[labnetwork] Practices for Aging Process Gas Cylinders

[Aamer Mahmood]

Dear Colleagues,
Despite a high level of user activity, we have identified several process gas cylinders in our facility that are 10 years old or older and still contain a significant amount of gas. We are evaluating whether our current practices remain appropriate from both a process reliability and safety standpoint.
I would appreciate learning how your facilities approach this issue, specifically:

  *   Whether you have established age limits for gas cylinders, regardless of remaining contents
  *   Any safety or process considerations that drive those limits
  *   Whether cylinder change‑outs are handled in‑house or by specialized contractors
Most of the gases of interest at our facility are:

  *   Hydrogen (H₂)
  *   Nitrous Oxide (N₂O)
  *   Ammonia (NH₃), Silane (SiH₄), SiH₄:He (5:95)
  *   Hydrogen Bromide (HBr)
  *   Methane (CH₄), Chlorine (Cl₂)
  *   Dichlorosilane (SiH₂Cl₂)
  *   Boron Trichloride (BCl3)
  *   Silicon Tetrachloride (SiCl4)
Your insights or references to existing policies would be very helpful as we determine next steps. You may also respond directly to me (aamer at uchicago.edu) if you prefer.
Thank you in advance for sharing your experience.
Best regards,

--
Aamer Mahmood

Executive Director
Pritzker Nanofabrication Facility
William Eckhardt Research Center
University of Chicago
5640 S. Ellis Ave., Chicago, IL 60637

Tel: +1 (773) 702 8903
Web: pnf.uchicago.edu

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