Introduction to balanced flow meter knowledge

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This post was last edited by ztj1118 on 2014-5-28 09:27. The GDPH series of balanced flow meters represent a significant improvement over traditional throttling devices; they feature functions such as balanced flow regulation. Traditional throttling devices have only one flow aperture, and throttling causes the fluid to lose its ideal state； The balanced flow meter features multiple functional apertures, which enable the flow field to be balanced and streamlined to an ideal fluid state to the greatest extent possible, thereby fully leveraging the advantages of differential pressure flow meters. This type of flow meter is suitable for measuring almost all types of fluids, representing a technological revolution in fluid measurement techniques. Currently, balanced flow meters are widely used in various industries such as chemicals, petroleum, metallurgy, power generation, natural gas, and water treatment. Working principle of the balance flow meter The balance flow meter is a revolutionary differential pressure type flow measuring instrument. Its working principle is similar to that of other differential pressure flow meters, as it is based on the principle of energy conversion within a sealed pipeline: in the case of an ideal fluid, the flow rate in the pipeline is proportional to the square root of the differential pressure ； The flow rate in the pipeline can be calculated using the measured differential pressure value and an equation; the balance flow sensor is a porous disc throttling regulator installed across the pipeline’s cross-section, with the size and distribution of each pore being determined based on specific formulas and test data, known as functional pores. When the fluid passes through the functional holes in the disk, it is evenly directed, vortexes are minimized, resulting in a flow that is nearly ideal. A stable differential pressure signal can be obtained using pressure sensing devices, and parameters such as volumetric flow rate and mass flow rate can be calculated based on Bernoulli’s equation. The characteristics of balance flow meters are as follows: First, their measurement accuracy is 5 to 10 times that of standard orifice plates. Second, the flow noise is 1/15 that of standard orifice plates. Third, the permanent pressure loss is 1/3 that of standard orifice plates. Fourth, the pressure recovery is twice as fast as that of standard orifice plates. Fifth, the minimum required straight pipe section can be less than 0.5D. First, they offer high linearity and good repeatability: The sensors of balance flow meters feature a symmetric porous structure that enables balancing of the flow field, thereby reducing eddies, vibrations, and signal noise. This improves the stability of the flow field, resulting in a linearity 5 to 10 times higher than that of orifice plates, as well as a repeatability of 0.15%. Based on these overall performance characteristics, balance flow meters belong to the category of high-end flow meters. At a range ratio of 5:1, the linearity can reach ±0.3% ； At a range ratio of 7:1, the linearity can reach ±0.5% ； At a ratio of 10:1, the linearity can reach ±1.0%. Second, the requirements for straight pipe sections are low: due to the stable flow field in balance flow meters, and the pressure recovery being twice as fast as that in orifice plates, **the requirements for straight pipe sections are reduced; typically, there is 3D of straight pipe before and 1D after the sensor, with a minimum of 0.5D being sufficient. This eliminates the need for large amounts of straight pipe section, especially in cases involving pipes made of expensive materials. III. Reduction of permanent pressure loss: The porous and symmetrical design helps to minimize turbulent shear forces and the formation of vortices, thereby reducing kinetic energy losses. Under the same measurement conditions, it reduces permanent pressure loss by 2.5 times compared to orifice plates, which leads to significant savings in operating energy costs. It is an energy-efficient instrument that deserves widespread adoption. IV. Resistant to dirt and less prone to clogging: The porous, symmetrical design reduces turbulent shear forces and the formation of vortices, thereby **decreasing the formation of dead zones where debris can accumulate. This allows dirty substances to pass through the various pores easily, reducing the chances of those pores getting blocked. V. Direct replacement of orifice plates: It has the same usage method and shape as orifice plates, so it can be replaced directly without any need for changes to the piping or related instruments. This makes it very suitable for replacing orifice plates with balanced flow meters during energy metering upgrades across entire plants. VI. Wide flow measurement range: Based on test results, we have found that the GDPH series of balanced flow meters enables flow rates to range from the lowest values up to the speed of sound ； Its minimum Reynolds number can be below 200, and its maximum Reynolds number is above 107 ； The β value can range from 0.25 to 0.90. VII. Good long-term stability: Due to the significant reduction in turbulent shear forces, the direct friction between the medium and the throttling element is greatly decreased. Its β value remains constant over time, and since the entire instrument has no moving parts, it can maintain stability for a long period. VIII. Measurable high-temperature and high-pressure media: Similar to throttle devices such as orifice plates, the operating temperature and pressure depend on the material and grade of the pipes and flanges; the operating temperature can reach 850°C, and the operating pressure can reach 42 MPa. IX. Media under complex measurable conditions: Due to its special structural design, it possesses unique properties. It can handle gas-liquid phases, various mixed gases (such as gas, biogas, coal gas, etc.), various low-temperature gases (such as LNG, liquid nitrogen, liquid oxygen, liquid argon, liquid hydrogen, liquid chlorine, liquefied ethylene, liquefied petroleum gas, etc.), gas-liquid phase media (such as humid air), slurries, multiphase water flows, vibrating water flows, electromagnetic interference-prone media, and two-way flows (since the balance flow meter is perfectly symmetrical on both sides). Selection of GD balanced flow meter: GDPH – GD balanced flow meter. Nominal pipe diameter: XXX; 100 denotes DN100. Installation type: pp for pipe-mounted, HF for flange-mounted, FW for welded, DF for double-flange, SP for square-tube type. Nominal pressure: A 0~0.6MPA, B 0~1.0MPA, C 0~1.6MPA, D 0~2.5MPA, E 0~4.0MPA, F 0~6.4MPA, G 0~10MPA, H 0~16MPA, J 0~40MPA. Pipe material: 0 for carbon steel, 1 for 304 stainless steel, 2 for 12CrMOV, 3 for others. Input signal: A for no output, B for 4~20MA, C for RS485 MODBUS