Separation Distance; Normal Approach - Tapeswitch GS-120 Technical Manual

Release 7/2009 Ver. 1.0 Technical Manual: GS-120 Light Curtain Systems
3.2.3

SEPARATION DISTANCE

Any machine, regardless of the efficiency of its braking
system, will take a certain time to come to rest after a
stop signal is generated.
The time from the instant that the curtain is broken to
the instant that dangerous motion actually ceases is
called the "overall system response time". The
dangerous parts will obviously continue to move during
this time. The curtain must therefore be positioned at a
certain minimum distance from the dangerous parts to
prevent a person who has obstructed the curtain from
reaching the dangerous parts before they have stopped.
This distance is the "minimum separation distance" and
is defined as the distance, in the direction of approach,
between the physical point at which the curtain detects
an obstruction and the nearest dangerous parts.
ANSI B11.19-1990 provides guidelines on how to
determine the minimum separation distance for a given
application. Tapeswitch GS-120 systems are primarily
intended for use in normal approach format where the
curtain is perpendicular to the direction of approach,
although they can be used in parallel and angled
approach formats.

3.2.3.1 Normal Approach

Figure 15
Normal approach format is shown in Figure 15. For
normal approach format the inner edge of the front
window of each unit (i.e. the edge which is nearest to
the machine) should be considered to be the point at
which an obstruction is detected. See plane X as
shown in Figure 15.
The effective sensing field of the device shall be located
at a distance from the nearest recognized hazard such
that the operator or others cannot reach the hazard with
a hand or other body part before stopping of the motion
during the hazardous portion of the machine cycle.
TAPESWITCH CORPORATION Phone: 631-630-0442
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100 Schmitt Boulevard Fax: 631-630-0454
Farmingdale, New York 11735 www.tapeswitch.com