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Interpretation Response #13-0131 ([Mr. Tim McLoughlin] [M & M Metrology, Inc.])

Below is the interpretation response detail and a list of regulations sections applicable to this response.

Interpretation Response Details

Response Publish Date:

Company Name: Mr. Tim McLoughlin

Individual Name: M & M Metrology, Inc.

Location State: FL Country: US

View the Interpretation Document

Response text:

September 24, 2013

Mr. Tim McLoughlin
M & M Metrology, Inc.
272 South Military Trail
Deerfield Beach, FL  33442

Ref. No.: 13-0131

Dear Mr. McLoughlin:

This is in response to your June 19, 2013 email requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to the calibration and certification of gauges used for pressure testing cylinders.  You request clarification of the accuracy of the pressure indicating device as required under HMR § 180.205.  Specifically, you ask if you are correct in calibrating an 1100 psig pressure gauge to ±5.5 psig (±0.5%) of its full range.

You are correct.  In accordance with § 180.205(g)(3)(i) the pressure indicating device itself (the pressure gauge) must be certified as having and accuracy of ±0.5%, or better, of its full range.

Section 180.205(g)(3)(i) also provides that the pressure indicating device as part of the retest apparatus must be accurate to within ±1.0% of the prescribed test pressure of any cylinder being tested.  Since the described gauge is calibrated to ±5.5 psig, the gauge would not be authorized for testing cylinders having a prescribed test pressure below 550 psig.

These requirements are consistent with the Compressed Gas Association Standard
CGA C¬-¬1¬¬-2009 paragraph which provides that the pressure indicating device shall be manufactured and certified to an accuracy grade of ±0.5% or better, and the pressure indicating device shall permit reading of  pressures to within 1% of the test pressure of each cylinder tested.

I trust this information is helpful.  If you have further questions, please do not hesitate to contact this office.


Delmer Billings
Senior Regulatory Advisor
Standards and Rulemaking Division

Regulation Sections

Section Subject
180.205 General requirements for requalification of specification cylinders