Development of safety guidelines and ISO standardization for turbo-molecular pumps

抄録

The Japan Surface Vacuum Society industrial award was presented to Shimadzu in 2022. This talk briefly introduces the background to the establishment of the standard and its main contents.

A turbomolecular pump is a vacuum pump capable of producing ultrahigh vacuum by rotating the rotor at high speed. Rotational energy of the rotor is very large, and there is a risk of pump falling and debris scattering by the failure of the rotor.

In response to these risks, from 2003 to 2005, the Japan Vacuum Industry Association held working sessions with committee members from turbomolecular pump manufacturers, sellers, AIST, etc., and published a document on the results of activities in March 2005. This guideline introduces a wide range of methods for measuring rapid shutdown torque at the time of rotor breakdown performed by manufacturers in Japan at that time, and summarizes what should be included in the test report.

Based on this, the Japan proposed a project to create an ISO standard, and a three-year activity began in 2006. I was appointed as the project leader by the ISO Technical Committee TC112 (vacuum technology). In September 2007, we rented a conference room at AIST, where engineers from Japan, Germany, and France manufacturers, as well as Japan corporations of overseas manufacturers, gathered to discuss Japan proposals. After four rounds of international vote revisions, with the addition of the test method submitted later by Germany, the international standard was published in 2010 as ISO 27892.

ISO 27892 describes two destructive test methods for forcing rotors to break. The first method is to add notches in the rotor or shaft in advance to cause centrifugal destruction. The second method is to hit the rotating rotor blades with a foreign object and destroy the turbine blades. There are two main types of pump fixing methods when measuring rapid shutdown torque: one method is to measure the torsional torque acting between the pump and the test frame by mounting it on the test frame (See figure below.), and the other is to measure the torque acting between the floor and the pump by fixing the pump to the floor. The more suitable test method should be selected by the manufacturer based on the intended use of the product. ISO 27892 describes a method of measuring rapid shutdown torque using a strain gauge or force sensor and other means.

ISO 27892 lists the items to be included in the test report. For example, destructive torque measured by the method or notes on the design for safe mounting to parts (bolts, clamp, and others) on the pump where rapid shutdown torque is transmitted directly.

Safety is not directly guaranteed in this international standard. If each manufacturer tests according to the standard, products that fall off or scatter debris when the rotor is destroyed will be disappear from markets. It is hoped that this will exert a checking effect.

1) Tomoaki Urano, Turbomachinery 23, 635 (1995)

2) Working on Safety Assurance of Turbomolecular Pumps, "Guidelines for Safety Assurance of Turbomolecular Pumps" (Japan Vacuum Industry Association, 2005)

3) ISO 27892: 2010 Vacuum technology — Turbomolecular pumps — Measurement of rapid shutdown torque (2010)