Northwest Fisheries Science Center

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Document Type: Contract Report
Center: NWFSC
Document ID: 6565
Title: The feasibility of using siphons for degassing water
Author/Editor: Earl M. Dawley, Clifford W. Long, Bruce H. Monk
Publication Year: 1978
Publisher: National Marine Fisheries Service
Contracting Agency: U.S. Army Corps of Engineers. Portland, Oregon
Contract Number: DACW57-76-F-1037
Pages: 19
Date: 1978

The intent of this feasibility study was to generate data of sufficient reliability to enable researchers to draw general conclusions regarding the efficacy of siphons for degassing water and to identify the most important variables for the process.  We believe the data generated by this brief study have achieved these goals but caution against using the data for designing siphons to achieve a specific level of degassing efficiency.  For this purpose, we strongly recommend a more elaborate and carefully conducted series of tests.  To provide a means of predicting the degassing efficiency of siphons of a given design, a general formula should be derived.  Such a formula might take into account the following factors:

  1. Total gas content of the water above 100% saturation at standard pressure, i.e., the input level.
  2. Total gas content of the water above 100% saturation for the pressure at the apex of the siphon, i.e., vacuum head.
  3. The Reynolds number (King 1954) of the conduit at the apex, or a suitable substitute associated with a special device used to increase turbulence.
  4. Travel time of the water through the apex.

The empirical determination of the accurate degassing efficiency of various devices for increasing turbulence was beyond the scope of this study. Until such studies are completed, a general formula for use in designing prototype siphons cannot be derived.