Campbell HMP45C Instruction Manual
  1. Manuals
  2. Brands
  3. Campbell Manuals
  4. Measuring Instruments
  5. HMP45C
  6. Instruction manual

Campbell HMP45C Instruction Manual

Temperature and relative humidity probe
Hide thumbs
Table of Contents

Advertisement

Quick Links

Download this manual
Model HMP45C Temperature
and Relative Humidity Probe
Revision: 2/07
Copyright © 1990 - 2007
Campbell Scientific Australia Pty Ltd

Advertisement

Table of Contents
loading
Need help?

Need help?

Do you have a question about the HMP45C and is the answer not in the manual?

Questions and answers

Related Manuals for Campbell HMP45C

Summary of Contents for Campbell HMP45C

  • Page 1 Model HMP45C Temperature and Relative Humidity Probe Revision: 2/07 Copyright © 1990 - 2007 Campbell Scientific Australia Pty Ltd...
  • Page 2 Warranty and Assistance The MODEL HMP45C TEMPERATURE AND RELATIVE HUMIDITY PROBE is warranted by CAMPBELL SCIENTIFIC AUSTRALIA Pty Ltd. 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.

  • Page 3: Table Of Contents

    8. Sensor Maintenance......14 9. Troubleshooting ........15 10. References .........15 Figures 3-1. HMP45C and 41003-5 Radiation Shield on a Tripod Mast ....4 3-2. HMP45C and 41003-5 Radiation Shield on a CM200 Series Crossarm.4 Tables 1-1. Recommended Lead Lengths.............. 1 4-1. Connections for Single-Ended Measurements........5 4-2.

  • Page 4: General Description

    12 volts. Users with these dataloggers can power the sensor continuously or purchase the model SW12V to switch power. Lead length for the HMP45C is specified when the sensor is ordered. Table 1-1 gives the recommended lead length for mounting the sensor at the top of the tripod/tower with a 2 foot crossarm.

  • Page 5: Specifications

    Model HMP45C Temperature and Relative Humidity Probe 2. Specifications Operating Temperature: -40°C to +60°C Storage Temperature: -40°C to +80°C Probe Length: 25.4 cm (10 in.) Probe Body Diameter: 2.5 cm (1 in.) Filter: 0.2 μm Teflon membrane Filter Diameter: 1.9 cm (0.75 in.) Power Consumption: <4 mA @ 12 V...

  • Page 6: Installation

    • UV resistant cable ties • small pair of diagonal-cutting pliers The HMP45C must be housed inside a radiation shield when used in the field. The 41003-5 Radiation shield has a U-bolt for attaching the shield to tripod mast / tower leg (Figure 3-1), or CM200 series crossarm (Figure 3-2). The radiation shield ships with the U-bolt configured for attaching the shield to a vertical pipe.

  • Page 7: Hmp45C And 41003-5 Radiation Shield On A Tripod Mast

    Model HMP45C Temperature and Relative Humidity Probe 41003-5 Split Nut U-bolt FIGURE 3-1. HMP45C and 41003-5 Radiation Shield on a Tripod Mast CM200 Series Crossarm FIGURE 3-2. HMP45C and 41003-5 Radiation Shield on a CM200 Series Crossarm...

  • Page 8: Wiring

    Model HMP45C Temperature and Relative Humidity Probe 4. Wiring Connections to Campbell Scientific dataloggers are given in Tables 4-1 through 4-3. The probe can be measured by two single-ended or differential analog input channels. When measuring the HMP45C with single-ended...

  • Page 9: Example Programs

    Scientific’s Short Cut Program Builder software. You do not need to read this section to use Short Cut. The temperature and relative humidity signals from the HMP45C can be measured using a single-ended analog measurement or a differential analog measurement.

