Part II: The Swimming Pool Case

David W. Spitzer

Last month I described a legal case involving a woman who allegedly damaged her lungs after allegedly inhaling chlorine gas at a hotel swimming pool. The cause appeared to involve a flow switch that did not reliably detect no-flow conditions.

The opposing lawyers’ expert witnesses cited swimming pool design standards and guidelines that were beyond our expertise. At our behest, our lawyer hired a pre-eminent swimming pool expert who had designed over 600 swimming pools including recreational, athletic, therapeutic, hotel, military pools, and historic renovations.

Evaluation of the swimming pool and control system design process revealed that swimming pool designers generally had little or no instrumentation and control experience. This appeared to be a result of considering swimming pool control equipment to be a complete package that is used in “cookbook” fashion — the pool designers would simply connect the field sensors, valves and interlocks per the control equipment wiring drawing. This is not necessarily bad, but it can lead to problems when a component in the control system (such as the control equipment or sensor) is deficient in some manner.

A report of findings described the chemical reactions that caused the generation of free chlorine; it also showed how the existing flow switch installation was not suitable to detect no-flow conditions and protect against the occurrence of these chemical reactions. The probability of a chlorine release occurring was also calculated and showed that it was only a matter of time before a chlorine release occurred.

A number of conditions existed that generated suggestions to improve the reliability of the installation with regard to various hydraulic, mechanical, instrumentation, and control aspects of the system. For example, locating the slipstream connections for the flow switch in the suction and discharge piping of the recirculation pump did not ensure that chemicals would always be fed into a flowing water stream — especially when pump prime may be lost. The installation manual should have provided better instructions and warnings stating that incorrect location of the slipstream connections could result in a hazardous condition. In addition, the extremely low-flow switch setting compromised the ability of the flow switch to detect prime and increased the likelihood of a problem. Of interest is that newer versions of the control system had already incorporated some of the suggested changes.

As in most legal cases, there was an out-of-court settlement that had no clear winners.

David W. Spitzer is a regular contributor to Flow Control magazine and a principal in Spitzer and Boyes, LLC offering engineering, seminars, strategic, marketing consulting, distribution consulting and expert witness services for manufacturing and automation companies. He has more than 35 years of experience and has written over 10 books and 250 articles about flow measurement, instrumentation and process control.

David can be reached at 845 623-1830 or www.spitzerandboyes.com. Click on the “Products” tab to find his “Consumer Guides” to various flow and level measurement technologies.

David W. Spitzer and Flow Control will be presenting a three-day Industrial Flow Measurement Seminar, June 12-14, in New Orleans. To learn more, visit FlowControlNetwork.com/FlowSeminar.