Hydraulic Oil Flow Meter Manufacturer

1. What is a hydraulic flow meter?

A hydraulic flow meter, simply put, is a device used to measure the flow of oil in a hydraulic system's pipelines. It's not a specific instrument, but rather a general term for this type of measuring device. It can calculate the total amount of liquid flowing through a fixed point in the pipeline, which we usually measure in liters per minute or gallons per minute.

Besides measuring the volumetric flow rate of liquids, it can also handle linear and nonlinear flow conditions, and even measure mass flow rate. For hydraulic engineers, flow rate and pressure are two key indicators they focus on most in their work. Only by accurately grasping these two data can they determine whether the hydraulic system is operating precisely and efficiently. After all, the core function of a hydraulic flow meter is to help determine the efficiency and accuracy of the system's operating status and performance.

However, the hydraulic oils used in different hydraulic systems vary greatly; some are viscous, some are thin, and their flow rates differ. Therefore, hydraulic flow meters must be adjusted and manufactured according to the type of oil being measured; you can't just use any type. For example, flow meters designed to measure high-viscosity hydraulic oil and those designed to measure thin hydraulic oil must differ in their design.

2. Why is compatibility important?

Let's first talk about the importance of compatibility. The core objective of a hydraulic flow meter is to accurately measure the flow rate of hydraulic oil, but problems arise if it is incompatible with the oil.

First, inaccurate measurements are like using a ruler with misaligned graduations, which disrupts the entire hydraulic system's operation. The amount of oil in the system can become too much or too little due to inaccurate measurements: too much oil accelerates component wear and reduces system efficiency; too little oil similarly affects component operation, and in severe cases, can even cause the entire system to malfunction and shut down.

Secondly, incompatible fluids can damage the flow meter. Some fluids contain special chemicals or impurities that can slowly corrode the internal parts of the flow meter. Just as an ordinary iron drum will gradually rust if it holds acidic liquid for a long time, corroded flow meter parts will need to be replaced soon, which is not only troublesome but also increases equipment maintenance costs.

3. Physical properties of hydraulic oil

To understand the compatibility between flow meters and hydraulic fluid, it is necessary to first understand the physical properties of hydraulic fluid, among which viscosity, density, and temperature have the greatest impact.

1. Viscosity

Viscosity is essentially the degree of viscosity of an oil or liquid. Honey and water, which are common in our daily lives, can clearly demonstrate the difference in viscosity—honey is viscous and pours out slowly; water is thin and flows quickly and smoothly.

Each flow meter has its own suitable range for measuring oil viscosity. If the oil is too viscous, the resistance encountered during flow is large, and the flow meter is likely to underreport the actual flow rate; if the oil is too thin, there is little resistance during flow, and the flow meter may overreport the flow rate. For example, in cold winter weather, hydraulic oil becomes more viscous. If a flow meter normally used to measure thin oil at room temperature is used in this situation, the measurement result will be inaccurate.

2. Density

Density refers to the mass of a unit volume of oil and is related to the weight of the oil. Like viscosity, flow meters can only be used for oils with a certain density range.

Some flow meters calculate flow rate by measuring the force generated when oil flows. If the density of the oil is different from the density the flow meter is calibrated for, the measured force will be inaccurate, and the resulting flow rate reading will also be inaccurate. For example, if a flow meter is originally calibrated for the density of ordinary mineral hydraulic oil, and it is used to measure water-based hydraulic oil with a higher density, the reading will be inaccurate because the force conditions have changed.

3. Temperature

Temperature has a significant impact on the physical properties of hydraulic oil, most notably its viscosity. As temperature increases, the oil becomes thinner and its viscosity decreases; conversely, as temperature decreases, the oil becomes thicker and its viscosity increases.

Most hydraulic flow meters can only operate normally within a specific temperature range. If the oil temperature is too high, the oil may decompose, and the resulting impurities will stick to the inside of the flow meter, affecting its normal operation. If the oil temperature is too low, the oil will be too viscous and may not even be able to flow smoothly through the flow meter, not only failing to measure the flow rate but also potentially damaging the internal parts of the flow meter. For example, in hot summer weather, after the hydraulic system has been running for a long time, the oil temperature rises, and the oil that was originally of suitable viscosity becomes thinner, which may affect the measurement accuracy of the flow meter.

4. Chemical compatibility

Besides physical properties, the chemical compatibility between hydraulic fluid and the flow meter is also crucial. Hydraulic fluid may contain various additives and contaminants, which may react with the materials used to manufacture the flow meter.

4. Additives

To improve the performance of hydraulic oil, many hydraulic oils contain additives such as anti-wear agents, antioxidants, and detergents. While these additives can protect the hydraulic system, making it more durable and stable in operation, they may not be compatible with flow meters.

For example, some anti-wear additives contain special metallic components or chemicals that, when in contact with the internal parts of the flow meter for a long time, may slowly corrode these parts. Just as some metals rust when exposed to certain chemicals, corrosion of flow meter parts will reduce measurement accuracy and shorten their service life.

