['Machine Guarding']
['Machine Guarding']
09/18/2023
Copyright 2024 J. J. Keller & Associate, Inc. For re-use options please contact copyright@jjkeller.com or call 800-558-5011.
...
Purpose
The purpose of the certification/validation of safety systems for presence sensing device initiation (PSDI) of mechanical power presses is to ensure that the safety systems are designed, installed, and maintained in accordance with all applicable requirements of 29 CFR 1910.217 (a) through (h) and this Appendix A.
General
The certification/validation process shall utilize an independent third-party validation organization recognized by OSHA in accordance with the requirements specified in Appendix C of this section.
While the employer is responsible for assuring that the certification/validation requirements in §1910.217(h)(11) are fulfilled, the design certification of PSDI safety systems may be initiated by manufacturers, employers, and/or their representatives. The term manufacturers refers to the manufacturer of any of the components of the safety system. An employer who assembles a PSDI safety system would be a manufacturer as well as employer for purposes of this standard and Appendix.
The certification/validation process includes two stages. For design certification, in the first stage, the manufacturer (which can be an employer) certifies that the PSDI safety system meets the requirements of 29 CFR 1910.217 (a) through (h) and this Appendix A, based on appropriate design criteria and tests. In the second stage, the OSHA-recognized third-party validation organization validates that the PSDI safety system meets the requirements of 29 CFR 1910.217 (a) through (h) and this Appendix A and the manufacturer’s certification by reviewing the manufacturer’s design and test data and performing any additional reviews required by this standard or which it believes appropriate.
For installation certification/validation and annual recertification/revalidation, in the first stage the employer certifies or recertifies that the employer is installing or utilizing a PSDI safety system validated as meeting the design requirements of 29 CFR 1910.217 (a) through (h) and this Appendix A by an OSHA-recognized third-party validation organization and that the installation, operation and maintenance meet the requirements of 29 CFR 1910.217 (a) through (h) and this Appendix A. In the second stage, the OSHA-recognized third-party validation organization validates or revalidates that the PSDI safety system installation meets the requirements of 29 CFR 1910.217 (a) through (h) and this Appendix A and the employer’s certification, by reviewing that the PSDI safety system has been certified; the employer’s certification, designs and tests, if any; the installation, operation, maintenance and training; and by performing any additional tests and reviews which the validation organization believes is necessary.
Summary
The certification/validation of safety systems for PSDI shall consider the press, controls, safeguards, operator, and environment as an integrated system which shall comply with all of the requirements in 29 CFR 1910.217 (a) through (h) and this Appendix A. The certification/validation process shall verify that the safety system complies with the OSHA safety requirements as follows:
A. Design certification/validation
1. The major parts, components and subsystems used shall be defined by part number or serial number, as appropriate, and by manufacturer to establish the configuration of the system.
2. The identified parts, components and subsystems shall be certified by the manufacturer to be able to withstand the functional and operational environments of the PSDI safety system.
3. The total system design shall be certified by the manufacturer as complying with all requirements in 29 CFR 1910.217 (a) through (h) and this Appendix A.
4. The third-party validation organization shall validate the manufacturer’s certification under paragraphs 2 and 3.
B. Installation certification/validation
1. The employer shall certify that the PSDI safety system has been design certified and validated, that the installation meets the operational and environmental requirements specified by the manufacturer, that the installation drawings are accurate, and that the installation meets the requirements of 29 CFR 1910.217 (a) through (h) and this Appendix A. (The operational and installation requirements of the PSDI safety system may vary for different applications.)
2. The third-party validation organization shall validate the employer’s certifications that the PSDI safety system is design certified and validated, that the installation meets the installation and environmental requirements specified by the manufacturer, and that the installation meets the requirements of 29 CFR 1910.217 (a) through (h) and this Appendix A.
C. Recertification/revalidation
1. The PSDI safety system shall remain under certification/validation for the shorter of one year or until the system hardware is changed, modified or refurbished, or operating conditions are changed (including environmental, application or facility changes), or a failure of a critical component has occurred.
2. Annually, or after a change specified in paragraph 1., the employer shall inspect and recertify the installation as meeting the requirements set forth under B., Installation Certification/Validation.
