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What is a PV Meter?
A 'PV Meter' is a flow meter that will HANDLE PROBLEM FLUIDS
that damage other meters. The Oilgear PV Meter (Proportional
Velocity) will pass sand, grit, stones (up to 0.25" diameter
in our smallest meter), bits of wood or rubber, and suspensions
that could stop and damage other meters. There are no close
clearances, no rotating seals, and no stuffing boxes. This simple
design provides little that can go wrong. If something should
malfunction, there is a simple field fix without having to remove
the meter from the line. |
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Here's how it works:
 The
Oilgear PV Meter looks like a short section of pipe, with a
rotor and rotor chamber offset and perpendicular to the flow
axis. The flow stream, combining the effects of a Pelton wheel
and a centrifugal flow turbine drives the rotor. This combination
gives a rotor speed PROPORTIONAL to the flow VELOCITY passing
through the rotor chamber, over a wide range of flow rates.
The combination gives the same performance and small size of
a typical axial flow turbine meter, but with the lower speed
and higher torque of a typical positive displacement meter. |
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| Advantages of the PV Meter |
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Large Particle Clearance |
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Due to the rotor-cage construction,
coupled with the offset chamber, large particles
(up to 0.5" diameter in the 2" size 20
meters) can pass through the meter body without
causing damage. |
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Long Life in Contaminated
Liquid |
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Low rotor speeds and a high torque
values allowed the PV Meter to be designed with
large journal bearings (both graphite and tungsten
carbide), that provide long life, even in the presence
of entrained particles. Additionally, the absence
of rotating seals and close tolerances minimizes
the potential effects of seal failure.
NOTE:
Ball Bearing rotor meters are available and have
lower end operating ranges but they are not recommended
for particle entrained or dirty fluids. They should
be used only for fluids that have lubricity such
as lubricating oils or gasoline etc. |
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High Tolerance to
Overranging |
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The low rotor speed and high torque
output also allow a strong, heavy-duty rotor and
shaft to be used. Thus, the Oilgear PV Meter is
more tolerant of excessive over speed conditions
than the small bearings and low-weight shafts of
other meters. This design difference means a sudden
flow rate surge, such as occurs when a gas slug
is pumped along with a liquid, is less likely to
cause damage. |
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| Readout Flexablilty |
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Mechanical Readouts |
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These devices are used where no
electrical power is available and battery power
is not desirable. A mechanical readout though, may
incorporate passive or active electronic or electrical
devices to provide the best of both worlds. This
system allows mechanical recording of meter output
as backup, in the event of the loss of power. |
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Electrical / Electronic
Readouts |
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The Oilgear Company has produced
electronic products for over thirty years and has
the capability of equipping the meters with up-to-date
readout devices to mate with almost any telemetry
equipment. These readouts range from a simple switch
closure type, to a square wave encoder. |
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Calibration |
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Rotor turns are proportional to
the fluid flow velocity through the meter. In most
meters there is a shelf type septum. By diverting
flow under or over the septum by a calibration plug,
more or less fluid is diverted to the rotor thereby
increasing or decreasing the number of turns the
rotor makes. Calibration in our shop requires no
compensation factors to compensate for machining
errors as in other meters. Field calibration allows
+/-3% of nominal values.
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Accuracy |
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The PV Meter typically exhibits
0.5% of reading accuracy throughout its specified
flow range. |
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Repeatability |
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The PV Meter exhibits 0.25% of
reading repeatability throughout its entire operating
range. |
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| Meter Sizes |
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Flow
Ranges GPM |
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Inches |
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TC,
Graphitar |
Ball
Bearings |
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0.75 |
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5 - 25 |
5 - 25 |
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1.00 |
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15 - 60 |
6 - 60 |
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1.50 |
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15 - 120 |
8 - 120 |
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2.00 |
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50 - 250 |
22 - 250 |
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3.00 |
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100 - 650 |
60 - 650 |
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4.00 |
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200 - 1250 |
120 - 1250 |
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6.00 |
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260 - 3000 |
120 - 3000 |
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8.00 |
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460 - 5000 |
460 - 5000 |
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Pressure Ranges:
Meter pressure ranges vary with the end connection types. Consult
the factory for specifics or send for our Bulletin 90901-C |
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Modifications:
Most meters are made to standard lengths but we can manufacture
to meet your specific requirements such as providing oversize
flange connections or fitting to precise lengths for your location.
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Oilgear Meter Readouts
 All
Oilgear mechanical readouts are designed around a field proven
simple counter mechanism. They are encased in a body of high
impact polymer or aluminum with blue anodizing, nickel plating
or epoxy paint available as appropriate. The instrument bearings
are stainless steel. The nine digit readout characters are
3/16” high and are white on black.
All mechanical readouts use a
universal polymeric mounting hub. The polymeric material eliminates
galvanic corrosion between the cast register body and the
carbon steel or stainless steel meter body. The universal
hub allows any register to mount on any Oilgear meter, old
or new; only the meter size and units of measurement need
be considered
There are four basic types of data acquisition available with
the Oilgear PV Meter:
- Mechanical totalizers, Local
- Switch pulsers (Reed switches)
- Magnetic Pick-ups, Standard or Explosion Proof or Intrinsically
Safe.(Passive or Active)
- Battery or Loop Powered LCD with variations.
