© ISO 2013 Safety of machinery — Pressure sensitive protective devices — Part 3 General principles for design and testing of pressure sensitive bumpers, plates, wires and similar devices Sécurité des[.]
General
Most pressure-sensitive protective devices covered by ISO 13856 are designed for specific applications It is essential that device manufacturers and machine builders collaborate to define application-specific requirements based on a thorough risk assessment They should also specify the critical force-travel data necessary for optimal performance and safety in each application.
The pressure-sensitive protective device must be designed with appropriate dimensions and strategically positioned to ensure that its sensor can detect human approach through touch This enables the device to identify when a person or part of a person is nearing a hazardous area, thereby enhancing safety measures Proper sensor placement is essential for effective risk prevention in hazardous zones.
There are two main types of safety application for sensors First, sensors can be used to deactivate hazardous machine parts located remotely, ensuring the machine stops before any body part reaches the danger zone, with the distance calculated based on ISO 13855 guidelines Second, sensors can be mounted directly on or near the hazardous part of the machinery, triggering the machine to stop or reverse to a safe position instantly upon activation to prevent injury.
All pressure-sensitive protective devices covered by ISO 13856 must meet the basic requirements outlined in this part of the standard Specific additional requirements apply to pressure-sensitive bumpers, plates, and wires, as detailed in sections 4.3 to 4.5 These specialized requirements take precedence over the general provisions specified in section 4.2, ensuring proper functionality and safety for different types of pressure-sensitive protective devices.
Basic requirements
For the test method, see 7.1.1 and 7.1.5.
The lowest actuating force(s) necessary to cause the output signal switching device to go to an OFF state shall not exceed those specified in Table 2, when applied
— over the effective sensing surface,
— at the relevant approach speed(s),
— with the sensor in the mounting orientations,
— with the relevant test piece, and
The temperature range over which the pressure-sensitive protective device is effective is specified by the manufacturer or established through an agreement between the device manufacturer and the machine builder Ensuring operation within this defined temperature range is crucial for the device’s optimal performance and safety Proper adherence to these specifications helps prevent malfunctions and maintains compliance with safety standards.
The minimum actuating force required for pressure-sensitive sensors may be lower than the values listed in Table 2, depending on specific applications and sensor designs Refer to section 4.5.3 for detailed information on the lowest actuating force needed to activate the control unit, causing pressure-sensitive wires to switch to the OFF state.
NOTE 1 A suitable risk assessment will show which body part(s) are to be considered for a particular application, enabling the relevant test piece(s) to be used.
Note 2 clarifies that the forces specified are primarily designed to evaluate the pressure-sensitive performance of the device These forces should not be regarded as universally safe for all applications, and users should consult the introduction and Annex C for additional guidance on appropriate force thresholds.
NOTE 3 Certain applications — for example, protecting the neck — can require a device with a higher sensitivity, i.e actuating forces lower than those shown in Table 2.
For the test method, see 7.1.1 and 7.1.6.
The actuating travel of pressure-sensitive protective devices must not exceed the limits specified by the manufacturer For devices designed for specific applications, the actuating travel should be appropriate to ensure proper functionality and safety Refer to Annex B for guidance on the force-travel relationship relevant to specific device types.
For the test method, see 7.1.1 and 7.1.7.
The overtravel of pressure-sensitive protective devices must meet or exceed the manufacturer’s specified minimum, ensuring proper functionality and safety For devices designed for specific applications, the overtravel should be tailored to suit the particular use case, providing optimal performance Refer to Annex B for guidance on the force-travel relationship of these devices to ensure correct selection and application.
For the test methods, see 7.1.1, 7.1.5, 7.1.6 and 7.1.7.
The sensor shall be able to cause an OFF state in the output signal switching device when actuated with the foreseeable approach speed(s) as stated by the manufacturer of the pressure-sensitive protective device For devices manufactured for a specific application, the approach speed shall be appropriate for the application.
For the test method, see 7.1.1 and 7.1.8.
The pressure-sensitive protective device must maintain normal operation and show no visible damage after the specified number of operations, as determined by the manufacturer For devices designed for specific applications, the permissible number of operations should be appropriate to ensure safety and functionality Proper performance of these sensors is essential for reliable protection in various industrial settings.
4.2.6 Response of output signal switching device to actuating force
4.2.6.1 Systems where sensor output remains in changed state as long as actuating force is applied
For the test method, see 7.1.1 and 7.1.9.
When an actuating force is applied to the sensor's sensing surface, the sensor output changes state, prompting the output signal switching device to switch from ON to OFF The sensor's output state is directly proportional to the applied force, and this new state remains as long as the force is continuously applied.
The output signal switching device shall only revert to the ON state when
— for systems with reset, the actuating force is removed and a reset signal is applied (see Figures A.1 and A.2), or
— for systems without reset, the actuating force is removed (see Figure A.3).
4.2.6.2 Systems where sensor output does not remain in changed state while actuating force is maintained
For the test method, see 7.1.1 and 7.1.9.
The sensor provides a signal when force is applied to its sensing surface, triggering the output switching device to change from ON to OFF It will only return to the ON state after a reset signal is received or additional safety measures, such as automatic reversal of hazardous movement, are implemented to eliminate potential hazards.
