Ground TDMA calibration
Calibration by _______________ on (date) ___________
Set up:
1. Turn on TDMA computer and run ground tdma.vi.
2. Start and stop program to shut off power relay.
3. Select “Calibration” from the folder list at the top of the front panel.
4. Record the previous defaults from the front panel.
Offset
Slope
Plumbing time =
+
/Qs
Smearing time =
+
/Qs
Up
Down
HV zero:
5. Change RH Equilibration time (located in the “0” frame of the main sequence) to 1000000
seconds.
6. Open “Corrected single scan G.vi” (adj. AI icon), “RH control G.vi” (RH cont icon), and
“Flow rates PID G.vi” (flows PID icon).
7. Record previous defaults from each of these files:
Flow rates G.vi
Qs upper limit
Qs lower limit
Qsh_up lower limit
Qsh_dn lower limit
RH and T control G.vi
Upper limit upstream
Lower limit downstream
Corrected single scan G.vi
Channel
Offset
0 (Qs)
Multiplier
1 (Qsh up)
2 (Qsh dn)
3 (HV up)
4 (vol T)
5 (RH 2)
6 (RH 3)
7 (RH 1)
8. Set all of the offsets in Corrected single scan G.vi to 0.0 and multipliers to 1.0.
9. Turn all power switches on.
10. Start the program.
Relative humidity probe calibration:
1. If probes are not already labeled, attach numbered labels to each.
2. Place all 3 probes in swagelok fittings in calibration system.
3. If available, place an HMP45A probe in the calibration system.
4. Calibrate the probes using each of the saturated salt solutions:
Magnesium
chloride
(33.0%)
Sodium
chloride
(75.6%)
Potassium
chloride
(84.5%)
Potassium
sulfate
(97.5%)
RH 1
In between nafion
tubes
RH 2
(Just upstream 2nd
DMA)
RH 3
(Downstream of 2nd
DMA)
HMP45A
5. Plot calibration data in Excel (actual values = Y, expected values = X).
6. Add linear trendlines to each set of points, and have equation and R2 value printed on plot.
7. Enter best fit values and R2 below and in Corrected single scan.vi
Multiplier
(equal to slope
in best fit)
Offset (include
sign from best
fit)
R2
Ch 7: RH 1
In between
nafion tubes
Ch 5: RH 2
(Just upstream
2nd DMA)
Ch 6: RH 3
(Downstream
of 2nd DMA)
HMP45A
8. Print out the graphs and tape in the space below.
9. Connect the Gilibrator to the “Humidty inlet” swagelok fitting.
10. Set the “upper limit RH” and “lower limit RH” voltages on the front panel of RH control
G.vi to 0.0 and measure the purge flow rate with the Gilibrator.
11. Incrementally increase these two limits (always equal) until finding the voltage that causes a
slight increase in the purge flow rate. Enter that lower limit voltage below.
Lower limit upstream (V)
12. Continue slowly increasing the two limits until no further increase in the purge flow rate is
observed. Enter that upper limit voltage below
Upper limit upstream (V)
13. Record several (~10) voltage and corresponding flow rate pairs in the table below.
Voltage applied to valve
Flow rate measured with
Gilibrator (L/min)
1
2
3
4
5
6
7
8
9
10
14. Plot these data, print out the graph, and tape in the space below.
15. Enter the new limits in RH control G.vi.
Tape RH 1 graph here
TapeRH 2 graph here
Tape RH 3 graph here
Tape saturator flow rate graph here
Flow rate calibration:
1. Start and stop program to shut off power relay.
2. Turn the regenerative blowers and the Qs / CNC pump off.
3. Start the program.
4. After the relay has been turned on (after a few seconds) zero each of the flow meters.
5. Start and stop program to shut off the power relay.
6. Turn the regenerative blowers and Qs / CNC pump on.
7. Attach Gilibrator tubes in line immediately before sample flow meter.
8. Start the program.
9. Change the Qs lower limit and Qs upper limit voltages on the front panel of flow rates PID
G.vi to 0.0.
10. Enter the voltage measured by the flow meter and the flow rate measured by the Gilibrator in
the “flow calibration data Table”.
11. Incrementally increase these two limits (always equal) until finding the voltage that causes a
slight decrease in the sample flow rate. Enter this lower limit voltage below.
Qs lower limit (V)
12. Adjust these limits such that flow rates of approximately 2.0 and 1.0 L/min are measured.
Enter the voltages measured by the flow meter and the flow rates measured by the Gilibrator
in the “flow calibration data Table”.
