Campbell HFP01SC User manual

MODEL HFP01SC
SELF-CALIBRATING SOIL HEAT FLUX PLATE
INSTRUCTION MANUAL
4/02
COPYRIGHT (c) 2002 CAMPBELL SCIENTIFIC, INC.

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Warranty and Assistance
The MODEL HFP01SC SELF-CALIBRATING 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. The customer shall assume all costs of
removing, reinstalling, and shipping defective products to CAMPBELL
SCIENTIFIC, INC. CAMPBELL SCIENTIFIC, INC. will return such
products by surface carrier prepaid. This warranty shall not apply to any
CAMPBELL SCIENTIFIC, INC. products which have been subjected to
modification, misuse, neglect, accidents of nature, or shipping damage. This
warranty is in lieu of all other warranties, expressed or implied, including
warranties of merchantability or fitness for a particular purpose. CAMPBELL
SCIENTIFIC, INC. is not liable for special, indirect, incidental, or
consequential damages.
Products may not be returned without prior authorization. To obtain a
Returned Materials Authorization (RMA), contact CAMPBELL SCIENTIFIC,
INC., phone [phone]. After an applications engineer determines the
nature of the problem, an RMA number will be issued. Please write this
number clearly on the outside of the shipping container. CAMPBELL
SCIENTIFIC's shipping address is:
CAMPBELL SCIENTIFIC, INC.
RMA#_____
815 West 1800 North
Logan, Utah 84321-1784
CAMPBELL SCIENTIFIC, INC. does not accept collect calls.
Non-warranty products returned for repair should be accompanied by a
purchase order to cover the repair.
815 W. 1800 N.
Logan, UT 84321-1784
USA
Phone [phone]
FAX [phone]
www.campbellsci.com
Campbell Scientific Canada Corp.
11564 -149th Street
Edmonton, Alberta T5M 1W7
CANADA
Phone [phone]
FAX [phone]
Campbell Scientific Ltd.
Campbell Park
80 Hathern Road
Shepshed, Loughborough
LE12 9GX, U.K.
Phone [phone]
FAX [phone]

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i
HFP01SC Table of Contents
1. General Description....................................................1
2. Sensor Specifications ................................................1
3. Installation...................................................................2
4. Wiring ..........................................................................4
5. Example Programs .....................................................4
6. Soil Heat Flux and Storage.......................................23
7. Maintenance..............................................................24
8. In-Situ Calibration Theory........................................24
9. References ................................................................25
Figures
1. Placement of Heat Flux Plates....................................................................2
2. HFP01SC Plate ...........................................................................................3
Tables
1. Datalogger Connections for a Single-Ended Measurement........................3
2. Datalogger Connections for a Differential Measurement...........................4
3. Wiring for Example 1.................................................................................5
4. Wiring for Example 2.................................................................................9
5. Wiring for Example 3...............................................................................14
6A. Wiring for Example 4 ............................................................................17
6B. Wiring for Example 4 ............................................................................17
7. Hukseflux and Campbell Scientific Variable Names................................24

