Machinery Update July / August 2020

10 MACHINERY UPDATE JULY/AUGUST 2020 www.machineryupdate.co.uk
Regulations
Inspecting light guards
should not be neglected
Lee Ray
OPERATIONS MANAGER FOR INDUSTRIAL PRODUCTS (UK) AT TÜV SÜD
As the use of electro-sensitive protective equipment (ESPE) increases to provide safe, barrier-free
access for machinery end-users, it is only regular testing that can prove its efficacy…
As technology has moved
on, the use of electrosensitive
protective
equipment (ESPE) has
significantly increased. For
example, collaborative robots
are designed to work alongside
human co-workers, performing
tasks simultaneously.
This means that unlike more
traditional machines, they
cannot be caged by a physical
guarding mechanism. ESPE,
such as light guards and laser
scanners, are therefore more
prevalent than ever before
as they provide safe, barrierfree
access. However, despite
its importance for the safety
of machinery end-users,
we often visit sites where ESPE
inspection and testing is
neglected. This is because
many machinery owners
are unsure how often their
equipment should be assessed
and believe the original
installation will retain the
same parameters throughout
its entire period of use.
SAFETY SYSTEM DESIGN
IEC 61496 series specifies
requirements for the design,
construction and testing of
ESPE designed specifically
to detect persons as part
of a safety-related system,
employing active optoelectronic
protective devices
(AOPDs) for the sensing
function. This is then used in
conjunction with ISO 13855
to determine the correct
installation location for the
light guard, to prevent a
person contacting a hazardous
moving part of the equipment.
This should be verified after
installation. However, there
are no specific references
to how often these systems
should be inspected to ensure
that they continue to provide
the same level of protection.
The Health and Safety
Executive’s HSG180 guide
(Application of electro-sensitive
protective equipment using
light curtains and light
beam devices to machinery)
helps machinery end-users
to answer this question of
timings. Concerning ESPE and
AOPDs that are used to protect
people from hazardous parts
of machinery, the guide covers
installation, use, inspection
and also testing.
HSG180 refers to Regulation
6 of the Provision and
Use of Work Equipment
Regulations 1998 (PUWER).
This covers the extent and
nature of inspections, to help
ensure that the appropriate
systematic checks are done.
HSG180 states that:
“inspection and testing is only
required under Regulation 6
where the safe operation is:
critically dependent on work
equipment being properly
installed or reinstalled and
failure to carry this out would
lead to a significant risk and
where the safe operation
is critically dependent on
its condition in use and
deterioration would lead to
a significant risk to the
operator or other worker.”
Inspection and tests
must first be done when the
complete ESPE and machine
package is installed, and
thereafter when modification
or repairs have been made.
In addition, periodic
inspections should be
completed. HSG180 defines
the recommended maximum
period between each periodic
inspection and test as being
six months for type 4 ESPE
and 12 months for type 2 ESPE.
However, this is still quite
subjective as the guidance
then says that the frequency of
Any system deterioration
cannot generally be seen, and so
testing is vital to prove safety
inspections ultimately depends
on the equipment that
the ESPE is fitted to and the
risk as a whole. TÜV SÜD
would always follow the
recommendation provided by
the HSE in the first instance
until a testing plan can be
provided. This would depend
on the equipment it is installed
on, the frequency of use and the
environment it is operating in.
The good news for
machinery end-users is that
HSG180 requires the machine
and the ESPE supplier to
supply information relating
to routine maintenance and
inspection requirements.
This should help the end-user
to develop a robust inspection
and set an initial test regime
frequency. The guide also
requires that the initial
inspection and test is carried
out by competent persons,
such as an in-house inspector,
the installer or supplier,
or an independent assessor.
RECORD THE WORK
The results of any inspections
must also be recorded.
The HSG180 guide also helps
the inspector to ensure that
the inspection and test process
achieves a good general
standard of performance.
For example, it should not be
possible for the dangerous
parts of the machine to be set
in operation while any part of
a person is in such a position
as to actuate the AOPD.
We have seen multiple
instances where the need
for light guard testing has
not been realised. While
functional safety checks are
recognised as good practice,
they are no substitute for the
required periodic testing.
The stop time test, performed
as part of the periodic test,
would detect any deteriorating
system parts which no longer
offer the required protection.
This is something that usually
cannot be seen, like in fixed
guarding, and therefore can
only be proven by testing.
i For more information contact
W www.tuv-sud.co.uk
TÜV SÜD is the PPMA
Group’s technical and
legislative partner