3. The third-party validation organization, annually or after a change specified in paragraph 1., shall validate the employer’s certification that the requirements of paragraph B., Installation Certification/Validation have been met.
(NOTE: Such changes in operational conditions as die changes or press relocations not involving disassembly or revision to the safety system would not require recertification/revalidation.)
Certification/validation requirements
A. General design certification/validation requirements
1. Certification/validation program requirements. The manufacturer shall certify and the OSHA-recognized third-party validation organization shall validate that:
(a) The design of components, subsystems, software and assemblies meets OSHA performance requirements and are ready for the intended use; and
(b) The performance of combined subsystems meets OSHA’s operational requirements.
2. Certification/validation program level of risk evaluation requirements. The manufacturer shall evaluate and certify, and the OSHA-recognized third-party validation organization shall validate, the design and operation of the safety system by determining conformance with the following:
a. The safety system shall have the ability to sustain a single failure or a single operating error and not cause injury to personnel from point of operation hazards. Acceptable design features shall demonstrate, in the following order or precedence, that:
(1) No single failure points may cause injury; or
(2) Redundancy, and comparison and/or diagnostic checking, exist for the critical items that may cause injury, and the electrical, electronic, electromechanical and mechanical parts and components are selected so that they can withstand operational and external environments. The safety factor and/or derated percentage shall be specifically noted and complied with.
b. The manufacturer shall design, evaluate, test and certify, and the third-party validation organization shall evaluate and validate, that the PSDI safety system meets appropriate requirements in the following areas.
(1) Environmental limits
(a) Temperature
(b) Relative humidity
(c) Vibration
(d) Fluid compatability with other materials
(2) Design limits
(a) Power requirements
(b) Power transient tolerances
(c) Compatability of materials used
(d) Material stress tolerances and limits
(e) Stability to long term power fluctuations
(f) Sensitivity to signal acquisition
(g) Repeatability of measured parameter without inadvertent initiation of a press stroke
(h) Operational life of components in cycles, hours, or both
(i) Electromagnetic tolerance to:
(1) Specific operational wave lengths; and
(2) Externally generated wave lengths
(3) New design certification/validation. Design certification/validation for a new safety system, i.e., a new design or new integration of specifically identified components and subsystems, would entail a single certification/validation which would be applicable to all identical safety systems. It would not be necessary to repeat the tests on individual safety systems of the same manufacture or design. Nor would it be necessary to repeat these tests in the case of modifications where determined by the manufacturer and validated by the third-party validation organization to be equivalent by similarity analysis. Minor modifications not affecting the safety of the system may be made by the manufacturer without revalidation.
Substantial modifications would require testing as a new safety system, as deemed necessary by the validation organization.
B. Additional detailed design certification/validation requirements
1. General. The manufacturer or the manufacturer’s representative shall certify to and submit to an OSHA-recognized third-party validation organization the documentation necessary to demonstrate that the PSDI safety system design is in full compliance with the requirements of 29 CFR 1910.217(a)-(h) and this Appendix A, as applicable, by means of analysis, tests, or combination of both, establishing that the following additional certification/validation requirements are fulfilled.
2. Reaction times. For the purpose of demonstrating compliance with the reaction time required by §1910.217(h), the tests shall use the following definitions and requirements:
a. Reaction time means the time, in seconds, it takes the signal, required to activate/deactivate the system, to travel through the system, measured from the time of signal initiation to the time the function being measured is completed.
b. Full stop or “No movement of the slide or ram” means when the crankshaft rotation has slowed to two or less revolutions per minute, just before stopping completely.
c. Function completion means for, electrical, electromechanical and electronic devices, when the circuit produces a change of state in the output element of the device.
d. When the change of state is motion, the measurement shall be made at the completion of the motion.
e. The generation of the test signal introduced into the system for measuring reaction time shall be such that the initiation time can be established with an error of less than 0.5 percent of the reaction time measured.
f. The instrument used to measure reaction time shall be calibrated to be accurate to within 0.001 second.
