3-12 Model 3775 Condensation Particle Counter
Internal Data Logging
A removable Flash Memory Card can be inserted in the slot on the
front panel to store particle concentration data and analog input
data. Data can then be transferred to a computer for further data
processing. Refer to
Chapter 4 for more details. It is not
recommended you use a Flash Memory Card and Aerosol
Instrument Manager software or terminal program to collect data
simultaneously to avoid data transfer interference.
Remote Access of Instrument
The Model 3775 CPC provides an Ethernet port to connect the
instrument to a network for monitoring status information. Status
information includes saturator, condenser, optics temperatures,
laser power, and particle concentration, etc. The data is updated
once every five seconds. Refer to
Chapter 7 for more details.
Optional External Pump
It is possible to use an external pump to provide sample flow for the
instrument. The pump must provide sufficient vacuum to maintain
a critical pressure across the aerosol flow critical orifice and
bypass/makeup air variable orifice, while providing a flow of
1.5 L/min (total instrument flow). At an atmospheric pressure of
100 kPa (1 atm), an external pump must provide at least 50 kPa (15
in. Hg) of vacuum and 1.5 L/min inlet volumetric flow for each CPC
supported. This option requires changing of the internal tubing
connections and routing. Procedures for use of an external pump
are provided in the maintenance section in
Chapter 8.
Flow Rate Control
The Model 3775 CPC uses a critical orifice and a variable orifice to
accurately control the air flows in the instrument. The critical
orifice operates at or below the critical pressure ratio to control the
0.3 L/min (nominal) volumetric aerosol flow. A variable orifice
controls the bypass/makeup air flow. It is also operated at a critical
pressure ratio for a flow of 1.2 L/min. More is found in Chapter 5
“
Technical Description.”
Problems with the aerosol flow can be detected by monitoring the
pressure drop across the nozzle, and verifying that the critical
orifice pressure is maintained.
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