Pool Safety with Layers of Protection and Balanced Hydraulics
As pool owners or managers, everyone must be aware of the hazards that swimming pools and spas can pose to the adults and children who use them. The most devastating dangers are those that lead to evisceration and/or drowning. We counter this ever present threat with a number of safety precautions such as teaching our children how to swim. We then place fencing to prevent unsupervised access. On the gates of this fencing we place locks and latches which assist in creating some additional restriction on access to pools and spas. With all of these precautions in place, our children are safer than ever. However, there is yet another hazard that even direct supervision cannot prevent. This danger can cause serious injury or even death to the most able and experienced swimmers or bathers. Many have never heard of it and even less understand it. This danger is called Suction Outlet Entrapment (SOE).
SOE is dangerous not only to children, but to adults as well. The force created by a pump(s) and the water depth at a blocked suction outlet can be enough to hold a strong man to the bottom of a pool or Spa without a chance to swim free, unless assisted by bystanders or a certified safety device. Do not make the mistake of assuming that this only happens in the deep end of swimming pools. Most entrapments occur in spas or hot tubs under only four feet of water.
Just as pool and spa owners or maintainers have employed "layers of protection" to keep young ones away from our pools and spas while unsupervised, there are additional layers of protection that you can employ to preclude Suction Outlet Entrapment.
- Education: Education is our most powerful tool. Advise all swimmers to avoid contact with suction outlets.
- Protect the Suction Outlets: Install ANSI/ASME A112.19.8-b 2009 Certified Suction Outlet covers on all suction outlets. Be aware of Consumer Product Safety Commission (CPSC) recall of Drain Covers; April 5, 2011. Not all covers are created equal; insist on covers manufactured with PVC or other chemically resistant materials. Low profile/high velocity covers can be hazardous in a single/multiple drain scenario. Domed covers and low flow velocity can mitigate hazards.
- Use properly designed Safety Covers: The suction outlet covers which are domed and or provide a larger footprint can prevent most types of entrapment because they make it difficult for a bather to create a complete seal over the suction outlet. If the cover has a large open surface area of 20 square inches or greater, it can also prevent hair entrapment/entanglement because there is not enough turbulence at 1.5 feet per second to cause hair to tangle around the cover. Secure attachment; utilize a cover that requires at minimum of four (4) install screws.
- Balanced Hydraulics: A slow flow rate through the suction outlet cover(s) is a great preventative measure. Not only does this save on power consumption, it assists your Certified Anti-Entrapment Suction Outlet Cover to mitigate entrapment or entanglement. Larger horse power pump(s) strain to pull as much water as it can through a suction outlet cover with a small open area and can create cover velocities that are dangerous even in multiple main drain situations. We suggest a suction outlet cover with a flow rating that results in a cover velocity of 1.5 feet per second or less.
- Break the Vacuum: Install a Certified Gravity Feed, Vent to Atmosphere, Safety Vacuum Limiting System (SVLS at time of construction), or retrofit an (SVRS) A112.19.17 VGB Compliant Safety Vacuum Release System. This is the direct back-up to the certified suction outlet cover. These vacuum breaking devices are designed to cease the pump function should there be a disruption in flow caused by an SOE event. Some vacuum breaking models are designed to turn off the pump. Other models relieve the suction by allowing air into the pool or spas circulation system thereby releasing the victim instantly.
Keep in mind that not all pools are constructed the same. Newer pools may have certified vented to atmosphere suction lines, gravity fed collection tanks, or even hydraulically sound/balanced dual/multiple drains. If there is only one layer of protection present, consider adding another. It is important to know what is in place to protect your friends, your family, and your clients. Please contact your local licensed pool contractor for more information.
Authors: Brandon Schroader, Technical Director
Ron Schroader, Aquatic Safety Director NSi/Tork
- Attn: CPSC Recall Certain Drain Covers (http://www.drainsafe.com/pdffiles/officialcpscrecall.pdf)
- Consumer Product Safety Commission (http://www.cpsc.gov)
- Consumer Product Safety Alert, Swimming Pool Safety Alert (http://www.cpsc.gov/cpscpub/pubs/5101.pdf)
- Drainsafe - Suction Hazards (http://www.drainsafe.com/suctionhazards.html)
- Drainsafe - Layers of Protection (http://www.drainsafe.com/drlayersofprotection.html)
- Drainsafe - Emergency Suction Entrapment Release Procedure (http://www.drainsafe.com/eserp.html)
- Drainsafe - Calculating the Hydraulics of a Suction Outlet Cover (http://www.drainsafe.com/calculation.html)
- The Aquapedia.com - Suction Entrapment (http://www.theaquapedia.com/index.php?title=Suction_entrapment)
- A Force to Reckon with (http://www.poolspanews.com/2009/061/061force.html)
- What is suction entrapment (http://www.poolspanews.com/2006/032/032baker2.html)