It was May 2011, and the pool season was about to begin. Aquatics facility operators across the country were in high gear, preparing to open seasonal pools in time for summer.

Then, two days before Memorial Day weekend, the Consumer Product Safety Commission announced the largest product recall in the industry’s history — approximately 1 million suction outlet covers sold by 10 manufacturers, all of which had been installed within the past three years to satisfy a national mandate intended to make pools and spas safer.

Now they were deemed hazardous, with the government advising that certain commercial vessels be closed immediately until repairs were made.

“I know this is a very difficult message for many communities to hear so close to Memorial Day weekend,” said CPSC Chairman Inez Tenenbaum in announcing the historic recall. “But we cannot risk a child becoming entrapped in a recalled drain cover. ... We know that drain entrapment is a hidden, horrific and preventable hazard.”

The news threw the industry into chaos: Pool managers and service technicians tried frantically to accommodate the massive recall, while manufacturers and distributors cleared the channels of “tainted” product and hurriedly began producing replacement units.

Across the country, many pool operators had to make split-second decisions on whether to shutter their most popular attractions — kiddie pools and shallow-water features — or keep them open and fly in the face of the CPSC’s directive.

Behind the scenes, plenty of finger pointing took place, with culprits ranging from the testing laboratories where covers were certified, to the standard governing the products’ design, to the CPSC itself, whose officials oversaw the timing of the initial requirements as well as the recall.

One year later, an update to the language that governs drain-cover production is in the works. In the meantime, test labs follow CPSC requirements that supplement the drain-cover standard. But getting beyond the controversy to examine the actual workings of drain covers is still no small feat.

Nevertheless, it’s critically important that industry professionals understand what these products do, the current standard and testing regulations governing them, and where discrepancies exist.

Not-so-simple science

Though basic in appearance, a properly engineered drain cover is the result of considerable research and design expertise.

Despite the nomenclature, pool and spa drains don’t utilize the same principles as their sink and tub counterparts. Rather than permanently ushering water out, via gravity, a pool (or spa) drain functions in a closed, pressurized circulation system in which water is pulled from the vessel by a pump for recirculation. Because of this distinction, many engineers use the more technically accurate term “suction outlet.”

Most suction outlets consist of a sump — a hole in the pool or spa shell containing the open end of the pipe leading to the pump — which is then capped by the drain cover, or “suction outlet fitting.” This last element has assumed a crucial role in mitigating suction entrapment, the sometimes deadly phenomenon that occurs when an outlet is blocked. When this happens, water is no longer fed into the pipe, and a powerful vacuum forms, pinning down whatever is causing the blockage. Other types of entrapment result when hair, limbs or objects connected to an individual enter the outlet and become stuck.

The covers act as the first line of defense against entrapment, creating a physical barrier between human and sump and incorporating design characteristics meant to resist the various forms of entrapment. To date, there have been no entrapments occurring on drain covers that meet current standards.

Preventing such incidents is a complex task. Compliant covers must address the five types of entrapment, each caused by slightly different combinations of proximity, access and suction. To accomplish this goal, manufacturers must attend to several aspects of the product’s design:

AAcceptable flow

It was this issue that led to the CPSC recall. Based on results from several tests, third-party laboratories determine the

maximum rate, in gallons per minute, at which water can move through the outlet cover without creating an entrapment hazard. This poses a balancing act: While lower flow rates mean safer drains, higher rates often are needed to provide power for features such as waterfalls and spa jets.

BHole size / configuration

In concert with appropriate flow rates, properly designed openings help prevent fingers, jewelry and even hair from entering and becoming affixed to internal hardware. Some manufacturers include patented design features such as tiny tubes that will help displace suction or larger slots that taper down to a small hole serving as a diffuser of suction. Hole placement also can help prevent body entrapment: Some manufacturers configure them in staggered patterns that may allow a victim to “peel off” by dislodging the vacuum in a single hole. Others position the openings on different planes so it’s unlikely that they can all be covered simultaneously.

CDome effect

Before entrapment prevention factored into the design of drain covers, most units sat flush against the floor or wall, potentially enabling the larger planes of a human body — back, side or abdomen — to block the entire cover and form a seal. Today, drain covers that are 18-by-23-inches or smaller feature a domed shape or raised design that holds the swimmer away from the pool floor or wall, thus helping to prevent a seal from developing. To reduce tripping or toe-stubbing hazards, these covers sit no more than 2 inches above the pool or spa shell.