Such additional protective measures shall be stated in information for use, see 6.3.1 a).
For some devices, additional protective measures are required See Figure A.4, C.3.6 and C.3.7.
Some devices, e.g air-pulse sensors, which are not regarded as well-tried components, shall comply with the requirements of category 2 according to ISO 13849-1:2006.
For the test method, see 7.1.1 and 7.1.10.
The reset function of a pressure-sensitive protective device shall fulfil the general requirements of
ISO 13849-1:2006, 6.2.2, and the functional requirements of Annex A of this part of ISO 13856.
To reset a start interlock or a restart interlock of a pressure-sensitive protective device, the reset signal shall be applied either
— directly to the control unit of the pressure-sensitive protective device, or
— via the machine control system.
When manual reset is provided, it shall function according to Figures A.1 and A.2 and ISO 13849-1:2006, 5.2.
For the test method, see 7.1.1 and 7.1.11.
The pressure-sensitive protective device must operate continuously under the environmental conditions specified by the manufacturer, in accordance with the guidelines outlined in section 4.2.7 Normal operation is maintained when these conditions are met, ensuring reliable performance of the device as intended.
— the output signal switching device remains in the ON state as long as no actuating force is applied, and
— the ON state changes to an OFF state when the actuating force is applied.
For the test method, see 7.1.1 and 7.1.11.3.
The system is designed to operate normally within a temperature range of 5 °C to 40 °C If the manufacturer confirms that the pressure-sensitive protective device is suitable for a broader temperature range, the system shall maintain normal operation throughout the specified extended temperature limits.
For the test method, see 7.1.1 and 7.1.11.4.
All equipment shall meet the requirements for humidity specified by the manufacturer.
The electrical equipment system must remain operational and maintain its electrical insulation integrity after being stored for four days at a relative humidity of 93% and a temperature of 40°C.
For the test method, see 7.1.1 and 7.1.11.5.
Pressure-sensitive protective devices must continue normal operation despite electromagnetic emissions, according to IEC 61000-6-2 standards and specified conditions Manufacturers may design devices to withstand higher levels of electromagnetic interference and specify these levels explicitly When necessary for safe operation in specific applications, a higher level of electromagnetic protection should be implemented to ensure the device's reliable and safe performance.
For the test method, see 7.1.1 and 7.1.11.6.
The pressure-sensitive protective device shall continue to operate without being actuated under the following vibration conditions in accordance with IEC 60068-2-6:
— frequency range: 10 Hz to 55 Hz;
— sweep rate: 1 octave per minute.
After this vibration test, the pressure-sensitive protective device shall continue in normal operation.
For the test method, see 7.1.1 and 7.1.12.
The pressure-sensitive protective device shall continue in normal operation as defined in 4.2.7.1 when subjected to the power supply variations according to 4.2.8.2 and 4.2.8.3.
For the test method, see 7.1.1 and 7.1.12.2.
The pressure-sensitive protective device shall meet the electrical power supply variation requirements of IEC 60204-1:2005, 4.3.
4.2.8.3 Non-electrical power supply variations
For the test method, see 7.1.1 and 7.1.12.3.
The pressure-sensitive protective device must remain operational under non-electrical power supply variations, as specified by the manufacturer This compliance aligns with ISO 4413 for hydraulic systems and ISO 4414 for pneumatic systems, ensuring continuous performance as outlined in section 4.2.7.1.
Where overpressure protective devices for this power supply are not incorporated, overpressure variations outside the stated range shall not result in a failure to danger.
Power supply variations outside the stated range shall not result in a failure to danger.
For the test method, see 7.1.1 and 7.1.13.1.
The electrical equipment (components) of pressure-sensitive protective devices shall
— conform to International Standards where these exist,
— be suitable for the intended use, and
— be operated within their specified ratings.
Protection against electric shock shall be provided in accordance with IEC 60204-1:2005, 6.1, 6.2 and 6.3.
Protection against over-current shall be provided in accordance with IEC 60204-1:2005, 7.2.1, 7.2.3,
Electromechanical control units and output signal switching devices shall meet the relevant requirements of IEC 60947-5-1.
The electrical equipment shall be suitable for pollution degree 2 in accordance with IEC 61439-1:2009, 7.1.3.
The electrical equipment shall be designed and constructed in accordance with IEC 61439-1:2009,
The electrical equipment shall be wired in accordance with IEC 61439-1:2009, 11.10.
For the test method, see 7.1.1 and 7.1.13.2.
Hydraulic equipment shall meet the relevant requirements of ISO 4413 and ISO 13849-2.
For the test method, see 7.1.1 and 7.1.13.3.
Pneumatic equipment shall meet the relevant requirements of ISO 4414 and ISO 13849-2.
For the test method, see 7.1.1 and 7.1.13.4.
Mechanical equipment shall meet the relevant requirements for pressure-sensitive protective devices of
For the test method, see 7.1.1 and 7.1.14.
Ensure the sensor is suitable for its specific environment, such as wet or dusty conditions, by selecting one that meets the appropriate protection standards The sensor must be specified according to the IEC 60529 protection grade, ensuring it can withstand environmental challenges Electrical components within the sensor should be housed in enclosures that comply with relevant protection requirements to guarantee durability and safety.
