Document ID: chunk:federal_register_of_legislation:F2016L00422:body:0:p26
Version: federal_register_of_legislation:F2016L00422
Segment Type: other
Provision Reference: 
Character Range: 63852–66603

an interlocked door is accidentally closed the machine should not automatically restart.

Figure 4 Perimeter fence guard with fixed panels and interlocking access door

Adjustable guarding incorporates movable sections or panels of the guard to allow materials to be fed into the guarded area while still preventing physical contact (see Figure 5).

Figure 5 Self-adjusting guard for a drop saw

Physical barrier guarding should be strong enough to resist normal wear and shock that may arise from failure of the parts or processes being guarded; and to withstand prolonged use with a minimum of maintenance.

Presence sensing systems
If physical guards are not reasonably practicable, then a presence sensing system can be used to control the risk. These systems detect when a person (or part of a person's body) enters the danger zone and stops the machine. Photoelectric light beams, laser scanners and foot pressure mats are examples of these type of guards. They rely on sensitive trip mechanisms and the machine being able to stop quickly, which may be assisted by a brake (see Figures 6 and 7).

Effective presence-sensing safeguard systems require the selection of a trip device appropriate for the work being done, and the correct location of beams with light activated devices, taking into account speed of entry and machine stopping time.

Figure 6 Paper cutting guillotine with a combination of guards including a photoelectric light curtain

Figure 7 Pressure sensitive mat

Environmental factors
When using a guard you should consider the environment in which it may be used. Some examples of poor guard selection include: guards on high frequency welders that become electrically charged, heating of guards in hot processes and wire mesh guards on machines emitting splashes.

If a guard is likely to be exposed to corrosion, you should consider corrosion-resistant materials or surface coatings.

Colour coding
It is good practice for all guards to be painted the same colour. For example:
    * use high visibility yellow, provided it is different to the plant's colour, so that it can be clearly seen when a guard has been removed or when it is not in its proper place, and
    * paint the surfaces behind the guard a contrasting or bright colour so that when the guard is removed, the exposed colour is clearly visible and it is easy to identify that the guard has been removed, alerting workers to possible danger.
For some types of plant, it may be necessary to choose colours that contrast with workpieces, where these need to be visible through the guarding.

Removal of guarding
If any type of guarding is removed for the purposes of maintenance or cleaning, it must be replaced before the plant is put back into normal