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Type
"T" |
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Mechanical Totalizers: |
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Type "T" Mechanical totalizers
use worm driven counters with nine digits. Options
include single or dual counters, reset or non-reset,
and horizontal or vertical readings. The type "T"
readout is used where local totalization is required. |
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Type
"Y" & "Z" |
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Combination Pulser-Mechanical
Totalizer: |
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Y and Z switch closure types combine
the pulser (reed switch) function with the totalizer
function, giving both local totalization and pulse
transmission. Type Y provides one pulse output,
and type Z provides dual simultaneous pulse outputs. |
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Type
"M" & "P" |
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Magnetic Sensor: |
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A direct hub mount magnetic sensor,
type M, can be added to size 06, 10, 15, 20 and
30 Oilgear meters. Separate housings, type ‘P’,
are required for size 40, 60 and 80 Oilgear meters. |
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These Sensors will provide: |
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- Square wave DC output using an active transducer.
- Sine wave AC output using a passive transducer.
- Non-contact, non-wetted, externally mounted
sensor is not subject to corrosion, contamination
or fluid pressure.
- Explosion-proof sensors as well as a full
line of active and passive transducers are available.
- Intrinsically safe devices are available.
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Type
"N" |
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Mechanical Totalizer: |
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Type "N" Mechanical totalizer
with analog rate of flow scale indicator (no power
supply required). Options include single counters,
reset or non-reset, and horizontal or vertical reading. |
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Type
"V" & "W" |
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Switch Pulsers: |
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Type "V" and "W"
switch closures (reed switches) have a solid cover
without a window for viewing the single counter.
Type "V" provides one pulse output and
type "W" provides dual simultaneous outputs.
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Type
"F" |
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LCD Displays: |
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Type "F" readouts are
Liquid Crystal Diode displays that may be locally
powered by batteries or by loop power. Their signal
is a locally mounted pick-up coil that senses the
rotor turns. They can be mounted locally or remotely.
They can display locally and provide remote signal
to a central location. They can be constructed in
Explosion Proof versions or Intrinsically Safe versions.
They come in many configurations for Batch Control,
Flow Computer, Etc.
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Oilgear
Quality Control
 The
Oilgear designed meter prover is typical of the quality assurance
steps Oilgear's quality control engineers have provided for
manufacturing and testing its flow meters. The prover uses
calibrated tanks traceable to the U.S. Bureau of Standards
to check the accuracy and repeatability of the PV meter. The
4,000 U.S. gallon capacity meter tester is used to check and
calibrate each meter manufactured.
Each meter has a serial number established for it. A calibration
curve is run from the prover and maintained on file for each
serialized meter.
Material Certifications are maintained on file for most pressure
bearing raw materials used in the meter manufacture.
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| Application and Selection Criteria |
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Viscosity: |
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The Oilgear PV Meter may be used
with fluids having 130 Centistokes viscosity or
less without significant change in accuracy. As
with all velocity inference meters, the PV Meter
accuracy will change with high viscosity fluids;
however, the change will be less than typical turbine
meters. Since the PV Meter's unique cage chamber
construction requires less cutting of the flow stream,
viscosity has less effect. Regardless of viscosity,
the PV Meter will be repeatable within 0.25%. Consult
the factory for application guidelines with higher
viscosity fluids. |
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Aeration and Flashing: |
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PV Meters are volumetric measuring
devices and, as such, will measure the volume of
any and all materials passed through the meter.
This includes entrained air, liquid vapors, and
entrapped gases. This should be remembered in designing
systems since vapor elimination may be required.
Volatile fluids, such as LPG and liquid anhydrous
ammonia, must be pressurized by pump or sufficient
gravity head to prevent vaporizing or "flashing"
within the meter. Pressure of the liquid should
be increased above that of the supply tank (or wherever
vapor and liquid are in equilibrium) so there is
a definite excess over tank pressure at the meter
outlet. A flow control valve downstream from the
meter is recommended. |
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Underranging: |
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Using the meter below minimum specified
flow rate will result in erroneous readings. |
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Overranging: |
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Consistently using the meter to
130% of maximum flow rate will not cause erroneous
readings but may result in lowering the potential
wear life of the meter and readout. |
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Intermittent Overranging: |
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Up to 130% of maximum flow rate
at less than 20% of the duty cycle will provide
satisfactory results with minimal effect on life. |
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Gross Overranging: |
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200% to 300% and more may not cause
damage depending on how often and how much. |
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Certifications Available
- Welding procedures certified to A.S.M.E. and others
- Quality assureance programs certified to A.S.M.E. and
others
- May be manufactured to NACE specifications
- Hydrostatic testing to 150% of rating
- Certified material tracing
- Radiographic X-ray testing
- Low or high temperature
- Charpy testing
- Magnet particle testing
- Dye penetrant testing
- Ultrasonic testing
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| Where the PV Flow Meter Excels |
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Typical Applications |
Typical Liquids |
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Aircraft Fueling |
Anhydrous Ammonia |
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Batch Blending |
Alcohol |
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Boiler Feed |
Ammonium Nitrate |
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Continuous Blending |
Aqua Ammonia |
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Compressor Fuel Consumption |
Butane, Propane |
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Custody Transfer |
Brine |
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Engine Test Stand |
Condensate |
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Oil Field Automation |
Crude Oil |
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Oil Well Production |
Diesel Fuel |
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Oil Well Testing |
De-ionised Water |
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Water Flood |
Gas Oil |
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Pipeline |
Gasoline |
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Shop Loading, Unloading |
Urea |
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Tank Car Loading |
Kerosene |
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Terminal Accounting |
Sea Water |
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Town Water |
Fertilizer Solutions |
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Truck and RR Car Loading Racks |
Water |
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Unit Accounting |
Suspensions |
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Waste Water Disposal |
Phosphate Solutions |
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Brine Disposal |
Phosphate Solutions |
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Selection of a PV Meter
Flow meter selection requires consideration of many factors
including the anticipated flow range, pressure, corrosion resistance,
entrained particles, fluid characteristics, etc.
Please contact us and ask for our Bulletin 90901-C for more
definitive technical information on selecting the meter for
your particular application. We would be pleased to help you
make your selection.
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