IP 54 as a minimum If the manufacturer specifies that the sensor may be immersed in water, the sensor enclosure shall meet the requirements of IP 67 as a minimum.
4.2.13.2 Control unit and output signal switching device
Specific requirements for pressure-sensitive bumpers
For the test method, see 7.1.1 and 7.2.1.
The force-travel relationship must, at minimum, align with the manufacturer's specifications Manufacturers are required to provide detailed force-travel relationship data, using an example such as Figure 2 for reference Additionally, they must specify the conditions under which the data were obtained to ensure transparency and accuracy.
For the test method, see 7.1.1 and 7.2.2.
If additional coverings are used, the requirements of this part of ISO 13856 shall be fulfilled by the covered sensor.
For the test method, see 7.1.1 and 7.2.3.
After the effective sensing surface of the sensor has been deformed or moved by the working travel for
24 h, the effective sensing surface shall recover in accordance with Table 1.
Recovery time Change in height percentage of working travel at 10 mm ⋅ s −1 at 250 N
If the manufacturer indicates that the pressure-sensitive bumper can withstand continuous deformation for over 24 hours, the sensor must recover as specified in Table 1 after this period Additionally, the sensor should have adequate overtravel to accommodate the extent of deformation during the specified duration.
After the effective sensing surface of the sensor has been deformed or moved by the working travel for
24 h, the pressure-sensitive bumper shall have normal function within 30 s.
4.3.4 Detection on bumpers with semi-rigid or rigid surfaces
For the test method, see 7.1.1 and 7.2.4.
On bumpers with an open structure, e.g as shown in Figures C.3 and C.4, it shall not be possible to stand undetected inside the structure of the bumper.
Specific requirements for pressure-sensitive plates
For the test method, see 7.1.1 and 7.3.1.
The pressure-sensitive plate must remain operational without activation under specific conditions outlined in IEC 60068-2-27 These requirements apply exclusively to sensors oriented in both the reference and opposite directions Ensuring continuous functionality under these conditions is essential for reliable performance of the pressure-sensitive plates.
— duration of the pulse: 16 ms;
— form of the pulse: half sine;
— number of pulses per direction: 1 000;
After the shock test, the pressure-sensitive plate shall continue in normal operation.
If the manufacturer states that the pressure-sensitive plate is suitable for a wider shock range, then it shall meet this requirement over the stated shock range.
For the test method, see 7.1.1 and 7.1.20.
Deformation of the plate, prevention of the movement of the plate (wedging, blocking) and other foreseeable faults shall not lead to the loss of the safety function.
Specific requirements for pressure-sensitive wires (trip wires)
For the test method, see 7.1.1.
Electrical switches used with pressure-sensitive wires shall meet the requirements of IEC 60947-5-5 In addition, the requirements given in 4.5.2 to 4.5.5 shall be met.
4.5.2 Breaking or disengagement of wire
For the test method, see 7.1.1 and 7.4.1.
The pressure-sensitive wire shall be designed such that, in the event of slackening, breaking or disengagement of the wire, an OFF state is generated (see Figure C.6).
For the test method, see 7.1.1 and 7.4.2.
The force required to activate the pressure-sensitive wire to trigger an OFF state in the control unit must be less than 100 N when applied in the effective sensing direction(s) at a 90° angle to any point along the wire's sensing surface This testing uses test piece 5, as specified in section 7.1.5.1 and Table 2 Manufacturers must specify the effective sensing surface of the wire, considering its intended usage for accurate performance.
4.5.4 Tensile strength of the sensor
For the test method, see 7.1.1 and 7.4.3.
The sensor (including any connections) shall resist a tension force of 1 000 N without failure.
4.5.5 Actuating deflection of the wire
For the test method, see 7.1.1 and 7.4.4.
The displacement of the pressure-sensitive wire needed to generate an OFF state shall be less than
150 mm in all the stated actuating directions (see Figure C.6) For special applications, a displacement of more than 150 mm can be acceptable when indicated by the risk assessment to be acceptable.
General
Pressure-sensitive protective devices marketed separately must be clearly marked in accordance with ISO 12100:2010, section 6.4.4 Additionally, electrical equipment should prominently display the rated voltage and current as a minimum requirement For comprehensive safety standards, refer to IEC 60204-1:2005, Clause 16, which provides further guidance on marking and electrical safety compliance.
Labels
All labels must be securely affixed and designed to remain durable and legible throughout the entire lifespan of the pressure-sensitive protective device component.
Marking of the control unit
The control unit label(s) shall also contain the following information or indicate where this information can be found:
— the performance level, category and B 10d value according to ISO 13849-1 for the system as a whole;
— the response time for the system as a whole;
— whether designed with or without reset;
Marking of the sensor
The sensor label shall also contain the part number or indicate where this information can be found.
6 Information for selection and use
General
Information and guidance regarding application, commissioning and regular inspection for inclusion in the information for use is given in Annexes D and E.
The delivery of information to users must adhere to ISO 12100:2010, section 6.4, ensuring clarity and comprehensiveness Information should be clearly linked to the specific product, such as the pressure-sensitive protective device, to ensure proper understanding and safe usage Effective presentation and identification are essential for compliance and user safety.
