Teledyne 4220 - Manual (Page 97)

4220 Flow Meter
Section 4 Submerged Probe Installation
4-3
Slanted Nose Section – Under certain conditions - low flow
rates in debris-laden small sewers, for example - the submerged
probe may catch and retain the debris, obstructing the flow
stream and causing erroneous level readings. To avoid this
problem, use the slanted nose section. This nose section has a
slanted leading edge that tends to shed debris more readily than
the standard nose section.
Use the slanted nose section with caution, however, Under condi-
tions of low flow and high velocity, the slanted nose section may
induce a hydraulic “jump” in the flow stream that can cause erro-
neous level readings.
Flume Cap – The flume cap is a small, blunt cap that replaces
the nose section. Most flume manufacturers can supply flumes
with a small cavity to accept an Isco probe. The probe cap pro-
tects the transducer while minimizing the total length
4.3 Mounting Rings The following sections describe sensor installation using the two
options available for mounting the probe in pipes or round-bot-
tomed flow streams. For pipes up to 15" (38.1 cm) in diameter,
stainless steel self-expanding mounting rings (Spring
Rings) are available. For pipes larger than 15" in diameter,
Teledyne Isco offers the Universal Mounting Rings (Scissors
Rings).
4.3.1 Spring Rings To install a spring ring, you compress the ring, slip it inside the
pipe, and then allow it to spring out to contact the inside
diameter of the pipe. The inherent outward spring force of the
ring firmly secures it in place. A typical self-expanding mounting
ring (with a probe mounted on it) is shown in Figure 4-1.
These mounting rings are available for use in pipes with inside
diameters of 6" (15.2 cm), 8" (20.3 cm), 10" (25.4 cm), 12" (30.5
cm), and 15" (38.1 cm). The Teledyne Isco part numbers for the
various size mounting rings available are listed in Appendix B.
These part numbers include not only the ring, but also the mis-
cellaneous hardware necessary to mount the sensor on the ring.
CAUTION
Always wear leather gloves when handling the rings (either
type). The metal is finished, but there is still a possibility of cut-
ting your hands on the edges.
Slanted Nose
Section
Flume Cap