3. Compliance with §1910.217(h)(2)(ii). For compliance with these requirements, the average value of the stopping time, Ts, shall be the arithmetic mean of at least 25 stops for each stop angle initiation measured with the brake and/or clutch unused, 50 percent worn, and 90 percent worn. The recommendations of the brake system manufacturer shall be used to simulate or estimate the brake wear. The manufacturer’s recommended minimum lining depth shall be identified and documented, and an evaluation made that the minimum depth will not be exceeded before the next (annual) recertification/revalidation.
A correlation of the brake and/or clutch degradation based on the above tests and/or estimates shall be made and documented. The results shall document the conditions under which the brake and/or clutch will and will not comply with the requirement. Based upon this determination, a scale shall be developed to indicate the allowable 10 percent of the stopping time at the top of the stroke for slide or ram overtravel due to brake wear. The scale shall be marked to indicate that brake adjustment and/or replacement is required. The explanation and use of the scale shall be documented.
The test specification and procedure shall be submitted to the validation organization for review and validation prior to the test. The validation organization representative shall witness at least one set of tests.
4. Compliance with §§ 1910.217(h)(5)(iii) and (h)(9)(v). Each reaction time required to calculate the Safety Distance, including the brake monitor setting, shall be documented in separate reaction time tests. These tests shall specify the acceptable tolerance band sufficient to assure that tolerance build-up will not render the safety distance unsafe.
a. Integrated test of the press fully equipped to operate in the PSDI mode shall be conducted to establish the total system reaction time.
b. Brakes which are the adjustable type shall be adjusted properly before the test.
5. Compliance with §1910.217(h)(2)(iii). a. Prior to conducting the brake system test required by paragraph (h)(2)(ii), a visual check shall be made of the springs. The visual check shall include a determination that the spring housing or rod does not show damage sufficient to degrade the structural integrity of the unit, and the spring does not show any tendency to interleave.
b. Any detected broken or unserviceable springs shall be replaced before the test is conducted. The test shall be considered successful if the stopping time remains within that which is determined by paragraph (h)(9)(v) for the safety distance setting. If the increase in press stopping time exceeds the brake monitor setting limit defined in paragraph (h)(5)(iii), the test shall be considered unsuccessful, and the cause of the excessive stopping time shall be investigated. It shall be ascertained that the springs have not been broken and that they are functioning properly.
6. Compliance with §1910.217(h)(7). a. Tests which are conducted by the manufacturers of electrical components to establish stress, life, temperature and loading limits must be tests which are in compliance with the provisions of the National Electrical Code.
b. Electrical and/or electronic cards or boards assembled with discreet components shall be considered a subsystem and shall require separate testing that the subsystems do not degrade in any of the following conditions:
(1) Ambient temperature variation from -20 °C to 50 °C.
(2) Ambient relative humidity of 99 percent.
(3) Vibration of 45G for one millisecond per stroke when the item is to be mounted on the press frame.
(4) Electromagnetic interference at the same wavelengths used for the radiation sensing field, at the power line frequency fundamental and harmonics, and also from outogenous radiation due to system switching.
(5) Electrical power supply variations of ± 15 percent.
c. The manufacturer shall specify the test requirements and procedures from existing consensus tests in compliance with the provisions of the National Electrical Code.
d. Tests designed by the manufacturer shall be made available upon request to the validation organization. The validation organization representative shall witness at least one set of each of these tests.
7. Compliance with §1910.217(h)(9)(iv). a. The manufacturer shall design a test to demonstrate that the prescribed minimum object sensitivity of the presence sensing device is met.
b. The test specifications and procedures shall be made available upon request to the validation organization.
8. Compliance with §1910.217(h)(9)(x). a. The manufacturer shall design a test(s) to establish the hand tool extension diameters allowed for variations in minimum object sensitivity response.
b. The test(s) shall document the range of object diameter sizes which will produce both single and double break conditions.
c. The test(s) specifications and procedures shall be made available upon request to the validation organization.
9. Integrated tests certification/validation. a. The manufacturer shall design a set of integrated tests to demonstrate compliance with the following requirements:
Sections 1910.217(h)(6) (ii); (iii); (iv); (v); (vi); (vii); (viii); (ix); (xi); (xii); (xiii); (xiv); (xv); and (xvii).
b. The integrated test specifications and procedures shall be made available to the validation organization.
