Water Quality Monitor for Continuous Field use
Authors: Carlberg B.L. , Matthews R.R. 
Published: December 2007

This paper was prepared for the 48th Annual Fall Meeting of the Society of Petroleum Engineers of AIME, to be held in Las Vegas, Nev., Sept. 30-Oct. 3, 1973. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor of the appropriate journal provided agreement to give proper credit is made.
Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussion may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines.

Introduction
The value of a water quality monitor is in its ability to record continuously several parameters over an extended period of time. The parameters over an extended period of time. The characteristics of a water system do not necessarily remain constant but are affected by numerous variables, including changes in bacterial action, chemical treatment, flow rates, etc. Periodic spot analyses are not reliable for detecting the effects of these variables. Composite samples can be analyzed to show the average effect over a period of time but only by continuous analysis and data recording can we ascertain the extremes and the mean for a given system. Continuous monitoring equipment is common in many fixed installations, such as water treating plants where it is needed to keep track of the effectiveness of plant operation. Most field installations, however, do not include monitoring equipment in their design. The costs cannot always be justified, nor is there always a need. Problems which require analysis and monitoring in these systems utilize either spot analyses or a portable monitor, such as the one to be described. This monitor a second generation unit termed the Mark II was designed for use either in short-term troubleshooting applications or, with different packaging, as a permanent installation. In its present permanent installation. In its present configuration, the Mark II weighs approximately 40 pounds and is contained within a suitcase 17 inches by 21 inches. Auxiliary equipment includes a flow cell to accommodate the necessary sensors in a side stream setup.

DESCRIPTION
The monitoring capability of the Mark II includes those parameters for which we have had the most need including corrosion rate, dissolved oxygen temperature, and pH. A turbidity sensor is also used with the monitor on occasion. In this version, modular construction has been used throughout with three circuit boards and one power supply board. Any one of the three circuit boards can be removed without affecting operation of the remaining boards. Construction of the electronic circuitry has been greatly simplified through the use of miniaturized, prepackaged components wherever possible. Only a minor part is made up of discrete possible. Only a minor part is made up of discrete transistors, diodes, etc. The use of these operational amplifiers, etc, minimizes design time, as well as fabrication time, and results in stabilized circuit. Repairs, should they become necessary, can frequently be handled by replacing one of these plug-in units. In view of the solid-state construction, heating of the unit during operation was not anticipated, and heat buildup has not been noticed.