V3 and 1V4 also form part of the safety function. These valves ensure there is a counter-pressure in the actuator which avoids sudden movement when the actuator is restarted. Safety-related block diagram potentially hazardous movement 1V1 1V2 1V3 1V4 For suitable products please see pages The framework conditions on page 32 must always be considered. 16

17 SAFETY FUNCTION CIRCUIT 7 Safely reduced force / torque Application Performance Level Category Clamping device rotary actuator horizontal actuator vertical actuator up to PL c (pneumatic subsystem) 1 (single-channel) Circuit description The safety-related regulator 1V1 and valve 1V2 ensure that the pressure in the downstream area of the pneumatic system is reduced. When the valve 1V2 switches to its safety related position, the regulator 1V1 must be set to the required safe pressure and then be secured against accidental adjustment and tampering. The safely reduced pressure can be used to limit the force/torque at the actuators of the downstream pneumatic system. Safety-related block diagram 1V1 1V2 System with reduced pressure For suitable products please see pages The framework conditions on page 32 must always be considered. ISO PNEUMATIC CIRCUITS 17

18 SAFETY FUNCTION CIRCUIT 8 Safe pressure monitoring Application Performance Level Category Clamping device rotary actuator horizontal actuator vertical actuator up to PL e (pneumatic subsystem) 4 (two-channel) Circuit description Safe pressure monitoring is carried out by the two pressure switches 1S1 and 1S2, which output a functional analogue signal to a safe logic controller. The two functional analogue signals must be compared on an ongoing basis in the logic (plausibility check). If the two signals differ (from a set tolerance level) or one or both signals remain static for a period to be defined, a fault must be assumed. Any upper or lower deviation from the pressure setpoint must trigger the deactivation of the safety-related logic outputs. The safe pressure to be monitored is generated by a functional electropneumatic pressure regulator. Safety-related block diagram Safety-related logic Safe analogue inputs Safety-related logic Safe outputs Safely monitored pneumatic range (depends on the structure of the respective pneumatic control and can only be decided by the machine manufacturer) For suitable products please see pages The framework conditions on page 32 must always be considered. 18

19 SAFETY FUNCTION CIRCUIT 9 Safe venting and prevention of unexpected pressure accumulation in the system Application Performance Level Category Pneumatic system up to PL e (pneumatic subsystem) 4 (two-channel) Circuit description The area of the pneumatic actuator to be vented is vented by two channels via safety-related valves 1V1 and 1V2. The volume of the pneumatic system that can be vented safely depends on the customer's pneumatic setup. The volume of the pneumatic system vented with this safety function can only be determined by the machine manufacturer. Safety-related valves 1V1 and 1V2 are used both to safely vent the pneumatic circuit (extent determined by circuit design) and to safely prevent the introduction of pneumatic energy to the downstream pneumatic system. For more descriptions of the safety functions, see pages 6-8. Safety-related block diagram Channel 1 Channel 2 1V1 1V2 Compressed air supply System to be protected Once the safe state at the machine is ensured, safety-related valves 1V1 and 1V2 are supplied with power through the safe outputs of logic O1 and O2, and the valves switch to their service positions. The closing or opening of the switch contacts input into I1 to I4 and evaluated by means of plausibility checks. As an alternative the switches 1S1 and 1S2 may be connected in series. Safe inputs Non-safe inputs Safety-related logic Safe outputs For suitable products please see pages The framework conditions on page 33 must always be considered. ISO PNEUMATIC CIRCUITS 19

20 SAFETY FUNCTION CIRCUIT 10 Safe venting of actuator and prevention of unexpected start-up Application Performance Level Category Clamping device rotary actuator horizontal actuator up to PL e (pneumatic subsystem) 4 (two-channel) Circuit description Channel 1: Channel 2: The pressure chambers of the pneumatic actuator (linear cylinder or rotary actuator) are vented by means of the safety-related 1V1 valve, while the flow of pneumatic energy to the pressure chambers of the pneumatic actuator is prevented. To do this, the valve must switch to its open centre position (safety-related position). The pressure chambers of the pneumatic actuator (linear cylinder or rotary actuator) are vented by means of safety-related valves 1V1 and 1V3, while the flow of pneumatic energy to the pressure chambers of the pneumatic actuator is prevented. To do this, the valves must be switched to their safety-related position (flow from 2 to 3). For more descriptions of the safety functions, see pages 6-8. Safety-related block diagram 1V1 potentially hazardous movement 1V2 1V3 Care must be taken in selecting the valves 1V1, 1V2, 1v3 to ensure equal flow rates when venting. For suitable products please see pages The framework conditions on page 33 must always be considered. 20