1
Model HFP01SC
Self-Calibrating Soil Heat Flux Plate
1. General Description
The HFP01SC Soil Heat Flux plate consists of a thermopile and a film heater.
The thermopile measures temperature gradients across the plate. During the in-
situ field calibration, the film heater is used to generate a heat flux through the
plate. The amount of power used to generate the calibration heat flux is
measured by the datalogger. Each plate is individually calibrated, at the
factory, to output flux.
In order to measure soil heat flux at the surface, several HFP01SCs are used to
measure the soil heat flux at a depth of eight centimeters. A TCAV Averaging
Soil Thermocouple is used to measure the temporal change in temperature of
the soil layer above the HFP01SC. Finally, a CS616 Water Content
Reflectometer is used to measure the soil water content. The temporal change
in soil temperature and soil water content are used to compute the soil storage
term.
The -L option on the model HFP01SC Soil Heat Flux plate (HFP01SC-L)
indicates that the cable length is user specified. The HFP01SC-L has two
cables, the first cable is the signal output cable and the second is the heater
input cable. Two analog inputs are required to measure the HFP01SC-L This
manual refers to the sensor as the HFP01SC.
2. Specifications
Operating Temperature: -30°C to +70°C
Storage Temperature: -30°C to +70°C
Plate Thickness: 5 mm (0.2 in.)
Plate Diameter: 80 mm (3.15 in.)
Power Consumption
During Self Calibration: 1.3 W (108 mA @ 12 vdc)
Sensor: thermopile and film heater
Measurement Range: ±100 W m-2
Signal Range (nominal): ±5 mV for the above range (sensor), 0 to 2 V
(while the film heater is powered)
Accuracy: ±3% of reading
Sensitivity (nominal): 67 µV W-1 m-2
Sensor Resistance (nominal): 2 Ω
Heater Resistance (nominal): 100 Ω
Current Sensing Resistor: 10Ω1% 0.25 W
Thermal Conductivity: 0.8 W m-1 K-1

Model HFP01SC Self-Calibrating Soil Heat Flux Plate
2
2 cm
6 cm
8 cm
Ground Surface
Up to 1 m
2.5 cm
FIGURE 1. Placement of Heat Flux Plates
3. Installation
The HFP01SC Soil Heat Flux plates, the TCAV Averaging Soil Temperature
probes, and the CS616 Water Content Reflectometer are installed as shown in
Figure 1.
The location of the heat flux plates and thermocouples should be chosen to be
representative of the area under study. If the ground cover is extremely varied,
it may be necessary to have additional sensors to provide a valid spatial average
of soil heat flux.
Use a small shovel to make a vertical slice in the soil. Excavate the soil to one
side of the slice. Keep this soil intact so that is can be replaced with minimal
disruption.
The sensors are installed in the undisturbed face of the hole. Measure the
sensor depths from the top of the hole. With a small knife, make a horizontal
cut eight centimeters below the surface into the undisturbed face of the hole.
Insert the heat flux plate into the horizontal cut.
Install the HFP01SC in the soil such that the side with the text
“this side up” is facing the sky.
NOTE
Partial emplacement of the HFP01SC and the TCAV
sensors is shown for illustration purposes. All sensors
must be completely inserted into the soil face before
the hole is backfilled.

Model HFP01SC Self-Calibrating Soil Heat Flux Plate
3
In order for the HFP01SC to make quality soil heat flux
measurements, the plate must be in full contact with the
soil.
Never run the sensors leads directly to the surface. Rather, bury the sensor
leads a short distance back from the hole to minimized thermal conduction on
the lead wire. Replace the excavated soil back into it original position after all
the sensors are installed.
H
U
K
S
E
F
L
U
X
H
E
A
T
F
L
U
X
P
L
A
T
E
FIGURE 2. HFP01SC Plate
TABLE 1. Datalogger Connections for a Single-Ended Measurement
Description Color CR10X CR23X & CR5000
Sensor Signal White Single-Ended Input Single-Ended Input
Sensor Signal Reference Green AG
Shield Clear G
Heater Resistor Signal Yellow Single-Ended Input Single-Ended Input
Heater Resistor Signal
Reference Purple AG
Shield Clear G
Power Red SW12 SW12
Power Reference Black G G
External Power Control jumper wire SW12-CTRL to
Control Port External Power Control Not Needed
CAUTION
Signal (White)
Signal Reference (Green)
Shield (Clear)
Heater Resistor Signal (Yellow)
Heater Resistor Signal Reference (Purple)
Shield (Clear)
Power (Red)
Power Reference (Black)