13. Continue to increase these limits until no further change in the sample flow rate is observed.
Enter this upper limit voltage below.
Qs lower limit (V)
14. Enter the voltage measured by the flow meter and the flow rate measured by the Gilibrator in
the “flow calibration data Table”.
15. Connect the Gilibrator to the sample inlet.
16. Change the Qs lower limit and Qs upper limit voltages on the front panel of flow rates PID
G.vi to 0.0.
17. Enter the flow rate measured by the Gilibrator and by the Qs flow meter below.
Qa flow rate (Gilibrator)
Qs flow rate (V)
18. Differences between these flow rates (after the Qs flow is corrected) could indicate that there
is a leak in one of the sheath flow lines upstream of the filter.
19. Stop the program.
20. Attach Gilibrator tubes in line with the upstream sheath / excess flow loop either downstream
of the filter or upstream of the regenerative blower.
21. Change the Qsh_up upper limit and Qsh_up lower limit on the front panel of flow rates PID
G.vi to 0.5.
22. Start the program.
23. Slowly (0.3 V at a time) increase both of these limits until reaching 2.2 V.
24. Enter the voltage measured by the flow meter and the flow rate measured by the Gilibrator
divided by 20.0 (to relate to the expected flow meter voltage) in the “flow calibration data
Table”.
25. Slowly adjust these two limits down such that flow rates of approximately 20.0 and 10.0
L/min are measured. Enter the voltages measured by the flow meter and the flow rates
measured by the Gilibrator divided by 20.0 in the “flow calibration data Table”.
26. Continue slowly decreasing these values until blowers stop and no further change in the flow
rate is observed. Enter this lower limit voltage below.
Qsh up lower limit (V)
27. Enter the voltage measured by the flow meter and the flow rate measured by the Gilibrator
divided by 20.0 (hopefully 0.0) in the “flow calibration data Table”.
28. Repeat steps 19 through 27 for the downstream sheath / excess loop
Qsh down lower limit (V)
29. Enter the new defaults in flow rates PID.vi.
30. For each of the three flows, plot the calibration data in Excel (for Qs, flow meter voltage = Y,
Gilibrator flow rate = X; for Qsh, flow meter voltage = Y, Gilibrator flow rate / 20.0 = X).
31. Add linear trendlines to each set of points, and have equation and R2 value printed on plot.
32. Enter best fit values and R2 below and enter the new multipliers and slopes in Corrected
single scan.vi
33. Print out the graphs and tape in the space below.
Flow calibration data Table
Qs
Qsh_up
Gilibrator Flow meter
[Gilibrator
Flow meter
flow rate
voltage
flow rate
voltage
(L/min)
(L/min)]/20.0
Qsh_dn
[Gilibrator
Flow
flow rate
meter
(L/min)]/20.0 voltage
Multiplier
(equal to slope
in best fit)
Offset (include
sign from best
fit)
R2
Ch 0: Qs
Ch 1: Qsh_up
Ch 2: Qsh_dn
34. Stop the ground tdma.vi, but do not re-start.
35. Within corrected single scan G.vi, flow rates PID.vi, and RH control G.vi, select
Operate<<Make current values default, and then save each of the files.
Tape Qs calibration graph here
Tape Qsh up calibration graph here
Tape Qsh dn calibration graph here
High voltage supply calibration:
1. Turn both high voltage on/off switches off (the pumps should still be on after finishing the
flow calibration).
2. Wait a few seconds to ensure high voltage is discharged, then disconnect the upstream high
voltage BNC connector from DMA.
3. Insert extension wire (single strand wire, stripped on both ends, with one end usually folded
over) into center of gold colored receptor inside of high voltage connector.
4. Plug high voltage probe leads into multimeter and ground clip onto HV supply.
5. Inexpensive multimeters often have a lower impedence than is necessary for the HV probe,
and should not be used to calibrate the supplies.
6. In some manner (aluminum tape, cable ties, …), fix the high voltage connector and
(preferably) the high voltage probe such that the probe tip remains in contact with the
stripped portion of the extension wire.
7. Open the analog output test panel (not data neighborhood) and select the channel number
corresponding to the upstream high voltage output (probably Ch 3).
