NFPA continues to develop reliability standard

In June 2002, NFPA's Board of Directors gave high priority to developing a standard for testing the reliability of fluid power components. Now, after almost two years of work, this industry-wide program continues to evolve. After the first general review ballot of NFPA/T2.12.11-2-200x in mid-2003, much progress has been made on the document and preliminary round robin testing of some components has begun.

Bayesian reliability testing
The issue of applying the Bayesian test method to all components by placing it in the general standard was discussed at a project group meeting of NFPA/T2.12.11-2-200x on Feb. 17. Proposed changes to the main document in light of an optional test method will be reviewed and developed. The Bayesian testing method relies on both a historical distribution of component failure data and a spec-ified reliability class rating system to be designed for use in this standard, and it specifies minimum component life in hours.

Pneumatic component reliability
The push for fluid power reliability standards has reached the international level as well. ISO Technical Committee 131 recently began work on three International Standards for determining the reliability of pneumatic components by testing:

• ISO/CD (committee draft) 19973-1, Pneumatic fluid power — Determination of component reliability by testing — Part 1: General procedures and calculation method
• ISO/CD 19973-2, Pneumatic fluid power — Determination of component reliability by testing —

Part 2: Valves

• ISO/CD 19973-3, Pneumatic fluid power — Determination of component reliability by testing — Part 3: Piston rod cylinders Due to this work at the ISO level, two annexes from the NFPA/T2.12.11-2-200x document were discontinued in February:
• Annex H for pneumatic cylinders — ISO/CD 19973-3 covers this topic. The NFPA project group has not completed enough work on the annex to consider preliminary round robin testing.
• Annex J for pneumatic valves — ISO/CD 19973-2 covers this topic. The NFPA project group has done preliminary round robin testing of the procedure and had further test data available for the February meetings.

Annex G for pneumatic regulators was updated during the Feb. 18 project group/component annex meeting, and then submitted for ballot as a new work item proposal at the ISO level.

Hydraulic component reliability

A proposal for a general hydraulic reliability-testing standard (Hydraulic fluid power — Determination of component reliability by testing — Part 1: General procedures and calculation method) was approved as a new work item at the ISO level. Work on this standard will begin at a meeting in May in Frankfurt, Germany.

If you are interested in participating on any of the committees working on the NFPA/T2.12.11-2-200x standard, call Jenna Wetzel at (414) 778-3362 or e-mail jwetzel@nfpa.com. If you would like to participate in the development of the ISO standards, call Karen Boehme at (414) 778-3345 or e-mail kboehme@nfpa.com.