The insertion meter has been applied to water flow monitoring applications for about 30 years. The reason that it has gained wide acceptance is because:

• it is easy to install in all types of pipe.
• it is relatively inexpensive compared to other devices such as turbine, ultrasonic, Doppler, magnetic, etc.
• it is very accurate.
• cost of maintenance is low and infrequent.
• calibration of the electronic register to a given line size is quick and easy.
• adaptability of the register to other devices such as chart recorders, PLC's, data loggers, and any device that takes either a digital pulse or analog 4-20ma signal.

The criteria that have to be reviewed in selecting an insertion meter are as follows:

• line size.
• material the pipe is made of and schedule.
• is the pipe used with water only or is there chemistry involved? Salt water requires special attention on materials of construction.
• what is the temperature of the water?
• what is the flow rate in the line?
• what is the plumbing configuration, ie. proximity of elbows, tees, etc.

Let us examine all of the above items in closer detail.

1. Line size - Seametrics insertion meters have had successful use in many water line applications through 48" pipe. IP80 series can go down to Vz" with the dedicated tee provided with the IP. Materials include PVC, polypropylene and stainless steel. These are adaptable to line size up to 8'" IP1O11115 cover line sizes through 10". The 201/215 cover to 48". They are in brass, stainless steel and Pvc. Isolation valves for probe removal under operating conditions are in the 115/215 series.
   
   The TX series is insertion turbine which allows lower flow monitoring down to .2 ft. per second, up to 30 ft. The IP is .3 -30ft/ second.
   
2. Pipe material and the wall thickness is critical to the K factor (US gallons per magnetic contact of the paddlewheel vane with the Hall effect sensor). The K factor is found in the instruction manual and it is programmed into the Ff420 to calibrate to the line size.
   
3. Water or chemistry - the K factor table in the manual is setup for water. Other liquids to be measured with higher specific gravity than water should be measured into a container and timed. With the K factor set at 1, the number of pulses registered for one gallon will equal the new K factor. Make sure the materials of construction on the insertion metet meet that of the chemistry. A ceramic shaft option will exceed the tungsten carbide chemical resistance which is standard.
   
4. Temperature - the maximum temperature for the PVC unit is 130 degrees F and 200 degrees F for brass and stainless steel. The limiting factor for the temperature is the potting compound on the inside of the meter where the Hall effect sensor is positioned.
   
5. Flow - knowing the maximum and minimum flow in the pipe is critical to proper mating of the insertion meter to the conditions., .3-30ft/second in the IP and .2-30 in the TX is the given range. The instruction m,flnual translates ft/sec into gpm (gallons per minute). 6.
   
6. Pipe elbows, tees, valves etc - all of these create turbulence. This will throw off the accuracy of the reading. Installing the insertion meter on a straight run 10 diameters of pipe in front and 5 downstream is the recommended distance. In a practical application, split the available distance 2/3 and 1/3.
   

INSTALLATION, OPERATION AND MAINTANCE

Some of the pointers have been mentioned above. Where in the pipe has just been discussed. The hole in the pipe is 1 3/4" in diameter for the entry of the insertion meter. The insertion meter is then saddle clamped to the pipe. In a smaller line size, say 3", the tee would be reduced to 11/2"pipe thread to receive the insertion meter.

Orientation of the insertion meter in the pipe is usually 12 o'clock by custom. However, the manual shows that 3 or 9 0' clock positions. The insertion depth is also critical. The chart on page 3 shows the C dimension minus the wall thickness of the pipe on table 2 is the insertion depth. The measurement is made from the top of the pipe to the break in the meter's junction box. This places the insertion meter into the turbulent and laminar flow profiles. The wire coming out of the junction box should be parallel with the water flow. The three conductor wire, red for 6-24 volts DC, white for signal and the black forpower should be fastened into the respective terminals of the FT420 flow indicator or other control with the terminals marked accordingly.

Over time there can be wear on the sapphire jeweled bearings. A rotor repair kit is available for your insertion meter as shown in the last part of the instruction manual. The part number 25902 is the standard kit for the IP1O1 with carbide shaft and kynar rotor. Installation of the kit is done by by backing out the bearing housing from the existing unit and tightening the new bearing. Do one side all the say and then the other. Correct positioning be verified by spinning the rotor and it should spin freely. You may use a business card as a feeler gauge and that should be the side to side play on the shaft.

CONTROLS - Ff420/415

The insertion meter sends its signals into the Ff series controller for the display of the indication and totalization of flow. The signals out are also 4-20ma and digital pulse. The unit may be panel mounted, meter mounted or wall mounted. 12-24volts DC are required to power the Ff controller. The FT415 is lithium battery powered and the 420ma output is sacrificed over the powered FT420.

Programming is simple. The Set K is for calibrating the controller to the line size. The Set P is for dividing the pulse output signal. If you have flow of 1O00gpm and you want 100 pulses to go to the PLC, make the Set P read 10. Set 20 means set the 20 milliamp output signal to maximum flow, ie 20 equals 1000. Lastly, you can set the decimal place of one digit showing tenths of a gallon or round it off to the nearest gallon.

The pulse out or 4- 20ma output signals can be directly interfaced with a chemical feed pump, PLC, chart recorder, data logger or any other device accepting these signals.

NEW PRODUCTS FROM SEAMETRICS JUST RELEASED

EM -101 Mag Meter - this product addresses a long requested item, namely to monitor the pulsating flow on the discharge side of a chemical pump without needing a pulsation dampener. The ranges include lA" .6-60gph, 3/8" 1.2-180gph and the W'2.4-600gph. Uses a kynar body for universal compatability and platinum plated titanium electrode.

DK75 Data Logger - the data logger is fitted to the current insertion meter junction box. A Palm Pilot is connected to the logger for downloading the information. One PDA (Palm Pilot) can receive data from up to 16 data loggers. The PDA in turn transfers the data to a desktop computer with the FlowInspector software. Up to 90 days of information can be accumulated at a single data logger.

APPLICATIONS

• Water transmission lines to 48".
• Bidirectional flow with a single insertion meter (2 sensors) and two indicators
• Insertion meter directly inputting signal to PLC
• PLC interface with radio transmission to a central computer tracking multiple flow points
• Chemical pump output with mag meter
• Proportional chemical feed for chlorination or any injection chemistry.
• Lechate transfer to a wastewater treatment plant.
• Other control devices available include flow switches. batch controls and pulse splitters.