Catalogs > Safety Products Catalog > Safety Switches > Selection Criteria
Selection Criteria
Selection Tips
|
Sequential Access Control
A Sequential Access Control system requires that a predetermined sequence of events takes place or that hazards have been reduced before operators can become exposed to them. Prosafe trapped key interlocks are a mechanical system based on coded keys that achieves this via the premise that no single key can be used in two places at once. And because of their mechanical operation, Prosafe trapped key interlocks are widely used in applications where the location of plant, environment or explosive atmospheres make the use of electrical interlock systems unsuitable or expensive to install.
|
High Inertia Machine (Long Run Down Time)
A High Inertia Machine is one on which hazardous motion does not cease immediately when the safety measures are engaged. As a result, there is a possibility that an operator can reach the hazard while it is “running down” and is still dangerous. Interlock switches with guard locking reduce the risk that the guard opens during hazardous machine motion.
Alternative measures:
- Install a braking device which stops the machine motion in a shorter time span.
- Increase the distance between the guard door and the hazard such that the operator cannot physically reach the hazard before it has stopped.
|
Washdown Environments
In many applications, primarily those in the pharmaceutical and food/beverage industries, frequent washdown of the machinery with water and/or cleaning fluids is common. Therefore, it is important to select a safety switch with the appropriate environmental protection as indicated by the product’s enclosure (Ingress Protection or IP) rating. Non-contact switches have no “traps” where debris can accumulate and are available in fully sealed versions (IP67/IP68/IP69K), making them ideal for washdown applications.
For details on enclosure ratings, refer to the General section of this catalog and IEC 529.
Other Application Considerations
| Non-Contact Switches | Hinge Switches | Tongue Switches | Limit Switches | |
| Large Door | ü | ü | ü | |
| Vibration | ü | ü | ||
| Misalignment | ü | ü | ||
| Debris | ü | ü | ||
| Washdown | ü | ü | ||