TSI Instruments DustTrak 8520, Operation And Service Manual

Page: 48 / 89

Chapter 4 38
When using the 1.0 or 2.5
µ
m inlet nozzles you need to clean the inlet more
frequently than for the standard 10
µ
m nozzle (black) because of the much
higher percentage of particles being removed from the stream. Table 4–1
represents estimates of how long you can run before cleaning is necessary.
The actual time you can run between cleanings varies with the size
distribution of particles you are measuring.
Table 4–1. Recommended Maintenance Schedule
Item Frequency
Perform zero check Daily (or before long tests)
Clean 1.0
µ
m nozzle
5 hr. at 1 mg/m
3
*
Clean 2.5
µ
m nozzle
30 hr. at 1 mg/m
3
*
Clean 10
µ
m nozzle, inlet, and sample tube
350 hr. at 1 mg/m
3
*
Replace internal filters 700 hr. at 1 mg/m
3
*
Clean cyclone Before each use
Return to factory for cleaning and
calibration Annually
*Pro-rated, see discussion above.
The D
UST
T
RAK
monitor keeps track of the accumulated amount of aerosol
drawn through it since its last cleaning. When sample tube cleaning or
internal filter replacement is due, the display shows the message
“SERVICE 4” or “SERVICE 5,” respectively, during power-up. Press any
key to bypass the message, but be sure to perform the maintenance
procedures at your earliest convenience.
TSI recommends that you perform a zero check each day the D
UST
T
RAK
monitor is used, before running any extended tests, and after the instrument
experiences a significant environmental change. Examples of significant
environmental changes would be ambient temperature changes that exceed
15
°
F (8 °C) or moving from locations with high aerosol concentrations to
low concentrations.
Zero Checking/Re-Zeroing
1. Put the D
UST
T
RAK
monitor in Survey mode.
2. Put zero filter on aerosol sample inlet. See Figure 4–1.
3. Set the time-constant to 10 seconds. Press and hold the TIME
CONSTANT
key until
“10”
is displayed, then release.
4. Wait 10–60 seconds for displayed values to settle to zero.
5. If the displayed value is between -0.001 and +0.001 mg/m
3
, the
D
UST
T
RAK
monitor does not need adjustment. If the displayed value
exceeds this limit, follow steps 7 to 9 below to re-zero the instrument.