Essential data for selection of suitable pressure-sensitive protective device
Manufacturers should provide comprehensive information to aid in selecting a suitable pressure-sensitive protective device This includes details on its suitability for tripping functions alone or combined with presence sensing, along with configuration, number, and length limits for sensors connected to a control unit Essential specifications cover connection length and type, mounting orientations, fixing methods, and the sensor's force resistance and directional application Key parameters such as sensing surface dimensions, maximum sensor size, weight per meter, and control unit specifications must be disclosed Additional covering options, force-travel characteristics, and overtravel force are necessary Manufacturers should specify the expected number of operations, chemical resistance, operating temperature range, power requirements, and enclosure standards per IEC 60529 They must also specify categories and performance levels per ISO 13849-1, guide the selection process per Annex D, and address critical connection lengths and deformation behavior over time Output switching device capabilities per IEC 60947-5-1, application guidance, contact configurations, finger detection suitability, minimum operating speed, fault exclusion indications, and performance level calculation methods considering operation time and cycle intervals are also essential Lastly, a clear statement emphasizing that the user must determine the performance level for their specific application is required to ensure proper device selection and safety compliance.
Information for use
6.3.1 Information for application and commissioning
The manufacturer shall make available the relevant information from the following: a) Information relating to the pressure-sensitive protective device:
1) detailed description of the device;
2) the limits as to the configuration, number and length of sensors connected to one control unit;
3) the limits as to the length and specifications of connections between sensor(s) and control unit(s);
4) the procedure for determining the overtravel for the pressure-sensitive protective device, which shall be included with examples (see Annex B);
5) range of applications and conditions for which the device(s) is intended or approved, including the category, performance level and B 10d values according to ISO 13849-1;
6) circuit diagrams providing schematic representation of the safety functions and examples of machine control interface;
7) additional protective measures, according to 4.2.6.2, necessary to achieve the required level of safety for specific applications;
8) the rating, characteristics and location of all input/output terminals (e.g maximum rating of fuses or setting of an over-current protective device);
9) type and frequency of automatic check system, where applicable;
10) guidance regarding chemical, physical and environmental resistance (e.g resistance to solvents, allowable weight loading, operating temperature range, allowable power supply variation);
11) guidance regarding use of the device in alternative mounting orientations;
The article specifies whether the device is designed with or without an external reset function, in accordance with Figures A.1, A.2, A.3, or A.4, to ensure proper identification and compliance Additionally, it emphasizes the importance of providing comprehensive information related to the packaging, transportation, handling, and storage of pressure-sensitive protective devices, supporting safety and durability throughout their lifecycle.
3) description of packaging and methods of unpacking to prevent damage to the device,
4) transportation and handling methods to prevent damage or personal injury, and
5) storage requirements (lay flat, straight or in coils, temperature range etc.). c) Information relating to installation and commissioning of the pressure-sensitive protective device, including
1) a warning that the information for use should be read in full before any installation work is attempted,
2) a warning that a reset function can be required,
3) requirements regarding the surface on which the sensor will be mounted,
4) methods of installation, including required tooling,
5) design features of the effective sensing surfaces which can influence the safety function and how the effects of dead surfaces can be minimized by installation (including drawing, where appropriate),
6) schedule of tests to be carried out after installation to establish that the device(s) are functioning and have been installed and interfaced with the machine control correctly,
7) warning that the overall safety of the machine and its safeguard depends on the quality, reliability and correct installation of the interface between them,
8) indication that the category(ies) and performance level(s) required for the device have to comply with the category(ies) and performance level(s) established by the risk assessment, and
9) record sheet which shall be completed by the installer, showing which control unit and sensor(s) are installed.
6.3.2 Information relating to operation and maintenance of the pressure-sensitive protective device
The manufacturer must provide essential information to the machine user, including details related to the proper use of pressure-sensitive protective devices This ensures safe operation and compliance with safety standards, emphasizing the manufacturer's responsibility to deliver relevant safety information to users.
1) purpose and method of operation of the control unit and indicators,
3) instructions for fault identification and for restarting after an intervention,
5) explanation to the calculated performance level with reference to the variable parameters, mean operation time, mean use time and cycle time, and
6) a statement that the user shall determine the performance level for his application by himself. b) Information for maintenance, including the following:
1) a warning that the maintenance instructions should be read before any maintenance is attempted;
2) nature and frequency of testing, inspection and maintenance;
3) instruction for allowable setting, adjustment and cleaning;
4) actions which require a definite technical knowledge and/or particular skills and hence should be carried out exclusively by skilled persons suitably trained;
5) information (e.g drawings and circuit diagrams) enabling trained personnel to carry out fault- finding tasks;
6) details of tests required after replacement of parts to establish that the device functions correctly;
Always ensure that all parts, such as covers, clips, edging strips, or fastenings, removed during maintenance are properly replaced afterward Failure to correctly refit these components can impair the device's performance and functionality Proper reassembly is essential for maintaining optimal operation and safety.
8) list of user-replaceable parts;
Only replace parts that are approved by the manufacturer to ensure optimal device performance Using non-approved spare parts or making unauthorized modifications can impair the device's functionality and safety Always follow manufacturer guidelines to maintain device integrity and prevent potential issues.
