ADG400 User Manual
16
99998 Issue 1, November 2022
OPERATION
3.6.8.1 Converting MFC Values to ml/min Flow Rates
MFC Name
Span (cc/min)
S1Dry
5000
Sat(C)
1000
Sat(F)
200
S2Dry
5000
S2Wet
200
Table 4
Span of Installed MFCs
MFC values are stored in the range of 0...32000.
At 0 the MFC is fully closed and will not let-by gas.
At 32000 the MFC is fully open and will be set to its maximum flow rate.
To calculate actual flow rate in cc/min, the following simple calculation is required:
MFCVAL = (FLOW/SPAN) * 32000
e.g. 1000 cc/min on S1Dry MFC which has a span of 5000 cc/min would be
(1000/5000)*32000 = 6400
3.6.8.2 Adjusting Set Points
If it is necessary to make an adjustment to a set point because it no longer matches,
follow the guidelines below:
•
Make adjustments in small increments, waiting for the reference
instrument to stabilize between adjustments.
•
For 2-stage points, the primary adjustment should be made by modifying
MFC5; at most points, +100 to +200 counts to MFC5 = +0.1 °C
•
If you run out of adjustment on MFC5 (by hitting 200 ml/min max), then
reduce MFC1 dry flow by 100 counts.
•
To make adjustments to a 1-stage point, it should only be necessary to
increase or decrease Sat(F) / Sat(C). The 0 °C point should be set to a
value of +1 °C to make it easier to measure with a chilled mirror, as 0...-5
°C is difficult to measure with a chilled mirror.
•
The +20 °C point should be set to a value of +18 °C to reduce condensation
risk in colder environments.
•
MFC flow rate must be within zero/span range (640...32000) for reliable
operation. Minimum saturator flow of 80 ml/min (12800) should be set,
except for the -80 °C point. MFC1 + MFC5 maximum total flow must not
be more than 7 L/min
•
Target flow rate is 5000 ±100 ml min for all points, decreasing to approx.
4 L/min at +1 °C, 2 L/min at +10 °C and 1 L/min.