21 SAFETY FUNCTION CIRCUIT 11 Safe stopping and prevention of unexpected start-up Application Performance Level Category Clamping device rotary actuator horizontal actuator vertical actuator up to PL e (pneumatic subsystem) 4 (two-channel) Circuit description Channel 1: Channel 2: The pneumatic actuator to be stopped (linear cylinder or rotary actuator) is stopped by safety-related valve 1V2. To do this, the valve must switch to its closed centre position (safety-related position). To stop the actuator, the pressurized air is trapped between safetyrelated valve 1V2 and the pilot check valves (acts as an air cushion). At the same time, valve 1V2 prevents pneumatic energy from being introduced into the pressure chambers of the pneumatic actuator. The pneumatic actuator to be stopped (linear cylinder or rotary actuator) is stopped by safety-related pilot check valves 1V3 and 1V4. To do this, the control lines of the pilot check valves must have been vented by means of pilot valve 1V1. After the pilot lines to 1V3 and 1V4 are vented the check valves close which stops air flowing from the actuator, thus preventing movement. Safety-related block diagram For suitable products please see pages The framework conditions on page 33 must always be considered. 1V2 1V1 1V3 1V4 potentially hazardous movement potentially hazardous movement ISO PNEUMATIC CIRCUITS 21

22 SAFETY FUNCTION CIRCUIT 12 Safe position Application Performance Level Category Horizontal actuator vertical actuator up to PL e (pneumatic subsystem) 4 (two-channel) Circuit description Channel 1: Channel 2: The piston-rod side of the pneumatic actuator to be reversed (linear cylinder or rotary actuator) is pressurized with system pressure by the safety-related valve 1V1. To do this, valve 1V1 must have switched to its safetyrelated position. The flow of air is thus directed through the safety-related OR valve 1V3. The piston-rod side of the pneumatic actuator to be reversed (linear cylinder or rotary actuator) is pressurized with system pressure by the safety-related valve 1V2. To do this, valve 1V2 must have switched to its safetyrelated position. The flow of air is thus directed through the safety-related OR valve 1V3. The safety-related OR valve 1V3 guarantees that either of the two 5 port 2-position valves 1V1 and 1V2 can apply pressurized air to the piston rod side of the pneumatic actuator. Safety-related block diagram For suitable products please see pages The framework conditions on page 33 must always be considered. 1V1 1V2 1V3 potentially hazardous movement potentially hazardous movement 22

23 SAFETY FUNCTION CIRCUIT 13 Safe hold-up Application Performance Level Category Clamping device rotary actuator vertical actuator up to PL e (pneumatic subsystem) 4 (two-channel) Circuit description Channel 1: Channel 2: The pneumatic actuator is safely stopped by the pilot check valve 1V3 which traps air in the actuator and holds it up. To do this, its pilot line must be vented by means of 5 port 3-position valve 1V2. After the pilot line is vented the check valve closes which stops air flowing from the actuator. At the same time, valve 1V2 prevents pneumatic energy from being introduced into the pressure chambers of the pneumatic actuator. The pneumatic actuator is safely stopped by pilot check valve 1V4. To do this, its pilot line must be vented by means of 5 port 2-position valve 1V1. After the pilot line is vented the check valve closes which stops air flowing from the actuator. This can also be used to prevent unexpected start-up. Safety-related block diagram 1V1 1V2 1V4 1V3 potentially hazardous movement For suitable products please see pages The framework conditions on page 33 must always be considered. ISO PNEUMATIC CIRCUITS 23

24 SAFETY FUNCTION CIRCUIT 14 Safely reduced speed Application Performance Level Category Horizontal actuator - vertical actuator up to PL e (pneumatic subsystem) 4 (two-channel) Circuit description Safety-related block diagram Safety-related valves 1V1 and 1V3 ensure that the piston rod will retract at a safely reduced speed. These valves must have switched to their safety-related position which vents the exhaust air from the pressure chamber through the inherently safe throttle 1D1. Safety-related valves 1V2 and 1V4 ensure that the piston rod will extend at a safely reduced speed. These valves must have switched to their safety-related position which vents the exhaust air from the pressure chamber through the inherently safe throttle 1D2. Working principle The air required to ensure the safe execution of the safety function is trapped in the actuator by means of the two pilot check valves 1V5 and 1V6. Safe pressure monitoring of the pressure chambers ensures that sufficient air volume is available before the traversing motion begins at a safely reduced speed. This must be implemented by a separate safety function. For more information see Circuit 8 in this safety catalogue. Extension 1V2 1V4 Retraction 1V1 1V3 potentially hazardous movement For suitable products please see pages The framework conditions on page 33 must always be considered. 24

