CLIMET INSTRUMENTS CI-154, Руководство пользователя, Страница: 32 / 98

CI-154 User’s Manual
Page 22
To set the CI-154 to take a fixed number of samples (for example, 4) press the
[
STOP AFTER N
] key from the sample group, which will turn from green to yellow. The
number of samples is then established by pressing the [
NUMBER
‘
N
’] key and entering
a value (4, for example). Press [
EXIT
] to return to the main sample screen.
2.5.5 Auto-average
The CI-154 will take a fixed number of samples and then print the average of the
samples if you press the [
PRINT AVERAGES AFTER N
] key. The key will turn green. If the
key is yellow, the auto-average feature has been disabled. The number of samples
to be averaged is determined by the number of samples entered.
If the [
STOP AFTER N
] key is enabled (green) the CI-154 will take the number of
samples listed in the number of samples box, print the average, and stop sampling.
If the [
STOP AFTER N
] key is disabled (yellow) it will continually take n samples and
average them without stopping.
Press the following series of keys to set the CI-154 to average four samples:
[
SET
-
UP
], [
PRINT AVERAGES AFTER N
], [
NUMBER
‘
N
’] [4](from the numeric keypad), [
EXIT
],
[
EXIT
]
2.6 Display modes
2.6.1 Total versus Differential count mode
In total count mode, the counts in each channel represent the number of particles
detected that are equal to
or greater than the size designated for that particle
channel. The counts in the 0.3  m channel, for example, include the particles that
are recorded in the 0.5  m channel above it, and the 1.0  m channel includes counts
recorded in the 5  m channel.
In some applications, it is of interest to know how many particles are in each size
range. This is called differential count mode. In this mode, the microprocessor
simply subtracts the 0.5
 m counts from the counts in the 0.3  m channel, the 1.0
 m counts from the counts in the 0.5  m channel, etc., until it has the number of
particles recorded that were between 0.3  m and 0.5  m, between 1.0  m and 5.0
 m, etc.
In total count mode, the channel size is preceded by the greater than (>) symbol. In
differential count mode, the range is indicated: 0.3–0.5  m, 0.5–1.0  m, etc.
To set the CI-154 to Total Count mode, press [
SET
-
UP
], [
TOTAL
] (in the display
group), then [
EXIT
]. To set the CI-154 up for Differential Count mode, press
[
DIFFERENTIAL
] instead of [
TOTAL
].
2.6.2 Count versus concentration mode
Standard cumulative count mode starts the count cycle at zero and displays the
accumulated particle count as the sample progresses. Concentration count mode
generates a number that represents the concentration of particles accumulated in
the volume sampled so far. The particle counter bases its calculations on counts
divided by elapsed time in seconds, with the result multiplied by the total time in
seconds to acquire the specified volume (cubic foot, cubic meter or liter).
While this is a calculation, the counts at the end of a 35.3 minute count period taken
at 1 CFM will be the same whether the counts were taken in
COUNT
or concentration