Model HFP01SC Self-Calibrating Soil Heat Flux Plate
4
TABLE 2. Datalogger Connections for a Differential Measurement
Description Color CR10(X) CR23X & CR5000
Sensor Signal White Differential Input (H) Differential Input (H)
Sensor Signal Reference Green Differential Input (L) Differential Input (L)
Shield Clear G
Heater Resistor Signal Yellow Differential Input (H) Differential Input (H)
Heater Resistor Signal
Reference Purple Differential Input (L) Differential Input (L)
Shield Clear G
Power Red SW12 SW12
Power Reference Black G G
External Power Control Jumper wire SW12-CTRL to
Control Port External Power Control Not Needed
4. Wiring
Connections to Campbell Scientific dataloggers are given in Tables 1 and 2.
The output of the HFP01SC can be measured using a single-ended analog
measurement (Instruction 1 or VoltSE()), however, a differential analog
measurement (Instruction 2 or VoltDiff()) is recommended.
The wiring convention is that the white wire is positive with respect to the
green wire, when energy is flowing through the transducer from the side with
the text “this side up” to the other side.
The switched 12 vdc port on the black CR10X wiring panel can
source enough current to calibrate five HFP01SC plates; the
CR23X and CR5000 switched 12 vdc port can be used to
calibrate four HFP01SC plates. If additional HFP01SC plates
are needed an external relay is required to power the additional
plates (see example 4).
For dataloggers without a SW12V output (CR7X, 21X and CR10), a relay
(A21REL-12) is required for the in-situ calibration (see Example 4).
5. Example Programs
This section is for users who write their own datalogger 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 use Short Cut.
The HFP01SC has a nominal calibration of 15 W m-2 mV-1. Each sensor is
accompanied by a calibration certificate. Each sensor also has a unique
calibration label on it. The label is located on the pigtail end of the sensor
leads.
NOTE

Model HFP01SC Self-Calibrating Soil Heat Flux Plate
5
TABLE 3. Wiring for Example 1
Description Color CR10(X)
Sensor Signal White 1H
Sensor Signal Reference Green AG
Shield Clear G
Heater Resistor Signal Yellow 1L
Heater Resistor Signal Reference Purple AG
Shield Clear G
Power Red SW12
Power Reference Black G
External Power Control jumper wire SW12-CTRL to C8
Example 1. Sample CR10(X) Program Using a Single-Ended Measurement Instruction
;{CR10X}
;
*Table 1 Program
01: 1 Execution Interval (seconds)
;Measure HFP01SC on smaller range.
;
1: Volt (SE) (P1)
1: 1 Reps
2: 22 7.5 mV 60 Hz Rejection Range
3: 1 SE Channel
4: 2 Loc [ shf_mV ]
5: 1 Mult
6: 0 Offset
;Measure HFP01SC on larger range.
;
2: Volt (SE) (P1)
1: 1 Reps
2: 23 25 mV 60 Hz Rejection Range
3: 1 SE Channel
4: 8 Loc [ shf_mV_a ]
5: 1 Mult
6: 0 Offset
;Load in the factory calibration.
;
3: If (X<=>F) (P89)
1: 3 X Loc [ cal ]
2: 1 =
3: 0 F
4: 30 Then Do

Model HFP01SC Self-Calibrating Soil Heat Flux Plate
6
;Factory calibration in W/(m^2 mV) = 1000/sensitivity.
;
4: Z=F (P30)
1: 1 F ; <- Enter the unique calibration here
2: 0 Exponent of 10
3: 3 Z Loc [ cal ]
5: End (P95)
;Use data from the larger measurement range.
;
6: If (X<=>F) (P89)
1: 2 X Loc [ shf_mV ]
2: 4 <
3: -99990 F
4: 30 Then Do
7: Z=X (P31)
1: 8 X Loc [ shf_mV_a ]
2: 2 Z Loc [ shf_mV ]
8: End (P95)
;Apply custom calibration to the raw soil heat flux measurement.
;
9: Z=X*Y (P36)
1: 2 X Loc [ shf_mV ]
2: 3 Y Loc [ cal ]
3: 1 Z Loc [ shf ]
;Output data.
;
10: If time is (P92)
1: 0 Minutes (Seconds --) into a
2: 20 Interval (same units as above)
3: 10 Set Output Flag High (Flag 0)
11: Real Time (P77)
1: 0110 Day,Hour/Minute (midnight = 0000)
12: Resolution (P78)
1: 1 High Resolution
;Do not include the calibration data in the soil heat flux.
;
13: If Flag/Port (P91)
1: 18 Do if Flag 8 is High
2: 19 Set Intermed. Proc. Disable Flag High (Flag 9)
14: Average (P71)
1: 1 Reps
2: 1 Loc [ shf ]
15: Do (P86)
1: 29 Set Intermed. Proc. Disable Flag Low (Flag 9)

