Clamp Filling Oval Gear Positive Displacement Flow Meter

Positive Displacement Flow Meter is also called PD Meter. A positive Displacement Flow Meter can directly measure the volume of liquid passing through. The PD Meter achieves this by trapping fluid between rotating parts in a high-precision chamber. This can be compared with repeatedly filling the beaker with liquid and pouring the contents downstream while counting the number of times the beaker has been filled.
The Sanitary Positive Displacement Flow Meter is made of stainless steel and is quickly connected by Tri-clamp. Can be used to measure viscous liquids in the food industry. Such as sweeteners, edible oil, palm oil, honey, fat, tallow, fat, syrup, molasses, etc.

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Sino-Inst offers a variety of Oval Gear Flow Meters for flow measurement. If you have any questions, please contact our sales engineers.

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Volumetric Flow Meters

Features of Sanitary Positive Displacement Flow Meter

  • The flow measurement has nothing to do with the flow state of the fluid, and the measurement range is wide.
  • The higher the viscosity of the medium, the smaller the leakage from the gear and the metering gap. Therefore, the larger the sticky skin of the nuclear test medium, the smaller the leakage error, and the more beneficial it is to the measurement.
  • The oval gear flowmeter has high measurement accuracy and is suitable for measuring the flow of high-viscosity media.
  • There is no need for straight pipe sections before and after the flowmeter, even if the flowmeter is close to valves, elbows, shrinking pipes, and expanding pipes, there is no need to install straight pipe sections.
  • The measurement accuracy is higher: 0.2 and 0.5.
  • It can measure various oil products and the metering of cast iron liquid media.
  • The spiral rotor rotates evenly, with little vibration and long life
  • Not sensitive to changes in the viscosity of the liquid being tested, especially suitable for the measurement of liquids with higher viscosity
  • The oval gear flowmeter has high measurement accuracy. It is suitable for the measurement of the flow of high-viscosity media. But it is not suitable for fluids containing solid particles. The solid particles will jam the gear and make it impossible to measure the flow. If the measured liquid medium contains gas, it will also cause measurement errors.

Specifications of Positive Displacement Flow Meter

Body Material Cast iron Cast Steel Stainless Steel
Signal Output Optional: Pulse or 4-20mA
Power supply None or  None or 24V DC
Accuracy Standard: 0.5%; Optional: 0.2%
Explosion proof ExiaIICT6 ExiaIICT6
Protection Rating IP65 IP65
Diameter DN15~DN200 DN10~DN200
Installation Method Flange,Tri clamp-stainless steel
Fluid Temperature -20ºC~200ºC -20ºC~100ºC
Ambient Temperature -20ºC~60ºC -20ºC~60ºC
Model Size(mm) Medium Viscosity (mPa. s)
0.3-0.6 0.6-2 2-200 200-1000 1000-2000
LC-10Ⅱ 10 0.08-0.2 0.1-0.25 0.05-0.25 0.08-0.25 0.05-0.25 0.03-0.05 0.02-0.05 –
LC-10 10 0.2-0.5 0.15-0.5 0.1-0.5 0.1-0.5 0.05-0.5 0.06-0.3 0.03-0.3 0.03-0.2
LC-15 15 0.75-1.5 0.5-1.5 0.3-1.5  0.3-1.5  0.15-1.5  0.2-1.0  0.1-1.0  0.07-0.7
LC-20 20 1.5-3 1-3 0.5-3  0.5-3  0.3-3  0.4-2.1  0.2-2.1  0.15-1.5
LC-25 25 3-6 2-6 1-6 1-6  0.6-6  0.8-4.2  0.4-4.2  0.3-3
LC-40 40 7.5-15 5-15 2.5-15 2.5-15  1.5-15  2.1-10.5  1.0-10.5  0.7-7.5
LC-50 50 8-24 8-24 4.8-24  4.8-24  2.4-24  2.4-16.8  1.6-16.8  1.2-12
LC-B40(50) 40,50 6-20 6-20 4-20  4-20  2-20  2.8-14  1.4-14  1.0-10
LC-65 65 20-40 15-40 8-40  8-40  4-40  5.6-28  2.8-28  2-20
LC-80 80 30-60 20-60 12-60  12-60  6-60  8.4-42  4.2-42  3-30
LC-100 100 50-100 34-100 20-100  20-100  10-100  14-70  6-70  5-50
LC-150 150 95-190 64-190 38-190  38-190  19-190  26.6-133  13.3-133  9.5-95
LC-200 200 170-340 114-340 56-340  56-340  34-340  47.6-238  23.8-238  17-170
Accuracy – 0.5 0.2 0.5  0.2  0.5  0.2  0.5  0.5

Note: when the viscosity is over 200 mPa. S, it belongs to high viscosity medium.

Positive displacement flow meter pdf

Positive displacement flow meterDownload

Positive displacement flow meter working principle

In principle, a positive displacement flow meter is a hydraulic engine that absorbs a small amount of energy from a fluid.