25 SAFETY FUNCTION CIRCUIT 15 Safely reduced force / torque Application Performance Level Category Clamping device rotary actuator horizontal actuator vertical actuator up to PL e (pneumatic subsystem) 4 (two-channel) Circuit description Channel 1: Channel 2: Safety-related valve 1V2 vents pressure from the pneumatic system to the reduced pressure level when switched to its safe position. Safety-related block diagram 1V2 1V1 1V3 System with reduced pressure Safety-related valve 1V3 vents pressure from the pneumatic system to the reduced pressure level when switched to its safe position. Once the pressure in the downstream pneumatic system has dropped to the level of reduced pressure, the OR valve reverses and the reduced pressure is maintained by the pressure reducing valve. The safetyrelated pressure limitation valve 1V1 prevents an overrun in the safely reduced pressure. For this valve, the fault "Failure to open or open fully when adjustment pressure is exceeded (internal parts are stuck or do not move fully)" as per EN ISO , Table B.6 can be ruled out if the applicable preconditions have been met. These can be found in EN ISO , Table B.6. The safely reduced pressure limits the force/torque of the actuators in the connected pneumatic system. For suitable products please see pages The framework conditions on page 33 must always be considered. ISO PNEUMATIC CIRCUITS 25

26 RESIDUAL PRESSURE VENTING VARIATION 1 KE (at actuator) The compressed air volume between the actuator (including the volume in the actuator's pressure chamber) and the 1V1 operational valve is vented inherently safely by the KE residual pressure venting valve. Venting must be actuated manually by the operator. During venting, the operator must stay clear of all potentially hazardous movements. If this is not possible, additional actions must be taken to ensure the safe execution of the venting process (e. g., by supporting with vertical axes, mechanical locking, etc.). potentially hazardous movement SMC products (more products as of page 28-31) Residual pressure venting valve with one touch fitting KEB Residual pressure venting valve with thread connection KEC For notes on the restriction of use to ensure adequate risk reduction, see page 34 26

27 RESIDUAL PRESSURE VENTING VARIATION 2 VM and ASP-X369 (outside the hazardous area) The compressed air volume between the actuator (including the volume in the actuator's pressure chamber) and the 1V1 service valve is vented by means of pilot check valves 1V3 and 1V4. Both pilot check valves are unlocked by the manually actuated 1V2 3 port 2-position valve. The 1V2 pilot valve must be located outside the hazardous area. During the venting process, the operator must have a complete view of the hazardous area. potentially hazardous movement Outside the hazardous area Hazardous area SMC products (more products as of page 28-31) Mechanically actuated 3 port 2-position valve VM Pilot check valve ASP-X369 For notes on the restriction of use to ensure adequate risk reduction, see page 34 RESIDUAL PRESSURE VENTING 27

28 SMC PRODUCTS Suitable components for your application Safety components Refer to safety function Venting valve Safety component as per Directive 2006/42/EC For maximum category 2 Venting capacity up to 3,700 L/min (ANR) VP-X536 SF1: 1V1 SF7: 1V2 SF10: 1V2/1V3 Venting valve Safety component as per Directive 2006/42/EC For maximum category 4 Venting capacity up to 2,180 L/min (ANR) Compatible with SMC air preparation units VP-X538 SF9: 1V1/1V2 SF15: 1V2/1V3 Venting valve Safety component as per Directive 2006/42/EC For maximum category 4 Venting capacity up to 2,180 L/min (ANR) Compatible with SMC air preparation units Soft-start function VP-X555 SF9: 1V1/1V2 SF15: 1V2/1V3 Venting valve Safety component as per Directive 2006/42/EC For maximum category 4 Venting capacity up to 13,000 L/min (ANR) VG342-X87 SF9: 1V1/1V2 SF15: 1V2/1V3 Two-hand control valve Safety component as per Directive 2006/42/EC Cat. 1 type IIIA as per EN 574 VR51 28