Model HFP01SC Self-Calibrating Soil Heat Flux Plate
7
16: Sample (P70)
1: 1 Reps
2: 3 Loc [ cal ]
;Add other processing here.
;Call calibration routine.
;
17: Do (P86)
1: 8 Call Subroutine 8
*Table 2 Program
02: 0 Execution Interval (seconds)
*Table 3 Subroutines
;Calibration routine.
;
1: Beginning of Subroutine (P85)
1: 8 Subroutine 8
;Perform in-situ calibratation.
;
2: If time is (P92)
1: 1 Minutes (Seconds --) into a
2: 180 Interval (same units as above)
3: 30 Then Do
3: Z=X (P31)
1: 2 X Loc [ shf_mV ]
2: 4 Z Loc [ mV_0 ]
;Begin heating for calibration.
;
4: Do (P86)
1: 48 Set Port 8 High
;Used to filter data during and after calibration.
;
5: Do (P86)
1: 18 Set Flag 8 High
6: End (P95)
;End site calibration three minutes after calibration started.
;
7: If time is (P92)
1: 4 Minutes (Seconds --) into a
2: 180 Interval (same units as above)
3: 30 Then Do

Model HFP01SC Self-Calibrating Soil Heat Flux Plate
8
;Measure voltage across current shunt resistor (10 ohm 1% 0.25 W 50
;ppm/deg C) during calibration. This measurement is used to
;compute power.
;
8: Volt (SE) (P1)
1: 1 Reps
2: 25 2500 mV 60 Hz Rejection Range
3: 2 SE Channel
4: 7 Loc [ V_Rf ]
5: .001 Mult
6: 0 Offset
9: Z=X (P31)
1: 2 X Loc [ shf_mV ]
2: 5 Z Loc [ mV_180 ]
;Turn off the soil heat flux plate heater.
;
10: Do (P86)
1: 58 Set Port 8 Low
11: End (P95)
;Stop filtering data.
;
12: If time is (P92)
1: 39 Minutes (Seconds --) into a
2: 180 Interval (same units as above)
3: 30 Then Do
13: Do (P86)
1: 28 Set Flag 8 Low
;Compute in-situ calibration.
;
14: Z=X (P31)
1: 2 X Loc [ shf_mV ]
2: 6 Z Loc [ mV_end ]
15: Z=X*Y (P36)
1: 7 X Loc [ V_Rf ]
2: 7 Y Loc [ V_Rf ]
3: 3 Z Loc [ cal ]
16: Z=X*F (P37)
1: 3 X Loc [ cal ]
2: 128.7 F
3: 3 Z Loc [ cal ]
17: Z=X+Y (P33)
1: 4 X Loc [ mV_0 ]
2: 6 Y Loc [ mV_end ]
3: 9 Z Loc [ work ]
18: Z=X*F (P37)
1: 9 X Loc [ work ]
2: .5 F
3: 9 Z Loc [ work ]

Model HFP01SC Self-Calibrating Soil Heat Flux Plate
9
19: Z=X-Y (P35)
1: 9 X Loc [ work ]
2: 5 Y Loc [ mV_180 ]
3: 9 Z Loc [ work ]
20: Z=ABS(X) (P43)
1: 9 X Loc [ work ]
2: 9 Z Loc [ work ]
21: Z=X/Y (P38)
1: 3 X Loc [ cal ]
2: 9 Y Loc [ work ]
3: 3 Z Loc [ cal ]
22: End (P95)
23: End (P95)
End Program
-Input Locations-
1 shf
2 shf_mV
3 cal
4 mV_0
5 mV_180
6 mV_end
7 V_Rf
8 shf_mV_a
9 work
TABLE 4. Wiring for Example 2
Description Color CR23X
Sensor Signal White 9H
Sensor Signal Reference Green 9L
Shield Clear
Heater Resistor Signal Yellow 10H
Heater Resistor Signal Reference Purple 10L
Shield Clear
Power Red SW12
Power Reference Black G