This energy is used to overcome the frictional force of the rotation of the flow detection element and the accessories, and at the same time form a pressure drop at the inflow and outflow ends of the meter.

The working principle of a typical Positive displacement flow meter (elliptical gear type) is shown in the figure.

The two OVAL gears have a special shape that rolls over each other for contact rotation.

P1 and p2 represent the inlet pressure and outlet pressure respectively, obviously p1>p2.

Figure 1(a) The lower gear rotates counterclockwise under the pressure difference between both sides, which is the driving wheel;
Because the pressure on both sides of the upper gear is equal, no rotating torque is generated. It is a driven wheel, driven by the lower gear, and rotates in a clockwise direction.

In the position in Figure 1(b), both gears generate a rotational torque under the action of differential pressure and continue to rotate.

When it is selected to the position of Fig. 1(c), the upper gear becomes the driving wheel, and the lower gear becomes the driven wheel, and it continues to rotate to the same position as Fig. 1(a) to complete a cycle.

One cycle action discharges the fluid volume of the four crescent-shaped cavities enclosed by the gear and the shell wall. This volume is called the “circulation volume” of the flowmeter.

Suppose the flow meter’circulation volume’ is υ, and the number of gear rotations in a certain period of time is N. Then the volume of fluid flowing through the flow meter in that time is V,

Then V=Nυ (1)

The rotation of the elliptical gear is transmitted to the counter through the magnetic seal coupling and the transmission reduction mechanism to directly indicate the total amount flowing through the flowmeter. If the sending device is attached, and then equipped with an electric display instrument, the remote transmission can only be instantaneous flow or cumulative flow.

Although there are many segmentation methods to form various forms of PDF, most of them have similar basic characteristics.

The main reason for the PDF error is the leakage of the gap between the movable measuring piece and the static measuring chamber that divides a single fluid volume.

One of the reasons for the leakage is to overcome the frictional resistance of the moving parts; the second is the pressure drop formed by the hydraulic resistance of the instrument.

Read more about: Positive Displacement Flow meter Technology

Positive displacement flow meter advantages and disadvantages

  • Positive displacement flow meter measurement accuracy is high, the basic error is generally ±0.5%R, and special ones can reach ±0.2%R or higher. Usually used in expensive media or occasions requiring precise measurement.
  • Positive displacement flow meter has no effect on the measurement accuracy when the flow velocity field of the rotating flow and the pipe choke is distorted, and there is no requirement for the front straight pipe section. This is of great significance in field use.
  • Positive displacement flow meter can be used to measure high viscosity fluids. The range is wide, generally 10:1 to 5:1, and special can reach 30:1 or more.
  • Positive displacement flow meter is a direct-reading instrument, no external energy is needed, and the cumulative total can be directly obtained, which is clear and easy to operate.
  • In the indirect method of mass flow measurement combined with volumetric flowmeters, PDF is compared with volumetric flowmeters derived from velocity equations. The volume is a direct geometric quantity, and the influencing factors of volumetric quantity are simpler.
  • In the measurement of high-pressure natural gas that is not suitable for density meter measurement, the compression coefficient of difficult gas can be obtained indirectly with PDF.
  • The Positive displacement flow meter structure is complex, bulky, and heavy, especially the larger-diameter Positive displacement flow meter is bulky, so it is generally only suitable for small and medium-sized.
  • Compared with other types of general flow meters (such as differential pressure, float, electromagnetic), PDF’s measured medium types, medium working conditions (temperature, pressure), and caliber limitations are larger, and the application range is narrow.
  • Due to the thermal expansion and deformation of parts at high temperatures, and the brittleness of materials at low temperatures, Positive displacement flow meter is generally not suitable for high and low temperatures. The current usable temperature range is roughly -30～+160℃, and the maximum pressure is 10MPa.
  • Most PDF instruments are only suitable for clean single-phase fluids. When particles and dirt are contained, a filter must be installed upstream, which will increase pressure loss and increase maintenance. If measuring liquids containing gas, a gas separator must be installed.
  • Positive displacement flow meter security is poor. If the detection moving parts are stuck, the fluid cannot pass through, and the cut-off pipe system cannot be used. However, some structural designs (such as Instromet’s waist wheel flowmeter) have a built-in bypass in the housing. When the detection moving element is stuck, the fluid can pass through the bypass.
  • Some forms of Positive displacement flow meter instruments (such as oval gear type, waist wheel type, rotary piston type, etc.) will bring pulsation to the flow during the measurement process. Larger caliber instruments will also produce noise, and even pipe vibration.

Read more about Mass Flow Rate vs Volumetric Flow Rate

Types of positive displacement flow meter

Positive displacement (PD) flow meters are volumetric flow measurement instruments. They are ideal for low flow rates, high viscosity fluids, and flow measurement involving start and stop or pulses.

Positive displacement flow meters are similar in design to gear pumps. However, the principle of operation is the opposite. It is not the gear that drives the fluid, but the fluid that drives the gear.

The non-intrusive Hall effect sensor detects the movement of the gear. When each gear tooth passes the sensor, a square wave pulse is generated and a discrete volume of liquid is measured. The pulse sequence generated is proportional to the actual flow rate and provides a highly accurate representation of the fluid flow.

