EQUIPMENT AND SUPPLIES: Water-Quality Field Instrumentation October 14, 1975 QUALITY OF WATER BRANCH TECHNICAL MORANDUM NO. 76.03 Subject: EQUIPMENT AND SUPPLIES: Water-Quality Field Instrumentation The Water Quality Advisory Committee at its last meeting recommended that the Quality of Water Branch periodically advise the operational program of field instruments that are considered to be the best, based upon field experience within the Water Resources Division. Criteria on which the evaluations should be based include ease of maintenance, calibration, and operation; reliability; accuracy; and precision. In consideration of the criteria, the following instruments are highly recommended for use by WRD personnel: Dissolved oxygen--Yellow Springs Instrument (models 54 and 57). pH--Leeds and Northrup (model 7417), Beckman model 100900), Fisher (model 150), Orion (model 301), Sargent-Welch (model PBL). pH electrode--Sargent-Welch combination. Specific conductance--Lab-line (model Mark IV) and Beckman (model RB3). The above list does not imply official endorsement of any particular instrument by the Geological Survey, nor does it imply that the listed instruments are the only ones that should be used in the Division's field activities. We realize that there are other instruments which can be used effectively in the field; however, the above came out on top by concensus of the Branch staff and the Regional Water-Quality Specialists. Because the Branch will be revising these recommendations periodically, you are encouraged to relay your experiences and observations of field instruments to the Chief, Quality of Water Branch, through your Regional Water-Quality Specialist. R. J. Pickering WRD Distribution: A, B, FO, PO