Using The Mpd As A Belay Device; Belaying A Lowering System - CMC Rescue MPD User Manual

12
AS A BELAY DEVICE
The MPD is designed to be used as a belay device to arrest a falling load
should the Main Line system fail. It is recommended that during edge
transitions, while either lowering or raising loads, that the Belay Line tension
be kept hand tight and without slack in the line. Stumbles by the rescuer or
litter tender(s) are most likely to occur during edge transitions, which may
result in the ropes being run across edges that can potentially damage or
cut them. It is less likely to damage both ropes if the Belay Line remains
untensioned during these transitions. Additionally, greater descent control
can be achieved if only one rope manages the rate of descent during edge
transitions.
If the Main Line system completely fails during an edge transition (e.g.
anchor failure or improper system connection), and if both ropes are
suspended above the terrain, as when using a high directional, then a
dynamic fall onto the Belay Line is likely. Among rescuers, this is widely
recognized as potentially the worst case dynamic event in rescue work.
While every effort should be made to rig and operate systems to minimize
the potential for such dynamic events, the MPD is designed and has been
tested using 11 mm and 13 mm KMIII Rope (UL Certified) to arrest a 60
cm fall onto 3 m of static rope with a 1.3 kN (300 lbf) load for the Technical
Use specification (T rating), and a 1.9 kN (440 lbf) load for the General Use
specification (G rating), and limit the peak force below 15 kN (3,372 lbf)
with no more than 1 m (3.3 ft) stopping distance. Meets NFPA 1983 Belay
Device performance criteria. Such a dynamic event is severe and warrants
that all involved equipment be properly inspected by a qualified individual.

BELAYING A LOWERING SYSTEM

When belaying a lowering system, once the rescuer has good control of the
load and is in the correct descent path (this often occurs within the first