Xylem XL Series H-522 - Plus - Manual (Page 83)

XL™ Series
System Status Menus / Options 8-9
PC Interface View Built In Display Screen
Not Available Using PC Menu Bubble Line Test?
This test is only available on the H-350XL™ Model. This option is used to test the orifice line
for noise and stability. Bubbler line noise can be caused by several conditions, for example, a
loose orifice line that is swaying with the water current, an orifice outlet that has an artificial
pressure or vacuum based on unstable water current, or the bubble growing and releasing, etc.
Press the ENTER key to start the test. The screen will change displaying the following message.
Line Noise = +x.xxxx
When the test is first entered a normal measurement is made and the stage value is saved in two
internal variables called MAX and MIN. Now the difference between the max and min is
displayed. Since the first measurement saves the same value for both the max and min, the
difference is 0.000. The initial measurement takes about 5 seconds as it also compensates for
atmospheric pressure, and A/D offsets. The system then measures the stage repeatedly using the
original atmospheric reading for compensation allowing for a 1 second measurement time. The
MAX and MIN values are updated as new max or min values are detected and the difference
between the MAX and MIN values is displayed on the screen. The difference between the MAX
and MIN will be small and will not increase too much if the line noise is small, but will increase
to a larger number if the line noise is significant. The displayed value is in the same units as set
by the stage ‘Slope’ Coefficient which defaults to feet.
When installing a new orifice line use this option to test for possible orifice line positions.
Temporarily position the outlet and run this test to see if the position is relatively quiet.
Reposition the line if it is too noisy. After the line is repositioned pressing the Enter key will
cause the H-350XL™ to take a new reference measurement, and start the process again.
Running this test with the orifice line disconnected will show how much noise the H-350XL™
sees internally. This test is used to see if a problem exists with the orifice line or with the H-
350XL™. This value should be extremely small and is relative to the PSI range of the system in
use. The following table list the approximate resolution for each PSI range and the bubble line
test with the orifice line disconnected should be less than the resolution value. In most cases the
bubble line test will give values less than the resolution even with the orifice line connected in a
good installation.
PSI Range Approximate Resolution
0 to 15 PSI 0.007 Ft
0 to 30 PSI 0.014 Ft
0 to 50 PSI 0.0233 Ft