. . . . .
R
S
A F E T Y
M
O U N T I N G
D
I S T A N C E
Determining the Safe Mounting Distance
SCIENTIFIC TECHNOLOGIES INC.
Call: 1/888/510-4357 in USA and Canada
Universal Safety Mat UM Series Rev. C
© STI 08/2000
7
Figure 4-1 Shows the Active Joining Strip System
5 S
AFETY
M
OUNTING
D
ISTANCE
5
5 . 1 . D
E T E R M I N I N G
T H E
S
A F E
M
O U N T I N G
D
I S T A N C E
The sensing area must cover enough area from the hazardous area such that the machine will stop
before any part of the operator’s body can reach into the hazardous area. This distance, called the
safety distance, is a calculated number based on the stopping time of the machine to be guarded.
5.1.1
EN M
INIMUM
S
AFE
D
ISTANCE
F
ORMULA
The following formula is based on the EN prEN999: method of calculating the minimum safe
distances for ground level trip devices.
The minimum safe distance shall be calculated using the following formula:S = (K x T) + C or
1.
S=(63 in./sec. x T) + 47.2 in. - (0.4H) or
S=(1600mm/sec. x T) + 1200mm - (0.4H)
where:
S is the minimum distance in inches in the horizontal plane from the hazardous area to the
detecting edge of the device furthest from the hazardous area.
K = 63 in./sec. (1600mm/sec.), which is the average calculated approach speed.
T = t
1
+
t
2
T is the overall system stopping performance,
t1 is the maximum time between the actuation of the safety mat and the controller output relays
being in the de-energized state.
t
2
is the response time of the machine being guarded. The time required to stop the machine or
remove the risk after receiving the output signal from the STI mat controller.
Wires
Active Trim
Joining Strip
Mat Assembly
Inactive Area
*This drawing shows that the mat is operating with force being applied to the joining strip.
