Product Information
When a barrier guard is used for safeguarding on
a machine, it must be designed, constructed,
applied, and adjusted so that people cannot
reach over, under, around, or through the barrier
guard and reach the hazard. However, the panels
inside the framework of most barrier guards
have openings in them because they are made
out of materials such as wire mesh, expanded
metal, rods, or hairpins. And these openings may
or may not be adjustable. In any case, when
barrier guards have openings in them, the
openings must be checked for safety compliance.
In North America, ANSI (American National
Standards Institute) and CSA (Canadian Standards
Association) standards are used for reference
when determining maximum guard openings
and minimum mounting distances of barrier
guards so that body parts such as hands and
fingers cannot reach the hazard area.
Although an original study and drawings for
machine guarding were created in the 1940s, it
wasn’t until the mid-1990s that a comparison of
newer studies to the original drawings had been
done. In 1995, a study entitled “A Review of
Machine-Guarding Recommendations” was
published in Applied Ergonomics (Vol. 26, No. 2,
pp. 141–145); Donald R. Vaillancourt and Stover
H. Snook of the Liberty Mutual Research Center
for Safety and Health conducted this study. The
purpose of their investigation was to determine
whether the original drawings from the 1940s
were still consistent with the data in the modern
studies, especially relating to women and
minorities, who are now much more prevalent
in the American workplace. In their study,
Vaillancourt and Snook compared data from six
anthropometric surveys to the original machine-guarding
recommendations.
Vaillancourt and Snook found many of the
dimensions in the original drawings to be valid.
However, they suggested several important
modifications. Moreover, several of the
dimensions from the original 1940s drawings
showed no correlation to body reference points,
so Vaillancourt and Snook suggested that they
be eliminated.
The drawings from Vaillancourt and Snook’s
study have been adopted and are used in several
current ANSI B11-series safety standards for
machine tools as well as in the ANSI/RIA R15.06
safety standard for industrial robots and robot
systems. The data from the study is also used by
Canadian safety standards CSA Z142 for power
presses, CSA Z434 for robots, and CSA Z432 for
safeguarding of machinery.
Since the Vaillancourt and Snook drawings have
been adopted and are used by the most current
and up-to-date North American safety standards,
we have created a guard safety scale that
can be used to check the openings for compliance
with these standards. The gold-colored, folding
scale has English units on one side and metric
units on the other. It is made out of anodized
aluminum and has easy-to-read text and graphics
that will not rub or scratch off. It can be used
during the design, installation, and inspection of
barrier guards to make sure they comply with
applicable machine safety standards.