10) name and address of manufacturer and/or competent service organization;
11) indication of the maximum test interval (e.g a test at least every three months). c) Training
It is essential to establish minimum training requirements for personnel installing pressure-sensitive protective devices to ensure compliance with ISO 13856 standards Proper training ensures correct installation and optimal performance of the equipment Additionally, conducting periodic functional tests is crucial to verify the ongoing effectiveness and safety of the protective devices over time Regular testing helps identify potential issues early, maintaining compliance and ensuring personnel safety.
The instructions for use should include clear guidance on performing the sensor’s functional test, such as manually deforming the sensor surface and observing the resulting signal changes This ensures users can accurately verify sensor performance, promoting proper functionality and reliability.
1) a statement that the sensor shall be tested in regular time intervals with a test piece of 80 mm diameter at optional test locations;
The test interval for pressure-sensitive protective devices varies depending on their specific application and use It is essential for operators to determine and specify the appropriate testing schedule in accordance with national legislative requirements to ensure ongoing safety and compliance.
NOTE Further advice for production of the instruction handbook and drafting and editing the information for use is provided in ISO 12100:2010, 6.4.5.2 and 6.4.5.3.
Verification of requirements applicable to all pressure-sensitive protective devices
All the tests in this part of ISO 13856 shall be considered as type tests for each type of pressure-sensitive protective device.
Verification of compliance with this section of ISO 13856 must be carried out through inspection and/or analysis When inspection and analysis are insufficient, testing should be conducted, especially when testing is more practical or specifically required by ISO 13856 The manufacturer is responsible for providing evidence demonstrating that all requirements have been fulfilled, ensuring thorough validation of the standards.
Pressure-sensitive protective devices are often integrated into machinery, allowing necessary tests to be conducted while the devices are mounted on the machine These tests must simulate worst-case safety scenarios by carefully controlling the test pieces, approach speeds, approach directions, and sensor locations Ensuring accurate simulation of body part approaches is essential for verifying the safety and reliability of these protective devices under real-world conditions.
Tests on ready-to-use pressure-sensitive protective devices must be conducted under the least favorable conditions, adhering to the minimum requirements outlined in ISO 13856 When manufacturers specify more severe test conditions, those should be followed; otherwise, tests should align with the manufacturer's specifications if they differ from ISO 13856 standards Unless explicitly stated otherwise, these tests are performed at a standard temperature of 20 °C, with applicable tolerances observed to ensure accuracy and compliance.
If the performance of the pressure-sensitive protective device is unaffected by temperature within a specified range, testing can be conducted exclusively at ambient temperature This simplifies the testing process by eliminating the need for temperature variation assessments when consistency is confirmed across the temperature range.
Other relevant ambient conditions, e.g atmospheric pressure and humidity, shall be recorded.
In order to perform the tests specified in this clause, one or more ready-to-use sensor(s) will be required.
A pressure-sensitive protective device should feature an effective sensing surface composed of a combination of sensors These sensors must be connected to a single control unit to ensure reliable and coordinated operation.
If relevant, the maximum stated number of combined sensors shall be used to verify the relevant requirements.
If the sensor dimensions influence the characteristics of the sensor output, a sensor of the least effective sensing dimension as specified by the manufacturer shall be used.
7.1.3.2 Control units with output signal switching devices
A single control unit with an output signal switching device must be provided for each production unit, ensuring reliable operation Additionally, if required, a dedicated control unit with a specialized output signal switching device should be available for testing under fault conditions This setup ensures effective control and safety testing capabilities across production units.
7.1.4 Test No 1 — Safety-related data for selection, installation, commissioning, operation and maintenance of suitable pressure-sensitive protective device
It shall be verified that the manufacturer’s data sheet contains all safety-related data.
7.1.5 Test No 2 — Actuating force and approach speed
The actuating force must be applied to the test pieces in the specified test directions at both maximum and minimum approach speeds It is essential to verify that, during each test, the output signal switching device switches to the OFF state at an actuating force less than or equal to the specified value in Table 2 This ensures compliance with safety and operational standards for the device's performance.
When establishing the maximum approach speed, it is essential to consider the combined maximum speed of the sensor as specified by the manufacturer or determined for the specific application, along with the anticipated approach speed of a person or part of a person This ensures accurate safety measures in accordance with ISO 13855 standards.
Table 2 — Test pieces, actuating forces and test directions
Test piece to simulate body part: Head or hand
For dimensions see IEC 61032:1997, probe 11.
Body part: Arm or leg
7.1.5.2 Test locations on the sensor
Testing must be conducted at a minimum of five distinct locations on the sensor's effective sensing surface, specifically where maximum actuating forces are likely to trigger an OFF state in the output switching device These test locations should be selected based on factors such as position, geometry, sensor technology, and prior experience When the pressure-sensitive protective device consists of multiple sensors, the transition points between sensors should also be considered during testing to ensure accurate performance evaluation.
7.1.5.3 Sensor mounting orientation for tests
The tests shall be carried out a) with the sensor in the least favourable of the stated mounting orientations, and b) after the sensor has stabilized to the test temperature used.
7.1.5.4 Test pieces to be used
Tests must be conducted using test pieces relevant to the targeted body part(s), either as specified by the manufacturer of the pressure-sensitive protective device or as determined by a risk assessment for the specific application.
When it is clear that one or more test pieces produce the least favorable results, subsequent testing should be conducted exclusively using those specific test pieces This approach ensures targeted analysis and accurate assessment of the worst-case scenario, optimizing testing efficiency.
