Dynasonics PFP-600 User Manual
SECTION 1
PFP-600 TECHNICAL NOTES
The below listed items are a number of technical points to observe when installing a
Dynasonics PFP-600 partially filled pipe flow meter. It is absolutely necessary to follow
these “guidelines” to insure proper operation of the unit!
1. In order to properly install the meter, access to the bottom-dead-center line of a
horizontal ( <4° ) pipe is necessary. The transducer mounting area should be free
of oxidation, scale, or other foreign accumulations. Clean the mounting surface
down to bare metal when need be.
NOTE: Pipes with well adhered coating such as paint or epoxy will not influence operation and need not
be removed.
2. The transducer cables provided with the unit may be cut to desired length,
however the cables cannot be extended. The maximum cable length available is
50ft.
NOTE: Splicing of the coaxial cables may degrade sensor performance beyond usable levels. The
shielded coaxial leads are designed to isolate the low level signals from undesirable ambient noise and
must be continuous to the transmitter.
3. There must be at least ten (10) straight pipe diameters upstream and five (5)
straight pipe diameters downstream from the transducer mounting location to
maintain the highest level of meter accuracy. Less than these straight pipe
requirements may degrade meter performance.
4. When locating the two transducers on the pipe, the non-connector ends should be
butted up against each other in the track provided. The transducer clamps should
be hand tightened only, over-tightening will squeeze out couplant. The level
sensor should have sufficient couplant to fill the gap between the rubber spacers
when mounted to the pipe. If the mounting location does not allow this
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configuration, the transducers should be located as close as possible to each other
to maintain system integrity.
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SECTION 2
SPECIFICATIONS
MODEL PFP-600 TRANSMITTER/INDICATOR/TOTALIZER
Flow Accuracy............................ +\-2.0% (Application Dependent) at 70° F (25° C)
Level Accuracy.......................... Better than +\- 1.% (Application Dependent) at 70° F (25° F)
Linearity...................................... Better than +\-0.5% under flow.
Repeatability............................... Better than +\-0.5% under flow.
Rangeability................................ 10:1 or greater.
Standard Scale........................... Gallons per Minute (as specified). Other engineering
units, optional.
Display......................................... LCD-BACKLIT, dual line, 20 Characters, 0.23” high.
Resolution................................... 0.01 Engineering unit.
Standard Output.......................... 4-20 mA dc into 1000 ohms max. isolated.
Totalizer...................................... Resettable, first line of LCD display, With multiplier.
Service........................................ Partially filled pipe flow in engineering units.
Wall or pipe stand mounting. General purpose areas only.
Enclosure.................................... Fiberglass, NEMA 4X, Water resistant.
Power.......................................... 115 VAC +/-10%, 50/60Hz.
Ambient Temperature Range...... 32° F. (0° C) to 122 . (50° C) Optional enclosure heater
available for extended low temperature operation.
Operation Liquids......................... Liquids containing 25 PPM 30 micron or larger suspended
solids, up to 1.0% suspended solids.
Minimum Velocity Sensing.......... 0.2 FPS
Minimum Level Sensing.............. 2.6”
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MODEL T-600-PFP FLOW TRANSDUCER
SERVICE......................... Non-invasive. General purpose areas only.
Housing material............... Aluminum, Stainless Steel, epoxy.
Cable............................... 20 ft. (6 meters) Standard. 50ft. (15.2 meters) optional.
Temperature...................... -40°F. (-40°C.) to 180°F. (82.2°C.)
Mounting.......................... Aluminum track, Stainless Steel Pipe Clamp. (Supplied).
Coupling........................... Silicone based adhesive (supplied), or epoxy.
MODEL L600-PFP LEVEL TRANSDUCER
SERVICE......................... Non-invasive. General purpose areas only.
Housing material............... Aluminum, Stainless Steel, epoxy.
Cable................................ 20 ft. (6 meters) Standard. 50ft. (15.2 meters) optional.