29 Directional valves Refer to safety function Solenoid valve Numerous valve options, including residual pressure venting Steel detent for bi-stable valves Rubber-sealing for bi-stable valves with detent (as per ISO ) Available with optional spool detection for direct monitoring Available as a single valve SY 3000 / 5000 / 7000 SF2: 1V1 SF3: 1V1 SF4: 1V1 SF5: 1V1 SF10: 1V1 SF11: 1V1/1V2 SF12: 1V1/1V2 SF13: 1V1/1V2 SF14: 1V0 RPV1 and RPV2: 1V1 Solenoid valve Numerous valve options Rubber-sealing for bi-stable valves with detent (as per ISO ) VQC-X SF2: 1V1 SF3: 1V1 SF4: 1V1 SF5: 1V1 SF10: 1V1 SF11: 1V1/1V2 SF12: 1V1/1V2 SF13: 1V1/1V2 SF14: 1V0 RPV1 and RPV2: 1V1 Solenoid valve 3 port 2-position directly actuated poppet seat valve VT SF6: 1V1/1V2 SF14: 1V1 1V4 Valve with soft start-up With manual override and adjustable soft start Also available in air operated version AV(A) Air operated valve Pneumatically actuated 5 port 2-position or 5 port 3-position valve in sizes ISO 1 and ISO 2 VSA7-6 Mechanical valve Mechanically actuated 3 port 2-position valve VM RPV2: 1V2 Manual shut-off valve 3 port 2-position manual shut-off valve suitable for maintenance units and lockout-tagout systems VHS SMC PRODUCTS 29

30 Check valves and flow control valves Refer to safety function Pilot check valve with speed controller Connection thread: 1/8" to 1/2" Installation directly on the cylinder ASP Pilot check valve with speed controller and residual pressure venting Connection thread: 1/8" to 1/2" Installation directly on the cylinder ASP-X352 Pilot check valve with state detection for direct monitoring Installation directly on the cylinder XT SF13: 1V3/1V4 Residual pressure venting valve Tube connection Ø 6 12 mm or Thread Rc 1/4 and Rc 3/8 KE RPV1: 1V2/1V3 Pneumatic logic valve Logic valve with AND function Logic valve with OR function VR12 SF12: 1V3 Pilot check valve Connection thread: 1/8 to 1/2 Installation directly on the cylinder ASP-X369 SF3: 1V2/1V3 SF5: 1V2 SF6: 1V3/1V4 SF11: 1V3/1V4 SF14: 1V5/1V6 RPV2: 1V3/1V4 30

31 Speed controller with residual pressure venting Connection thread: 1/8 to 1/2 AS#000E-# Precision regulator Precise pressure regulation IR SF7: 1V1 Sensors for diagnostics Refer to safety function Digital pressure sensor Adjustable pressure and vacuum sensor PS1000 SF11: 1S1 SF12: 1S1/1S2 SF13: 1S1 SF14: 1S1-1S4 Mechanically adjustable pressure switch Contact type (reed contact) Modular assembly with FRL unit IS10 Auto switch Electronic Rounded groove D-M9 SF10: 1S4/1S5 SF11: 1S2/1S3 SF13: 1S5/1S6 Digital pressure sensor Adjustable pressure sensor with analogue output ISE30A SF8: 1S1/1S2 SMC PRODUCTS 31

32 CIRCUIT 1 7: FRAMEWORK CONDITIONS Category 1 requirements corresponding to ISO W Component-related, basic and well-tried safety principles fulfilled W System-related, basic and well-tried safety principles fulfilled W Well-tried components in compliance with ISO W The MTTF D, which is based on the MTTF D values of the individual components, must be no less than 30 years (permissible MTTF D range: high). Reliability values (B 10D ) The specified Performance Level is based on the B 10D values of the safety-related components of the pneumatic subsystem. Annual number of cycles (n op ) Achieving the Performance Level also depends on the annual number of cycles n op of the components. The calculation of the PL for the circuits shown in the catalogue are based on the following assumptions: W average operating time in days/year d op = 240 days W average operating time in hours/day h op = 24 hours W average time between the start of two consecutive cycles of the system t cycle components = 30 seconds W n op = 691,200 cycles/year Additional Note Safe hold-up (circuit 5) For safe hold-up of loads, check valve 1V2 must be screwed firmly into the cylinder. If this is not possible, the compressed air line must be made with solid piping between check valve 1V2 and the cylinder. A 1 TE hose (EN 854: Type 1 TE, DIN Type 1: 1 TE) can be used as an alternative to solid piping. Safely reduced speed (circuit 6) When metering valves with silencers are used, the machine manufacturer must take steps to ensure they are securely fixed in place and cannot be tampered with (eg using adhesive). CIRCUIT 8: FRAMEWORK CONDITIONS Safe pressure monitoring (circuit 8) The pneumatic components in this safety function have a purely functional character and thus do not form part of the safety function. The safety function consists of only one electrical subsystem. 32