Test pieces are illustrated in Figures 3 and 4 and in Table 2.
For the requirements, see 4.2.2 and 4.2.4.
The test should be performed using test piece 1 or the relevant test pieces specified in Table 2 for the specific body part or application During testing, the test piece must be applied to the sensor at both minimum and maximum approach speeds outlined in section 7.1.5.1, at a location where contact is typically expected during operation The actuating travel must stay within the manufacturer’s specified limits to ensure proper functionality Additionally, for pressure-sensitive protective devices designed for specific applications, the actuating travel should be suitable and appropriate for their intended use.
For the requirements, see 4.2.3 and 4.2.4.
The test must be conducted using test piece 1 or the relevant test piece(s) corresponding to the specific body part involved, as outlined in Table 2 During testing, the test piece should be applied to the sensor at an approach speed of no more than 10 mm/s, targeting a contact point where contact typically occurs for the intended application Overtravel should stay within the manufacturer’s specified limits for distance and force, ensuring safe operation of the pressure-sensitive protective device For devices designed for particular applications, the overtravel limits must be appropriate to ensure safety and functionality.
7.1.8 Test No 5 — Number of operations
Testing of the sensor must be conducted using Test Piece 1 at the appropriate approach speed and for the specified number of operations Post-test, the sensor should show no visible damage while still meeting the required actuating force, pre-travel, and overtravel specifications.
The required number of actuations should be based on the manufacturer’s specifications or the application's needs, whichever is higher Test piece(s) should be applied to the areas on the sensor’s effective sensing surface where actuating force is most frequently applied Each actuation must trigger an OFF state in the output signal switching device Test parameters, including speed, should closely simulate real-world, lifetime application conditions to ensure accurate testing and safety.
Dimensions in millimetres/Tolerances on radii: ± 0,2 a) Test piece 1 b) Test piece 2 c) Test piece 3 a Mounting proposal only.
Dimensions in millimetres/Tolerances on radii: ± 0,2 a) Test piece 4 b) Test piece 5 c) Test piece 6 a Mounting proposal only.
7.1.9 Test No 6 — Output state of sensor and output signal switching device
For the requirements, see 4.2.6.1 and 4.2.6.2.
Verification of requirements for pressure-sensitive bumpers only
7.2.1 Test No 20 — Force-travel relationship
The requirements of 4.3.1 shall be verified by inspection, analysis and, if necessary, testing.
Testing of the force-travel relationship must be conducted according to Figure 2, using test piece 1 (refer to Figure 3 and Table 2) applied to the sensor (see Figure 5) at maximum approach speed up to point A If a different test piece from Figure 3 or Figure 4 is more suitable for the specific application, it should be used instead Continuous measurement of the sensor's reaction force and the displacement of the test piece should be performed from contact until the actuating force is reached Points B1, B2, and C are to be confirmed following Figure 2 by testing with test piece 1 at speeds ≤10 mm/s The resulting force-travel curve is plotted by connecting points A, B1, B2, and C with straight lines The test must be performed at a representative location, such as the center of the sensing surface, at a temperature of 20 °C to ensure consistent and accurate results.
7.2.2 Test No 21 — Additional coverings for sensors
If additional coverings are specified by the manufacturer, then it shall be verified that the requirements of 4.3.2 have been met.
7.2.3 Test No 22 — Recovery after deformation
The requirements of 4.3.3 shall be verified by inspection, analysis and, if necessary, testing.
After exposing the sensor's effective sensing surface to deformation or displacement caused by working travel using test piece 1 (see Figure 5) for 24 hours, the surface is expected to recover, as detailed in Table 1 The working travel applied in this test is based on test no 4, which was conducted at a speed of 10 mm/sec under a force of 250 N.
After being deformed or displaced by the working travel during testing with test piece 1 for 24 hours, the pressure-sensitive bumper is designed to reliably restore to normal operation within 30 seconds, ensuring consistent sensor performance and safety functionality.
7.2.4 Test No 23 — Detection on bumpers with semi-rigid or rigid surfaces
Inspection must confirm that no undetected access is possible within the bumper structure, which is ensured if no openings exceed 50 mm in diameter Proper verification involves checking for any gaps larger than 50 mm to prevent unauthorized entry, thereby maintaining security and compliance.
Figure 5 — Test location and test direction on surface of pressure-sensitive bumper
Verification of requirements for pressure-sensitive plates only
The requirements of 4.4.1 shall be verified by inspection, analysis and, if necessary, testing.
It shall be verified that the output signal switching device remains in the ON state during the test in accordance with Table 7.
IEC 60068-2-27 Pressure-sensitive plate is connected to the supply.
The sensor shall be tested in the relevant reference direc- tion and in the opposite direction only.
After completing the shock test, it is essential to verify the normal functioning of the pressure-sensitive plate and inspect it for any mechanical damage or loose parts, ensuring its integrity and reliability.
Verification of requirements for pressure-sensitive wires only
7.4.1 Test No 25 — Breaking or disengagement of the wire
An OFF state shall be generated when normal tension is removed from the wire.
The test should be conducted using test piece 5 at a maximum speed of 10 mm/sec in the designated directions It must be performed at the least favorable locations on the effective sensing surface to ensure accurate and reliable results, adhering to specified testing protocols.
