CHAPTER 5
Maintenance and
Troubleshooting
5-1
This chapter provides maintenance and troubleshooting information
for the Model 3786 Ultrafine Water-based Condensation Particle
Counter (UWCPC).
Replacing Wick
It is recommended that a new wick be installed in the UWCPC a
minimum of every six months. Refer to Chapter 2, “
Unpacking and
Setting Up the UWCPC,” for steps involved in removing the old wick.
Once the inlet assembly has been removed, simply slip off the old
wick from the assembly and slide on the new one. Reinstall the inlet
assembly and tighten the thumbscrews. Once the unit is returned to
service, prime the new wick with 5 cc water (100 injections).
When replacing the wick it is a good time to also clean any
accumulated material from the drain reservoir. See the section on
drying the UWCPC in Chapter 2, “
Unpacking and Setting Up the
UWCPC,” for instructions on removing the reservoir cover from the
bottom of the instrument. Wipe out any residue from the reservoir
with a wet cloth. Reinstall the reservoir cover making sure the
O-rings are properly seated.
Flow Calibration
The inlet and sheath flows of the UWCPC are feedback-controlled to
set point values stored in non-volatile memory. The inlet flow can be
readily checked by connecting a volumetric flow meter to the sample
inlet and turning on the pump. The indicated flow value should be
0.6 L/min plus or minus about 5%. The actual aerosol flow rate is
the difference between the inlet flow rate and the sheath flow rate.
To check this value the instrument cover must be removed and a
flow meter connected to the sheath flow tube. The sheath air flows
through a tube marked with a green marking tag, refer to Figure 5-1.
The tube connected to the UWCPC engine assembly should be
separated from the stainless-steel fitting marked with the green tag.
Once separated the open end of the stainless-steel fitting can be
connected to a flow meter with a short length of flexible tubing. The
air flow out of this fitting contains both the sheath flow and the
To Next Page
Loading...
Need help?
General