10. Analysis. a. The manufacturer shall submit to the validation organization the technical analysis such as Hazard Analysis, Failure Mode and Effect Analysis, Stress Analysis, Component and Material Selection Analysis, Fluid Compatability, and/or other analyses which may be necessary to demonstrate, compliance with the following requirements:
Sections 1910.217(h)(8) (i) and (ii); (h)(2) (ii) and (iii); (h)(3)(i) (A) and (C), and (ii); (h)(5) (i), (ii) and (iii); (h)(6) (i), (iii), (iv), (vi), (vii), (viii), (ix), (x), (xi), (xiii), (xiv), (xv), (xvi), and (xvii); (h)(7) (i) and (ii); (h)(9) (iv), (v), (viii), (ix) and (x); (h)(10) (i) and (ii).
11. Types of tests acceptable for certification/validation. a. Test results obtained from development testing may be used to certify/validate the design.
b. The test results shall provide the engineering data necessary to establish confidence that the hardware and software will meet specifications, the manufacturing process has adequate quality control and the data acquired was used to establish processes, procedures, and test levels supporting subsequent hardware design, production, installation and maintenance.
12. Validation for design certification/validation. If, after review of all documentation, tests, analyses, manufacturer’s certifications, and any additional tests which the third-party validation organization believes are necessary, the third-party validation organization determines that the PSDI safety system is in full compliance with the applicable requirements of 29 CFR 1910.217(a) through (h) and this Appendix A, it shall validate the manufacturer’s certification that it so meets the stated requirements.
C. Installation certification/validation requirements
1. The employer shall evaluate and test the PSDI system installation, shall submit to the OSHA-recognized third-party validation organization the necessary supporting documentation, and shall certify that the requirements of §1910.217(a) through (h) and this Appendix A have been met and that the installation is proper.
2. The OSHA-recognized third-party validation organization shall conduct tests, and/or review and evaluate the employer’s installation tests, documentation and representations. If it so determines, it shall validate the employer’s certification that the PSDI safety system is in full conformance with all requirements of 29 CFR 1910.217(a) through (h) and this Appendix A.
D. Recertification/revalidation requirements
1. A PSDI safety system which has received installation certification/validation shall undergo recertification/revalidation the earlier of:
a. Each time the systems hardware is significantly changed, modified, or refurbished;
b. Each time the operational conditions are significantly changed (including environmental, application or facility changes, but excluding such changes as die changes or press relocations not involving revision to the safety system);
c. When a failure of a significant component has occurred or a change has been made which may affect safety; or
d. When one year has elapsed since the installation certification/validation or the last recertification/revalidation.
2. Conduct or recertification/revalidation. The employer shall evaluate and test the PSDI safety system installation, shall submit to the OSHA-recognized third-party validation organization the necessary supporting documentation, and shall recertify that the requirements of §1910.217(a) through (h) and this Appendix are being met. The documentation shall include, but not be limited to, the following items:
a. Demonstration of a thorough inspection of the entire press and PSDI safety system to ascertain that the installation, components and safeguarding have not been changed, modified or tampered with since the installation certification/validation or last recertification/revalidation was made.
b. Demonstrations that such adjustments as may be needed (such as to the brake monitor setting) have been accomplished with proper changes made in the records and on such notices as are located on the press and safety system.
c. Demonstration that review has been made of the reports covering the design certification/validation, the installation certification/validation, and all recertification/revalidations, in order to detect any degradation to an unsafe condition, and that necessary changes have been made to restore the safety system to previous certification/validation levels.
3. The OSHA-recognized third-party validation organization shall conduct tests, and/or review and evaluate the employer’s installation, tests, documentation and representations. If it so determines, it shall revalidate the employer’s recertification that the PSDI system is in full conformance with all requirements of 29 CFR 1910.217(a) through (h) and this Appendix A.
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Copyright 2024 J. J. Keller & Associate, Inc. For re-use options please contact copyright@jjkeller.com or call 800-558-5011.