SI-111-PWInfrared Radiometer for Prewired Enclosures

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1. What maintenance is required for the SI-111?

   The window in the Apogee infrared sensor is inset and protected, but it can become partially blocked in three ways:

   1. Spiders can make a nest in the entrance. Campbell Scientific recommends using a cotton swab to apply a spider repellent around the entrance to the aperture. Do not apply the repellent, however, to the sensor window itself.
   2. Calcium deposits can accumulate on the window if irrigation water sprays up on the head. These deposits typically leave a thin white film on the surface, which can be removed with a diluted acid, such as vinegar. Calcium deposits cannot be removed with solvents such as alcohol or acetone.
   3. In windy environments, dust and dirt can be deposited in the aperture. The aperture can be cleaned with deionized water, rubbing alcohol, or in extreme cases, acetone.

   Clean the inner threads and sensor window using a cotton swab dipped in the appropriate solvent. For additional cleaning information,see the Maintenance section of theinstruction manual.

2. Does the SI-111 need to be protected from short-wave radiation?

   There are two accuracy specifications listed for the SI-111:

   • One for when the difference in the target and sensor body temperatures is less than 20°C (more accurate)
   • One for when the difference in the target and sensor body temperatures is greater than 20°C (less accurate)

   Using a radiation shield with the sensor helps keep the sensor body temperature in close approximation to the ambient air temperature. Ultimately, the need to protect the sensor from short-wave radiation is dependent on what is being measured and under what conditions. For example, Campbell Scientific recommends using a radiation shield for canopy measurements.

3. How often should the SI-111 be calibrated?

   As a general recommendation, recalibration should be done every two years.

4. What is the maximum cable length that can be ordered for the SI-111, and is there a loss of accuracy with long cable lengths?

   The SI-111 has been successfully calibrated with a maximum cable length of 100 m without a loss in accuracy. Ideally, the sensor is calibrated with the overall cable length already configured. Our tests have shown, however, that adding a few meters of cable in the field has a negligible effect on the calibration, provided the measurement device has significantly high input impedance, such as with the CR1000.

5. What type of surfaces can be measured with the SI-111? Can it be used to measure the surface temperature of water or snow?

   si - 111可用于测量各种of surfaces, including water and snow. When measuring objects with low emissivity, however, it is particularly important to apply corrections to the measurement.

6. If a sensor automatically ships with a calibration sheet, what information is included on it?

   信息包含在一个测量仪器的标定ion sheet differs with each sensor. For some sensors, the sheet contains coefficients necessary to program a data logger. For other sensors, the calibration sheet is a pass/fail report.

7. If the original calibration sheet gets lost, can another copy be requested?

   This depends on the information contained in the calibration sheet:

   • If the calibration sheet contains coefficient information, Campbell Scientific keeps a copy, and a replacement copy can be requested.
   • If the calibration sheet does not contain coefficients, Campbell Scientific does not keep a copy. It may be possible to contact the original manufacturer for a replacement copy.