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Maximum duration between two Calibrations cycles in GC-370XA

Please guide about following,

  • What are the maximum number of days i can run my GC-370XA (on Analysis) without performing  calibration through Cal gas. As my calibration gas has expired.

Thanks and Regards,

MUSAB SHABBIR

3 Replies

  • Hi MUSAB SHABBIR
    Calibration frecuency varies On 370XA Analyzers , under normal conditions the analyzer can retain it's calibration for days, months, in fact for process analysis a yearly calibration is acceptable, however other applications(custody transfer) requires having the analyzer calibrated every 24 hrs.
    If the analyzer has been recently calibrated with in the last 3 or 6 months and it is for process , it should be fine.
    Thanks
    Ray
  • In reply to Raymundo Morin:

    We run Daniels Danalyzer GC's - 2351 so I can't reply exactly to your 370-XA. We auto calibrate all our GC's every day, regardless of internal information or custody transfer use. I would rather run an "expired" bottle than none at all as the GC will drift without a cal standard to reference to.
    We use a heat blanket to keep the cylinder at least 30 deg F above cricondentherm to eliminate the heavies dropping out and calibrating to the lights, ruins a cal bottle fairly quickly. I inherited a GC that had been neglected by a former employee, the bottle was expired and it went below 50 psi before I could get a new standard mixed and delivered. The GC analyzed the new bottle as an unknown and reported the contents accurately after calibrating on the date-expired bottle for several months. If you have kept it warm the mixture in the bottle hasn't changed, just the date.

    An option may be to connect the cal bottle from another GC and run it as an unknown, if your GC analyzes that gas correctly your GC hasn't drifted.
  • You can potentially go several weeks or months without calibration, we rarely calibrate our machines even in custody transfer applications but we do perform regular validation cycles to ensure that the GC has not drifted significantly. Some of our machines have not been "calibrated" in more than a year and still pass the GPA guidelines for repeatability and reproducibility. As far as an expired calibration standard, going past the expiration date does not automatically mean that your standard is no longer valid nor does a certificate that isn't expired ensure that the standard is valid. A fidelity plot for your response factors along with a "Round Robin" sample of an alternate calibration standard as an unknown can ensure that your calibration blend composition has not changed significantly both before the expiration date and after. I have seen companies utilize these methods to use their standards beyond the expiration date to reduce waste.