Rotameter flow meter-Variable Area Flow Meters

Rotameter flow meter

What is a rotameter flow meter?

A Rotameter flow meter is a variable area flow meter based on float position measurement. It is suitable for liquid and gas volumetric flow measurement and control.

The LZ series Rotameter Flowmeter provided by Sino-Inst adopts a 304/316 stainless steel structure. It can be used to measure the flow of liquid, gas, and steam. Especially suitable for low flow velocity and small flow. Flow measurement of high temperature, high pressure, strong corrosion, conductive or non-conductive media.

Rotameter Flow meter Features

LZ series metal Rotameter Flowmeter (also known as metal Variable Area Flow Meters) is divided into two series, LZH and LZ. It has the characteristics of simple structure, reliable operation, wide application range, high precision, and convenient installation.

This series of flowmeters is compared with glass rotor flowmeters. It has the characteristics of high-pressure resistance, high temperature, a strong sense of safety, and concise readings.

It can also be used for flow measurement of opaque and corrosive media. The pipe body and flange of the instrument are made of stainless steel (1Cr18Ni9Ti or OCr18Ni12Ho2Ti).

Extended reading: How does a rotameter work

LZH series: Conventional orifice plates and floats are made of stainless steel. Anticorrosive orifice plate floats and tubes inner linings are made of PTFE.

LZ series: The float and tapered tube are made of stainless steel, and this series is non-corrosive.

The LZH series consists of an instrument tube, a standard orifice plate, a cone float, and a magnetic converter;
The LZ series consists of an instrument tube, a standard float, a tapered tube, and a magnetic converter.

The working parameters of this series of meters and their conversion and correction are provided by the meter calculation software to provide standard calculation methods. The meter’s measurement accuracy is guaranteed.

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

Rotameter Flow meter Specifications

Type LZH series LZ series
Flow range Water 2.5~100000L/h;
Air 0.07~3000m3/h
Water 6~100000L/h
Air 0.2~1000m3/h
Turndown ratio DN≤100mm(10:1);
Precision Standard type 2.5 grade,
special order can reach 1.0 grade
Work pressure DN15, DN25, DN40, DN50: 4.0MPa.
DN80, DN100, DN150: 1.6MPa
Medium temperature Ordinary type H1:-40℃~100℃
High temperature type H2: -80℃-250℃
Ambient temperature Pointer type: -40℃~65℃
Intelligent type: -25℃~65℃
Connection method Flange connection (flange standard: refer to GB9115-88, JB82-59 (6.4IPa), special specifications are determined according to user requirements)
Explosion-proof grade Intrinsically safe: ExibIICT4 with safety barrier LB987S, explosion-proof certificate number GYB06884
Explosion-proof: ExdIIBT4, explosion-proof certificate number GYB071017
Protection level IP65
Viscosity DN15: ≤5mPa·s, DN25~DN150: ≤250mPa·s
Product performance standards JB/T6844-1993

Rotameter flow meter applications

The metal Rotameter flow meter is suitable for the flow measurement of small-diameter and low-velocity media. It can measure most media such as gas and liquid.

The metal Rotameter flow meter can measure the instantaneous flow and cumulative flow of gases and liquids, including corrosive acid, alkali, and salt solutions. It is especially preferred when the flow is low or when a purely mechanical or inconvenient power supply is required.

Extended reading: Metal Tube Flow Meter Applications

Rotameter flow meters are mostly vertical installation, bottom entry, and top exit type, and can also be installed horizontally. The price is higher. Let me show you a sample.

This is an explosion-proof type for measuring corrosive liquids.

This is a smart type. It can measure gas and liquid. There should be no impurities.

This one is installed horizontally to measure nitrogen. It is purely mechanical to display instantaneous flow rate.

Extended reading: Flow Totalizer F3000X for Data collection and calculation

Read More about: Digital Rotameter

Rotameter flow meter structure

A Rotameter flow meter is a variable area flow meter. It consists of measuring tube, float, indicator, process connection, and so on.

Rotameter flow meter working principle

When the measured fluid passes through the annulus formed by the cone and floats from the bottom to top.

The differential pressure produced at the upper and lower ends of the float forms the force for the float to rise.