7.4.3 Test No 27 — Tensile strength of the sensor (including any connections)
The test shall be carried out on a sample sensor to ensure that the sensor does not break under a tensile force of 1 000 N for at least 1 min.
7.4.4 Test No 28 — Actuating deflection of the wire
The test shall be carried out using a sample sensor with the maximum length of wire stated by the manufacturer.
Other tests
The requirements of Clause 5 shall be verified by inspection.
7.5.2 Test No 30 — Information for selection and use
The requirements of Clause 6 shall be verified by inspection.
Timing diagrams for pressure-sensitive bumpers, plates, wires and similar devices with/without reset
Figures A.1 to A.4 shows the relationship between actuating force, reset signal and outputs of the sensor and output signal switching device (see 4.2.6).
Key a) power to pressure-sensitive protective device e) output of output signal switching device(s) b) actuating force t time c) reset signal t r response time d) sensor output
A power to pressure-sensitive protective device ON: output of output signal switching device remains in OFF state because pressure-sensitive protective device not reset
B reset achieved: output of output signal switching device turns to ON state because sensor output turned ON due to operation of reset button without actuating force on sensor
C output of output signal switching device turns to OFF state because sensor output turned OFF due to actuating force on sensor
The D reset signal, when present, causes the reset button to have no effect on the output of the output signal switching device as long as force is applied to the sensor Under these conditions, the output of the switching device remains in the OFF state, ensuring consistent operation despite reset commands.
E actuating force removed from sensor: output of output signal switching device remains in OFF state even though reset signal still present
F reset signal removed: release of reset button has no effect on output of output signal switching device even when force removed from sensor
The G reset is achieved when the output of the switching device turns ON, triggered by the sensor output This occurs when the reset button is pressed, activating the sensor without applying any actuating force This process ensures reliable system reset without physical contact with the sensor, improving operational efficiency Proper understanding of this reset mechanism is essential for optimizing sensor performance and ensuring accurate system responses.
H power to pressure-sensitive protective device OFF: output of output signal switching device turns to OFF state because sensor output turned OFF
Figure A.1 — Sensor output initiated by reset function
Key a) power to pressure-sensitive protective device t time b) actuating force t r response time c) reset signal d) sensor output e) output of output signal switching device(s)
When the power is turned ON, the sensor output activates, but the pressure-sensitive protective device remains in the OFF state until it is reset This causes the output signal switching device to stay OFF, indicating that the protective device has not been reset Proper resetting of the pressure-sensitive protective device is essential to enable the output signal and ensure safe operation.
B reset signal achieved without actuating force on sensor: output of output signal switching device turns to ON state due to operation of reset button while sensor output turned ON
C actuating force on sensor: sensor output turned OFF, turning output of output signal switching device to OFF state
When the D reset signal is active, pressing the reset button does not affect the output of the signal switching device as long as the sensor's force remains present Under these conditions, the output of the switching device stays in the OFF state, ensuring stable operation despite reset attempts.
E actuating force removed from sensor: sensor output turns ON but output of output signal switching device remains in OFF state even though reset signal still present
F reset signal removed: release of reset button has no effect on output of sensor, which remains ON; output of output signal switching device remains in OFF state
G reset signal achieved without actuating force on sensor: output of output signal switching device turns to ON state due to operation of reset button while sensor output turned ON
H power to pressure-sensitive protective device OFF: output of output signal switching device turns to OFF state because sensor output turned OFF
Figure A.2 — Sensor output independent of reset function
Key a) power to pressure-sensitive protective device e) output of output signal switching device(s) b) actuating force t time c) reset signal t r response time d) sensor output
A power to pressure-sensitive protective device ON: sensor output turned ON when power turned ON
B output of output signal switching device turns to ON state because no actuating force on sensor
C actuating force on sensor: sensor output turned OFF, turning output of output signal switching device to OFF state
G output of output signal switching device turns to ON state because sensor output turned ON due to removal of actuating force from sensor
H power to pressure-sensitive protective device is OFF: output of output signal switching device turns to OFF state because sensor output turned OFF
Figure A.3 — Sensor output without reset function
The pressure-sensitive protective device features an electrical output that signals the activation of the sensor, such as an air-pulse switch Its key function involves generating a pressure pulse within the sensor, which creates an actuating force over a specified response time The device's reset signal is determined by the response time (t_r), ensuring reliable operation Additionally, the power supplied to the electrical circuits is crucial for maintaining the device's performance, while the output of the switching device effectively transmits the sensor's output signal, enabling accurate detection and response in safety systems.
A power to pressure-sensitive protective device ON
B reset signal present: output of output signal switching device turns to ON state
C actuating force on the sensor: electrical output of sensor turned OFF, turning output of output signal switching device to OFF state
D electrical output of sensor turns to ON state due to pressure decay in sensor
E reset signal present: output of output signal switching device turns to ON state, although actuating force is still applied —can lead to danger
The point at which “D” occurs will depend on a number of factors, for example the level of force applied and the controlled rate of leakage of air from the system.
As indicated in 4.2.6.2, air-pulse systems are not considered to fulfil the requirements of category 1 according to ISO 13849-1:2006 See C.3.6 for additional information on air-pulse systems.
