Description
1. Product Title
Watlow CLS216 – Series CLS 1/16 DIN Limit Controller
2. Product Overview
The CLS216 is a legacy high-limit safety controller from Watlow’s “CLS” series. In a thermal system, a limit controller acts as a critical safety watchdog. While a standard PID controller manages the temperature for the process, the CLS216 monitors the system independently; if the temperature exceeds a predefined safety threshold (high limit) or falls below a low limit, the module trips a mechanical relay to cut power to the heaters.
The CLS216 is specifically designed in a 1/16 DIN form factor, making it compact enough for dense control panels. It features a latching relay that requires a manual reset once a limit is tripped, ensuring that a human operator must inspect the system for faults before restarting the process—a key requirement for many industrial safety standards (such as FM approvals).
3. Technical Specifications
- Brand: Watlow
- Model: CLS216
- Format: 1/16 DIN (Panel Mount)
- Input Type: Universal (Thermocouples J, K, T, N, E, R, S, B; RTD 100Ω Platinum)
- Output: Electromechanical Relay (typically Form C)
- Reset: Manual reset (via front key or external input)
- Power Supply: Available in 100-240V AC or 24V AC/DC models
- Display: Dual 4-digit LED (Process value and Limit setpoint)
- Approval: Factory Mutual (FM) approved for safety limit applications
4. Key Features & Benefits
- Independent Safety: Operating separately from the primary temperature controller, the CLS216 prevents “runaway” heating conditions caused by sensor failure or stuck power relays.
- Latching Relay: The output remains “tripped” even after the temperature returns to a safe range, preventing the system from cycling on and off in a dangerous state.
- Simple Interface: Designed for ease of use, it allows operators to see the actual temperature and the safety limit setpoint simultaneously.
- FM Approval: Meeting rigorous safety standards ensures that the controller is suitable for insurance-mandated safety loops in ovens, furnaces, and boilers.
5. Application Scenarios
- Industrial Ovens: Acting as the over-temperature safety cut-off to prevent fire or damage to the product being baked/cured.
- Plastics Processing: Monitoring heater bands on extruders to ensure they do not exceed the flashpoint of the plastic material.
- Boiler Systems: Providing a high-limit trip to prevent steam pressure buildup beyond the vessel’s mechanical limits.
- Laboratory Equipment: Protecting sensitive samples in incubators or environmental chambers from accidental overheating.
6. Frequently Asked Questions (FAQ)
- Q: Can I use the CLS216 to control my heater’s temperature?
- A: No. A limit controller is an “On/Off” safety device. It is not designed for PID control. It should be used in conjunction with a dedicated temperature controller (like a Watlow PM6 or EZ-ZONE series).
- Q: What happens if the thermocouple breaks?
- A: The CLS216 is designed with “sensor break protection,” which will automatically trip the safety relay if the input signal is lost.
- Q: Is there a modern replacement for the CLS216?
- A: Yes. The Watlow EZ-ZONE® PM (PM6L) is the modern equivalent, offering updated features, better accuracy, and a more robust display while maintaining the 1/16 DIN size.
