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Free Flow Palmer-Bowlus Flume Installation

The Palmer-Bowlus flume was designed for flow measurement in a non-pressurized pipeline.

When setting the flume in concrete, pay attention to the following points:

1. The flume must be installed with the floor of the throat level.
2. The flume must not float out of position due to grout pressure.
3. The flume’s internal dimensions must not be distorted due to grout pressure.

Very small Palmer-Bowlus flumes can be set in place as follows:

All-thread rods can be embedded in the concrete below the flume, with the rods aligning with the anchor clips on the flume's exterior. Either grout the rods in place below the flume or drill holes and epoxy them in place. After the all-thread rods are firmly anchored in place, the flume can then be locked in place and leveled by using a nut and washer on both sides of the anchor clips. The flume can then be grouted in place. The first pour of grout should just cover the bottom of the flume and allowed to set before additional pours are made. The finished surface should be sloped toward the flume so that any water will drain back into the flume.

Installation procedure for large Palmer-Bowlus flumes:

The positioning procedure described above can also be used to secure larger flumes in the correct position. Large flumes must also be weighted and lined on the interior to prevent floating or distortion due to the grout's hydrostatic pressure.

Large flumes may require blocks or other support on the underside of the flume to support the interior weights during installation. Block the underside of the flume such that the throat is level and at the correct elevation. Install temporary wooden cross braces and plywood lining inside the flume to prevent distortion due to the grout pressure.

The flume is then weighted inside with sandbags or other weight. Additional weight can be positioned by placing a board across the top of the flume and using a 5 gal. bucket filled with sand or other heavy items. If there is any doubt as to the weight required, calculate the interior volume of the flume, from the bottom of the flume to the top of the first pour of grout. The weight required must be equal to the weight of the grout that is displaced by this volume. Grout is 2.5 times heavier than water. Water is 62 lbs/cu.ft., grout can be estimated at 155 lb/cu.ft.

If all-thread is not used to secure the flume at the correct location a piece of "U" bent rebar can be placed through the anchor clip holes to insure that the flume is firmly locked into the grout. Weighting must be done if the all-thread is not used.

A large flume should be grouted in several lifts, with the first one only reaching slightly above the invert of the flume. Before proceeding with the next pour, be sure the grout is hardened to the point where the pressure of the next lift cannot be transmitted through the previous pour and possibly float the flume. Continue with additional pours, letting each set, until the surface is even with the top of the flume. The finished surface should be sloped toward the flume so that any water will drain back into the flume.

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