Teledyne API Ultrafine Particle Monitor - Model 651 Instrument Description
07506C DCN6727 39
SETUP screen) is an electronic valve used to turn on/off the
vacuum from the external source.
Water System The water separator removes water from the vapor stream coming
from the optics head. This prevents water from condensing and
blocking the flow orifices. Water from the separator is pumped out
by the water ejector pump.
The instrument flow orifices operate under critical pressure with
flow determined by the orifice diameter. Each orifice is protected by
a glass fiber filter followed by a separate inline screen to remove
contamination which can result from an accidental flooding event.
Fans Two internal fans cool the instrument; one cools the internal
electronics and one dissipates the heat generated during cooling of
the condenser.
Circuit Boards The Model 651 contains the following circuit boards:
Main board
Laser board
Detector board
The main circuit board controls all the primary functions. Feedback
circuits on the main electronics board control the internal
temperatures (displayed on the Status screen).
Internal Clock The clock used in the Model 651 is a quartz crystal component
embedded in the microprocessor. The accuracy is on the order of
about a second per day, but time drift during long periods of data
logging is possible. If a higher level of time accuracy is needed, one
of the following options should be implemented:
1. Send a serial command to the instrument once per day to reset
the M651 clock to synchronize with the data collection tool.
2. If collecting data via the USB stick, reset the clock on the
instrument as needed.