DOC-0128 Rev F
© 2017 DROPLET MEASUREMENT TECHNOLOGIES
1 6
1.5.3
Leak Test (for Dual CCNs Installed in Pressurized Aircraft)
If CCN-200 unit will be installed in pressurized aircraft, perform the following leak test in addition to
the zero-count.
1)
Install a loop of tubing between inlet A and inlet B (Figure 7
Figure 7: Connecting Inlet A to Inlet B with Tubing
2)
Install a valve or plug on the inlet A while the instrument is running. (Note: Only Column A
has a sample pressure sensor, so do not install the plug on Column B.)
3)
Allow the unit’s internal air pump to evacuate the system. This may take several minutes.
Monitor the progress on the
Flows
tab
Sample Pressure
field.
4)
When the unit has pumped down below approximately 400 mb, go into the
Flows
tab and
turn off the
Air Pump
.
This will turn off power to the pump, which will also act as a seal.
5)
If unit does not pump down below 400 mb, there is a leak that needs to be fixed prior to
retesting.
6)
Wait 60 seconds to allow pressure to stabilize, and then monitor how fast the sample
pressure rises. Typically 5 mb or less per second is good.
7)
If unit leaks at an unacceptable rate, try isolating and fixing leak then retest using above
method.
8)
To shut down the CCN-200, always start by shutting down
Dual CCN.exe
. Go to the
Prog
Control
tab and press the
Shutdown
button. You can then simply turn off the main power switch on the
side of the unit. You can also close Windows first by turning off the computer and then turning off
the power switch on the side of the unit when the screen goes blank.