5. Pollutants

Hydraulic oil inevitably contains contaminants such as dust, water, and metal particles, which can cause problems for flow meters.

Dust and metal particles can scratch the smooth internal surface of a flow meter, just as sand falling into the gaps of mechanical parts can cause wear. This not only makes the measurement results inaccurate, but also accelerates the aging of the flow meter. Water can easily cause the flow meter to rust, especially those flow meters made of metal. Once rusted, the internal structure will be damaged and it will not be able to work properly.

5. How to choose a suitable oil flow meter?

Since compatibility is so important for flow meters, how do you select the right hydraulic oil flow meter for a specific hydraulic oil? You can follow these steps:

6. Understand your oil

The first step is to understand the physical and chemical properties of the hydraulic oil you are using. This information can usually be found in the hydraulic oil's technical data sheet, such as its viscosity, density, suitable operating temperature range, additives, and potential contaminants. Only after understanding this information can you guide the selection of a flow meter.

7. Match the instrument panel with the oil level.

Once you understand the characteristics of the oil, you can find a flow meter that suits these parameters. For example, if the oil viscosity is high, you cannot choose a flow meter that can only measure thin oils; you must choose one that can handle high-viscosity fluids. If the oil may contain a lot of impurities, you should choose a flow meter with a wear-resistant internal structure that is not easily scratched.

8. Other considerations

• Installation and Maintenance : Proper installation and regular maintenance are crucial for ensuring the compatibility of the flow meter and the hydraulic fluid. During installation, always follow the manufacturer's instructions. For example, the flow meter's installation direction must be aligned with the hydraulic fluid flow direction. When connecting to the hydraulic system, select appropriate seals and gaskets to prevent fluid leakage.

In daily use, the flow meter should be cleaned regularly to remove the contaminants accumulated inside. It should also be checked frequently for signs of wear or damage. If any worn parts are found, they should be replaced in time to avoid affecting the measurement accuracy.

• System Requirements : Finally, the overall requirements of the hydraulic system must be considered. If the system requires high measurement accuracy, such as for hydraulic equipment used in precision machining, a more accurate flow meter needs to be selected. If the system operates in harsh environments, such as mines or chemical plants, a flow meter with strong corrosion resistance and damage resistance should be selected to ensure stable operation in complex environments.

6. Working principle of hydraulic flow meter

In different application areas and industries, hydraulic flow meters are also known by various names such as pressure gauges, indicators, and liquid flow meters. Their manufacturing materials must be able to withstand the pressure of hydraulic oil; common materials include brass, aluminum, and stainless steel. For example, aluminum flow meters are suitable for measuring the flow rate of non-corrosive water-based or oil-based fluids and can withstand relatively high pressures.

Hydraulic flow meters can be installed anywhere in a hydraulic pipeline to measure flow rate. Because different hydraulic systems have different pipeline dimensions, flow meters also come in various interface sizes to facilitate adaptation to different systems. Structurally, a flow meter mainly consists of three parts: the main body, the sensor, and the transmitter.

During operation, the sensor first measures the flow velocity of the oil, sensing the flow of oil through the flow meter, and then transmits the collected signal to the transmitter. The transmitter calculates the flow rate based on the signal: the flow rate is related to the cross-sectional area of the pipe and the flow velocity of the oil, while the mass flow rate is also related to the density and volume of the oil. Finally, the calculated flow rate result is displayed on the flow meter's instrument for easy viewing by operators.

7. Types of hydraulic flow meters

While hydraulic flow meters are essential in many operations, choosing the right flow meter is crucial. When selecting one, the main factors to consider are the consistency, viscosity, and characteristics of the fluid being measured, such as the lubrication effect of the oil, its compressibility, its ability to quickly separate water, its flammability, and its heat dissipation capacity.

The main types of flow meters used are oval gear flow meters and circular gear flow meters . Each type of flow meter is suitable for measuring different types of hydraulic oil, and the output results also differ in format. When selecting a flow meter, engineers will first determine the required data presentation method and how to use this data to measure system efficiency.

Among them, the gear flow meter uses the volumetric principle, with a pair of gears inside. When the fluid flows in the pipeline, it drives the gears to rotate, just like wind turning a windmill. The sensor is connected to one of the gears. When the other gear runs below it, the sensor generates a pulse signal, which can be used to calculate the flow rate of the oil.

8. Advantages of hydraulic flow meters

Hydraulic flow meters are not just simple measuring tools; they also have many practical functions. When hydraulic equipment operates for extended periods, these precisely calibrated devices provide detailed operational data, which helps staff identify potential problems early and prevent accidents.

For example, by observing changes in flow rate, staff can determine if there are any issues with the hydraulic system, such as oil leaks or component wear, and perform timely maintenance to prevent sudden equipment failures. At the same time, this data also allows staff to clearly understand the operating status of the equipment, whether it is operating efficiently, and provides a reference for optimizing equipment performance.