Stevens A Series - Technical Notes; Instrument Accuracy and Errors; Float Line and Tape Types

5 Technical Notes
11
5.1 Instrument Accuracy
Standard float systems are subject
to small errors due to float lag and
line shift. These errors can be
minimized by selecting proper floats
and counterweights. Table 8
through 13 show the line shift errors
and float lag where standard float
systems are used. Line shift errors
can be eliminated by using special
loop line float configurations if higher
accuracy is required.
Further discussion on errors in float
operated systems can be found in
the Stevens Water Resources Data
Book, available from the factory at a
nominal cost.
5.1.1 Beaded Float Line
Standard beaded float line supplied
by Stevens is 1 mm (0.040 in.) in
diameter, and is beaded to match
the recessed grooves in the float
pulley. This stainless steel line is
slip proof, exceptionally strong, and
light weight to minimize errors.
5.1.2 Float Tape
Stainless steel float tapes are
perforated to match pulley spines at
regular intervals. Tapes are
available plain, or they may be
graduated in either English or metric
scaling (feet, tenths and hundredths
for English; meters, decimeters and
centimeters for metric). Also
available is a separate mounting
bracket with adjustable index pointer
to indicate a water level reading on
graduated tapes.