Water Weir Flow Controller. Introduction. Safety Precautions. Mounting the Hardware

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1 Introduction Safety Precautions This instruction sheet describes how to set up and use the Hach (Figure 1). A water weir is a device that raises or diverts water to regulate the flow. Hach s water weir relies on gravity feed and head pressure to maintain a constant flow rate through the particle counting sensor. A constant flow rate allows a computer or particle counter to calculate the particle concentration. The vertical mounting position, relative to the water level in the filter, determines the head pressure. The particle sensor is mounted to the water weir so that the sensor plumbing connectors are lower than the water weir overflow drain. This allows the sensor to prime by gravity feed. Please read this instruction sheet before unpacking, setting up, or operating this instrument. To ensure your safety, use and install the only as specified in this instruction sheet. Figure 1 Mounting the Hardware Using Vertical Position to Set the Required Head The head pressure at the water weir inlet should be greater than four feet even when the water filter is at maximum head loss. If the maximum head loss of the filter is six feet, then adding the six feet of head loss to the required four-foot head yields 10 feet. Therefore, with six feet of head loss the water weir inlet would have to be positioned 10 feet below the water level in the filter. Thus the water weir will probably be positioned near the floor. (See Figure 2.)

2 , continued Four feet of head will maintain a sensor flow greater than or equal to 100 ml/min. Manually enter flow rates other than 100 ml/min. into the controlling computer to obtain correct particle concentration readings. Avoid tapping small diameter tubing, such as head-loss sensor tubing. Using small diameter tubing for the water weir input line can cause increased head loss and further lower the mounting height. In addition, bubbles may accumulate in the smaller line and prevent the water weir from priming after a filter backwash. If an optional strainer is used with the water weir, the strainer should be checked for clogging on a regular basis to minimize head loss. Selecting the Best Mounting Position After selecting the proper height for the water weir and sensor enclosure, determine the horizontal position of other components. Two factors influence the horizontal position: Length of sample tubing from tap Available wall space for each component The 2200 PCX ships with a 10-foot length of black, semi-rigid tubing that connects the sample tap and the water weir inlet. Do not lengthen this tubing. (Refer to Connecting the Plumbing for more information.) When selecting a tap location, make sure that the 10-foot sample tube will reach the particle counter and the water weir. Each particle counting component requires wall space for itself and the associated cables and plumbing connectors. Brackets and pre-drilled holes for mounting the water weir directly to the sensor s clips are provided for your convenience. Mount the water weir and sensor enclosure very close to each other. The water weir must be mounted vertically, but the sensor can be mounted in any position as long as the plumbing connectors on the sensor are lower than the water weir overflow. Mount the power supply enclosure above the flood level of the pipe gallery. If the six-foot long power supply-to-sensor cable is not long enough to elevate the power supply above flood level, use a longer cable (up to 25 feet, available only with a NEMA 4X enclosure). The required wall space and relative position of each component are shown in Figure 3. Page 2

3 , continued Figure 2 Determining the Required Head Maximum Head Loss plus 4 feet AC Power Adapter Power Counting Alarm Clean Sensor 2200 PCX Particle Counter Filter Sample Inlet tubing should not extend beyond 10 feet. Plumbing Tap with Shut Off Drain Page 3

4 , continued Figure 3 Mounting the PCX Plug-In AC Power Adapter 5.5 inches x 3.9 inches x 2.6 inches deep Note: Water Weir Flow Controller requires additional space mm 8.30 inches mm 7.00 inches mm 6.00 inches mm inches Power Counting Alarm Clean Sensor mm inches 2200 PCX Particle Counter 9.52 mm.375 inches 4 places Connecting the Plumbing Plumbing connections involve connecting the particle counter (large enclosure) and a flow controller to the water system. The most important part of connecting the plumbing is tapping the best sampling location in the water system. A good sampling location ensures a meaningful measurement. Use the guidelines below to tap the best location: The tap location must be able to supply more than 100 ml/min. flow with at least four feet of head. Tap upstream of a pressure reduction valve or a point where the plumbing becomes larger. These locations tend to create bubbles that can be erroneously counted as particles. Page 4

