5-2
Model 3786 Ultrafine Water-based Condensation Particle Counter
purge flow. To measure the sheath flow without the influence of the
purge flow, pinch off the purge flow using a hemostat or thin-nosed
pliers on the tube marked with a yellow indicator tag. The value of
the flow in the sheath flow line should be 0.3 L/min plus or minus
about 5%. Restoring the purge flow should add about 10% to the
sheath flow value. The actual value of purge flow is not critical, but
the change in flow measured by pinching off the purge line indicates
that the line is working and is unobstructed. The flow measurement
should be made only when the instrument has been warmed-up and
running for at least 15 minutes. Also, the instrument must be fully
primed to ensure the internal water trap is filled. Remember to
reconnect the sheath flow back to the tube connecting it to the
UWCPC engine assembly.
W A R N I N G
High voltage is accessible in several locations within this instrument.
Figure 5-1
Location of Sheath and Purge Flow Lines
Purge
Flow Line
(yellow)
Sheath
Flow Line
(green)
