1. Thermatel FCI 12-64 Sensor Design Active RTD Reference RTD Heater
Constant wattage heater (5 watt, maybe even 10 watt depending upon application). Reference RTD measures process temperature. Active RTD measures temperature of heater. Sensors are 3/8" diameter by 1.5 " long (big thermal mass) Flow cools heater, detected by active RTD. Set point adjusts the delta Temp where the switch will trip.
Note the large thermal mass which results in long response time. and the sensor will overheat if run dry.
Reference RTD
Heater

2. Thermatel FCI FLT 93 Sensor Design FLT-F FLT-S RTD RTD Heater Heater
After Magnetrol introduced the TDF, FCI developed a twin pin sensor. One sensor has a heater and a RTD. The other sensor has a RTD. The operation is the same as the However the FLT-93 now has smaller thermal mass, faster response time, and one sensor for any fluid. The FLT-S is a heavier duty sensor with greatr thermal mass.
RTD
RTD
Heater
Heater

3. Thermatel vs FCI Magnetrol Magnetrol FCI FCI TDF/TDL TSF/TSL
12-64 Basic
FLT 93
Tiempo de respuesta (seg)
1 a 10
1 a 10
10 a 300
1 a 10
Diseño del sensor
Twin tip
Spherical tip
Twin tip
Spherical tip
3 high mass
2 medium mass
Calentador (vatios)
0.5 max.
0.5 max.
5 a 10
0.6 a 3.0
Calentador
Variable
Variable
Constante
Constante
Operación seco Si Si No
Quizás
Construcción del sensor
316 SS Welded
316 SS Welded
316 SS with nickel braze
316 SS Welded