Having an independent safety system in the machine's control system is essential to prevent hazardous restarts For powered doors, safety measures may include automatic machine reversal or manual reset mechanisms The proper operation of these safety controls should be outlined in the relevant type-C standards to ensure compliance and safety.
This system currently lacks the capability to verify sensor operation in response to pressure impulses To meet Category 2 requirements under ISO 13849-1:2006, door control systems must incorporate functionality that ensures proper sensor response and safety verification.
Figure A.4 — Sensor output for trip devices where the sensor output does not remain in OFF state when actuating force is still applied (e.g air-pulse or piezo-electric systems)
Device characteristics — Explanatory remarks and recommendations
Figure B.1 gives the principle of operation only For some pressure-sensitive protective devices, such as example pressure-sensitive plates, the curve can have a different shape depending on the design.
X travel, mm a sensor before contact g established stopping travel of machine
Y force, N b point of contact h actuating travel
1 reference forces c point of actuation i overtravel
2 lowest actuating force d deformation at point B2 j working travel
3 hazard speed e deformation at point C k total travel
Forces are related to test piece 1 of Table 2 and are examples only.
Figure B.1 — Force-travel relationship for pressure-sensitive protective devices
The force exerted increases upon contact with an obstruction, prompting the sensor to signal the control unit to switch to the OFF state, which then sends a stop signal to the machine to prevent hazardous movement The distance the mechanism travels between detecting the obstacle and coming to a complete stop is known as the actuating travel, and this distance can vary depending on the approach speed and environmental conditions Additionally, overtravel refers to the further movement beyond the point of stopping, and total travel encompasses the entire distance covered by the mechanism from the start of movement to its final position.
Overtravel refers to the distance during which the mechanism's speed decreases while the applied force increases It is essential to ensure that the maximum permissible force, as specified by the supplier and selected based on the application, remains below the reference force outlined in the type-C standard or risk assessment This force should be achieved within the overtravel distance to ensure safety and compliance (See Figure B.2 for detailed illustration.)
Exceeding the maximum permissible force can result from various factors such as brake deterioration due to aging, extended response times, mechanical wear, and increased hazard speeds, all of which can lead to injuries caused by excessive force acting on the affected body part when sensor deformation is no longer possible.
The overtravel of pressure-sensitive plates can vary significantly based on their design, ranging from minimal movement due to deliberate restrictions to unlimited travel allowing the plate to completely move out of the way This flexibility in design enables tailored solutions for different industrial applications, ensuring optimal performance and safety Understanding whether a pressure-sensitive plate has limited or unlimited overtravel is crucial for selecting the right sensor system for specific operational needs.
In all applications, it is essential to minimize the force exerted on individuals to ensure safety and comfort The maximum permissible force depends on factors such as the duration of contact, sensor dimensions, sensor material, and the specific body parts being protected special care should be taken when designing systems to safeguard vulnerable populations like children and the elderly, prioritizing gentle force application to prevent injury Implementing these considerations helps optimize safety in medical, occupational, and consumer applications while adhering to SEO best practices.
The moving power transmission elements and tools are protected with fixed and interlocked guards Bumpers are used to protect a person who may enter the path of the moving enclosure.
1 direction of travel b overtravel d overall bumper height a actuating travel c total travel
Figure B.2 — Example of bumper mounted on woodworking machine
This annex provides essential guidance on designing pressure-sensitive protective devices to ensure safety and effectiveness While following these design recommendations is important, neglecting them does not automatically imply that the final device will be unsafe Proper adherence to these guidelines can enhance device safety, but even with deviations, the device may still meet safety standards Ultimately, careful design and testing are crucial for ensuring the safety of pressure-sensitive protective devices.
Pressure-sensitive protective devices are frequently used in applications where they are not actuated for many months However, when they are actuated, they should work safely.
Conversely, some pressure-sensitive protective devices are used on applications where they are frequently activated This can sometimes result in a change of sensitivity over time.
Components of pressure-sensitive protective devices should be fully protected from foreseeable damage, e.g with protective sheaths.
To ensure optimal performance, sensors in environments exposed to liquids like oils, chemicals, or water must be constructed from corrosion-resistant and chemically inert materials Using appropriate materials prevents degradation, swelling, and sensitivity loss, maintaining the sensor's accuracy and durability in challenging conditions Selecting suitable materials for liquid contact is essential for reliable sensor operation and long-term stability.
The profile material of the sensor should withstand the operating duty and environmental conditions.
Sensors often have pressure-sensing surfaces with varying sensitivity, where certain areas may be less responsive, impacting overall accuracy Additionally, parts of the sensor are more susceptible to damage, particularly near connection points such as cables, tubes, fibers, or leads Sensitivity tends to decrease near the connection interfaces and at contact points where elements are spaced apart, highlighting the importance of careful placement and design to ensure optimal sensor performance.
C.2.6 Use of position detection switches
Where position detection switches are used, e.g as a part of the sensor of pressure-sensitive plates or pressure-sensitive bumpers, the following design characteristics should be considered:
— displacement or removal of the sensor;
— permanent deformation of the top surface due to overloading;
— sticking of position detection switches due to infrequent use;
— excessive wear or misalignment of cams on cam-operated systems;
— position detection switches becoming loose on brackets causing misalignment.