at the same time, and ….
at the same time, and if one drain is blocked, suction is then shifted to the other drain. Some of the dual main drain systems will have one drain on the side pool wall and the other far enough on the pool floor.
Secondary Safety Devices Safety Vacuum Release System(SVRS)
These devices connect to the pool pump wiring and are installed in the suction plumbing side of the pump. Sensors in the plumbing prior to the pump detect if there is a spike in vacuum pressure; if so, the system shuts off power to the pump or it makes the pump suck air to cavitate it.
Vac-Alert ® is one of the safety vacuum release systems often used on pools. It is manufactured by Vac-Alert Industries, LLC since 1997. There are over 100,000 Vac-Alert SVRS devices installed and operating in the world today. Vac-Alert has been highly active with the Pool Safety Council since the Council’s inception in 2005, and is dedicated to overall pool safety and the prevention of child drowning nationwide. Paul Pennington, Managing Partner of Vac-Alert Industries, stated, “what a great way to end my working career by doing something good like saving children’s lives.” Since 2007, when the VGBA went into effect, Paul Pennington and the Vac-Alert team worked diligently to promote this life saving federal legislation. It was designed to prevent the tragic and hidden hazard of drain entrapments and eviscerations in pools and spas. The VGBA requires all public pools to install layers of protection that will guard swimmers against suction entrapment. This law was a victory for pool safety advocates, parents and communities everywhere. The company has truly taken part in manufacturing a device that has been proven to work and help prevent entrapment on main drains. “The vast majority of entrapments were from private pools and especially private spas due to the closeness to the main drain. Also, flat main drain grates were easier to get entrapped on.” Paul also went on to say, “that layers of protection are very important for main drain safety to prevent entrapment and a safety vacuum release system is definitely part of those layers.” As mentioned earlier, layers of protection, if all used, are very effective in reducing or eliminating entrapment risk.
This system is simply a pipe plumbed into the main drain pipe that is vented to a height above the pool water level. If it is engineered properly, the vent pipe can be used as a vacuum breaking system. Once the vacuum pressure reaches a threshold, then the water from the vent pipe will be sucked into the pump followed by a large amount of air which results in breaking the vacuum suction.
Gravity Feed System
In this main drain system design, the main drains are fed into a collection tank downhill located at a point lower than the pool pump, and then the collection tank is plumbed directly to the pool pump. This system design only produces suction on that tank and not on the main drains. Public pools in Florida have been required to be built with a gravity feed system since 1977; gravity feed systems for public spas have been required since 1992.
Experiences from the Florida Pool Inspector
Main drain safety is one of the major items that are checked by your local health inspector. If there is a violation on this single item, it can result in your pool being closed.
Main drain covers shall be present, secured, undamaged and meet VGBA requirements.
I believe pool techs who service public pools are more aware of main drain safety than those pool techs who service private pools. Thus, I did not cite as many main drain safety violations as one might think.
Main drain cover violations that were cited during my career with the Florida DOH included a missing drain cover, an unsecured drain cover and a hole in the drain cover.
Vac-Alert & Vacless SVRS units installed on commercial spas.
Hole in old main drain grate
Some pools techs were unaware that main drain covers expire based on manufacturer expiration dates. Pool techs should note the expiration date engraved on the main drain cover and ensure they are changed out with a new VGBA compliant main drain cover prior to that date. The FLDOH documents and monitors these main drain cover expiration dates and can close the pool if the drain cover is no longer deemed VGBA compliant.
Pool techs are also unaware that a Florida licensed pool contractor is required to install these drain covers. Many are also unaware that when these drain covers are replaced, FLDOH Form DH4157 is required to be submitted by licensed pool contractors to the local health department.
Secondary safety device violations cited included missing or inoperable devices on direct suction pools. This violation results in immediate public pool closure. Pool techs need to be aware that missing or inoperable secondary safety devices on direct suction pools poses a large public safety threat. The installation of these devices shall be done by a licensed pool contractor with submittal of FLDOH form DH4157 to the local health department. The other big unknown to pool techs is the FLDOH code requirements on safety testing of these devices. Written documentation has to be kept on the safety testing and when it was conducted for SVRS per manufacturer.
Vac-Alert and Vac-Less are both manufacturers of the most common SVRS devices.
They used monthly testing of the devices to show they are functioning properly. An SLVS device, per Florida Statute, shall be tested annually. Written documentation of the safety testing must be maintained by a licensed pool contractor.
Residential pools and spas are the locations at greatest risk for entrapment due on the main drain of the pool. Pool techs should be aware of the following: 1) Replace all flat main drain grates or anti-vortex covers with VGBA compliant drain covers; 2) Dive and check expiration dates and condition of covers regularly; 3) Educate children on staying away from the main drain; and 4) If the main drain cover is loose, has a hole in it or is missing, then Do Not Swim!!
Top picture: Damaged SVRS. Bottom picture: SLVS missing screening over opening.