Empirical Investigation of the Average Deployment Force of Personal Fall-Arrest Energy Absorbers

The personal energy absorber (PEA) is a critical component of a personal fall arrest system (PFAS), and it is meant to dissipate the energy generated during a fall to prevent injuries to the user. When designing PFASs, engineers need to estimate the fall distance of the user, and one of the parameters needed is the average deployment force ($F_a$) of a PEA. However, currently there is a lack of empirical information on $F_a$. The guidance for the estimation of $F_a$ stipulated in the North American standards Z259.16 and Z359.6 did not provide supporting empirical data and appeared to be focused on lower-capacity PEAs (class E4 or Type 1) that are not common in regions like Australia, New Zealand, Europe, and Singapore. Thus, this study aims to provide empirical data for the estimation of $F_a$ of higher-capacity PEAs (class E6 or Type 2) represented by AS/NZS 1891.1:2007 PEAs. Thirty-one force–time charts of drop tests conducted on AS/NZS 1891.1-certified PEAs were evaluated, and it was found that the $F_a$ ranged from 3.2 to 4.7 kN with a mean of 3.9 kN. In contrast to the guidance in Z259.16 and Z359.6, the data does not support estimating $F_a$ based on 80% of maximum arrest force. The study also provided empirical basis for approximating $F_a$ using energy-balance calculation. This paper recommends that in the absence of manufacturer’s information on $F_a$ and other test data, a reasonable estimate of $F_a$ of PEA certified to AS/NZS 1891.1:2007 is 3.4 kN (10th percentile) and a conservative estimate is 3.2 kN (minimum). In the absence of publicly available empirical data of PEA certified to other standards, the results in this paper can provide useful guidance for estimation of $F_a$ certified to other similar standards.