The Advantage and Disadvantage of oval gear flow meter

The Oval gear flowmeter is a type of positive displacement flowmeter. It is one kind of the most accurate type flowmeters. It is used for precise continuous or intermittent measurement of flow measurement in liquids with higher viscosity. The oval meter can display instant flow and totalized flow. It is especially suitable for heavy oil, polyvinyl alcohol, petro, resin, etc.


Oval gear flow meters have high accuracy, so it is often used to measure the total amount or flow of expensive media in industrial sectors such as petroleum, chemical, coatings, pharmaceuticals, and energy.


The oval gear flowmeter has a unique advantage in petroleum metering. The key reason is the self-lubricating effect of the fluid itself, which enables the flow instrument to operate in a long-term and stable manner.


A high-quality oval gear flow meter  with high precision, long-term performance retention and good repeatability is used as a standard master flow meter for flow rate measurement in flowmeter calibration.


Oval gear flowmeters are relatively bulky, especially for high-flow, large-diameter flow instruments, which are gradually replaced by turbine flowmeter, electromagnetic flow meter, vortex flowmeter, and Coriolis masses flow meters.


However, its superior repeatability and long-term retention performance guarantees many application areas and will not be replaced by other instrument .Oval gear flowmeters are also widely used in liquefied petroleum gas in foreign countries, but they are still in the initial stage of startup in China.

Advantages of oval gear flowmeter

1.  It has high measurement accuracy, the basic error is generally ± 0.5% R, special up to ± 0.2% R or higher. It is usually used in expensive media or where precise metering is required.

2.  The flow measurement is independent of the flow state of the fluid. That is, the oval meter has no influence on the measurement accuracy when the rotational flow and the flow path of the pipe choke are distorted, and there is no requirement for the upstream straight pipe section. This is because the oval gear flow meter is measured by the rotation of the oval gear by the pressure of the measured medium. This is of great significance in field use.

3.  Oval gear flow meters can be used for the measurement of high viscosity fluids. The larger the viscosity of the medium, the smaller the leakage amount leaked out from the gear and the metering gap.

4.  It has large turn down ratio, usually 10:1 to 5:1, special up to 30:1 or larger.

5.  It is a direct-reading flow instrument. It can obtain the total flow directly without external power source. It is clear and easy to operate.

Disadvantage of the oval gear flowmeter

1. The crude oil flowmeter has a complicated structure, large volume and heavy weight, especially the large-diameter oval gear flowmeter is bulky, so it is generally only suitable for small and medium size flow meter.

2. It can be used for some limited medium, and cannot work in high temperature medium.

3. Oval gear flowmeters are generally not suitable for high and low temperature applications. Due to the thermal expansion and deformation of the parts at high temperatures, the material becomes brittle at low temperatures, and the current temperature range is approximately -30-+160 ° C, and the maximum pressure is 10 MPa.

4. It is only suitable for clean single-phase fluid. When it contains particles and dirt, it needs to install filter in the upstream, which not only increases the pressure loss, but also increases the maintenance work; if measuring the liquid containing gas, it must be equipped with a gas separator. If the measured liquid medium is mixed with gas, it will also cause measurement error.

5. Oval gear flowmeter safety is poor, such as detecting the moving parts stuck, the fluid cannot pass, the flow tube system cannot be applied. However, some structural designs have a bypass built into the housing. When the active component is detected to be stuck, fluid can pass through the bypass.

6. The oval gear flowmeter will pulsate the flow during the measurement process, and the larger diameter gauge will also generate noise, even the pipeline will vibrate.

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