28
14. The “Line Delay” box is defaulted to 0 milliseconds. This is where you will tell
the program how often to read a line from the script file you’ve created. 1000
milliseconds is one second, so if you want a line of data every 30 seconds, you
would enter 30000 into the box. If you want a line every 5 minutes, you would
enter 300000 into the box.
15. When you have entered the value you want, click on OK and OK in the
Properties dialog box.
16. Go the Transfer menu and select “Send
Text
File…” (NOT Send File…).
17. Browse and select the text “script” file you created.
18. Click Open.
19. The program will begin “executing” your script file, reading one line at a time
with the line delay you specified and the flow device will respond by sending one
line of data for each poll it receives, when it receives it.
You can also capture the data to another file as described in the manual under
“Collecting Data”. You will be simultaneously sending it a script file and capturing
the output to a separate file for analysis.
Operating Principle
All 819-Series Gas Flow Meters (and
829-Series Gas Flow Controllers) are based on
the accurate measurement of volumetric flow. The volumetric flow rate is
determined by creating a pressure drop across a unique internal restriction, known
as a Laminar Flow Element (LFE), and measuring differential pressure across it.
The restriction is designed so that the gas molecules are forced to move in parallel
paths along the entire length of the passage; hence laminar (streamline) flow
is established for the entire range of operation of the device. Unlike other flow
measuring devices, in laminar flow meters the relationship between pressure drop
and flow is linear.
STANDARD GAS DATA TABLES:
Those of you who have older products may
notice small discrepancies between the gas property tables of your old and new
units. MATHESON has incorporated the latest data sets from NIST (including
their REFPROP 9 data where available) in our products’ built-in gas property
models. Be aware that the calibrators that you may be using may be checking
against older data sets such as the widely distributed Air Liquide data. This may
generate apparent calibration discrepancies of up to 0.6% of reading on well
behaved gases and as much as 3% of reading on some gases such as propane and
butane, unless the standard was directly calibrated on the gas in question.
As the older standards are phased out, this difference in readings will cease to
be a problem. If you see a difference between the MATHESON meter and your
in-house standard, in addition to calling MATHESON at 800-828-4313, call the
manufacturer of your standard for clarification as to which data set they used in
their calibration. This comparison will in all likelihood resolve the problem.
Summary of Contents for 819 Series
Page 46: ...46 Notes...
Page 47: ...Notes 47...
