Measuring Total Hydrocarbons in U.S. Navy Diving Air
Abstract
Any total contaminant measurement (such as total hydrocarbons [THC] in diving air), whether taken in the laboratory or in the field, can be significantly affected by (1) the specific sensor in the analyzer used to detect the contaminants and (2) the chemical species chosen to calibrate that sensor. Furthermore, when quantifying THC, the type of THC sensor will not only affect the magnitude of the sensor signal representing THC, but also determine what contaminants are detected (and perhaps just as importantly what contaminants are not detected), and thus determine which contaminants are included in the THC measurement. The specific question this document addresses is the following: When measuring THC in U.S. Navy diving air samples using flame ionization detector (FID)-based analyzers, is the current practice of (1) quantifying these THC measurements relative to a methane standard, thus producing a THC value in units of methane equivalents, and (2) comparing this methane-equivalent value to a THC limit in terms of methane, an acceptable way to judge the chemical safety of an air sample? This report is based on a white paper delivered to the Naval Sea Systems Command Supervisor of Salvage and Diving (NAVSEA 00C) in 2013 that assisted in subsequent change in the divers breathing air standards (Table 4-1) in revision 7 of the U.S. Navy Diving Manual. Recent feedback from NAVSEA 00C in 2020 has suggested the need to have the information in white papers presented in a more citable and available form. For this report, much of the content of the original white paper is left unchanged in order to keep the information that was delivered to NAVSEA 00C intact. However, some of the exposure limits reported earlier have been updated, and discussion has been added regarding implementation of NEDUs white paper recommendations into revision 7 of the Diving Manual.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 2020
- Accession Number
- AD1107125
Entities
People
- Richard S. Lillo
Organizations
- United States Navy Experimental Diving Unit