Drain Covers
Pool and spa owners and operators can either have older covers tested against the standard to determine if they comply, or replace these covers with new compliant drain covers. If covers are field fabricated, then a Registered Design Professional or a licensed professional engineer (PE) must specify the covers meet the ASME/ANSI A112.19.8-2007 standard.
As of Jan. 30, 2009, Underwriters Laboratory, the National Sanitation Foundation and the International Association of Plumbing and Mechanical Officials (IAPMO) are conducting third-party testing and certification of drain covers.
While there is no requirement in the Act that there be a specific marking on drain covers, the CPSC has asked manufacturers to mark them “VGB 2008.” Since Nov. 12, 2008, drain covers should have the “VGB 2008” marking.
Some drain covers manufactured during the summer of 2008 used the ASME symbol and/or the “ASME/ANSI A112.19.8-2007” mark. And in the fall of 2008, no marking was placed on drain covers made to comply with the standard.
The drain cover manufacturer should provide a certification document with each drain cover stating that it complies with the requirements of the VGB Act. If there is no mark or you are otherwise in doubt, contact the manufacturer and ask for a copy of the certificate. The CPSC encourages you to keep a record of where and when you purchased the cover and its installation.
The ASME standard requires covers to display:
- Use—single or multiple
- Flow rate GPM
- Life or the number of years
- Wall and/or floor mount
- Manufacturer’s name
- Model number
- Flow Rates and Single Drains
Drain cover ratings are based on allowable flow in gallons per minute (GPM). Covers are tested in the laboratory to determine maximum flow rate, which can result in velocities through the open area of the cover that are greater than 1.5 feet per second (fps).
Drain cover manufacturers determine approved flow rates, but some state standards require that the water velocity through grates not exceed 1.5 feet per second (fps) with one drain 100 percent blocked.
Given the pool volume and turnover rate required by the state/local authority, the minimum required GPM should be known and the cover GPM determined based on the number of covers present.
Generally, to calculate flow for multiple drains, you subtract one drain (presuming it is blocked) so the total flow through the remaining drains should meet the system requirements.* Flow rate calculations for single drain would be:
- One drain = total system flow (plus a secondary anti-entrapment system if the single main drain is not unblockable)
Note: The flow-rate calculations are independent of ‘unblockable.’
*This is a CPSC staff position that coincides with the ANSI/APSP-7 Entrapment
Avoidance standard. The Act does not reference APSP-7 and owners/operators/service companies should comply with the ASME/ANSI standard first and foremost.
