1126700 SmartPAC 2 User Manual
6-26 Run Mode
The Ts value should also include a percentage factor added for brake wear. A factor of 20
percent is recommended for presses with new brakes or brakes in good condition. A factor of
10 percent is recommended for presses with older brakes. See Calculating the Stop Time
Limit, page 4-9 for further details.
Example: Calculating the Safety Distance Using the OSHA Formula
The OSHA formula for calculating the safety distance is
Ds = K x Ts
The hand-speed constant K is 63 inches per second. The components of Ts are as follows:
The result of the 90° stop time test is .190 seconds, which includes press stopping time and the
response time of SmartPAC 2.
The response time of Shadow 8 light curtains is .059 (202 in. combined length including
extensions–see Table 6-2.
The braking percentage factor will be based on the assumption that our brakes are new. If we
take 20% of the stop time at top stop, which is .175, we come up with a braking factor of .035
(0.20 x .175 = .035).
Therefore, T
s
= .190 + .059 + .035 = .284
Now we can calculate the safety distance:
D
s
= 63 x .284
D
s
= 17.89 in. or, rounding, 17.9 in.
The light curtains in this example must be mounted at least 17.9 in. from the pinch point.
When using the OSHA formula, be sure to do the calculations in this order:
(1) Add the factors involved in the stopping time Ts first.
(2) Multiply the result by 63. This is Ds.
If you do no follow this order, your safety distance calculation will be incorrect.
Adding to Safety Distance for Blanking Windows
When using fixed or floating blanking windows with your Shadow 8 light curtain, you must
add a factor to the calculated safety distance for each beam that is blanked. This applies
whether you use the ANSI or the OSHA formula. For a one-beam fixed blanking window,
you must add 5.38 in. (136.6 mm) to the calculated safety distance (ANSI formula). You
must add 5.76 in. (146.3 mm) to the calculated safety distance for a one-beam floating
blanking window (ANSI formula). See your Shadow 8 user manual for further details about
fixed and floating blanking.
If you are using another Shadow light curtain, refer the appropriate Shadow user manual for
the additional distance factor to add to the safety distance formula for each blanking window.
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