Rockford Systems, LLC
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8
OSHA REGULATIONS AND ANSI STANDARDS
(continued)
ANSI B11.1-1988 Safety Distance Formula for Presence Sensing Devices
According to the ANSI (American National Standards Institute) B11.1-1988, the total stopping time of the press (for presence
sensing devices) should include the total response time of the presence sensing device, as stated by the manufacturer, the
response time of the interface, the response time of the control system, the time it takes the press to cease slide motion,
and the added time for brake monitoring (Tbm). The following formula should be used when calculating the safety distance
to meet the ANSI Safety Standard:
Ds = K (Ts+ Tc+ Tr+ Tbm) + Dpf where:
K = the hand speed constant = 63 inches/second.
Ts = the stop-time of the press measured from the final
deenergized control element, usually the air valve.
Tc = the response time of the control.
Note: T
s
+ T
c
are usually measured by a stop-time
measuring device.
Tr = the response time of the presence sensing device and
its interface, if any, as stated by the manufacturer or
Tbm = the additional time allowed by the brake
monitor before it detects stop-time deterioration.
Dpf = the added distance due to the penetration factor. The
minimum object sensitivity is stated by the manufacturer.
If beam blank-outs or floating window features are
used,these figures should be added to the object sensitivity
figure. No increase in safety distance is required for fixed-
channel blanking applications if the blanked area is entirely
occupied by the material or fixtures.
ANSI B11.1-1988 Safety Distance Formula for Two-Hand Control
According to ANSI B11.1-1988, the total stopping time of the press (for two-hand control) should include the total response
time of the control system and the time it takes the press to cease slide motion. The following formula can be used when
calculating the safety distance:
D = K (T
s
+ T
c
+ T
bm
) where:
K = the hand speed constant = 63 inches/second.
T
s
= the stop-time of the press measured from the final deenergized control element, usually the air valve.
T
c
= the response time of the control.
Note: T
s
+ T
c
are usually measured by a stop-time measuring device.
T
bm
= the additional time allowed by the brake monitor before it detects stop-time deterioration.
Note: When the press stroke STOP command or stopping performance monitor (brake monitor) timer or angle setting is
changed, the safety distance should be recalculated.
0 1 2 3 4 5 6 7 8
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
Penetration Factor Dpf In Inches
DEPTH PENETRATION FACTOR
This table represents the depth of penetration into the light
curtain at which an object will be detected.
Blanked Dimensions Of Minimum
Object Sensitivity In Inches
SECTION 1—TABLE OF CONTENT
Stop-Time Measurement Device
