10-28-2012, 12:10 AM #1
RPM setups in confined space and LARRO
I am puzzled by something. I have attended both confined space and LARRO training, both being CA state fire marshal certified courses.
Here's the thing;
In my confined space rescue tech (CSRT) class, both the manual and instructor showed us to clip the pulley on the end of the LRH. See image:
Now in my LARRO course, both the manual and instructors had us attach the pulley directly to the anchor plate. See image:
Is there a reason for this difference. It confuses me, whats the deal?
10-28-2012, 04:57 PM #2
I thought I should mention. For the CSRT course, our manual is from CMC.
Text from CMC page.
Recently revised, the CMC Confined Space Entry & Rescue Manual is the textbook for confined space rescue courses taught by the CMC Rescue School. It is the official textbook for the California State Fire Marshal’s statecertified confined space rescue courses.
The LARRO manual is produced by the State Fire Marshal office.
Does anyone see an advantage of using the CMC method over the other I posted?
10-29-2012, 02:20 PM #3
- Join Date
- Oct 2002
- Port Allen, LA
Yep. You are right Michael. It confuses me too.
Why would you put an LRH on a raising system? They are typically used on lowering systems to pass a knot or on a tandem prusik belay system to free up the prusiks when they get jammed up. The first diagram (on the left) looks like a 3:1 Z-Rig. It's a little hard to tell for sure because it doesn't show what the moving pulley is attached to but the progress capture device is on the load side of the line which indicates to me that it is in fact a Z-rig. Whether a 2:1 or a 3:1, the raising system can also be used as a lowering system, hence, no real need for an LRH.
I'm very confused by the second set of pics as well. Why would you put a tandem prusik set up on a lowering system? It absolutely makes efficient operation of the lowering system much more difficult and complicated. Tandem prusiks are used when a significant shock load is expected. That shock load will be on the belay line, not the main line. It takes two hands to operate the rack effectively and at least one hand to keep the prusiks loose enough to allow the main line to slide through them. It also makes the prusiks more prone to failure from (1 - being too loose to grip the moving rope) and (2 - failing by melting from the heat of friction of rope on rope).
If the operator loses control of the rope then a belay line should be in place for protection and back-up. If it used as part of a SRT (single rope technique) then it serves no purpose if the rope between the prusiks and the load gets cut on a sharp edge.
Call me strange or old fashioned or whatever but in 45 years of rope rescue work, I have come to believe that simple is a lot safer than the overly complicated systems pictured above.
I guess they might have a very valid place if the instructor is teaching the class with the intent of selling you as much useless gear as possible. If that is the case then by all means, the more complicated the better because there is a pretty good mark up on some of the rescue gear on the market.
10-29-2012, 03:32 PM #4
- Join Date
- Oct 2002
- Port Allen, LA
Just so there is no misunderstanding, I wasn't slamming CMC or anyone else. James Frank and his group do an outstanding job but I have seen other isolated instructors around the country teach classes with the main purpose being the selling of equipment and the more equipment intensive you can make a class, the better the profit.
10-29-2012, 06:36 PM #5
Michael, What I see are two complicated systems. Both are for low angle and neither, in my humble opinion, need LRH's. There is a point in rope rescue when a sexy system becomes innefficent because of all the bells and whistles.
The CMC (Confined Space) diagram is on page 9-37 of the book, and describes a 3:1 and 2:1 MA. The only purpose I would see in a LRH there is to pass a knot, but the simpler way would be to add a thrid pulley below the knot once it is sucked up to the prusick and tension the system up on the new pully using a jigger (mini 4:1). With the LRH where it is you would have to extend an anchor off the rigging plate, add the pulley and then use the LRH take tension off the first pulley and onto the new one. You loose distance from your anchor and distance in your throw when you do this (might be critical if working near the edge).
To answer your question, the LARRO system is built to release their prusicks if they engage the rope. I will try not comment further on LARRO, their system is safe and methods work fine. Just not how I would go about it.~Drew
USAR TF Rescue Specialist
10-29-2012, 11:33 PM #6
10-30-2012, 11:23 AM #7
- Join Date
- Mar 2010
- eastern WA
In the top figure, maybe the LRH is there to facilitate switching from a raise to a lower? Just in case?
Like this: Lower the load onto the prusik, remove the haul pulleys, put a DCD in above the prusik, use the LRH to lower the load onto the DCD, remove the prusik.
For a single man pick-off with a hanging subject, I think this was an "old" way of transitioning back to a lower after the "petite raise" is used to unload the subject's own line. [This is not my preferred method.]
Anyways, maybe that's their preferred way to be ready for transitioning back to a lower if the need should arise.
As far as the lower figure is concerned, it looks (to me) like one half of a mirrored two-tensioned rope lower i.e. both lines sharing the load, each rigged with a DCD and a whistle test compliant belay device. In this case, the LRH would be needed in the event that the operator allowed to prusiks to lock up.
I'm just saying...
10-30-2012, 01:02 PM #8
- Join Date
- Jan 2000
- Somewhere in the Backcountry...
I'm not sure why the pulley placement varies. In mountain rescue ops when we use a LRH we set it up so that the pulley, DCD, etc. remain fixed in relation to the rescuers operating the system. A confined working area, e.g., a ledge, narrow trail, etc. may limit the working area and we don't want key elements of the system to go "over the edge" and become unreachable.
I agree with the comments re: building excessively complex systems. Adding unnecessary elements to a system doesn't make much sense but is something I've seen when working with less experienced rescuers. I can see getting things set-up for transitioning from a lower to a raise.
I could absolutely be missing something here as well!
10-30-2012, 05:53 PM #9
I asked my training officer. A man of few words; his response was " ah tomato tamato..."
10-30-2012, 05:56 PM #10
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