ANSI Standard for Descent Devices

Few devices in your gear bag are as versatile as your descender. Whether you need to descend quickly, slowly over time, or perform a rescue, this device can do it all and keep you safe in the process. This week our Gear ExpertsÂ®Â are going to break down the ANSI Standards for descent devices.

ANSI Z359.4-2013

ANSI Z359.4-2013 outlines the safety requirements for assisted-rescue and self-rescue systems, subsystems and components. I know what youâ€™re thinking: that title doesnâ€™t say anything about descent devices. But, in the scope of the standard, it does mention descent control devices. An important clarification for you to know is that this standard is for rescue, not work positioning. We will cover more about that later.

Section 3.2.7: Descent Devices

The ANSI Z359.4-2013 standard is further broken down by sections. Section 3.2.7 specifically covers descent devices and is broken down into additional subsections for additional clarification.

Section 3.2.7.1

Section 3.2.7.1 covers descent energy and capacity for both single-use and multiple use devices.

Section 3.2.7.2

This section looks at descent speed â€“ setting requirements for the maximum distance that you can lower yourself. For devices like the Petzl Iâ€™D Small Self-Braking Rope Descender or WestFall Pro D4 Descender for 7/16â€ Rope the maximum descent speed is 6.6 feet per second.

Section 3.2.7.3

This section covers static strength. Static strength is defined as a singular force being put on the device. Think of this a constant rate of force â€“ similar to holding and maintaining a load.

Section 3.2.7.4

Section 3.2.7.4 covers dynamic strength. Dynamic strength is defined as a peak force being put on the device. Think of this as a sudden shock of force â€“ similar to the force that is exerted in the event of a fall.

Section 3.2.7.5

This final section covers the general function of the device. This is where features like anti-panic come into play. If excessive force is applied or if you let go of the device completely, the device should halt the descent within 6 inches.

Work Positioning

Earlier we mentioned that the ANSI Z359.4-2013 standard is for rescue and not work positioning. In fact, at the time of this writing, there is no ANSI Standard that covers the use of descent devices for work positioning. This doesnâ€™t make them unsafe or mean they are not suitable for work positioning. It just means that no official standard has been released for specifications and requirements. Devices like the Petzl Iâ€™D or WestFall Pro D4 are great devices for descending down to work in suspension in a range of situations like on a tower, painting, or cleaning windows. Of course, you still need to have proper fall arrest in place like a rope grab on a backup lifelineÂ or an SRL. **The content of this blog is not intended to replace proper, in-depth training. Manufacturerâ€™s instructions must also be followed and reviewed before any fall protection equipment is used. Not sure which descender is right for you or have questions about the ANSI Z359.4-2013 Standard? Click hereÂ to contact one of our Gear ExpertsÂ®. â†’ Click here to see the Petzl Iâ€™D Small Self-Braking Rope Descender â†’ Click here to see the WestFall Pro D4 Descender â†’ Click here to see our full selection of Descenders