The effect of pipe size and sump depth on flow rating
Now that the SOFA model has been defined as the cover, the sump, and the pipe depth (including pipe orientation and size), it is important to realize each SOFA model will have its own flow rating. This is a new requirement of VGBA-2017. All sump dimensions must also be documented as tested by an ISO 17025 test lab.The previous version included a Figure 2, allowing the use of untested sump depths based on one and a half times the nominal pipe diameter as the minimum sump depth. This option has been deleted and replaced. The concept can still be used; however, the cover manufacturer must provide the physical minimum dimensions of each compatible sump and not just the formula to measure the pipe and calculate the sump depth. These minimum sump dimensions must be provided in the product specifications, allowing installers to make an informed purchase.
The applicable product instructions are based on manufacturing date
Product manufactured before May 24, 2021, remains legal to buy, sell, install, and use until the end of the product’s service life. These products are easily recognized, as certified compliant products will be marked with either ASME/ANSI A112.19.8-2007, -2008a, or -2009b; VGB-2008; or ANSI/APSP-16 2011. For products certified to those standards, professionals can follow the applicable instructions. Anything manufactured on or after May 24, 2021, will be marked with VGBA-2017. Those products will also be marked as “blockable” or “unblockable,” to give more information on the product at hand. Instead of having a floor or in-wall flow rate, they will indicate something like, “For flow rates, see instructions,” because most drain covers are intended to go over various pipes, applications, and sumps. Each one of those SOFA configurations is going to have its own minimum sump depth and flow rating.
How to perform an inspection
It is imperative for service professionals to inspect drain covers in pools and hot tubs to ensure they are assembled properly and not compromised in any way. Many retrofittable drain covers have multiple screw hole patterns, and they will always have unused screw holes, which can make inspections a bit tricky. It is also important to confirm whether the covers are within the manufacturer-specified lifespan. This may vary by the cover, but it is often is five years from the installation date.
Plastics become brittle over time, even underwater, as the sun’s damaging ultraviolet (UV) rays pass through the pool and provide the brilliant colour professionals strive to maintain. Brittle plastic cannot be seen until it cracks, then it is too late. Proactively tracking and replacing plastic drain covers is key to long-term suction safety. VGBA-2017 product packaging will include forms specific to the cover model, making this information easier to track.
How pool pumps have changed
By now, most professionals are aware of the regulation changes regarding pool pumps, which took effect on July 19, 2021. What many do not realize, however, is the increased usage of variable speed pumps can absolutely be impacted by VGBA-2017. The practical effect of the dedicated purpose pool pump regulation is it outlaws most single-speed pool pumps with 1 to 5 horsepower (hp), the workhorses found on most residential pools, spas, and water features.
Pool professionals must use caution when they change from single-speed to variable-speed pumps. In most cases, the replacement variable-speed pump will have the ability to move significantly more water than the old pump. While the goal is to run the pump at a lower speed to save energy, the pump itself will still maintain the ability to run at a high speed. When pump performance increases, suction entrapment risk can do the same. This increased risk must be looked at carefully before considering the job complete.
It is crucial to look for any faulty drains connected to the pump. Missing, broken, or damaged drain covers can be dangerous. Excessive flow through drain covers is the leading cause of reported suction entrapments (these reports include VGBA-compliant covers). When picking up a new pump, it is a good idea to select replacement drain covers with a VGBA flow rating that can handle the high-speed flow rating of the pump. This is often referred to as the max flow. Drain cover manufacturers should offer support materials to assist as needed.
