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Environmental Chamber Heater Control

FTA chambers and syringe heaters can be controlled from external, dedicated controllers or from a software controller internal to the FTA software. In either case you must exercise caution not to burn yourself on the possibly hot walls of the chamber or heater.

Never thrust the indicated readout temperature if it says a low value andf there is any reason to believe the chamber may still be hot. The readout may be in error.

External Controllers

Each controller can run only one heater. If you have both a chamber and a syringe heater, there will be two controllers. The controller will have one display that can be switched back and forth between the setpoint (the desired) temperature and the actual (current) temperature. There will be a way to enable or disable the heater. The current actual temperature can be readout while the heater is disabled. The temperature is not recorded automatically in the FTA software.

Fta32 Software Controller

The software controller can control up to two heaters. There are separate checkboxes to enable measurement of the actual temperature and enable control of the heater. You should never turn off the measurement before turning off the heater control checkbox. The software will not let you start the heater if the measurement is not turned on. Prior to Build 220, however, it can not be guaranteed that the software would turn off the heater if you disabled the measurement before turning off the heater. The heater enable is automatically turned off with no measurement in Build 220 and later.

You can enter a desired setpoint temperature for the software controller. When the heater is enabled, the current drive, as a fraction of full on 100% is shown. Depending on the PID settings, it may take a few seconds for the drive to come up after you start the heater.

You should not presume the software has turned off the heater if there is any sort of software error or loss of communications between the computer and the control box for the instrument. To be on the safe side, turn off electrical power to the instrument when the Fta32 program is not running.

Temperature Readout and Sample Temperature

The temperature readout and the actual sample temperature may differ. Eventually they will become very close, but significant differences can exist during heat up.

  • FTA2000: the enclosure heats slowly. The measured temperature is air temperature at the camera level. The sample can be expected to be very similar.

  • Syringe Heaters: these heat fairly rapidly and the syringe is in good thermal contact with the heater. Temperature is measured in the wall of the heater body. The syringe should equilibrate within 5 minutes.

  • Environmental Chambers: temperature is measured by an Pt100 RTD. The actual sensor is at the end of the probe. The end of the probe can be adjusted (by loosening a setscrew) to be in contact with the end wall of the chamber (the factory default) or it can be pulled back a bit and be only in the air. Having the probe in only air is a more representative of the actual sample temperature but the controller will have some tendency to overshoot during heat up. However, the sample will always take some time to heat up to the setpoint because it must be heated through contact with the air inside the chamber.

Checking Temperature Measurement Accuracy

In all of these cases, check the sensor with the heaters turned off.

For the FTA2000 sensor, place a thermometer in the enclosure with its bulb at approximately the level of the camera. Close the enclosure doors and let the thermometer stabilize for 5 minutes. It should read within 1 degree of the software measurement.

For the Pt100 RTD sensors in the syringe or environmental chamber heaters, loosen the setscrew holding them and slide them out so they can be placed into a bowl of cold or hot water. Measure the water temperature with a known good thermometer. Allow the RTD and thermometer to stabilize for 5 minutes in the bowl of water. You should read within 1 degree.