There are many styles of positive displacement flow meters, and we provide three of them:

Gear flow meter for Micro flow

In a positive displacement spur gear flowmeter, the fluid moves around two circular gears and passes through the inner cavity of the flowmeter from the inlet to the outlet. Measure the discrete volume of liquid trapped between each gear tooth. Contrary to the oval gear meter. In an oval gear meter, the larger volume between the gears is swept through the chamber.

Gear flow meter is a micro digital positive displacement flow meter. Can measure very small flow rates and quantify small volumes of liquid. High and low-temperature resistance (-196℃-200℃).

The Gear flow meter for Microflow is made of stainless steel and is used for precise continuous or intermittent measurement of the flow or instantaneous flow of liquid. It is especially suitable for the flow measurement of heavy oil, polyvinyl alcohol, grease, and other high-viscosity media. It can measure the viscosity of Fluid up to 10000Pa.s.

Extended reading: Cylinder Gear flow meter for micro flow measurement.

Helical Gear-PD Flow Meter

Probably the most accurate PD meter, in which two intersecting cylindrical holes are fitted with two interlocking helical gears. Since the gear direction is in line with the flow, when the fluid passes through, the gear rotates with a small pressure drop. These flow meters are very accurate over a wide range of flow rates and are compatible with very high viscosity fluids.

Helical Gear-PD Flow Meter is also called, spiral double rotor flowmeter, LLT, LZ double rotor flowmeter, or UF-Ⅱ spiral rotor flowmeter.

As a high-precision flow meter, PD Flow Meter has an accuracy of 0.2 level. It is especially suitable for the measurement of industrial liquids such as crude oil, refined oil, and light hydrocarbons. It is a new generation volumetric flowmeter. Because it uses a pair of spiral rotors with special teeth, it is also called “Helical Gear Flowmeter”.

In this design, the rotating piston oscillates in a circular cavity, and a fixed amount of fluid is discharged every time it rotates. This type is suitable for ultra-low flow and high flow as well as high pressure.

Extended reading: Stainless steel flow meters|304-316 optional

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FAQ

For different working principle, We offer different types of flow meters, like:
Differential Pressure Flow Meters
Orifice Plate
Venturi Tube
Flow Nozzles
The Sonic Nozzle – Critical (Choked) Flow Nozzle
Calorimetric Flowmeter
Ultrasonic Doppler Flowmeter
Positive Displacement Flowmeter
Variable Area Flowmeter or Rotameter
Velocity Flowmeters
Pitot Tubes
Electromagnetic Flowmeter
Turbine Flowmeter
Vortex Flow Meter
Thermal Flowmeter
Coriolis Flowmeter
Mass Flowmeters
Open Channel Flowmeters

Extended reading: How does a rotameter work

A positive displacement meter is a type of flow meter that requires fluid to mechanically displace components in the meter in order for flow measurement. Positive displacement (PD) flow meters measure the volumetric flow rate of a moving fluid or gas by dividing the media into fixed, metered volumes (finite increments or volumes of the fluid). A basic analogy would be holding a bucket below a tap, filling it to a set level, then quickly replacing it with another bucket and timing the rate at which the buckets are filled (or the total number of buckets for the “totalized” flow). With appropriate pressure and temperature compensation, the mass flow rate can be accurately determined.

The industries where they are used in descending order are oil and gas, water and wastewater, chemical, power, pharmaceutical, food and beverage, pulp and paper, metals and mining and aerospace.

Rotameter measures the fluid flow based on the throttling principle. But it changes the flow area of the fluid to keep the differential pressure between the top and bottom of the rotor constant, so it is also called variable flow area constant differential pressure flowmeter, also called float flowmeter.

Sino-Inst, Manufacturer for Positive Displacement Flow Meters. For example crude oil flow meter, diesel flow meter, gasoline flowmeter.

Sino-Inst’s Positive Displacement Flow Meters, made in China, Having good Quality, With better price. Our flow measurement instruments are widely used in China, India, Pakistan, the US, and other countries.

SS-Tri clamp Sanitary Positive Displacement Flow Meter

Positive Displacement Flow Meter is also called PD Meter. A positive Displacement Flow Meter can directly measure the volume of liquid passing through. The PD Meter achieves this by trapping fluid between rotating parts in a high-precision chamber. This can be compared with repeatedly filling the beaker with liquid and pouring the contents downstream while counting the number of times the beaker has been filled.The Sanitary Positive Displacement Flow Meter is made of stainless steel and is quickly connected by Tri-clamp. Can be used to measure viscous liquids in the food industry. Such as sweeteners, edible oil, palm oil, honey, fat, tallow, fat, syrup, molasses, etc.

Product SKU: Tri clamp-Stainless steel Sanitary Positive Displacement Flow Meter

Product Brand: Sino-Inst

Product Currency: USD

Product Price: 500

Price Valid Until: 2029-09-30

Product In-Stock: PreOrder

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