Teledyne 4220 Submerged Probe Installation, General Mounting Considerations

4220 Flow Meter

Section 4 Submerged Probe Installation

4.1General Mounting Considerations

The following sections describe installation of the submerged probe. The first section presents general mounting consider- ations common to all submerged probe mounting techniques. The following sections describe probe installation using the two systems available for mounting the submerged probe in pipes or round-bottomed flow streams. For pipes up to 15 inches (38.1 cm) in diameter, spring stainless steel self-expanding mounting rings are available. For pipes larger than 15 inches in diameter, Teledyne Isco offers the Universal Mounting Ring. For use in similarly-sized manhole inverts, you can use the base and extension sections of the Universal Mounting Ring without the scissors section. The straps are held in place by studs installed in the wall of the flow stream using a power-activated stud gun. Submerged probes are also installed in primary measuring devices.

The location of the probe in the stream is usually dependent on the flow rate conversion used. For example, if you are using the probe with a primary measuring device (WEIR/FLUME flow con- version when programming the flow meter), there is a specific location for the probe with each primary device. The Isco Open Channel Flow Measurement Handbook provides much useful information in this regard.

If you want to measure flow using a gravity flow equation, such as the Manning equation, you will generally install the probe in the entrance (upstream) pipe of a manhole. If you want to measure flow by calibrating a manhole invert, you would probably locate the probe directly in the manhole invert.

In any case, you must determine the appropriate location of the probe, based on the hydraulic characteristics of the site and the method of level-to-flow rate conversion used.

You do not have to install the submerged probe at the bottom of the flow stream. Although the bottom is the normal position, the Parameter to Adjust step in the program allows you to mount the probe at any vertical location in the stream, and then adjust the indicated level to match the actual level. (The flow meter can indicate negative levels.)

A location other than the bottom of the flow stream may be useful for various reasons: to avoid heavy concentrations of silt, sand, or other solids; to make installation easier in tight loca- tions; to maximize level resolution over a specific level range; to avoid hydraulic obstructions in the flow stream, etc.

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