DSump depth specifications

To avoid hair entrapment, flow should be dispersed as evenly as possible over the area of the suction outlet cover, rather than concentrated directly above the pipe. To this end, manufacturers specify a minimum distance between the outlet cover and the pipe’s opening below it, often affecting sump depth or doming height. (Some drain covers meant for spas can function without a sump by incorporating internal flow channels.)

EMaterials, hardware

The products must be strong enough to withstand abuse and sun exposure without deforming, cracking or becoming unattached. This is addressed by certain tests for wear, including ultraviolet, mechanical, strength and impact resistance protocols, and minimum criteria for attaching screws.

Regulatory measures

The increasing emphasis placed on suction outlet covers — and the road to this year’s recall — largely began in late 2007 with the passage of the Virginia Graeme Baker Pool and Spa Safety Act.

The federal law’s requirements stated that, within a year, all commercial pools, spas and waterfeatures were to be fitted with certified suction outlet covers. Additionally, only compliant fittings could be entered into commerce after Dec. 19, 2008.

To become certified, a drain cover must undergo third-party testing to determine whether it meets a set of design specifications and performance parameters to ensure entrapment resistance. The certification standard named in the VGB Act — ASME/ANSI A112.19.8-2007 — lies at the heart of the recall. (Last year, it was replaced by ANSI/APSP-16.)

The standard first came under fire in 2010 amid allegations of misconduct in the testing. Broadcast network ABC and the Chicago Tribune publicized the issue, and Sen. Dick Durbin (D-Ill.) called for action, prompting the CPSC to launch an investigation. It was then revealed that some product readings were off by as much as 35 percent, with one extreme case seeing a variance of more than 600 percent.

Inconsistencies were found in all three of the labs approved to conduct the testing required under ASME/ANSI A112.19.8-2007, but lab officials claimed the standard’s language was too vague. Some accused the International Association of Plumbing and Mechanical Officials — the lab with the most variances in results — of purposely conducting tests to meet the letter of the standard while violating its spirit, so that the lab could market higher flow ratings. IAPMO denied these accusations and others maintained that, even if the lab had such intentions, such malfeasance wouldn’t have been possible if the standard were more specific.

The standard writers concurred and began a rewrite to fill in the gaps. That rewrite is currently in its final stages.

The rating discrepancies leading to the recall involved two controversial areas: the body block and hair-entrapment tests.

Body block test

Added in 2007, this test was devised to simulate a body entrapment, thereby gauging a drain cover’s ability to prevent the phenomenon, even when installed in a single-outlet configuration without a backup anti-entrapment device.

The suction outlet cover under review is mounted onto a backing plate meant to replicate the floor or wall of a pool, and a pump is activated to achieve the maximum flow for which the cover is rated. The key to this process is the “body-blocking element,” a form made of plywood and foam meant to represent the area between the shoulders and hips of a large adult male. The technician uses an air cylinder to thrust the body-blocking element onto the drain with 120 pounds of force, approximating the downward pressure of a 240-pound man lying, with minimal buoyancy, on the outlet cover in a wading pool. This sizable pressure compacts the foam on the blocking element, forcing it to conform to the drain cover, even if the unit is domed the full 2 inches.

The technician then reverses the air cylinder to pull the blocking element from the drain, measuring the amount of force required to do so. To meet the standard, the force needed cannot surpass the maximum allowed for drains of its size. For example, when testing an 8-inch drain cover, the body-blocking element must be removed with 15 pounds of pull or less, to correlate with the amount of strength reasonably expected of a small child. This allowance increases with the size of the drain cover, following the logic that the larger the drain, the more sizable — and, presumably, stronger — the person would have to be to block it.

Most of the problems leading to the recall centered on the body-block test. Some labs conducted the procedure using a variable-speed pump set on low, which could generate the necessary flow, but would not achieve the vacuum pressure seen in most real-world applications because this configuration is still relatively rare. The affinity law that causes variable-speed pumps to be so efficient actually worked against the objectives of the body-block test: A pump run at half speed only generates a quarter of the pressure, which means in theory it could only produce one-fourth the vacuum.

The practice of setting the pumps on a low speed allowed drain covers to be awarded higher flow ratings artificially, since not enough negative pressure was created to accurately assess them. Pool and spa pumps can produce up to about 26 inches of mercury, enough for the unit to self-prime when placed as high as 10 feet above water level, as is historically required for pump certification. However, a variable-speed pump set on low speed only generates a few inches of mercury — not enough to provide real-world ratings of suction outlet covers.

Today, the CPSC stipulates that pumps be operated at a speed capable of producing 26 inches of mercury during testing, and this language will be included in the forthcoming version of ANSI/APSP-16.

