Pmt Adjustment - Teledyne T640 User Manual

4.1.4.

PMT ADJUSTMENT

08354A DCN7303
The Particle Sensor PMT Adjustment uses our SpanDust™, a monodisperse dust
with a specific refractive index. All T640 instrument PMTs have a very specific
response to this span dust which allows for the sensor to be checked and adjusted
in the field for drift caused by contamination of the optics. It is important to note
that this is not a calibration of the optical sensor based on the mass of dust being
used, but simply a mechanism to check and adjust the PMT response to particles
with a specific and known refractive index.
1. Navigate to the PMT Adjust screen.
2. Remove the T640 sample inlet or the 640X Option sample inlet and press the
Start button on this screen to suspend normal data acquisition and start this
adjustment process.
3. Prepare the SpanDust™ bottle by uncapping the "air intake" at the bottom of
the silica gel drier attached to the bottle.
4. Place the tube from the SpanDust™ bottle into the top of the Upper Inlet
Tube for the instrument.
5. Ensure that the silicone tube fits snugly inside the aluminum inlet tube, and
do not allow the bottle to hang, as it could dislodge the silicone tube from the
inlet tube.
6. Gently tap the SpanDust™ bottle to barely agitate the contents just enough to
allow the dust to be pulled into the sensor, and allow 30 seconds for the Peak
Channel reading in this screen to respond.
7. If the Peak Channel reading is not at 11.3, ± 0.5, then adjust the PMT Setting
by pressing the Peak Adjust left (decrement) or right (increment) buttons to
center the Peak voltage. Each press of a button is 1 volt, so press the Peak
Adjust button by as many times as the number of volts the reading is off.
Teledyne API T640 PM Mass Monitor 52