The Hygrometer is used to measure the degree of humidity in the air near this unit. The amount of humidity is measured by transferring the differences in length from a humidity sensitive material to a pointer on the scale. A hygrometer should be calibrated at least once per year. You can do this by soaking a towel with water. Put the hygrometer for at least 20 minutes on this towel. The hygrometer should now indicate 97-98%. If the hygrometer shows some other value, it can be set to 97% on the back of the hygrometer using a small screwdriver. Please do not use force when setting the hygrometer!
Barometer Calibration
As with all other barometers a tendency barometer has to be set for the local altitude if your location is more than about 150 feet above sea level. Check with your town or city hall for your altitude if you don’t know it.
Put the needle stub onto the syringe if it is not already installed and remove the protective cover over the needle stub.
Carefully slide the thin plastic tube over the needle stub.
When the air pressure is 1013 millibars or 29.92 inches of mercury, remove as much fluid as needed to make both red and blue fluid level equal with each other. A difference of 1 dash on the Celsius scale between both fluid levels represents 0.16 inches of mercury pressure. (Note: You can find your local air pressure by watching TV such as The Weather Channel, or going onto the internet to http://www.weather.com/ or other such weather web sites.)
The tendency barometer is now calibrated
|
Problem |
|
|
Air bubble in the
left hand red
fluid |
Use the thin
plastic tube to prick through the air bubble |
|
Air bubble in the
right hand red fluid |
Put the
instrument upright in the refrigerator for approx. 1 hour. The air bubble will
disappear. Or, attach the rubber tube and rubber plug to the end of
the open barometer tube. Squeeze the rubber tube until the
gaps are gone, then remove the rubber tube and plug. |
|
Barometer not
working Properly |
You are at a
higher altitude than the one the instrument is calibrated for. |
|
Hygrometer not
working properly |
Calibrate the
hygrometer. (see
hygrometer section) |
|
In case of glass
breakage. |
Try to collect
the colored fluid and all pieces of glass in a container. The red
fluid consists of red
pigment in oil, the blue fluid is alcohol. If the red fluid is spilled,
remove it with paper towels.
Rinse the stained places |
|
Air bubble in
blue thermometer fluid |
Heat the
thermometer tube carefully using a hair dryer on low setting |
|
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DD Barometer Main Page
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