Annular Orifice Plate Flowmeter Dirt Resistant Anti Clogging For Precise Flow Measurement

The annular orifice flowmeter is a throttling type flow measurement instrument based on the differential pressure principle. It measures flow by setting a circular plate coaxial with the pipe in the pipeline and calculating the flow based on the pressure difference generated when the fluid passes through the annular channel.

• Common orifice plate: It is a thin plate with a circular hole in the center.
• Annular orifice plate: It is not a solid plate but consists of a circular disc (core block), an outer ring, and supporting ribs connecting them. The disc and the outer ring are not concentric, thus forming a crescent-shaped annular flow gap between them.

The design of the annular orifice plate aims to overcome the fatal flaws of standard orifice plates when measuring special media. Its core advantages are:

1. Exceptionally excellent anti-dirt and anti-clogging capability (the most crucial and primary value).
   • The central hole of a standard orifice plate is prone to clogging by solid particles, bubbles, tar, and other impurities, leading to measurement failure.
   • The crescent-shaped channel of the annular orifice plate provides a smooth, dead-zone-free flow path. Solid particles, fibers, and bubbles are "washed" through by the high-speed fluid and are almost impossible to clog the throttling element.
2. Highly suitable for multiphase flows and complex media
   • Wet gas (natural gas or gas containing liquid droplets), gas-liquid two-phase flow;
   • Liquids or gases containing a large amount of solid particles (such as mud, slurry, sewage, coke oven gas);
   • Media prone to crystallization or solidification (such as certain chemical raw materials).
3. No need for long straight pipe sections for flow straightening
   • The structure of the annular orifice plate itself is insensitive to the upstream velocity distribution and has a similar "straightening" effect.
   • It has very low requirements for the upstream straight pipe section, typically only 0-2D (pipe diameter multiples), far lower than the 10D-40D required by standard orifice plates. This is a significant advantage in space-limited retrofit projects.
4. High accuracy and wide range
   • Accuracy can reach ±1.0%, superior to many other dirty medium flowmeters.
   • The range ratio can reach 10:1, better than the 3:1 of standard orifice plates.

• Material Selection: Choose stainless steel, Hastelloy, or PTFE-lined material based on the corrosiveness of the medium.
• Connection Method: Flange connection (conventional) or welding connection (high temperature and high pressure).
• Pressure Taking Method: Ring chamber pressure taking (clean medium) or remote diaphragm box (dirty medium).

• Dirty media: Such as coke oven gas, blast furnace gas, dusty exhaust gas, cooling circulating water, sewage, etc. The annular channel design prevents clogging.
• Steam system: Saturated steam, superheated steam. When the steam stops, the condensate water can flow away from the annular gap, preventing water hammer and measurement errors.
• High-temperature and high-pressure fluids: Temperature resistance -200~450℃, pressure resistance up to 40MPa, suitable for harsh environments in chemical, power and other industries.

• Metallurgy and Power: Measurement of blast furnace gas and hot air flow, solving the problem of numerous elbows and insufficient straight pipe sections.
• Petrochemical: High-viscosity fluids such as heavy oil and residue oil, with jacketed insulation structure to prevent condensation.
• Municipal Environmental Protection: Monitoring of wastewater and flue gas, suitable for media containing suspended particles.

The annular orifice plate flowmeter is a special forces soldier in the differential pressure flowmeter family, specializing in solving difficult problems. Through its unique crescent-shaped annular flow channel design, it perfectly addresses the core issue of easy clogging faced by standard orifice plates when measuring dirty and multiphase flow media.

Although it does not have an advantage in energy consumption and cost, in its specific application fields (such as coke oven gas, wet gas, and slurry), the unparalleled reliability and extremely low maintenance requirements it offers make it one of the irreplaceable best choices. When you are dealing with a complex fluid that is prone to clogging and multiphase, the annular orifice plate should be your top priority.