1、 How to Calibrate Vacuum OvenNOTE: Before calibration, please make sure you are familiar with the procedure of oven heating, otherwise, please review the operation manual.When you try to achieve more accurate temperature control, you must calibrate temperature of oven and set-up temperature off if a
2、ny based on your sample and container placed in chamber, because temperature inside oven will vary with size of sample and container changing. Please kindly follow the following procedure to calibrate oven temperature.1. Find hot zone with temperature uniformity The vacuum oven is heated from side w
3、all of chamber. Temperature varies up to 30 oC from wall to door. You shall find uniform temperature zone (+/- 5 oC) inside chamber before putting your sample in. MTIs calibration for the oven is as the follow as your reference. (However, you shall calibrate temperature based on your sample size).Fi
4、gure 1a. As shown in Fig. 1, Omega precision Temperature Calibration Kit (right click here to open hyperlink) is used in the experiment. Two K type thermal couples are placed inside chamber and attached to creamer sample.b. Use temperature controller to heat the oven to your desired temperature (For
5、 details, consult operation manual, this process may be maintain a long time, please set the time parameter named “TI” up to 999 minutes ).c. When the PV displaying on the control panel is to be the desired temperature and stable, apply the function “Auto-tune” (For details, consult operation manual
6、, and then, wait until the this function finish automatically, which may take 30 90 minutes ).d. Place the sample or container with thermocouple at the point you are interested in. Waiting for temperature stable within +/- 1 oC, then record temperature from oven display and from thermometer.e. Open
7、the door, wear the gloves, move the sample with thermocouple to another position, then record temperature difference from oven display and thermometer for calibration.f. Repeat step “e” to finish all the positions to be measured, and show all temperature points vs chamber position. (see Fig. 2 ) Bel
8、ow is example that we measure 7 temperature points in hot zone of vacuum at 100 oC. The result shows that the oven has +/-5 oC temperature uniformity at 6”x6” central area (The chamber is 12”x12”).:Figure 2The temperature of the position:Position Number Temperature (C)1 ( reference point in the cent
9、er) 932 953 924 965 976 977 96Table 1When we set the desire temperature is 200 C, we find the uniformity in this zone is 10 C, the data and figure are shown below: Figure 3Position Number Temperature (C)1 ( reference point in the center) 1862 1913 1994 1925 1966 1897 1968 1989 190Table 22. Temperatu
10、re offset: From step 1, you may notice that the readouts from the oven meter and the thermometer are different, so, in order to get the exact value, please do offset as following:a. Compare the actual temperature you measured in setp1 with the readout from the oven meter.b. Calculate the offset value by the following formula:Offset value = (error value * measurement range) / desired valuec. Push the function key “SET” 5 seconds. Go to “SC2” and set the new offset value.d. Push “SET” key 5 seconds and return to standard display mode.
