We are sending this letter to let you know a potential risk concerning the turbo molecular pump.  As you may know, the rotor of the turbo molecular pump has a finite service life.  Extended use may lead to longitudinal fracture of the rotor during operation due to creep or corrosion.  Accordingly, we recommend that periodic maintenance should be performed and the rotor should be replaced if necessary.
  In designing our turbo molecular pump, we have aimed at avoiding any danger resulting from longitudinal rupture of the rotor during operation, for example, one caused by scattering of debris of the rotor.

 

  However, it has recently come to our attention that rupture of the rotor may take a mode that has not been considered during the design of the product.
  If the rotor is broken in the mode that has recently come to our attention, a load that has not been considered in the design phase can be applied to the stator side, and it could cause failure of bolts connecting the casing and the stator or rupture of the aluminum casing（ET800H/ET801H only）.  It may further cause separation of the stator from the main body, or the casing.  Therefore, we are offering voluntary enhancement counter-measures for enhancing safety of the product.

 

  Accordingly, we hereby urge our customers of the models specified in Paragraph 1 below to replace or install components following the instructions given by contact to EBARA in accordance with our procedure specified in Paragraph 2.

 

  In this regard, you should be warned that continuing use of the turbo molecular pump without taking counter-measures may result in leakage of the gas contained in the pump, scattering of debris of pump components or a falling stator as a result of rupture of the casing, separation of the stator or separation between the stator and the casing.  Consequently, if the rupture occurs when a worker is around the pump, he/she may be injured by the leak of the process gas or the scattering of the debris of the pump components.  Therefore, we urge our customers to take the voluntary enhancement counter-measures as soon as possible and to keep workers away from the pump vicinity until the counter-measures are taken.

 

  When you install the components for the counter-measures, you should follow the instructions given in the note accompanying the components.  Special attention must be paid to the torque for tightening the bolts.  Insufficient tightening should be of course avoided, but excessive tightening will also deprive the counter-measures of their effectiveness because it causes deformation of the female thread, which is made of aluminum.   Therefore, the torque specified in the instructions must be strictly followed.

 

  Finally, we would like you to understand that we are still studying the effectiveness of the counter-measures.  Although we now believe that the counter-measures that we are now asking our customers to take are effective enough to secure safety of the product, our study may bring about more effective counter-measures.  Therefore, we would like you to understand that we may ask you for further cooperation when we have completed confirmation tests of the counter-measures.

 

  Your questions, inquiries can be brought to either nearest EBARA representatives of you, or contact information specified in paragraph 3.

 

  We would like to express our commitment to enhance and improve the quality of our products.  And we thank you in advance for your continuing support and patronage toward our products.

 

Very truly yours,

 

1.  Applicable models for voluntary enhancement program

Table1 shows EBARA turbo molecular pump (TMP) model names.

Applicable TMP models

ET300W/ET300WS/ET300WS-A/ET300WS-H/ET300W-TF/ET300WS-TF (Note 1)  ET600WS-A

ET600W/ET600WS/ET600WS-TF

ET800W/ET800WS/ET800WS-A

ET800H/ET801H/ET800H-TF/ET801H-TF

ET1600W/ET1600WS/ET1600WS-A

Table 1 List of Applicable Model

Note 1)	ET300W Series has two types of external construction as shown in Figure 1--the “One” casing type and the “Two” casing type. For the ET300W pumps, only the “Two” casing type requires Countermeasure A.
Fig. 1 ET300WS Exterior to Check Modification Requirement

