What You Should Know About Swimming Pool Drains and Entrapment

by Pool Builders on 06-02-2009 in Articles

Swimming pool drains have received a lot of attention lately; with warmer weather and the opening of public pools approaching. The talk concerns the new federal standards enacted with the passing of "The Virginia Graeme Baker Pool and Spa Safety Act" , which became effective on December 19, 2008. The major changes resulting from the act are the requirement of barriers to prevent access to small children and that the swimming pool drains on all public pools be equipped with anti-entrapment devices or systems. Though the law applies only to public pools; it is highly recommended that the same protective measures be taken with residential pools and spas. For those who may be unfamiliar with the dangers of entrapment and the preventative methods; we've provided answers to some commonly asked questions.
 
What Is Entrapment?
Answer: Entrapment involves someone being held against a pool or spa drain by vacuum pressure from the pool pump. Pool water is circulated by being pulled through the main drain, pushed through the filter, and back to the pool through return lines. Many older pools and spas were built or made with only one drain. When these single drains are cover by parts of the body or if a persons hair or limbs are somehow inserted into the drain; a powerful suction, or vortex is created. The suction can be strong enough to prevent a child, or an adult, from freeing themselves. There have also been instances where sitting on the drain and having their intestines sucked out by the pressure have disemboweled children.
 
What measures can be taken to prevent entrapment?
Answer: The first step of prevention is to have the main drains split with dual anti-vortex drain covers and at least 36 inches from center of sump to center of sump.
The law now makes it a crime to sell or install pools or spas that are not equipped with dual main drains and anti-entrapment drain covers. In addition, all public pools, regardless of age, must meet those same requirements or have other anti-entrapment systems or devices installed.
 
What Are the Options for Pools With Only One Drain?
Answer: There are several compliance options for older pools with single drains.

  • Cut out the bottom of the pool and re-plumb the line to install split drains with at 36 inches from center of sump to center of sump
  • Install a gravity drain system
  • Install a suction limiting vent system
  • Install an automatic pump shutoff
  • Disable the main drain
What is the best option for my pool?
Answer: Re-plumbing the main drains or installing a gravity drain are viable options, but the high cost of either of these repairs make them much less practical for residential pools than the other systems. Disabling the drain, while not as costly, would greatly reduce the rate of circulation, unless changes are made to the pump and filter system. This leaves us with two feasible and reasonably priced options.
  • Suction Limiting Vent System (SVRS)-This system involves the installation of an atmospheric vent on the suction side of the pump, which opens and introduces air into the suction lines when there is a sudden increase in vacuum pressure. There are several manufacturers of these systems including Vac-Alert and Hayward, with prices ranging from $500 to $800.
  • Automatic Pump Shutoff-This is an electrical device that monitors the system and automatically shuts off power to the pump when there is a sudden increase in vacuum pressure. There are several manufacturers of this equipment and prices are about the same as the SVRS systems. There are also some devices available that combine both types of systems.

Hopefully we've helped shed some light on this vitally important issue. As I mentioned earlier, the new law currently applies only to public pools. However, the very real danger of entrapment makes this an issue you can't afford to ignore. As a precaution; I recommend the use of more than one type of device or system and the devices should be tested periodically to insure proper operation.

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