Designed for use specifically in the clean or hygienic process industry, the Thermatel® TD2 is an outstanding flow/level device, where easy external wipe down and a sensor free of cracks and crevices are required. The TD2 thermal dispersion flow/level switch provides continuous diagnostics, temperature compensation, narrow hysteresis, and fast response time for superior performance.
The TD2 switch uses either AC or DC input power and provides a DPDT relay output with a visual LED indication of status through the glass window in the cover. Other features include ability to electronically measure the set point, an mA output signal for trending and diagnostics and time delay.

Operating Principle

The THERMATEL TD2 switch utilizes Magnetrol® proven thermal dispersion technology. The sensor consists of two RTD elements. One is the reference and the second is heated to a temperature above the process temperature. The electronics detect the temperature difference between the two elements. The temperature difference is greatest in air, then decreases when cooling occurs due to a change in media. An increase in the flow rate further decreases the temperature difference.
The set point is adjusted for the switch to alarm at the desired temperature difference. Once the set point is reached, the relay will change state.


- CIP systems
- Mixing and blending vessels
- DI/WFI applications
- Biowaste tanks
- Sterile liquid media tanks
- As a level switch, the TD2 can be used in applications where a high viscosity liquid might plug up an ultrasonic unit's transducer gap


- Temperature compensated to provide repeatable alarm under varying process temperatures
- Continuous diagnostics detect sensor fault
- A non-linear mA output signal can be used for trending, diagnostics and repeatable flow/level indication
- Detects minimum flow or presence/absence of flow
- Simple/fast calibration
- Excellent low flow sensitivity


- DPDT 8 amp relay or DPDT 1 amp hermetically sealed relay
- Glass window enclosure
- Tri-Clamp® or Varivent® sanitary process connections


+ Product Catalog
+ Instruction & Operating Manual