ERGODYNE 3197 Manual Del Usuario página 4

(Fig. 3) shows an Anchor Point Location (APL) that is
9FT above the surface that the average height worker is
standing on. Since an average height worker's full body
harness Dorsal D-Ring Location (DDL) is 5FT above the
surface he or she is standing on, there is a 4FT difference
between the APL and DDL (9FT – 5FT = 4FT). With a
lanyard length of 6FT, the Free Fall Distance (FFD) =
6FT – 4FT = 2FT
APL 4FT
ABOVE
DDL
When the Anchor Point Location (APL) is below the
Dorsal D-ring Location (DDL) on the worker's full body
harness, the Free Fall Distance is calculated by adding
the distance between the vertical location of the dorsal
D-ring and the anchor point to the length of the
shock-absorbing lanyard.
APL BELOW DDL: LL + (DDL – APL) = FFD
(Fig. 4) shows an Anchor Point Location (APL) below the
worker's Dorsal D-Ring Location (DDL), on the surface
that the average height worker is standing on. Since an
average height worker's full body harness DDL is 5FT
above the surface he or she is standing on, there is a 5FT
difference between the APL and DDL (5FT – 0FT = 5FT).
With a lanyard length of 6FT, the Free Fall Distance (FFD)
= 6FT + 5FT = 11FT. In this example, the Free Fall Distance
would exceed the maximum 6FT allowed by OSHA and
a different personal fall arrest system configuration must
be used.
DDL 5FT
ABOVE
APL
WARNING! AT NO TIME MAY FREE FALL DISTANCE
EXCEED 6 FEET ACCORDING TO OSHA 29 CFR
1910.140(D)(2)(II).
Deceleration Distance (DD): The distance it takes for the
personal energy absorber to stop a fall once engaged.
According to OSHA 29 CFR 1926.502(d)(16)(iv), this
distance may not be longer than 3FT 6IN. Deceleration
distance may vary when arresting a fall, so it is important
to read and understand the specifications of the shock-
absorbing lanyard being used.
Dorsal D-ring Height (DDH): The dorsal D-ring height is
measured as the distance between the dorsal D-ring and
the sole of the worker's shoe while the harness is worn by
the worker. Typically standardized as 5FT for workers 6FT
tall. Workers shorter than 6FT will also be protected using
the 5FT standard, but it is necessary to adjust the dorsal
D-ring height for workers taller than 6FT.
4
6FT LANYARD
FIG. 3
6FT LANYARD
FIG. 4
Dorsal D-ring Shift (DDS): Typically 1FT, this is the
distance the dorsal D-ring moves as the harness shifts
when supporting the worker's full weight. As the personal
fall arrest system pulls upward, the harness can shift so
the D-ring location moves higher on the worker than
before the fall.
Safety Factor (SF): Typically 3FT, this is the additional
length added to the total fall clearance formula to ensure
there is enough distance between the worker and the
ground, equipment or obstruction in the event of a fall.
The Total Fall Clearance distance is calculated by adding
Lanyard Length, Deceleration Distance, Dorsal D-Ring
Height, Dorsal D-Ring Shift and Safety Factor values
together and subtracting Anchor Setback when present:
CALCULATING TOTAL FALL CLEARANCE (TFC)
FROM ANCHOR POINT:
LANYARD LENGTH(LL) + DECELERATION
DISTANCE(DD) + DORSAL D-RING SHIFT(DDS)
+ DORSAL D-RING HEIGHT(DDH) + SAFETY
FACTOR(SF) = TFC
(Fig. 5) below shows the calculation of Total Fall Clearance
(TFC) for an average height worker with a Dorsal D-ring
Height (DDH) of 5FT using a 6FT shock-absorbing lanyard
attached to an anchor point 4FT above the dorsal D-ring
on his/her full body harness. In this example, the Free Fall
Distance (FFD) is 6FT - 4FT = 2FT. Adding everything
together, Total Fall Clearance = 6FT(LL) + 3 ½FT(DD) +
1FT(DDS) + 5FT(DDH) + 3FT(SF) = 18 ½FT
BEFORE FALL AFTER FALL
6FT LANYARD
WARNING! SWING FALLS: BEFORE USING THE
ERGODYNE FULL BODY HARNESS, BE SURE TO
ELIMINATE OR MINIMIZE ANY HAZARD OF A SWING
FALL. SWING FALLS OCCUR WHEN THE ANCHOR
POINT IS NOT DIRECTLY ABOVE OR BELOW THE
LOCATION OF THE FALL. ALWAYS WORK AS CLOSE
TO IN LINE WITH THE ANCHOR POINT AS POSSIBLE.
SWING FALLS SIGNIFICANTLY INCREASE THE
LIKELIHOOD OF SERIOUS INJURY OR DEATH IN
THE EVENT OF A FALL.
APL 4FT
ABOVE DDL
6FT LANYARD
LENGTH
2FT FFD
3.5FT DD
1FT DDS
5FT DDH
3FT SF
FIG. 5
18.5FT
TFC