Dwyer PDWS User Manual
Series PDWS
PADDLE WHEEL FLOW
SENSOR INSTRUCTIONS
F-PDWS
TABLE OF CONTENTS
GENERAL INFORMATION
General Information
Features, Specifications ........................................................................................................Page 3
Installation
Insertion Depth, Distorted Flows, Fitting Installation, Meter Installation, Positioning the Meter......................Page 4
Straight Pipe Recommendations .............................................................................................................
Page 5
Full Pipe Recommendations ..........................................................................................................Page 6
Connection Diagrams
RTI/BAT, Connecting to PLC's..............................................................................................................Page 7
Operation
Minimum Flow, Flow Range Table, Calibration (“K-Factor”), Field Calibration..................................................Page 8
Maintenance
Rotor Replacement, Signal Troubleshooting, Sensor Replacement .............................................................Page 9
Parts Explosion
Parts List ......................................................................................................................................................Page 10
Troubleshooting
Problems, Probable Causes, To Check, To Repair ..................................................................................Page 11
The PDWS Series are impeller (or “paddlewheel”) insertion meters designed for use with a wide variety of liquids in pipe sizes
1/2" to 8". Sensors are available in brass, 316 stainless steel,
PVC, and polypropylene. Bodies are machined from a solid rod
for maximum precision. High-quality jewel bearings and nickelbound tungsten carbide shafts are used for extreme low friction
and long life. Low-ow performance is good, although other
Dwyer Instruments Inc. ow meters are recommended where
extremely low ows are being measured.
The rotation of the rotor is detected by a non-drag Hall-effect
sensor. Output is a current-sinking pulse (square wave), which
can be sent long distances (up to 2,000 feet) without a transmitter. This signal can be connected directly to PLC's, counters,
and computer cards, as well as a variety of Dwyer Instruments
Inc. controls and displays.
FEATURES
Cover or Optional Module
Housing Screw
(connect ground to one)
Cable-Seal Strain Relief
Lower Housing (optional)
PDWS meters are ideal for chemical proportioning applications.
If no display is required, a simple divider such as the PWD
provides adjustable pump pacing. For rate and total display,
the Series RTI (loop powered) ow indicator can be mounted
directly on the Series PDWS meter, or remotely on a wall or
panel. The Series BAT blind analog transmitter can be used to
convert to a 4 to 20 mA output.
The Series PDWS require special ttings that ensure correct
depth placement in the pipe. Fittings come in a variety of ma-
terials for compatibility with specic applications. Tee ttings
are individually wet-calibrated at the factory and marked with
the K-factor (pulses per gallon). Saddle ttings must be eld-
installed on the pipe and do not come wet-calibrated. K-factors
for saddles are based on factory-testing. Please see Series PWF
for appropriate ttings.
Caution: Clip(s)
must be installed
before use.
High Pressure Model
TABLES AND DIAGRAMS
Specifications, Features ...............................................................................................................Page 3
Distorted Flows, Positioning the Meter .............................................................................................Page 4
Straight Pipe Recommendations .................................................................................................
Full Pipe Recommendations ...........................................................................................................Page 6
Connections Diagrams .......................................................................................................................Page 7
Flow Range Table, K-Factor Number on Tee Fitting, K-Factor Chart, Pressure vs. Temp Chart...................Page 8
Rotor and Sensor Replacement .............................................................................................................Page 9
Parts Explosion, Parts List ........................................................................................................................Page 10
Troubleshooting............................................................................................................................................Page 11
Page 2
Page 5
Retaining Slot (for U-Clip)
For easy installation at correct depth setting
O-Ring
Jewel Bearings for superior low-ow performance
Rotor
SPECIFICATIONS*
Materials Sensor Body
Rotor
Shaft
Bearings
O-Ring
Rotor Pickup
Maximum
Pressure
High Pressure
Flow Range
Accuracy
Signal
Power
Maximum Current
Cable
*Specications subject to change
Temperature
Brass, 316 Stainless Steel, PVC, or Polypropylene
PVDF
Nickel-bonded tungsten carbide (Ceramic optional)
Ruby jewel
EPDM (Fluoroelastomer optional)
GMR (Giant Magnetoresistive) Sensor
Brass 316 SS PVC or Polypropylene
(See Pressure vs. Temp. Chart)
200 PSI (14 bar) 250 PSI (17 bar) 175 PSI (12 bar) @ 75˚ F
Not Available 400 psi (28 bar) Not Available
200˚F (93˚C) 130˚F (55˚C)
0.3 to 30 ft/s
+/- 1.5% of full-scale
Hall-effect current sinking pulse
6-24 Vdc, 2 mA
20 mA
#22 AWG, 3 Cond, 18' (maximum 2000’ run)
Page 3
INSTALLATION
INSTALLATION
Insertion Depth. The PDWS Series are xed-depth meters
that must be used with matched ttings appropriate to the
application and pipe size. This ensures that the ow sensor
is installed at the correct insertion depth to measure the av-
erage ow velocity of the stream.
Straight Pipe. Straight pipe of at least 10 diameters up-
stream and ve diameters downstream of the meter is
strongly recommended for proper accuracy. This is neces-
sary because the shape of the velocity prole changes as the
rate increases around an elbow; placing the meter too near
the elbow causes a distorted reading. Additional straight run
may be needed under specic adverse circumstances (see
next page).
If you can’t provide enough straight run to smooth out the
velocity prole, some decrease in accuracy may result. This
does not mean the meter’s reading is meaningless, however.
In some applications (e.g., control system, valve operation)
a repeatable reading may be more important than a highly
accurate one.
POSITIONING THE METER
Okay, if no air in pipe
BEST
Okay, if no sediment in pipe.
STRAIGHT PIPE RECOMMENDATIONS
(X = diameter)
Reduced Pipe
Two Elbows In Plane
10X
5X
PDWS
5X10X
PDWS
DISTORTED FLOWS
Faster Flow
Causes Meter
Distorted
To Read High
Flow Prole
FLOW
10X
Diameter Minimum
(See Below)
Diameter Minimum
5X
(See Below)
Fitting Installation. Stainless steel and brass ttings have
female pipe threads, requiring the appropriate male thread-
ed ttings. Saddle ttings require a hole to be cut in the
pipe (recommended hole size is 1-3/4”). Before cutting into
the pipe, observe the drawing below to choose your meter
orientation.
PVC Fittings. A PVC tting is usually installed by solvent
welding. PVC tees are supplied with some upstream straight
pipe, less than the recommended straight pipe requirements. It is not advisable to connect directly to the end of
these ttings with a ow disturbing device (valve, elbow), but
rather add straight pipe to the end of these ttings to meet
the straight pipe requirements for your application.
Meter Installation. After the meter tting is installed in the
pipeline, the meter can be installed in the tting. Press the
meter into the tting as far as it will go. Retain the meter in
place by inserting the u-pin. The pin can be installed from
either side. It may be necessary to rotate the probe back
and forth slightly to start the pin into the slots on the probe.
Slide the pin in as far as it will go.
Caution: Never remove the u-clip retainer when
the pipe is under pressure. Always remove
pressure from the pipe before you attempt to
remove the meter. Removal under pressure
may result in damage or serious injury.
Two Elbows, Out Of Plane
Expanded Pipe
Spiral Flow
Propeller Meter
20X
20X
5X
PDWS
5X
PDWS
30X
PDWS
50X
Page 4
Swirling Flow
Partially Open
Buttery Valve
PDWS
Page 5
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