How to safely stop and start circulation
It might not seem like a big deal, but stopping and starting a commercial swimming pool treatment system is dangerous for those unaware of the hazards! In this topic, we’ll go through the issues and discuss a real-life case study where the pool operators gassed several unfortunate swimmers due to procedural errors!
Take a look at the diagram (it can be enlarged) and think about what might happen if the circulation pumps are switched off but the chemical dosing continues.
“Our chemical dosing shuts off when we turn the circulation pumps off – do we need to worry about this?”
You need to at least check that the chemical dosing system has stopped dosing when the pumps have been turned off – don’t assume that the auto-shut-off system will always work. They can and do fail.
- 0:00 Start
- 0:09 Loss of prime
- 2:10 Backflow
- 2:50 Chlorine gas hazard
- 3:44 Stopped circulation hazard
- 4:13 Chemical dosing interlock vulnerability
- 7:54 Distance between chemical injection points
- 8:35 The importance of knowing your system
- 9:08 Restarting circulation system after stoppage
- 10:43 Serious incident at David Lloyd Ipswich
“In the video you mention ‘acid’ chemicals! Why is acid dosed into pool water?”
Good question! It’s all to do with something called pH, which we’ll be discussing later in the course. The most commonly used disinfectants used in the UK are highly alkaline and tend to push the pool water pH levels up past where we need them to be for effective disinfection. So, we add acidic substances to counteract this and stop the pH from going too high.
HAZARD WARNING!
There is a risk of the generation and emission of extremely hazardous chemicals when power to the circulation pumps is cut (intentionally or because of power failure). A system should NEVER be restarted following a failure of the circulation system while there are people in the pool. If there is a concern that there may have been inadvertent mixing of chemicals within the pipework of the circulation system, the fire service should be contacted and the circulation and chemical dosing systems left stopped.
Don’t Forget…
After restarting the system, you will need to ensure chemicals levels are within acceptable ranges by carrying out tests for Free Chlorine, Combined Chlorine, pH, Total Dissolved Solids.