Belay Device Tests (Beverly and Attaway, 2005)

(or, Why Friction is Our Friend)

How do belay devices work? What forces are generated by falls? What are UIAA requirements for belay devices?

These are some of the questions the paper (link below) addresses, and it raises the issue that some manufacturers do not recommend using their gear in falls with a fall factor greater than 1. And, there is no strength standard for belay devices, mostly because CE standards are for passive activites, rather than actions like a human stopping a fall with a belay device. The paper argues for a strength standard for belay devices and covers the minutiae of testing variables, like age of the rope, the use of an 80-kg weight to represent a more pliable and stringy human, auto-locks vs. hand braking, etc. This part will appeal to Climbing Nerd Level 3 (whatever that is-- maybe I should define it?).

But, what might be of interest to recreational climbers is the static pull testing Beverly and Attaway performed on many belay devices on the market today. Check out Figure 11 on page 17-- a reminder that ascenders are designed for ascending. Think before using these devices on fixed lines-- could you generate a 5-kN force? Quite possibly. And, Figure 13 confirms that dynamic events are a whole other story. Avoid fall factor 2 dynamic events (duh!). Climbing Nerd Level 2.

Link to belaydevice_Hang_Em_High_Final.pdf:

http://www.sendmefile.com/00547691