  • Page 10: Calibration For Temperature

    Model HMP45C Temperature and Relative Humidity Probe The HMP45C output scale is 0 to 1000 millivolts for the temperature range of -40°C to +60°C and for the relative humidity range of 0 to 100%. Tables 5-1 and 5-2 provide calibration information for temperature and relative humidity TABLE 5-1.
  • Page 11 Public AirTC Public RH DataTable(Temp_RH,True,-1) DataInterval(0,60,Min,0) Average(1,AirTC,IEEE4,0) Sample(1,RH,IEEE4) EndTable BeginProg Scan(1,Sec,1,0) 'HMP45C Temperature & Relative Humidity Sensor measurements AirTC and RH: Portset (1 ,1 ) Delay(0,150,mSec) VoltSE(AirTC,1,mV2500,2,0,0,_60Hz,0.1,-40.0) VoltSE(RH,1,mV2500,1,0,0,_60Hz,0.1,0) Portset (1 ,0 ) If RH>100 And RH<108 Then RH=100 CallTable(Temp_RH) NextScan...

  • Page 12: Long Lead Lengths

    There will be a voltage drop along those leads because the wire itself has resistance. The HMP45C draws approximately 4 mA when it is powered. The wire used in the HMP45C (P/N 9721) has resistance of 27.7 Ω/1000 feet. Since the signal reference and the power ground are both connected to ground...
  • Page 13 Public RH DataTable(Temp_RH,True,-1) DataInterval(0,60,Min,0) Average(1,AirTC,IEEE4,0) Sample(1,RH,IEEE4) EndTable BeginProg Scan(1,Sec,1,0) 'HMP45C Temperature & Relative Humidity Sensor measurements AirTC and RH: Portset (1 ,1 ) Delay(0,150,mSec) VoltDiff (AirTC,1,mV2500,2,True,0,_60Hz,0.1,-40) VoltDiff (RH,1,mV2500,1,True,0,_60Hz,0.1,0) Portset (1 ,0 ) If RH>100 And RH<108 Then RH=100 CallTable(Temp_RH) NextScan...
  • Page 14 Model HMP45C Temperature and Relative Humidity Probe CR10(X) Program using Differential Measurement Instructions Using 12V on Datalogger ;Turn the HMP45C on. 01: Do (P86) ;Orange wire (C1) 1: 41 Set Port 1 High ;Pause 150 mSec before making measurements so the ;probe can stabilize on true readings.

  • Page 15: Absolute Humidity

    Model HMP45C Temperature and Relative Humidity Probe 7. Absolute Humidity The HMP45C measures the relative humidity. Relative humidity is defined by the equation below: ∗ where RH is the relative humidity, e is the vapor pressure in kPa , and e is the saturation vapor pressure in kPa.
  • Page 16 DataTable(Temp_RH,True,-1) DataInterval(0,60,Min,0) Average(1,AirTC,IEEE4,0) Sample(1,RH,IEEE4) Sample(1,e_kPa,IEEE4) EndTable BeginProg Scan(1,Sec,1,0) 'HMP45C Temperature & Relative Humidity Sensor measurements AirTC and RH: Portset (1,1) Delay(0,150,mSec) VoltSE(AirTC,1,mV2500,2,0,0,_60Hz,0.1,-40.0) VoltSE(RH,1,mV2500,1,0,0,_60Hz,0.1,0) Portset (1,0) If RH>100 And RH<108 Then RH=100 'Calculate Vapor Pressure 'Convert RH percent to RH Fraction RH_Frac = RH * 0.01...

  • Page 17: Sensor Maintenance

    4 Z Loc [ e 8. Sensor Maintenance The HMP45C Probe requires minimal maintenance. Check monthly to make sure the radiation shield is free from debris. The black screen at the end of the sensor should also be checked for contaminates.

  • Page 18: Chemical Tolerances Of Hmp45C

    Weak Acids 100 to 1000 Bases 10,000 to 100,000 Recalibrate the HMP45C annually. Obtain an RMA number before returning the HMP45C to Campbell Scientific for recalibration. 9. Troubleshooting Symptom: -9999, NAN, -40 deg C, or 0 % relative humidity 1. Check that the sensor is wired to the correct excitation and analog input channels as specified by the measurement instructions.

Table of Contents