Catalogs > Safety Products Catalog > Principles, Standards and Implementation > Protective Measures and Complementary Equipment
Protective Measures and Complementary Equipment
| Protective Measures |  |
Preventing Access | |
Detection Devices | |
Safety Switches | |
Guard Locking Switches | |
| Non-Contact Interlock Switches | |
Hinge Switches | |
Position (Limit Switch) Interlocks | |
Trapped Key Interlocks | |
Operator Interface Devices | |
| Logic Devices | |
Integrated Safety Controllers | |
Safety Networks | |
Output Devices | |
Connection Systems | |
Fixed Enclosing Guards
If the hazard is on a part of the machinery which does not require access, a guard should be permanently fixed to the machinery as shown in Figure 23. These types of guards must require tools for removal. The fixed guards must be able to 1) withstand their operating environment, 2) contain projectiles where necessary, and 3) not create hazards by having, for example, sharp edges. Fixed guards may have openings where the guard meets the machinery or openings due to the use of a wire mesh type enclosure.
Windows provide convenient ways to monitor machine performance, when access to that portion of the machine. Care must be taken in the selection of the material used, as chemical interactions with cutting fluids, ultra-violet rays and simple aging cause the window materials to degrade over time.
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| Figure 23: Fixed Guards |
The size of the openings must prevent the operator from reaching the hazard. Table O-10 in US OHSA 1910.217 (f) (4), ISO 13854, Table D-1 of ANSI B11.19, Table 3 in CSA Z432, and AS4024.1 provide guidance on the appropriate distance a specific opening must be from the hazard.
Detecting Access
Safeguarding is used to detect access to a hazard. When detection is selected as the method of risk reduction, the designer must understand that a complete safety system must be used; the safeguarding device, by itself, does not provide necessary risk reduction.
This safety system generally consists of three blocks: 1) an input device that senses the access to the hazard, 2) a logic device that process the signals from the sensing device, checks the status of the safety system and turns on or off output devices, and 3) an output device that controls the actuator (for example, a motor). Figure 24 shows the block diagram of a simple safety system.
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| Figure 24: Simple Safety System Block Diagram |