User manual

USB DrDAQ User's Guide 23
Copyright © 2011 Pico Technology Ltd. All rights reserved. usbdrdaq.en
Preparation
The standard solutions may be harmful to your skin, eyes or when
swallowed. Take all necessary precautions to avoid contact when
preparing and using the standard solutions.
Prepare your standard solutions before you start the calibration procedure. Follow the
instructions given by the manufacturers of the solutions you are using. A slurry of
undissolved chemical in your solution should improve the stability. Make sure that all
the containers you use for preparation are thoroughly clean before use as
contamination of the solution will alter the humidity. Do not use tap water to make
up the solution as this is insufficiently pure: use distilled and de-ionized water. Allow
time for the solution to reach room temperature before use. Always use fresh
solutions to ensure that the chemicals have not become contaminated or degraded.
Allow the standard solutions and other equipment to reach the same temperature
(ideally 20 C) before you start.
Measure humidity
1. Set up the equipment
2. Clean the equipment. Make especially sure that the test container is clean; rinse it
out with distilled water.
3. Put the test container into your insulated box.
The standard solutions may be harmful to your skin, eyes or when
swallowed. Take all necessary precautions to avoid contact when
preparing and using the standard solutions.
Caution: It is very important that the standard solution does not enter the case of the
DD101. The solution may damage the electrical components of the sensor.
1. Put some of the standard solution into the test container. The solution should
occupy about 5% of the volume of your container.
2. Put the stand into the test container. The stand should give you a clear platform
above the level of the liquid. Do not allow any standard solution to spill on to the
top of your stand.
3. Put the DD101 and DD100 sensors onto the stand. [If you are using a calibrated
reference put this in too.]
4. Connect the DD101 and DD100 sensors to USB DrDAQ.
5. Take your measurements
6. Start the PicoLog Recorder software for USB DrDAQ. Make sure USB DrDAQ is
receiving readings from the sensors on Ext 1 or Ext 2.
7. Seal the test container and close the insulated box (if you are using a fan, start
the fan).
8. Record the temperature and humidity inside the test container for at least one
hour. You must wait for the temperature to stabilise and the DD101 to provide
correct readings. This may take up to eight hours if you have used a large
container.
9. Check that the USB DrDAQ plots for temperature and humidity have been
constant over the last few minutes of your measurements. [If you are using a
calibrated reference take a reading of this now. Take care to minimise the
changes in the setup so that the reading does not change significantly.]
10. Save your results.
11. Dispose of the solution as recommended by the supplier of the chemical.
Remember to take adequate precautions to protect your skin and eyes when
disposing of the chemicals.
12. Do the measurements again for the other standard solutions. You should end up
with a set of recorded measurements for each standard solution. Remember that
you must provide at least two fixed points for calibration of the sensor.