Bath, Pennsylvania - U.S.A.
Charles A. Giannetta
Meteorologist
Professor
Picture of a "Sling Psychrometer" used to measure the wet and dry bulb
temperature for determining the relative humidity.
A"Sling Psycrometer" is an instrument which consists of two idental thermometers
mounted side by side. One thermometer is covered with a muslin cloth on the bottom.
The thermometers are mounted on a bracket which is attached to a swivel handel.
The one thermometer is called "Dry Bulb" and the other with the muslin cloth
is called a "Wet Bulb". The thermometers are then twirled through the air
to obtain the wet and dry bulb readings. As the thermometers are being twirled the air
is passing by both thermometers.
The dry bulb will indicate the air temperature and the wet bulb will indicate the
temperature produced by the cooling effect of the water being evaporated by the air
passing over the muslin cloth. This difference of temperature from the dry bulb to
the wet bulb is called: "THE WET BULB DEPRESSION".
"EXAMPLE"
Dry Bulb Temp. = 80
Wet Bulb Temp. = 70 The difference is 10.
This is called the: "THE WET BULB DEPRESSION".
The drier the air the larger the wet bulb depression. Should the air be saturated,
100 % humidity, the wet and dru bulb temperatures will be the same.
There are many types of psychrometers. Each require the use of two thermometers,
one dry and the other wet. Air must pass over both thermometers. In many instruments
this is done by a motor driven fan. Many times the sensor units are some distance
from the from the temperatures indicators. In these types the sensor unit and
temperature indicators are connected with electrical wires and have digital readouts.
How to construct a "Sling Psychrometer"
"Materials Required"
1. You will need two identical thermometers which can be
bought in any hardware store for a few dollars.
2. Some muslin cloth.
3. Some string.
4. A small piece of wood to mount the thermometers onto.
5. A short piece of small chain.
6. A short piece of a broom stick which will used as the
handle to twril the "Sing Psychrometer"
Estimate Cost: About $5.00 to $15.00 depending
how much the thermometers cost.
Mount the two thermometers back to back on the small
piece of wood. Attach the short piece of chain to the top
end of the samll piece of wood, then attach the chain to
the small piece of broom stick which is used as the
handel to twirl the thermometers. Also attach a piece
of muslin cloth to the bottom of one of the thermpmeters.
© 1998 - 2013 Charles A. Giannetta
BACK TO MAIN PAGE
Charles A. Giannetta |
|---|
Meteorologist
Professor
Picture of a "Sling Psychrometer" used to measure the wet and dry bulb
temperature for determining the relative humidity.
A"Sling Psycrometer" is an instrument which consists of two idental thermometers
mounted side by side. One thermometer is covered with a muslin cloth on the bottom.
The thermometers are mounted on a bracket which is attached to a swivel handel.
The one thermometer is called "Dry Bulb" and the other with the muslin cloth
is called a "Wet Bulb". The thermometers are then twirled through the air
to obtain the wet and dry bulb readings. As the thermometers are being twirled the air
is passing by both thermometers.
The dry bulb will indicate the air temperature and the wet bulb will indicate the
temperature produced by the cooling effect of the water being evaporated by the air
passing over the muslin cloth. This difference of temperature from the dry bulb to
the wet bulb is called: "THE WET BULB DEPRESSION".
"EXAMPLE"
Dry Bulb Temp. = 80
Wet Bulb Temp. = 70 The difference is 10.
This is called the: "THE WET BULB DEPRESSION".
The drier the air the larger the wet bulb depression. Should the air be saturated,
100 % humidity, the wet and dru bulb temperatures will be the same.
There are many types of psychrometers. Each require the use of two thermometers,
one dry and the other wet. Air must pass over both thermometers. In many instruments
this is done by a motor driven fan. Many times the sensor units are some distance
from the from the temperatures indicators. In these types the sensor unit and
temperature indicators are connected with electrical wires and have digital readouts.
How to construct a "Sling Psychrometer"
"Materials Required"
1. You will need two identical thermometers which can be
bought in any hardware store for a few dollars.
2. Some muslin cloth.
3. Some string.
4. A small piece of wood to mount the thermometers onto.
5. A short piece of small chain.
6. A short piece of a broom stick which will used as the
handle to twril the "Sing Psychrometer"
Estimate Cost: About $5.00 to $15.00 depending
how much the thermometers cost.
Mount the two thermometers back to back on the small
piece of wood. Attach the short piece of chain to the top
end of the samll piece of wood, then attach the chain to
the small piece of broom stick which is used as the
handel to twirl the thermometers. Also attach a piece
of muslin cloth to the bottom of one of the thermpmeters.
© 1998 - 2013 Charles A. Giannetta
BACK TO MAIN PAGE
Picture of a "Sling Psychrometer" used to measure the wet and dry bulb
temperature for determining the relative humidity.
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How to construct a "Sling Psychrometer" "Materials Required"
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