8. Enter 0.0 and press “update channel”.
9. Turn the on/off switch for the upstream HV power supply on.
10. Slowly vary the control voltage (could be up or down) until the zero is found. It is possible
that the voltage measured by the probe will not be zero, but it should not change when the
control voltage is decreased slightly, but should when the control voltage is increased
slightly.
11. To ensure the true zero was found, vary the control voltage above and below the zero and
enter the results below (It’s probably wise to use pencil first in case the zero has to be
changed.
Control V
Zero – 0.0010 =
Probe
Control V
Zero – 0.0010 =
Zero – 0.0008 =
Zero – 0.0008 =
Zero – 0.0006 =
Zero – 0.0006 =
Zero – 0.0004 =
Zero – 0.0004 =
Zero – 0.0002 =
Zero – 0.0002 =
Zero
Zero
=
Probe
=
Zero + 0.0002 =
Zero + 0.0002 =
Zero + 0.0004 =
Zero + 0.0004 =
Zero + 0.0006 =
Zero + 0.0006 =
Zero + 0.0008 =
Zero + 0.0008 =
Zero + 0.0010 =
Zero + 0.0010 =
12. Plot the values in the table above with the control V along the x-axis and the probe V along
the y-axis. The kink in the curve should be located at the HV zero. Print out the graph and
tape in the space below.
Tape HV up zero determination graph here
Tape HV down zero determination graph here
13. Enter the upstream HV zero on the front panel of ground tdma.vi, and in the table below.
14. Sequentially change the input voltage to 0.1 V, 1.0 V, and 3.0 V and record the probe voltage
measured by the multimeter below (just the voltage, don’t multiply by 1000).
15. Repeat steps 1 through 14 for the downstream high voltage supply.
Input
(zero =)
Upstream HV
Probe
Input
(zero =)
0.1 V
0.1 V
1.0 V
1.0 V
3.0 V
3.0 V
Downstream HV
Probe
Plumbing time calibration:
1. Add 1 drop of 60 nm PSL to 750 mL of water (D.I. or better) in the atomizer.
2. Fully open the atomizer flow valve, fully close the dilution flow valve, and adjust the
compressed air pressure to 25 psi.
3. On the ground tdma.vi front panel, set the Qsh maximum to 25 L/min, Qsh/Qa to 10.0, the
plumbing time slope to 0.0, the diameter range to 0.01 to 0.4 m, and the scan time to 60 s.
4. Change the RH equilibration time to 60 seconds and begin the ground tdma.vi program.
5. Wait until the DMA scan is complete, then stop the program and adjust the plumbing time
offset to improve up and down scan agreement (increasing the value pushes the upscan
distribution to the left and downscan distribution to the right).
6. Once the PSL peaks within the up and down scans are at the same location, enter the
plumbing time offset used in the table below.
7. Change the Qsh maximum to 10.0, and repeat steps 4 and 5.
8. Note: It is very important that the sample flow be controlled during this calibration. If the
sample flow is not controlling well, it may be necessary to alter the PID parameters or
increase the RH equilibration time.
Qsh
25.0
Plumbing time offset (s)
10.0
9. Calculate the plumbing time slope and offset:
slope 
offsetQsh 10 L / min  offsetQsh  25 L / min
0.6
offset  offsetQsh 10 L / min  slope
Plumbing time slope (s / L/min)
Plumbing time offset (s)
10. After entering the new plumbing time slope and offset, select Operate<<Make current values
default, and then save the file.
Hygroscopic growth calibration:
1. Turn the compressed air flow to the atomizer off.
2. Rinse out the atomizer solution bottle and add 0.75 g of NaCl to 750 mL of D.I. water.
3. Fully open the dilution flow valve on the atomizer cart and close the atomizer valve ~ ¾ of
the way.
4. Increase the number of TDMA bins by a factor of 5 (but not the scan time), change the upper
limit of the RH range to 85.0%, and change the RH Equilibration time to 1800 seconds.
5. Change the DMA scan time to 20 seconds, and enter 0.03, 0.08, and 0.2 m in the Dp_up for
TDMA array.
6. Run the program and wait until all of the TDMA measurements are finished.
7. Once the scans are complete and the distributions plotted, open loop_1.txt from the for_plot
folder in which the data the saved using Excel.
8. Plot the data and identify the peak in the growth factor distributions for each of the dry sizes
considered. Locate the corresponding peaks in the concentration column and enter the
growth factors corresponding to each of these peaks below:
Dp_up (m)
0.03
Measured Growth factor
Expected Growth factor
2.047
0.08
2.110
0.2
2.136