ENSA Recommendations: APE SYSTEMS and TRAINING
At ENSA we make recommendations that any person who works at height using a fall arrest system should have the maximum body weight of 256 lbs. This allows for the addition of PFPE, communication system (radio), hydration allowance (water bottle) and personal affects (LOTO, 10lb of tools/tethering).
Under safety culture we are always striving to learn more about the implications and limitations confronted by heavier workers who must work at height, and as a safety community we must take the necessary measures to ensure the safety of those who work at height. We may yet see a time when new equipment standards are written and methods of training developed to ensure a safer work at height environment for the heavy worker.
We are well within the capacity and capability limits of the APE D2 Descender, rope and connectors that have been manufactured and assembled with in our [ENSA] rescue and evacuation systems when used to provide a descent option for 2 persons.
The Descender is meets a certificate of conformity for both a British Standard and U.S. NFPA 1983-12 Standard for Life Safety Rope and Auxillary Components. The system has achieved, through third party testing, a certification to the life safety standard for escape.
The Escape Standard Test requirements ensure the use of 136Kilogram (300lb) test torso and the battery of tests performed prove to Underwriters Laboratories that the APE D2 Descender was indeed capable of performing to this standard.
What the systems certifications do not tell you is that a design factor (safety factor) of 10:1 at 310lb loads is inherent in the system ENSA has assembled.
American National Standards Institute ANSI Z359.4-13 has a capacity range requirement of 130lbs. to 620lbs. which maintains a minimum safety factor of 5:1 for a two person load at 3100lbs for rescue anchoring requirements.
I´m sure you received information similar to this in your ENSA training I just want to put it into perspective when it relates directly to persons of heavier weight.
A worker who weighs more than 310lbs but less than 410lbs is certainly under the 620lb max for two persons which the system is capable of functioning at so long as a secondary friction point is installed before the standing end of the rope passing through the device. You should have received training in this for two person pick off rescues.
ENSA would maintain that a single user with in the weight range mentioned in the last paragraph who has successfully completed training with the system would only be limited in two areas.
1. Descent rescue would be for self only not two person
2. An additional point of friction be added to maintain control throughout the descent
Has any of this made any sense or did I dive too deep in the weeds on this?
In a nutshell the system is effective for the heavier worker with proper training and part of that is learning the theory of how a heavier person can protect themselves while working at height in the event of a fall and the limitations they have.
I would suggest that if they have passed the skill evolutions successfully that a brief session on limitations for heavier workers might be a good idea. The APE systems would certainly provide a safe system for use by a heavier worker though.