Teledyne 4220 - Manual (Page 105)

4220 Flow Meter
Section 4 Submerged Probe Installation
4-11
the mounting ring are not suitable, you must build your own
mounting hardware. Figure 4-6 shows the dimensions of the
probe for your reference when building your own hardware.
Figure 4-7 shows the probe installed in several primary devices.
Certain flume manufacturers produce flumes with built-in cav-
ities for Isco’s submerged probe. Contact the flume manufacturer
for details on the special flumes.
Note
Always install the submerged probe pointing toward normal
flow at the head-measuring point of the device. The location of
the measuring point varies with each device. Refer to Table 4-1
or to the Isco Open Channel Flow Measurement Handbook.
Note
When installing the probe with custom hardware, remember to
attach the probe securely to the side or bottom of the flow
stream and tie the cable down so that it does not collect debris.
For many primary measuring device installations, the sub-
merged probe mounting rings or base sections discussed previ-
ously may be used to mount the probe at the appropriate
location. In many installations, though, the mounting rings or
bases may not be suitable.
Mounting hardware may have to be fabricated locally to allow
the level sensor to be mounted at the correct location in the
primary device. The only requirements for custom mounting
hardware are:
• The probe must be securely attached to the side or
bottom of the flow stream.
• The cable must be tied down and led out of the flow
stream in an orderly manner.
• The hardware be made from corrosion-resistant
materials.
It should be noted that the mounting rings may be used to install
the probe in rectangular channels by simply putting right angle
bends in them at the appropriate locations. It should be noted
Table 4-1 Locating the Head-Measuring Point
Device Head-Measuring Point
Weirs Upstream from the weir plate by at least 3 times the
maximum head.
Parshall Flumes
1
/ 3 of the way into the converging section.
Palmer-Bowlus
Flumes Upstream from the flume entrance by half the pipe
diameter.