By Lauren Broom Chemical Controller Electrical Interlock Safety Protection Why it’s important
Accidental chlorine gas emissions are a real danger when there is an improper electrical interlock between a dis infect ion chlorine feeder, a muriatic acid pH adjustment feeder, and the main recirculation pump. Accidental exposure to pool patrons and staff can cause symptoms such as: shortness of breath and vomiting. Some people may need treatment at a hospital for upper respiratory problems.
Under normal circumstances, sodium hypochlorite(liquid chlorine) and muriatic acid are injected into the plumbing at separate points by peristaltic pumps. As the water flows through the pipe, the chemicals move with the water and there are no problems. The problems occur when the circulation system stops and the chemical feed continues. This results in water coming to a halt in the pipes and a static environment is created where chlorine and acid are able to contact and mix. A toxic chlorine gas accumulates inside the waterless pipes.
Once the circulation system turns back on and water starts moving through the pipes, this forces the toxic chlorine gas mixture into the pool through the return inlets. The toxic mixture will form a cloud in the pool area where pool patrons and staff can be exposed to hazardous levels of chlorine gas.
This scenario has occurred enough times that it prompted the American Chemistry Council along with other public health and swimming pool industry experts to create a free YouTube video to highlight this safety issue.
What can be used
An electrical interlock between the pool circulation
Lauren Broom
Lauren Broom is a Certified Pool Operator Course, CPO
, instructor and a former health inspector for the Florida Department of Health. Lauren has a Bachelor of Science Degree in Biology and is a registered sanitarian.
She has 16-years of experience in commercial pool inspections and waterborne disease outbreak investigations.
Lauren lives in Palm Bay, Florida with her husband of 17 years and their 3 children.
Lauren can be reached at spacecoastpoolschool@yahoo.com pump and the chemical feed system will ensure that if the pool pump is disabled or loses prime that the chemical feed system is also disabled. This interlock will avoid the production of chlorine gas in the pipes. The electrical interlock can be accomplished with the following methods from the table on page 16:
What techs should know
Pool techs need to remember that any device can fail. For example, flow switches can fail and send a false signal of water flow and thus the pool tech is not getting correct information. Pool techs should conduct an initial test of the interlock system upon installation and then monthly thereafter. The testing results are recommended to be recorded and maintained onsite so that it can be shown to pool owners, or the local public pool regulatory agency. Pool techs should develop their checklist to following on testing their interlock system and then notate that the system is operational.
