Sierra FLAT-TRAKTM 780S - Manual (Page 33)

Series 780S Instruction Manual Chapter 3 Operation
IM-78S-B 3-7
User Full Scale Adjustment
The user full scale (UFS) feature adjusts the flow meter output range
anywhere within 50% to 100% of the factory full scale (FFS). This
feature allows you to re-range the voltage or current output of the
meter to accommodate different flow rates. Note: when entering a
new user full scale setting for Range 2, it cannot be less than 10% of
the Range 1 user full scale.
Changing the User Full Scale using the LCD Display
The factory full scale is shown on the flow meter label. If you want a
UFS equal to the FFS, adjust the display to match the FFS. If you
want to use 50% of FFS, adjust the display to read 50% of the FFS.
1. Select the desired range. Select FUNCTION, enter the password.
Select FUNCTION again until User Full Scale appears on the dis-
play.
2. Use UP or DOWN to enter the desired UFS value in engineering
units.
3. Select FUNCTION to advance to the next option, or after 12
seconds of non-activity the meter returns to the Run Mode and
the new UFS is in effect.
Changing the User Full Scale using the Single-Digit LED
If the FFS is set to 11,000 sfpm and UFS is set to output 5.0 VDC,
or 100%, the flow meter will indicate 5.0 VDC when 11,000 sfpm
is present on the probe. If you want 6,000 sfpm for UFS, used in
Step 3 below, adjust the UFS to 6000/11000 or 54.55% of factory
full scale. Adjust the voltage to 2.73 VDC (2.73 = 5 x .5455). Use
this formula to determine the desired UFS voltage:
VOLTS = 5 x User Full Scale / Factory Full Scale
1. Set the DVM to voltage mode and connect between Vout+ and
Vout– on the flow meter terminal block.
2. Select the desired range. Press the FUNCTION button until a
solid “8” appears on the LED.
3. Adjust the UP or DOWN button until the DVM indicates the de-
sired user full scale as described above.
4. Press FUNCTION to advance to the next option, or after 12
seconds of non-activity the meter returns to the Run Mode and
the new UFS is in effect.
Caution!
The flow meter must not be
reporting or measuring gas
flow during adjustments.