Selection Criteria
Selection Criteria
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Selection Tips
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Is the hazardous area stationary or mobile?
A stationary hazard refers to a fixed machine or work cell where one or more mechanical hazards exist. A mobile hazard is generally a fixed-rail linear transfer mechanism (e.g. a transfer cart or conveyor) or an Automatic Guided Vehicle (AGV). Use of a safety device on a mobile hazard generally relates to collision avoidance with personnel or surrounding machinery.
In the instance that the hazard moves toward the operator (such as with powered doors) as opposed to the operator moving toward the hazard, a pressure sensitive safety edge can be mounted to the leading edge of the door. Any contact between the door and personnel will stop the machine before injury can occur.
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What do we mean by full- versus partial-body access?
Full-body access generally refers to the requirement for a person to be standing or walking in (or have access to) the hazardous area around a machine that does not require frequent interaction between personnel and the hazard during regular operation; generally this is for maintenance and troubleshooting. Full-body perimeter or area access control (PAC or AAC, respectively) is achieved through the use of a vertical or horizontal safety field, either opto-electronic (i.e. a light curtain or scanner) or by contact (safety edges and mats).
Partial-body access, on the other hand, is required for applications where an operator must regularly reach into a machine hazard as part of the process at the point of operation (known as POC or Point of Operation Control). In the case of opto-electronic safety devices such as light curtains and area scanners, full- or partial-body detection is directly related to the resolution of the safety device. Below is the relationship of sensing field resolution to the type of detection:
| Object to be Detected/Protected | Resolution |
| Finger (vertical field) | 14 mm |
| Hand (vertical field) | 30 mm |
| Limb (horizontal field for leg detection) | 50 mm, 70 mm |
| Full Body (horizontal or vertical fields) | 150 mm |
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Blind Spots
In some cases it may be possible for a person to enter the guarded area and be lost from view, potentially allowing the guard door to be shut and the machine started by another person. Often used in conjunction with hard guarding and a gate outfitted with an interlock switch, presence sensing safety devices such as pressure sensitive safety mats, laser scanners and horizontal light curtains can be used to check for the presence of a person anywhere within the enclosed safety area.
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Is the shape of the hazardous area rectangular?
When the hazardous area to be monitored is a rectangle (or a shape consisting of contiguous rectangles), access to the area can be easily—and cost-effectively—controlled with a standard safety mat. When the hazardous area is irregularly shaped a custom mat is a viable option, but not necessarily the most cost-effective or readily available. In such a case, a safety scanner is the best option as its scanning field can be easily programmed to scan irregular areas and ignore obstacles (walls, columns) while detecting moving objects (people, AGVs, etc.) as required.
Other Application Considerations
| Safety Mats | Safety Scanner | Point of Operation Control | Perimeter Access Control | ||
| Partial Body Detection | Finger Detection | 14 mm | |||
| Hand Detection | 30 mm | 30 mm | |||
| Limb Detection | 50/70 mm | 50/70 mm | |||
| Full Body Detection | ü | ü | ü | ||
| Uneven Floor | ü | Horizontally Mounted | Horizontally Mounted | ||
| Corrosive Chemicals | ü | ü | ü | ||
| High Pressure Washdowns | ü | IP 67 Enclosure | IP 67 Enclosure | ||
| Steam, Dust Environment | ü | ||||
| Reflections, Bright Ambient Light | ü | ||||
Technology Overview
Safedge Pressure Sensitive Safety Edges
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Features/Benefits
Pressure sensitive safety edges are flexible strips that can be mounted to the edge of a moving part—such as a machine table or powered door—that poses a crushing or shearing risk. Contact of the edge with an object or personnel switches off the machine hazard. Safety edges are a cost-effective solution for constant safety monitoring in smaller areas, especially those applications requiring physical flexibility and a tight turn radius. Rated to Category 3, safety edges do not develop ‘dead spots’ like some other pressure-sensitive safety offerings. They are also easy to install and maintain, and can withstand high pressure washdowns, making them suitable for a wide range of applications and environments. Multiple profile sizes and the availability of custom edge systems also lend to a high degree of application flexibility. It is important to note that Safedge requires a dedicated safety relay for monitoring and control, which can be connected to other safety systems.