Temperature...................... -40°F. (-40°C.) to 180°F. (82.2°C.)
Mounting........................... Aluminum track, Stainless Steel Pipe Clamp. (Supplied).
Coupling............................ Silicone based adhesive (supplied), or epoxy.
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SECTION 3
THEORY OF OPERATION
The Dynasonics PFP-600 partially filled pipe flow meter combines a traditional clap-on
Doppler type velocity sensor with a unique non-invasive bottom-up level monitor to
accurately determine volumetric flow in horizontal pipes that have dynamically changing
velocity and level characteristics. Unlike traditional velocity sensing flow meters which
assume a full pipe condition and make volumetric flow calculations based on a known
fixed cross-sectional pipe area, the Dynasonics flow meter senses both velocity and
level which allows the micro-processor based electronics to calculate the crosssectional area of pipe that is displaced by the liquid and then factored by the sensed
velocity to determine volumetric flow data, regardless of the liquid level in the pipe.
This distinctive technology allows the user to address partially filled pipes as never
before. The major advantages to this type of technology are unparalleled by other
partially filled pipe flow metering devices. First the Dynasonics PFP-600 is noninvasive. This is extremely important in applications where liquid contact is undesirable.
Secondly, because the systems sensors are located external to the pipe, installation
costs are considerably lower. Finally, because the sensors have no moving parts, are
insensitive to coating materials, or have no pressure sensing ports to clog the system it
is virtually maintenance free.
The PFP-600 is designed around three basic building blocks. The Doppler velocity
sensing electronics, the non-invasive level monitor, and a micro-processor which
controls the timing of velocity and level sensing sequences. The micro-processor
evaluates the flow and level data and calculates the instantaneous volumetric flow, the
total volumetric flow, and drives the 4-20 mA dc output for recording instantaneous
volumetric flow information.
The velocity sensor is a Doppler type sensor. This sensing methodology requires that
the liquid being sensed contain a minimum of 25 PPM of 30 micron suspended particles
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or entrained gas. The system will also sense velocity from turbulence caused by
flowing liquids. It should be noted that in un-pressurized partially filled pipes, most
liquids will contain a sufficient amount of entrained gas for proper operation even though
the liquid may be virtually clean. For sensing velocity, the transmitted signal from the
velocity transducer is passed through the pipe wall material and comes in contact with a
discontinuity in the liquid. The transmitted signal is reflected off of the particle or gas
bubble: This reflected signal, according to Doppler theory, has change in frequency
with respect to the transmitted frequency: This shift in frequency is proportional to the
velocity of the liquid.
The level sensor is a pulsed ultrasonic transit time type. A carefully selected
transmission frequency and beam spread have been incorporated into this non-invasive
transducer. This design allows for bottom-up sensing of liquid level without coming in
contact with the liquid. The transmission frequency has been selected for its unique
ability to penetrate pipe wall material, pass freely through the contained liquid, yet
effectively reflect off the liquid/air/vapor interface within the pipe.
The electronics is designed to emit a short duration ultrasonic pulse. during the
transmitter “off” period the transducer then “listens” for a reflected signal. At the
moment of transmission a timer determines the beginning of the transmit cycle to the
end of the received cycle. The circuit then divides this time by two and then relates this
time to distance or level in the case of the PFP-600.
The micro-processor acts as a controller for the timing of the periods (1 second) in
which the Doppler circuit detects velocity and the level monitor senses level. This circuit
is essential to eliminate the possibility of flow and level data from becoming entangled
with each other thus producing erroneous information. The micro-processor essentially
turns on the Doppler circuit while turning off the level circuits and visa versa on a
continual basis to keep the micro-processor updated as to the latest occurrences in
velocity and level changes. The micro-processor section of the PFP-600 is the heart of
the system. This is the portion of the electronics that evaluates the flow and level data
and then, converts the data to volumetric flow information based on the equation:
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