When the rise of the float is greater than the weight of the float immersed in the fluid. The float rises.

The annulus area increases accordingly. The fluid velocity in the annulus drops immediately.

The differential pressure at the upper and lower ends of the float is reduced. The lifting force acting on the float also decreases.

Until the rising force equals the weight of the float immersed in the fluid, the float will stabilize at a certain height.

The height of the float in the tapered tube and the flow rate through it correspond to each other.

Extended Reading: What is difference between rotameter and flow meter


  • Cheap price.
  • Observe intuitively.
  • easy installation
  • No external power needed
  • Can Measure Liquid or Gas Flows
  • Better rangeability
  • Low cost and low-pressure drop


  • Compared with other flow meters, the accuracy is low.
  • The service life is short.
  • Maintenance is required after using for a period of time!

Read more General-purpose Flow Totalizer for Data collection and calculation

  • Installed vertically on a vibration-free pipe. The fluid flows through the meter from bottom to top.
  • When measuring dirty fluids, a filter should be installed upstream of the meter
  • If the fluid itself is pulsating, a buffer tank can be installed. If the instrument itself oscillates, a damping device can be installed.
  • The gas in the instrument must be drained of the liquid.
  • The control valve in the measurement and control system should be installed downstream of the flowmeter. When used for gas measurement, ensure that the working pressure is not less than 5 times the pressure loss of the flowmeter. In order to make the flowmeter work stably.
  • Before installing the metal rotor flowmeter, the welding slag in the pipeline should be purged. Remove the stop element from the flowmeter when installing. When using after installation, open the control valve slowly. Avoid impact damage to the flowmeter.
  • If the measurement requires a wide range of flow, the range exceeds 10 o’clock. Two floats of different shapes and weights can be placed in one instrument. Take the frivolity reading when the flow is small. After the float reaches the top, take the reading of the heavy float. The range can be expanded to 50-100.
  • Liquid meters are usually calibrated with water, and gas meters are calibrated with air. The fixed value is in the engineering standard state. If the fluid density, gas pressure, and temperature of the use conditions are inconsistent with the calibration. Make necessary conversions.

Extended reading: Gas Rotameter Tips

Read more about: Beginner’s Guide: Variable area flow meter

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Rotameter flow meter price

Sino-Inst offers over 30 Rotameter flow meter products. About 50% of these are for liquids. 40% are for gas. At best price.

You can refer to the product price of the following Rotameter flow meter price:

Metal rotor flowmeter
Pipe size 1/2 inch
Medium: oxygen
FOB Price: USD 281.50/pc

A wide variety of Rotameter flow meter options are available to you, such as free samples, paid samples.

Extended Reading: Collection of Industrial Insertion Flowmeter Type

Sino-Inst is a globally recognized supplier and manufacturer of Rotameter flow meters, located in China.

The top supplying country is China (Mainland), which supply 100% of the Rotameter flow meter respectively.

Sino-Inst sells through a mature distribution network that reaches all 50 states and 30 countries worldwide. Rotameter flow meter products are most popular in Domestic Market, Southeast Asia, and Mid East.

You can ensure product safety by selecting from certified suppliers, with ISO9001, ISO14001 certification.

Rotameter flow meters for Sale|Manufacturer Best Price

A Rotameter flow meter is a variable area flow meter based on float position measurement. It is suitable for liquid and gas volumetric flow measurement and control.

Product SKU: Rotameter flow meter-Variable Area Flow Meters

Product Brand: Sino-Inst

Product Currency: USD

Product Price: 200

Price Valid Until: 2099-09-09

Product In-Stock: InStock

Editor's Rating:
This entry was posted in DP Flow Meters, Flow Meters by KimGuo11. Bookmark the permalink.

About KimGuo11

Wu Peng, born in 1980, is a highly respected and accomplished male engineer with extensive experience in the field of automation. With over 20 years of industry experience, Wu has made significant contributions to both academia and engineering projects. Throughout his career, Wu Peng has participated in numerous national and international engineering projects. Some of his most notable projects include the development of an intelligent control system for oil refineries, the design of a cutting-edge distributed control system for petrochemical plants, and the optimization of control algorithms for natural gas pipelines.