4 The record articles

CMS Daily Calibration Tolerances: Could You Be Operating to Double the Allowable Standard?

Posted: July 9th, 2019

Authors: Matt C.  All4 Staff 
Matt Carideo Project Engineer

Within various subparts of 40 CFR Part 63, there are General Provisions applicability tables, detailing which general provisions are applicable to the source category regulated by the corresponding subpart.  The format and location of this table often varies between subparts, but the significance cannot be understated.  For certain continuous monitoring systems (CMS), one applicable reference in this table can drastically affect the out-of-control (OOC) criteria of that CMS.

Specifically, we are referring to §63.8(c)(7)(i)(A), which specifies that a CMS is out of control following calibration drift (CD) checks if the CD exceeds two times (2X) the applicable performance specification (i.e. the pass/fail point for CD tests), as stated in the applicable 40 CFR Part 60, Appendix B, Performance Specification.  This standard is more stringent than the four times (4X) the applicable performance specification criteria detailed in 40 CFR Part 60, Appendix F, Procedure 1 (Procedure 1).  Essentially, the General Provisions of Part 63 have half the leniency for CD check results as Procedure 1.

We bring this up as a point of emphasis because ALL4 has recently worked for clients whom operate multiple 40 CFR Part 63 CMS under subparts with varying applicability of this section of the General Provisions.  This causes the CMS compliance picture at a facility in this scenario to be a bit greyer than we might like.  While there are many 40 CFR Part 63 CMS operated in accordance with Procedure 1 (and subject to the 4X OOC criteria), other CMS must consider the 2X OOC criteria of §63.8(c)(7)(i)(A) based on the General Provisions applicability table within each respective subpart.

Understanding which CD check standard applicable to a CMS is critical in maximizing the amount of valid CMS data captured and reported by your data acquisition and handling system (DAHS), and for maintaining compliance with your monitoring requirements.  Furthermore, it is important to make sure that your DAHS vendor is aware of the 2X performance specification standard for sources subject to the General Provision of 40 CFR Part 63.  Your DAHS records and evaluates CD checks to determine whether the drift is within the applicable tolerances.  The results of CD check impact the validity of your CMS data and set the status of your data (i.e. valid or OOC) from the time that it is completed until the performance of another CD check.  Having said that, we can see how evaluating the CD check results against the incorrect standard could result in erroneous reporting of data.

So, what 40 CFR Part 63 Subparts (and CMS required by the Subpart) are applicable to both 40 CFR §63.8(c)(7)(i)(A) and Procedure 1?  Quite a few, actually, but we’ll detail those specific subparts in a follow-up blog-post to this in the coming weeks.

In the meantime, if you have questions about your CMS or the OOC criteria used to evaluate CD checks, please reach out to Matt Carideo (610.933.5246 x139 or mcarideo@all4inc.com) or ALL4 staff (all4staff@all4inc.com).  Additionally, to ensure that you do not miss out on future articles, signup below for our 4 The Record for timely updates of current hot issues, plus an in-depth article each month that highlights a regulatory topic.


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