Swimming Pool Blog
by Rob Cox, May 20, 2011
Is your pool main drain unsafe?
Pool main drains and spa drains have the ability to hold a person down under water. This boy to the left was lucky, pulled off the drain by 3 grown men. Entrapment injuries in pools and spas have become a hot topic in the last few years. With the passage of the Virginia Graeme Baker Pool & Spa Safety Act in 2007, commercial pool operators were forced to upgrade their pool and spa drains.
Single main drains can be hazardous when connected to a large pump. Many drownings, injuries and even bowel evisceration have occured in hundreds of cases in the U.S. in the last 10 years.
Commercial pools in the U.S. are now required to:
1. Install Dual Main Drains in the place of single main drains. Dual pool drains will not trap a swimmer.
2. Install modified drain covers, which can prevent entrapment, due to their raised, ridged design.
3. Install Safety Vacuum Release Systems (SVRS) which shuts off the pump when a vacuum is sensed.
But what about Residential Pools? Is your residential pool main drain safe?
If you have a dual main drain in your swimming pool, which has been required in most areas now for many years, then you can rest easy. Splitting the flow between two main drain pots will simply shift the suction if one drain cover becomes blocked.
If you have a single main drain in the bottom of your pool or spa, -and- you have a separate valve at the pump to control the flow of the main drain - you may have a potentially unsafe situation. If other lines are also open and flowing, suction will shift to the skimmers for example, if the main drain cover is blocked. However, if the skimmers are shut off completely, and the pump is drawing only from a single main drain, the suction force could be enough to trap a person by suctioning to a body part or drawing in long hair.
Pool / Spa combinations commonly have one suction line coming from the spa attached to the pool. When "turning on" the spa, one adjusts the valves to close off pool suction ports, drawing all of the pumped water from the spa drain. If your spa has only one drain grate, the suction of your filter pump could be enough to trap a seated adult under water.
If your main drain is connected into the skimmer line, and controlled under the skimmer basket by means of a diverter, then you can rest easy. Only when the main drain (for pool or spa) has a separate valve controlling the flow - does a potentially lethal condition exist.
If you have a single main drain in your pool or spa, controlled by a separate valve:
1. Consider the renovation of cutting the pool floor, and replacing the single main drain with dual main drains.
2. Install anti-vortex safe pool drain covers. Flat grates are considered unsafe. Modern, safe main drain covers have a raised dome, and a design that prevents entrapment.
3. Remove the valve handle from the main drain valve to prevent accidental isolation of the main drain line.
4. Install an SVRS device to sense entrapment on the suction.
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