ANSI Requirements for Self-Rescue Descent Devices

The requirements for a self-rescue descent device are outlined in ANSI Z359.4-2007, section 3.2.7. This section covers all of the information about how to make sure that your descent device is compliant with ANSI requirements. Section 3.2.7 covers five different topics about fall protection that include: descent energy and capacity, descent speed, static strength, dynamic strength, and function.

According to ANSI, a descent device can only be used by one person at a time and should be rated for a maximum capacity of 310 pounds. Some descent devices can be rated for multiple uses, whereas other systems can only be rated for one time use. Single-use descent devices must have an energy rating of 30,000 ft-lbs. Multiple use descent devices must have a descent energy rating of no less than 300,000 ft-lbs.

In order to calculate the descent energy rating, ANSI uses the formula: E=WxHxN
In that formula, E=Descent energy rating (ft-lbs); W=test weight (310 pounds); H=descent height (feet); and N=number of descents. If a system qualifies as a multiple-use system, it can withstand testing up to 300,000 ft-lbs. Otherwise, a system that meets the qualifications for single use will withstand 30,000 ft-lbs. Regardless of how the system is rigged, the system must meet the specifications of either classification after descent energy testing has occurred.

Descent speed is based upon the type of descent device. There are automatic devices and there are hand-operated device. An automatic descent device can only move at a maximum speed of 6.6 feet/second (2m/s) and a minimum speed of 1.6 feet/s (.5m/s). If the device is hand-operated, the maximum speed that the device can allow a person to descend is 6.6 feet/second (2m/s).

The static strength of the descent device and the descent line must be able to hold 2,700 pounds (12kN) for at least one minute without releasing.

The dynamic strength of the descent device must support a test weight (220 pounds) dropped from a height of 24″ onto the device’s lanyard (essentially a drop test). If set in “automatic” mode, the device must not lower the weight any faster than 6.6 feet/second.

And finally, the function of the descent device must meet the requirements set forth in the ANSI standards. The descent device capacity, speed, and strength must all meet the requirements as outline by ANSI. And, these conditions must be met during both dry and wet testing to ensure that the environment does not impact the functionality of the system.

Stay Safe!

Hannah Addison