INSTRUCTION MANUAL HFT3 Soil Heat Flux Plate Revision: 10/03 C o p y r i g h t ( c ) 1 9 8 7 - 2 0 0 3 C a m p b e l l S c i e n t i f i c , I n c .
Warranty and Assistance The HFT3 SOIL HEAT FLUX PLATE is warranted by CAMPBELL SCIENTIFIC, INC. to be free from defects in materials and workmanship under normal use and service for twelve (12) months from date of shipment unless specified otherwise. Batteries have no warranty. CAMPBELL SCIENTIFIC, INC.'s obligation under this warranty is limited to repairing or replacing (at CAMPBELL SCIENTIFIC, INC.'s option) defective products.
HFT3 Table of Contents PDF viewers note: These page numbers refer to the printed version of this document. Use the Adobe Acrobat® bookmarks tab for links to specific sections. 1. General Description....................................................1 2. Specifications .............................................................1 3. Installation...................................................................2 4. Wiring ..........................................................................3 5.
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Model HFT3 Soil Heat Flux Plate 1. General Description The HFT3 Soil Heat Flux plate uses a thermopile to measure temperature gradients across the plate. Each plate is individually calibrated to output flux. In order to measure soil heat flux at the surface, several HFT3s are used to measure the soil heat flux at a depth of eight cm. A TCAV Averaging Soil Thermocouple is used to measure the temporal change in temperature of the soil layer above the HFT3.
Model HFT3 Soil Heat Flux Plate Up to 1 m 2.5 cm 2 cm Ground 6 cm Surfac e 8 cm Partial emplacement of the HFT3 and the TCAV sensors is shown for illustration purposes. All sensors must be completely inserted into the soil face before the hole is backfilled. FIGURE 1. Placement of Heat Flux Plates 3. Installation The HFT3 Soil Heat Flux plates, the TCAV Averaging Soil Temperature probes, and the CS615 Water Content Reflectometer are installed as shown in Figure 1.
Model HFT3 Soil Heat Flux Plate Never run the sensors leads directly to the surface. Rather, bury the sensor leads a short distance back from the hole to minimize thermal conduction on the lead wire. Replace the excavated soil back into it original position after all the sensors are installed. Signal Black Signal Reference White Shield Clear White Dot on Top FIGURE 2. HFT3 Plate to Datalogger Connections TABLE 1.
Model HFT3 Soil Heat Flux Plate The wiring convention is that the black wire is positive with respect to the other insulated wire, when energy is flowing through the transducer from the side with white dot to the side without the white dot. 5. Example Programs This section is for users who write their own dataloger programs. A datalogger program to measure the sensor can be created using Campbell Scientific’s Short Cut Program Builder software. You do not need to read this section if you use Short Cut.
Model HFT3 Soil Heat Flux Plate Example 2 Sample CR23X Program using a Differential Measurement Instruction ;Measure the HFT3 Soil Heat Flux plate. ; 01: Volt (Diff) (P2) 1: 1 Reps 2: 21 10 mV, 60 Hz Reject, Slow Range ;CR510, CR10(X) (7.5 mV); 21X, CR7 (5 mV) 3: 9 DIFF Channel ;Black wire (9H); White wire (9L) 4: 1 Loc [ HFT3 ] 5: 1 Mult ;Enter Calibration 6: 0 Offset 6.
Model HFT3 Soil Heat Flux Plate 7. Maintenance The HFT3 requires minimal maintenance. Check the sensor leads monthly for rodent damage. Recalibrate the HFT3 every two years of continuous use. Obtain an RMA number before returning the HFT3 to Campbell Scientific for calibration. 8. References Hanks, R. J., and G. L. Ashcroft, 1980: Applied Soil Physics: Soil Water and Temperature Application. Springer-Verlag, 159 pp. Klute, A., 1986: Method of Soil Analysis. No.
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