Applications
- Sliding doors
- Garage doors
- Pinch points
Common Misapplications
- Submersible applications
- Exposure to volatile chemicals (that can damage the rubber profile)
- Applications where physical contact can injure personnel
MatGuard Pressure Sensitive Safety Mats
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Features/Benefits
Pressure sensitive safety mats provide constant guarding and monitoring of a floor area around a machine; 66 lbs. or more of pressure on the mat (e.g. an operator’s footstep) causes the mat controller unit to switch off power to the hazard. Like safety edges, MatGuard safety mats are easy to apply and maintain, can withstand high pressure washdowns and are not susceptible to dead spots. An ideal solution for relatively small areas. MatGuard products also offer a high degree of application flexibility, offering reversible mats; direct micro quick connectivity to controllers; simple connection to standard and DeviceNet Safety I/O blocks; custom system configurations and quick-delivery standard sizes. However, mats can be damaged by dropped objects, such as tool dies, and pose a potential trip hazard if trim is not used.
Applications
- Work cells
- Area detection
Common Misapplications
- Uneven floors
- Lack or improper use of uniting trim
- Presence of volatile chemicals
SafeZone Multizone Safety Laser Scanner
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Features/Benefits
The SafeZone multizone safety laser scanner is an opto-electronic device that creates a user-configurable scanning field with multiple safety zones. If a person or object enters the warning field, the SafeZone scanner switches a single output that can be used to initiate a warning signal, such as an optical or acoustic alarm. If the inner protective field is breached, the scanner switches two independent safety outputs initiating a machine stop signal to halt dangerous machine motion. Offering warning fields up to a 49 meter radius, the SafeZone multizone is easy to install—either horizontally or vertically—and requires no dedicated controller for operation. Suited for Category 3, SIL2 applications, the scanner is easily interfaced with other safety systems and the easy-to-use configuration software allows for customization of the field shape.
Applications
- Work Cells
- Robot Cells
- Stationary or mobile application
- Rotary and index tables
- Moving automated vehicles (AGVs)
- Infeed machinery
- Overhead cranes
Common Misapplications
- Oil, mist, dust, or steam environments
- Outdoor applications
- Extreme temperatures
Technology Overview (continued)
Point of Operation Control (POC) Light Curtains
Features/Benefits
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Point of Operation Control light curtains are placed close to the hazard, at the point of operation where personnel may frequently interact with the machine as part of a process. POC light curtains are designed for partial-body detection—finger, hand and arm detection—and are offered in multiple resolutions and protective heights with ranges up to 16 meters. An easy-to-install Category 4 solution, these light curtains are easily connected to other safety systems, but require no separate controller and can therefore be operated as standalone units (i.e. without a safety relay). Since they are located at the machine’s point of operation, POC light curtains eliminate the need for gates, allowing frequent and easy access to the hazardous area, and can be used as an ergonomic workstation control that increases safety while enhancing productivity. These light curtains can be mounted vertically or horizontally. However, it is important to note that these light curtains do not detect people or objects once they have passed through the light curtain.
POC light curtains are also suitable for use in washdown applications when used in conjunction with the IP67 light curtain enclosure accessory.
Applications
- Conveyors
- Electronic fences
- Forming operations
- Robot Cells
- Presses
- Workstations
- Washdown applications (use IP 67 tube accessory)
Common Misapplications
- Used on full revolution machinery
- Mounted too close to hazard
Perimeter Access Control (PAC) Light Curtains
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Features/Benefits
Perimeter Access Control light curtains are an easy-to-install, Category 4 solution for full-body or access detection. Designed to create a safety perimeter around a machine that does not require frequent interaction between personnel and the hazard during regular operation (i.e. for maintenance and troubleshooting), PAC light curtains provide large object pass-through sensing with detection ranges up to 70 meters. Like their POC counterparts, PAC light curtains are not floor dependent and can be easily interfaced with other safety systems or used as standalone units without a dedicated control unit/safety relay. However, it is important to note that these light curtains do not detect people or objects once they have passed through the light curtain.
Applications
- Conveyor Systems with muting
- Robot cells
- Opto-electronic fence
- Washdown with IP 67 tube
Common Misapplications
- Used as POC device
- Used on machine that does not stop until completing a full revolution
- Horizontal installation