Alicat LC Series Liquid Flow Controller - Manual (Page 39)

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13. Click on the “ASCII Setup” button.
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.
FLOW MEASUREMENT OPERATING PRINCIPLE
All L or LC-Series Water Flow Meters/Controllers accurately determine the
flow rate 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 water 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.
In order to have an accurate reading of the flow rate, the absolute viscosity of
the fluid must be established. The rate at which liquids change viscosity with
changes in temperature is not linear. The relationship between temperature
and viscosity for water is well established and Alicat Scientific L and LC-Series
units utilize a high accuracy temperature sensor and this relationship to provide
an accurate viscosity reference. For this reason, these meters and controllers
are generally recommended only for use with pure water. Any additives to
water (such as antifreeze or disinfectants) that might affect the viscosity should
be avoided.
Please visit the Alicat web site for a detailed explanation this principle.
http://www.alicat.com/technical-information/theory-of-operation/