5 , continued Tap 18-inches downstream of a bend in the plumbing. Bends create turbulence, which mixes the particles, giving a better particle-size distribution. The 18 in. distance from the bend restores an even flow, making sure the mixing is complete, but not allowing enough time for the larger particles to settle. Tap a location that has a fast flow rate. This keeps the heavy particles suspended. Tap the pipe as shown in Figure 4 to avoid air or sediment contamination of the sample: Figure 4 Tapping the Best Sampling Location Air (Typical) Sediment (Typical) Poor Good Best Poor Connecting the Water Weir to the Tap 1. Install a separate plumbing tap, including a shut-off valve, for the water weir. Locate the best sample location as shown in Figure Attach the compression fitting to the plumbing tap. A white compression fitting for ¼ tubing is provided. Note: Do not remove the nut from the compression fitting. Removing the nut may result in small washers and ferrules falling out of the fitting and becoming lost. 3. Route the black, semi-rigid tubing to the water weir controller. Do not lengthen the tubing. Tubing lengths longer than 10 feet will cause the larger particles to drop out of the sample and distort the accuracy of particle-size readings. 4. Purge the sample tap and tubing of debris and sediment before connecting to the water weir. 5. Attach the remaining end of the ¼ tubing to the water weir as shown in Figure 5. Page 5

6 , continued Figure 5 Installing the Tubing in the Inlet Fitting Connecting the Water Weir to the Sensor 1. Cut another segment of black, semi-rigid tubing one inch longer than the length required to reach the inlet fitting on the bottom of the water weir. 2. Insert the tubing into the inlet fitting using the Quick Disconnect shown in Figure 6. Finger tighten the nut, then tighten until snug (no more than ¼ turn). 3. Attach the remaining end of the tubing to the water weir using a compression fitting. 4. Repeat steps 1 3 for the tubing that connects the sensor outlet fitting to the flow meter. Figure 6 Installing the Tubing in the Quick Disconnect Fitting Connecting the Water Weir Drain 1. Attach clear flexible tubing to connect the particle counter outlet (front side of sensor) and the water weir return. See Figure Install the drain on the water weir. Slide a clear, ½ in. I.D. hose over the barbed fitting on the water weir drain and route to the appropriate drain. 3. Open the shut-off valve on the plumbing tap and check for leaks. Page 6

7 , continued Adjusting the Flow Rate Initial Use of the Water Weir Adjust the flow rate to 100 ml/min. by changing the head. To decrease the head, move the white cap up; move it down to increase the head. See Figure 7. Nominal 100 ml/min. flow is typically achieved at 33 in. separation from the overflow port to the end of the sensor outlet line. Move the cap two or three inches to change the flow rate by approximately 1 ml/min. Measure the flow using a 100-mL graduated cylinder and a stopwatch. Purge the water weir and particle counter until any initial burst of sediment or debris is removed. This may take several minutes to several hours depending on the contamination and particle sizes being monitored. Particle counting may be performed during this cleanup period, but may be inaccurate due to this contamination. Figure 7 Water Weir and Particle Counter Configuration Sensor Sensor Outlet Flow Control Device (Water Weir) 2200 PCX Particle Counter To adjust the flow rate, slide this cap up or down mm (1 inch) = 1-2 ml/min To measure the flow rate, rotate the cap as shown and use a graduated cylinder and a stop watch. Measure for one minute mm (33 inches) from the overflow to the white cap is about 100-mL/minute. To Drain or Waste Page 7

8 , continued Technical Data The following table provides the head height for a specific flow rate. Table 1 Sensor Flow Table Sensor Model Head Height (inches) Flow Rate (ml/min.) PCX Hach Company, All rights reserved. Printed in the U.S.A. aa/dp 12/99 1ed