Controls, Indicators, and Connectors
3–3
Rotameters
The rotameters regulate the flow rates of air and CO
2
to the
Electrospray chamber. The air and CO
2
flow rates are typically 1.0
and 0.1 L/min, respectively.
Pressure Regulator and Gauge
The pressure drop across the capillary is regulated and measured
with these two components. See Appendix B, “
”
for details on how the pressure drop is measured and how it can be
used to approximate the flow rate of the liquid through the
capillary.
Pressure Chamber
The pressure chamber holds a sample vial, which contains the
liquid solution to be electrosprayed. A platinum wire and capillary
extend from the top half of the pressure chamber into the liquid
solution to charge and transport the liquid solution, respectively.
To change the sample vial, the bottom half of the pressure chamber
can be removed by twisting
1
⁄
8
-turn counterclockwise. High voltage
is
not
supplied to the platinum wire if the bottom half of the
pressure chamber is removed. In addition, an in-line orifice
provides a pressure drop equal to the differential pressure set
point, eliminating the need to reduce the pressure when changing
samples. See Chapter 4, “
” for detailed
instructions for handling or changing the sample vial.
Viewing Window
The viewing window provides a visual inspection of the capillary tip.
This is useful when observing the different operating modes of the
Electrospray and when installing a capillary. It is also a good tool
for troubleshooting the Electrospray. The viewing window is backlit
by a green LED and the lens can be adjusted to focus on the
capillary tip by rotating the lens mount.
Ionizer Retainer
The ionizer retainer allows a Model P-2042 Polonium-210
radioactive ionizer to be installed in the Electrospray chamber to
meet all radiation safety requirements. The ionizer reduces the
charge on the droplets produced by the Electrospray to increase the
exit aerosol concentration.