The second problem with the body-blocking test arose from the artificial human form or “element.” Members of the standard-writing committee stated an intent for an 18-by-23-inch element to be used, no matter the size of the outlet, to represent an adult male in the 99th percentile of size.

However, some testing labs employed a variety of sizes, taking their cues from comments made at a meeting regarding the standard, and from a reference chart pertaining to another aspect of the test. In addition, though the standard states that the body-blocking element should be positioned in a specific manner, some laboratory technicians didn’t follow this instruction to the letter. One tech might hold the form horizontally, another vertically, resulting in different readings.

The upcoming version of ANSI/APSP-16 is expected to stipulate the methodology in more detail to achieve consistent results.

Finally, at least one lab was known to have performed the body-block test by affixing drain covers to a sump at the end of a suspended pipe, a scenario that’s virtually impossible in a real-world setting, since suction outlets are always found within pool walls or floors. Without a flat surface surrounding the opening, it becomes significantly more difficult for the body-blocking element to form a seal. For the past few years, the drain-cover standard has required a simulated pool floor backing plate to be used. The CPSC specified that this happen during the retesting that led to the recall, and the upcoming standard will make that language clearer and more specific.

Hair test

Hair entanglement has been the most challenging type of entrapment to test for, and the protocols have yielded inconsistent results, placing them on the CPSC’s radar.

 The 1987 version of the ASME/ANSI drain-cover standard called for a test in which a ponytail was placed over a drain to see at what flow rate it would get entangled and/or entrapped by suction. In 2007, it became apparent that the ponytail test was insufficient because a swimmer’s hair wouldn’t always be tied back. A second procedure, the full-head-of-hair test, was added.

These two procedures address different aspects of the way hair strands interact with a drain. A full head of hair can become entangled within the holes on the cover. A ponytail, which has fewer strands, can descend into the openings more easily and wrap around screw posts.

The wig is made with natural, fine, European blonde hair, which is the easiest to tangle. The ponytail contains human hair that is medium to fine, straight and light brown. The hair is placed on the drain and moved from side to side, with the ends of the strands fed into the fitting for 60 seconds. The technician then holds the base of the wig or ponytail directly against the fitting for an additional 30 seconds, then releases the hair and allows it to float for approximately 30 seconds more. The hair is finally disengaged, and the tech measures how much force is required to extricate it. If the number is more than 5 pounds, the drain fails. It’s important to note that if even one or two hairs become snarled, it may require a minimum of 10 pounds to remove them.

Developing effective hair-test methods has been difficult because hair is an unpredictable material and generally won’t replicate the same pattern from test to test.

Additionally, the standard, once again, proved vague. Technicians weren’t informed exactly how to position the ponytail or wig: One might hold it in the center, another near a corner, without taking into account where the drain might be pulling water most forcefully. The 2007 standard stipulated use of a pull mechanism, often an air cylinder, which is notorious for causing stiction — a jerky action that changes the speed and force applied during the test. Additionally, the gauges were analog rather than digital, allowing technicians to read them differently.

The updated version of the standard likely will specify where to hold the wig or ponytail. In addition, technicians will be required to suspend the hair over the outlet cover with an apparatus that utilizes frictionless pulleys and a 5-pound weight, in order to eliminate stiction from the equation. Standards writers hope this change also will remove the inaccuracy and vagueness of the gauges that had been used. Technicians must perform the test with water flowing at progressively higher rates until the drain cover fails. The last flow rate to pass then becomes the maximum rate allowed.

Final revisions to the current standard are expected later this year.

These video captures show Steve Barnes, product manager, safety and compliance with Pentair Aquatic Systems and chairman of the APSP Technical Committee, trapping off on a compliant 12-by-12-inch drain cover to study body entrapment. By pushing himself down, Barnes was able to apply 95.8 pounds of downward force onto the grate. He was able to release with 5.6 pounds of force. Tests such as this have confirmed that skin behaves similarly to the body-blocking element, but it is slightly more likely to adhere to the cover and easier to remove. Some hope to find a closer match to human skin.

Editor’s Note: This article originally appeared in Aquatic International’s sister publication, Pool & Spa News, which would like to thank the following experts for their contributions: Steve Barnes, Pentair Aquatic Systems; Dominick Conn, Paramount Pool & Spa Systems; Brooks Hilton, Waterway Plastics; Mike Huppert, Hayward Pool Products; Alison Osinski, Aquatic Consulting Services; David Peterson, Watershape Consulting; Bill Rowley, Rowley International; Ron Schroader, Drainsafe/New Water Solutions; and Leif Zars, Gary Pools.