Model HFP01SC Self-Calibrating Soil Heat Flux Plate
10
Example 2. Sample CR23X Program Using a Differential Measurement Instruction
;{CR23X}
;
*Table 1 Program
01: 1 Execution Interval (seconds)
;Measure HFP01SC on smaller range.
;
1: Volt (Diff) (P2)
1: 1 Reps
2: 21 10 mV, 60 Hz Reject, Slow Range
3: 9 DIFF Channel
4: 2 Loc [ shf_mV ]
5: 1 Mult
6: 0 Offset
;Measure HFP01SC on larger range.
;
2: Volt (Diff) (P2)
1: 1 Reps
2: 25 5000 mV, 60 Hz Reject, Fast Range
3: 9 DIFF Channel
4: 8 Loc [ shf_mV_a ]
5: 1 Mult
6: 0 Offset
;Load in the factory calibration.
;
3: If (X<=>F) (P89)
1: 3 X Loc [ cal ]
2: 1 =
3: 0 F
4: 30 Then Do
;Factory calibration in W/(m^2 mV) = 1000/sensitivity.
;
4: Z=F (P30)
1: 1 F ; <- Enter the unique calibration here
2: 0 Exponent of 10
3: 3 Z Loc [ cal ]
5: End (P95)
;Use data from the larger measurement range.
;
6: If (X<=>F) (P89)
1: 2 X Loc [ shf_mV ]
2: 4 <
3: -99990 F
4: 30 Then Do
7: Z=X (P31)
1: 8 X Loc [ shf_mV_a ]
2: 2 Z Loc [ shf_mV ]
8: End (P95)

Model HFP01SC Self-Calibrating Soil Heat Flux Plate
11
;Apply custom calibration to the raw soil heat flux measurement.
;
9: Z=X*Y (P36)
1: 2 X Loc [ shf_mV ]
2: 3 Y Loc [ cal ]
3: 1 Z Loc [ shf ]
;Output data.
;
10: If time is (P92)
1: 0 Minutes (Seconds --) into a
2: 20 Interval (same units as above)
3: 10 Set Output Flag High (Flag 0)
11: Real Time (P77)
1: 0110 Day,Hour/Minute (midnight = 0000)
12: Resolution (P78)
1: 1 High Resolution
;Do not include that calibration data in the soil heat flux.
;
13: If Flag/Port (P91)
1: 18 Do if Flag 8 is High
2: 19 Set Intermed. Proc. Disable Flag High (Flag 9)
14: Average (P71)
1: 1 Reps
2: 1 Loc [ shf ]
15: Do (P86)
1: 29 Set Intermed. Proc. Disable Flag Low (Flag 9)
16: Sample (P70)
1: 1 Reps
2: 3 Loc [ cal ]
;Add other processing here.
;Call calibration routine.
;
17: Do (P86)
1: 8 Call Subroutine 8
*Table 2 Program
02: 0 Execution Interval (seconds)
*Table 3 Subroutines
;Calibration routine.
;
1: Beginning of Subroutine (P85)
1: 8 Subroutine 8
;Perform in-situ calibratation.
;