2.  Action Procedure for implementing voluntary enhancement countermeasures

Please follow the steps below to procure, replace and install parts for countermeasures. Your questions, inquiries can be brought to either nearest EBARA representatives of you, or contact information specified in paragraph 3.
1)	Contact nearest EBARA representatives of you, or contact information specified in paragraph 3 and ask to obtain detail information document as well as work procedure.
2)	Fill out “Request Sheet for EBARA Turbo molecular pump replacement parts” on the final page of the detail information document you receive from EBARA (or attached) with applicable TMP models, quantities, pump serial numbers, etc. and send to the address described in paragraph 3 by fax or e-mail.
3)	After receiving the request sheet, EBARA will ship replacement parts for pump quantities on the sheet and work procedures for at no charge within 10 days upon notice.
4)	Upon receiving the countermeasure parts, install them as soon as possible for your safety.
5)	Once replacement and/or installation are completed, fill out and send back “Confirmation Note”, which EBARA ships with parts, to the address on the procedures.
6)	As far as ET800H and ET801H are concerned, please send pumps for overhaul to replace aluminum casing with stainless steel casing as permanent solution.  EBARA will ship overhauled pumps within 30 days after receiving the pump so far as Japan market is concerned. We are welcome to discuss with you for a turn around time of pump overhaul in overseas market.  The upgrade of casing replacement on ET800H and ET801H will be made at no charge. However, normal charges for replacement of other parts and refurbishment work will apply.

3.  EBARA Contact Information

Your questions, inquiries can be brought to either nearest EBARA representatives of you, or contact information as below.  Please be advised that our contact point is in accordance with your location, country, so please find your nearest contact point unless/otherwise you have specific EBARA contacts.
•	Contact to EBARA CORPORATION (Japan market only)
	Contact:	EBARA CORPORATION TMP Voluntary Enhancement Program Team
	Free Dial:	0120-488-287 (Japan only, From Mon ~ Fri, 09:00 ~ 16:30)
	TEL/Fax:	0466-83-9000/ 0466-83-8885
	E-mail:
•	Contact to EBARA affiliated companies (for oveseas market)
	China: Shanghai Ebara Precision Machinery Co.,ltd Address: No.76 , Lane887, Zuchongzhi Rd, Zhangjiang High-Tech Park Pudong, Shanghai,P.R.China Contact: Sales Dept TEL/FAX: +86-(0)21-5131-7008 / 7048 E-mail: Web: Not Available Korea: Ebara Precision Machinery Korea Inc Address: 20FL, Kangnam Bldg., 1321 Seocho-Dong,Seocho-ku, Seoul Contact: Component Sales Dept TEL/FAX: +82-(0)2-581-6901 / 4211 E-mail: Web: http://ebara.co.kr Taiwan: Ebara Precision Machinery Taiwan Inc Address: 5, Tzu-Chiang Rd., Hsin-Chu Ind.Park Taiwan 303 Contact: Component Sales Dept TEL/FAX: +886-(0)3-597-8811 / 8833 E-mail: Web: Not Available Singapore: Ebara Engineering Singapore Pte. Ltd Address: No 1, Tuas Link 2 Singapore 638550 Contact: Component Sales Dept TEL/FAX: +65-6862-3536 / 6863-1201 E-mail: Web: http://www.ebara.com.sg U.S.A: Ebara Technologies Inc Address: 51 Main Avenue, Sacramento, CA 95838 Contact: TMP Safety Enhancement Project TEL/FAX: +1-916-923-7543/ +1-916-920-1033 E-mail: Web: http://www.ebaratech.com Europe: Ebara Precision Machinery Europe GmbH Address: 2-4, Adam Square, GB-Livingston, West Lothian EH54 9DE Contact: Component Operation Dept TEL/FAX: +44-1506-460232 / 460222 E-mail: Web: http://www.ebara-pm.eu

4.  Safely caution

Do not approach near to a running EBARA TMP until these countermeasures are completed.  If you need to do any work near to EBARA TMP, you must stop the pump (turn off the power) before starting the work.  An accident with injuries may result if the casing or screw(s) on the pump should break.

5.  Scheduling Overhauls

The above countermeasures permit TMP’s to be used safely.  However, rotor blades of TMP’s are consumable parts.  Without periodic overhauls, the probability of a broken rotor increases.  Periodical TMP overhaul/maintenance will reduce likelihood of failure and to use TMP’s safely.  Please contact EBARA for periodical TMP overhaul/maintenance.