33 CIRCUIT 9 15: FRAMEWORK CONDITIONS Category 4 requirements as per ISO W Component-related, basic and well-tried safety principles fulfilled W System-related, basic and well-tried safety principles fulfilled W The MTTF D, which is based on the MTTF D values of the individual components, must be no less than 30 years (admissible MTTF D range: high). W The average DC avg must be no less than 99 % (permissible DC avg range: high). W Sufficient actions for preventing failures due to common causes (CCF) are to be implemented by persons responsible for the system. Reliability values (B 10D ) The specified Performance Level is based on the B 10D values of the safety-related components of the pneumatic subsystem. Annual number of cycles (n op ) Achieving the Performance Level also depends on the annual number of cycles n op of the components. The calculation of the PL for the circuits shown in the catalogue are based on the following assumptions: W average operating time in days/year d op = 240 days W average operating time in hours/day h op = 24 hours W average time between the start of two consecutive cycles of the system t cycle components = 30 seconds W n op = 691,200 cycles/year Test frequency If technically feasible, potentially hazardous faults in safety-related components used in category 4 systems must be automatically detected by the control system during or prior to the next safety function request. If all potentially hazardous faults cannot be detected, the accumulation may not lead to a safety function failure. Additional Note Safe stopping, prevention of unexpected start-up and safe hold-up (circuit 13) For safe hold-up of loads, the compressed air line must be made with solid piping between the safety-related valves and the cylinder. A 1 TE hose (EN 854: Type 1 TE, DIN Type 1: 1 TE) can be used as an alternative to solid piping. Safely reduced speed (circuit 14) When metering valves with silencers are used, the machine manufacturer must take steps to ensure they are securely fixed in place and cannot be tampered with (eg using adhesive). FRAMEWORK CONDITIONS 33

34 LEGAL INFORMATION The circuits shown introduce sample applications for our products and assemblies, with which various pneumatic subsystems for safety functions can be realised. The circuits are merely examples for the listed safety functions and do not represent a binding solution or application recommendation for a specific application. Even if a similar type of safety function is being considered it is not guaranteed that the existing risk can be adequately reduced by the example in a real application (see Chapter 5.5, EN ISO 12100). The machine manufacturer or control system integrator is solely responsible for testing each individual application independently, and if required, making additions or changes to the circuits. In so doing, the machine manufacturer or control system integrator must independently examine and comply with all laws, guidelines, standards and product information pertaining to the design and manufacture of the system, and to observe them during implementation. The machine manufacturer or the control system integrator bear Working together with you, we at IAC can sole responsibility for the suitability of the circuit realistically simulate for the installed components. SMC assumes no various tasks and production options from the warranty or liability for a solution designed, following sectors: developed and implemented by the machine manufacturer or control system integrator for their respective, specific application, or that the sample circuits shown here are suitable for the application. The circuits show only the pneumatic subsystem (control component "actuator"). For the complete safety functions, the machine manufacturer or control system integrator must generally add additional safety-related subsystems (usually "sensor" and "logic" control components). NOTE A performance level up to the indicated PL can be achieved only when the framework conditions are met. The PL achieved by the sub-system is directly related to the overall MTTF D and to the average annual number of of cycles of the component. A greater number of annual cycles therefore leads to a lower PL. NOTE ON RESIDUAL PRESSURE VENTING The residual pressure venting circuits 1 and 2 are one-channel solutions and can only be used for risks that correspond to a required Performance Level of up to PL r c. Such a single channel system would be at risk of unintentional venting of the actuator (for example when applying the safety function safe hold-up ) as well as non-venting when required (for example if the venting valve becomes stuck). 34

35 NOTES NOTES 35

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