From 1999 to 2010, there were 97 entrapment incidents reported in the United States — 12 of them fatal. Currently, suction outlet covers are the only piece of equipment with the ability to prevent all five types of entrapment. Because of this, the drain-cover standard, ANSI/APSP-16,  outlines separate tests to address the tragedy in all its forms. Here is a short definition of each type of test, as well as an explanation of the entrapment it is designed to stop.


Test procedure: Technicians install the cover on a flat surface and verify that the pump can create a vacuum of 26 inches of mercury at the manufacturer-stated flow rate. A body-blocking element is pressed onto the drain while technicians measure the force required. For the product to pass, the amount of removal force must fall under the maximum, dictated by the cover’s size.

Entrapment description: A person’s back, abdomen or other large surface area completely covers the drain, creating a suction force that traps the individual.

Drain cover’s role: Besides physically separating the person from the sump and drain pipe, the cover’s dimensional geometry and hole configurations are designed to help prevent a seal from forming.


Test procedure: Two key tests are performed, one using a ponytail and the other a full wig. Technicians determine which area of the drain allows the most flow, wave the hair above that zone, and then rest it on the cover for a set period of time. If more than 5 lbs. of force is required to remove the hair, the unit will not pass the standard at that flow rate, and additional tests are conducted.

Entrapment description: Hair migrates into the drain, tangling on hardware or in the cover’s openings.

Drain cover’s role: Smaller holes and certified flow rates keep strands from entering the drain and tangling. Some manufacturers include other, patented design features to help with this role.


Test procedure: In addition to the protocol listed under evisceration, a test is performed to make sure fingers and other objects cannot penetrate the openings. A probe designed to simulate a human digit is placed in an opening. This “finger” is the length of an adult basketball player’s but the width of a toddler’s. If it penetrates past a certain point, the cover fails.

Entrapment description: An arm or limb enters the drain pipe, swells and becomes trapped. Knuckles or jewelry can also become stuck in a fitting.

Drain cover’s role: To shield limbs from entering into the drain pipe.


Test procedure: Several protocol help ensure that the cover will remain in place and intact until its expiration date. Strength and ultraviolet tests ascertain that the unit won’t deteriorate past an acceptable level. A pull load test, required on drain covers with holes larger than 0.375 inches, ensures that a person can’t reach his or her fingers into the openings and lift off the unit.

Entrapment description: Evisceration occurs when the drain is completely blocked by one’s backside. If the anus is positioned directly above the suction outlet, the resulting vacuum force can pull intestines from the body.

Drain cover’s role: To shield the anus from the pipe opening and prevent a large differential force, making it more difficult to access intestines.


Test procedure: The combination of proper flow and tests listed in the hair and limb entrapment sections help reduce this hazard.

Entrapment description: An object attached to the swimmer, such as a bathing suit string or jewelry chain, enters the drain and catches or wraps around an internal component.

Drain cover’s role: To limit flow and keep openings small enough that such objects cannot enter, or by prohibiting pinch points and edges inside larger openings.