CHAPTER 3 - OPERATION
FLUID COMPONENTS INTL
Doc. No. 06EN003291 Rev. A
3 - 5
Model ST98 Flow Meter
COMMAND:
B. Sensor Balance
Summary:
Permits the instrument's flow element to be balanced or rebalanced. A passcode must be entered. This function
has already been performed at the factory. This function should only be performed if there is a new flow element
installed or a re-calibration is necessary.
Description:
For the instrument to function properly, the flow element and electronics need to be balanced. Balancing means
that at the same temperature, the RTD's in the flow element should be at the same resistance. Due to physical
differences in the RTD's, the current needs to be adjusted for one of the RTD's so that they will both have the same
voltage. The differential should be as close to zero as possible. A passcode is necessary to enable this command.
The instrument will either balance itself or it can be done manually.
Note:
Use M (Manual) command when the circuit board or flow element has been replaced and where the
balance value representing the digitized current used for balancing has been written down.
If the Heater was ON prior to sensor balancing, be sure to turn the Heater back ON after the RTD's have
been balanced.
Example:
Pressing [B] [ENTER] will display “Enter Code #”
Press in the passcode [ENTER]. “Enter temp. #” will be displayed.
After the temperature is entered, “Auto or Manual?” and “Enter A or M<” are displayed.
Pressing [A] [ENTER] will display “xxx xxxx Balancing”. Then “Balanced!” will appear on line 1 and
“Saved! xxx” will appear on line 2.
If [M] [ENTER] is pressed instead of [A] [ENTER], the prompt “Enter Balance #” will be displayed. Once
the balance value [xxx] is entered, the balanced value entered appears on line 1 and “Saved!” is displayed on
line 2. After a couple of seconds "Saved! xxx" will be displayed on line 1 and "Input mode?<" will be
displayed on line 2. (Typical Balance values are; 234-237. Factory Balance # is on in the Delta R Table.)
COMMAND:
C. Calibrate Display
Summary:
Displays A/D Delta-R and Ref-R. Data values are useful for calibration. The instrument is calibrated at the
factory. This function does not need to be performed unless the instrument has been repaired or needs to be re-
calibrated.
Description:
The flow element RTD's need to be interpreted by the electronics as a function of flow-rate. This is done by
recording the raw signal A/D values at certain flow points and then curve-fitting the points using an equation to
linearize the output at the calibrated flow-rate. This command makes it possible to view both the raw A/D Delta-R
value, which is the difference between the Active and Reference RTD, and the Ref-R value, which is for the
Reference RTD. This is a view only selection, the user has no other input commands.
Example:
Pressing [C] [ENTER] will display “d= xxxx R= xxxx”. The display is updated continuously.
Note:
Pressing [ENTER] at any time will exit this menu and display "Input mode?<"
