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Interpretation Response #16-0047 ([National Aeronautics and Space Administration] [Mr. Russell Clautice])

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

Interpretation Response Details

Response Publish Date:

Company Name: National Aeronautics and Space Administration

Individual Name: Mr. Russell Clautice

Location State: FL Country: US

View the Interpretation Document

Response text:

July 14, 2016

Mr. Russell Clautice
ESH&Q, Institutional Services Contract
URS Federal Technical Services, Inc.
National Aeronautics and Space Administration
Kennedy Space Center
P.O. Box 21025, M/C: ISC-8000
Florida 32815-0025

Reference No. 16-0047
Dear Mr. Clautice:
This responds to your February 23, 2016 email requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR parts 171-180).  Specifically you ask if a weight scale used in lieu of a burette to measure water displacement in hydrostatic testing of compressed gas cylinders is required to be calibrated.
In accordance with 49 CFR 180.205(g)(3), each day before restesting, a cylinder retester is required to use a calibrated cylinder or other method authorized in writing by the Associate Administrator to verify the accuracy of a hydrostatic retest system, including both the pressure-indicating device and the expansion-indicating device (EID).  The pressure-indicating device, as part of the retest apparatus, must be accurate within ±1.0% of each individual test pressure to be tested that day. The expansion-indicating device, as part of the retest apparatus, gives a stable reading of expansion and is accurate to ±1.0% of the total expansion of any cylinder to be tested that day or 0.1 cc, whichever is larger.1  However, if the pressure indicating device or EID, as applicable, is not in compliance with an accuracy of ±0.5%, or better, of its full range, retesting is not permitted on that day.  
Section 180.205(g)(4) specifies that the calibrated cylinder must show no permanent expansion.  This is a separate requirement and is not related to the test equipment ±1.0% accuracy requirement.  This means that the water level in the burette or the weigh bowl must return to the same point where it began - not slightly higher or lower. After depressurization of the calibrated cylinder, all of the displaced water must return to the water jacket. Any volume of water measured in the EID above zero (or the original reading) indicates permanent expansion of the calibrated cylinder.  If this occurs, the equipment has not been proven to be accurate in accordance with the HMR.

With regard to your reference to CGA C-1, currently the HMR do not incorporate the publication by reference.  We may consider incorporating by reference this publication or certain provisions of the CGA C-1 publication in a future rulemaking.  
I hope this satisfies your inquiry.  Please feel free to contact us if we can be of further assistance.


Duane A. Pfund
International Standards Coordinator
Standards and Rulemaking Division

180.205(g)(3), 180.205(g)(4)

Regulation Sections

Section Subject
180.205 General requirements for requalification of specification cylinders
180.205 General requirements for requalification of specification cylinders