How does the Kestrel measure humidity
so accurately?
The Kestrel features a patented dual temperature sensor configuration for rapid
response and accurate measurement. Every Kestrel is calibrated against NIST-traceable
standards, and can be recalibrated in the field with the Kestrel RH kit.
Why are the RH readings on my Kestrel sometimes different than my sling?
It is not uncommon for the humidity measurements to differ when
comparing the Kestrel Meter to a sling psychrometer (or belt
kit). Typically, you might
see that the sling gives a reading 5-10% higher than the Kestrel
Meter.
Slings are susceptible to the following errors:
- If
the sock on the wet bulb thermometer is not clean, the humidity
measured from a sling will err on the high side.
- If the water
used for the wet bulb thermometer is not clean, the humidity
measured from a sling will err on the high side.
- If the sling
is not swung around long enough, the humidity measured from a
sling will err on the high side.
- If the thermometer measurements
are not read quickly enough after swinging the sling, the humidity
measured from a sling will err on the high side.
Unfortunately, all of the common errors with a sling
psychrometer will yield humidities that err on the high side. With
a properly calibrated Kestrel Meter and sling, and with proper
use, the humidity measurements are likely to both be within the
manufacturer's specification.
How can I ensure that my Kestrel’s
RH readings are as accurate as possible?
It is also important to use the Kestrel Meter correctly in order
to measure an accurate humidity. Ideally, the instrument
should be left in the environment for at least 15 minutes. This
allows the entire unit to equilibrate to the surrounding conditions.
If this is not possible, especially if the
Kestrel Meter is being moved to significantly different conditions,
then it is best to hold the instrument into an air flow of at
least 3mph for 15-30 seconds. If there is no wind, the
unit can be waved back and forth to create air flow past the
sensors for the same amount of time.
What's so great about the Kestrel impeller?
The Kestrel impeller measures 1 inch across, and turns on a Swiss
precision pivot mounted on sapphire bearings. Its large size ensures
accurate readings even if pointed off-angle from the wind, and
its very low start-up speed allows measurement of the lightest
puffs of wind. If damaged, a new calibrated impeller can be purchased
for $19 and popped in without tools, restoring like-new performance.
What's that curly looking thing?
That's the patented Kestrel temperature sensor. Unlike most watches
and other products with a temperature measurement, the Kestrel
sensor is outside the case to ensure it measures the air, not your
hand or pocket. The "curls" serve to further isolate
the temperature sensor from the effects of the case temperature.
How does the Kestrel measure altitude?
The Kestrel uses an atmospheric pressure sensor and calculates
altitude based on a standard atmosphere. This is just like the
altimeter in an airplane, or an altimeter watch. It's more accurate
than a GPS altimeter, but does require periodic reset of the reference
pressure to eliminate weather effects.
Does the Kestrel have a GPS in it?
No, not yet. We may add basic GPS location to a future Kestrel
model, but we'll leave the full-blown mapping and navigation to
the companies that specialize in GPS as much as we specialize in
weather.
How does the altimeter work? Is the reference pressure
the same as an altimeter setting?
The Kestrel models with altimeter calculate altitude from barometric
pressure in exactly the same manner and according to the same rules
as an aircraft altimeter. The "reference pressure" on
the Altitude screen is the same as the altimeter setting obtained
from a local airfield.
Can the Kestrel 4000 communicate directly with a PDA or
computer?
No. Due to the rapidly changing standards for product communication,
data upload is presently limited to a USB or serial interface to
communicate with a PC. Additional communication options may
be developed in the future as a predominant standard emerges among
Kestrel users.
Does the Kestrel 4000 provide location?
At present, there are no Kestrel meters offering built-in GPS. This
product may be developed in the future.
Do you really mean MADE in the USA?
Yes. The entire Kestrel line is designed and built in the
USA. Some electronic components have to be sourced overseas these
days, but we buy American wherever we can.
Who do I call if I have a problem?
You call us! From our Customer Service Representatives to
the President of the company, we all answer the phone and know
these products inside and out. If you have a problem, we'll
fix it. Kestrels hardly ever break, but if they do, they're covered
by a two-year warranty. |