Model HFP01SC Self-Calibrating Soil Heat Flux Plate
12
2: If time is (P92)
1: 1 Minutes (Seconds --) into a
2: 180 Interval (same units as above)
3: 30 Then Do
3: Z=X (P31)
1: 2 X Loc [ shf_mV ]
2: 4 Z Loc [ mV_0 ]
;Begin heating for calibration.
;
4: Do (P86)
1: 49 Turn On Switched 12V
;Used to filter data during and after calibration.
;
5: Do (P86)
1: 118 Set Flag 18 High
6: End (P95)
;End site calibration three minutes after calibration started.
;
7: If time is (P92)
1: 4 Minutes (Seconds --) into a
2: 180 Interval (same units as above)
3: 30 Then Do
;Measure voltage across current shunt resistor during calibration.
;This measurement is used to compute power.
;
8: Volt (Diff) (P2)
1: 1 Reps
2: 25 5000 mV, 60 Hz Reject, Fast Range
3: 10 DIFF Channel
4: 7 Loc [ V_Rf ]
5: .001 Mult
6: 0 Offset
9: Z=X (P31)
1: 2 X Loc [ shf_mV ]
2: 5 Z Loc [ mV_180 ]
;Turn off the soil heat flux plate heater.
;
10: Do (P86)
1: 59 Turn Off Switched 12V
11: End (P95)
;Stop filtering data.
;
12: If time is (P92)
1: 39 Minutes (Seconds --) into a
2: 180 Interval (same units as above)
3: 30 Then Do

Model HFP01SC Self-Calibrating Soil Heat Flux Plate
13
13: Do (P86)
1: 218 Set Flag 18 Low
;Compute in-situ clibration.
;
14: Z=X (P31)
1: 2 X Loc [ shf_mV ]
2: 6 Z Loc [ mV_end ]
15: Z=X*Y (P36)
1: 7 X Loc [ V_Rf ]
2: 7 Y Loc [ V_Rf ]
3: 3 Z Loc [ cal ]
16: Z=X*F (P37)
1: 3 X Loc [ cal ]
2: 128.7 F
3: 3 Z Loc [ cal ]
17: Z=X+Y (P33)
1: 4 X Loc [ mV_0 ]
2: 6 Y Loc [ mV_end ]
3: 9 Z Loc [ work ]
18: Z=X*F (P37)
1: 9 X Loc [ work ]
2: .5 F
3: 9 Z Loc [ work ]
19: Z=X-Y (P35)
1: 9 X Loc [ work ]
2: 5 Y Loc [ mV_180 ]
3: 9 Z Loc [ work ]
20: Z=ABS(X) (P43)
1: 9 X Loc [ work ]
2: 9 Z Loc [ work ]
21: Z=X/Y (P38)
1: 3 X Loc [ cal ]
2: 9 Y Loc [ work ]
3: 3 Z Loc [ cal ]
22: End (P95)
23: End (P95)
End Program
-Input Locations-
1 shf
2 shf_mV
3 cal
4 mV_0
5 mV_180
6 mV_end
7 V_Rf
8 shf_mV_a
9 work

Model HFP01SC Self-Calibrating Soil Heat Flux Plate
14
TABLE 5. Wiring for Example 3
Description Color CR5000
Sensor Signal #1 White 11H
Sensor Signal Reference #1 Green 11L
Shield #1 Clear
Sensor Signal #2 White 12H
Sensor Signal Reference #2 Green 12L
Shield #2 Clear
Sensor Signal #3 White 13H
Sensor Signal Reference #3 Green 13L
Shield #3 Clear
Sensor Signal #4 White 14H
Sensor Signal Reference #4 Green 14L
Shield #4 Clear
Heater Resistor Signal #1 Yellow 17H
Heater Resistor Signal Reference #1 Purple 17L
Shield #1 Clear
Power #1 Red SW12
Power Reference #1 Black G
Heater Resistor Signal #2 Yellow 18H
Heater Resistor Signal Reference #2 Purple 18L
Shield #2 Clear
Power #2 Red SW12
Power Reference #2 Black G
Heater Resistor Signal #3 Yellow 19H
Heater Resistor Signal Reference #3 Purple 19L
Shield #3 Clear
Power #3 Red SW12
Power Reference #3 Black G
Heater Resistor Signal #4 Yellow 20H
Heater Resistor Signal Reference #4 Purple 20L
Shield #4 Clear
Power #4 Red SW12