A Comprehensive Analysis of Mechanical Water Flow Meters

Mechanical flow meters measure water flow by measuring the movement of mechanical components such as gears, propellers, or rotors. They typically display the flow rate using a pointer or gear-based control panel. Generally, they do not require a power source.

Mechanical flow meters are reliable flow meters used to accurately measure water consumption in various industries and environments. Understanding the types, principles, and applications of mechanical flow meters can help us select the appropriate one and further optimize water resource management.

Mechanical Water Flow Meter Types

Mechanical water flow meters come in various types, each suited to specific applications and flow measurement needs. The most common types include:

  • Oval Gear Flow Meters: Measure flow rate through the rotational motion of two meshing oval gears under pressure differential. Accuracy can reach 0.2%~0.5%.
  • Metal Rotameters: Measure fluid flow rate by the positional change of a float within a tapered tube. Suitable for high-temperature and high-pressure flow measurement. Accuracy can reach 1.5%.
  • Rotary Vane Meters: These utilize a series of vanes that rotate with the flow of water, providing accurate measurements for low to moderate flow rates.
  • Turbine Flow Meters: Featuring a turbine wheel that spins as water passes through, these are widely used for their precision and reliability.
  • Piston or Reciprocating Meters: These employ pistons moving within cylinders, typically used in larger industrial settings.
  • Nutating Disc Meters: These use a disc that wobbles or nutates as water flows, suitable for clean water applications.
  • Oscillating Piston Meters: These measure flow by the oscillations of pistons driven by water movement.

Understanding the different mechanical water flow meter types helps in selecting the appropriate device for specific needs, whether for residential, commercial, or industrial water management.

Mechanical Water Flow Meter Working Principle

The core principle behind a mechanical water flow meter involves translating the kinetic energy of flowing water into measurable mechanical movement. For example:

In turbine meters, water flow causes a turbine wheel to spin, and the rotation speed directly correlates with the flow rate.

In an Oval Gear flow meter, the core components are two meshing elliptical gears and a metering chamber. When fluid passes through the flow meter, the pressure difference in the fluid drives the gears to rotate. Each rotation of the gears discharges a fixed volume of fluid.

Oval gear flow meter for diesel fuel

In a metal rotor flow meter, flow rate is measured by the balance between the force exerted by the fluid flow on a float and the float’s weight and buoyancy. When fluid flows in from the lower end of the tapered tube, the fluid flow exerts an upward force on the float. The magnitude of this force is proportional to the flow rate. As the flow rate increases, the float is lifted to a new equilibrium position. At this point, there is a direct correlation between the float’s height within the tapered tube and the flow rate.

These devices typically incorporate gears or mechanical counters to record the total volume of water passing through, providing a reliable and straightforward way to how to measure water flow rate accurately.

Mechanical Water Flow Meter Specification

In industry, the two most commonly used types of mechanical water flow meters are oval gear flow meters and metal rotor flow meters. The specifications of both of them are as follows:

Rotameter Flow Meters-Metal Variable Area Flow Meters

Measuring rangeWater (20℃): 1-200000 L/h Air (20℃, 0.1013MPa): 0.03~4000m³/h
TurndownStandard type 10:1, special type 20:1
AccuracyGas 2.5%FS;
Liquid 1.5%F.S
Pressure LevelStandard type: DN15-N50 4.0MPa;
Special type: DN15-N50 25 MPa;
The pressure rating of the jacket is 1.6MPa. For special models, please consult and confirm before selecting and ordering. 
pressure loss2kpa-20kpa
Medium temperatureStandard type: -40℃~100℃; PTFE: 0℃~120℃;
High temperature type: 100℃~450℃;
Medium viscosityDN15: η<5mPa.s(F15.1-F15.3) η<30mPa.s (F15.4-F15.8)
DN25: η<30mPa.s DN50-DN150: η<30mPa.s 
ambient temperatureRemote transmission type: 40℃~185℃ (the liquid crystal will not be damaged), the liquid crystal normally works at -30℃~80℃; local pointer type: -40℃~100℃
Connection TypeConnection method: flange connection standard HG20592-2010, DIN 2501 standard flange; or produced according to customer requirements;
Threaded connection: produced according to diameter or customer requirements;
Sanitary clamp connection: produced according to diameter or customer requirements;
Cable interfaceThe flameproof type is 1/2NPT internal thread; other M20*1.5 internal thread;
Power supplyStandard type: 24VDC two-wire system 4-20mA (12VDC-32VDC);
Alarm type: 24VDC three-wire system 4-20mA (18VDC-28VDC);
AC type: 85-265VAC50Hz;
Battery type: 3.6V, 7.5AH battery, used continuously for three years;
Load characteristicsTwo-wire system: RLmax=50*(-12)Ω=600Ω@24V
Alarm type: the maximum load resistance is 200Ω AC type: the maximum load resistance is 200Ω
Alarm OutputUpper or lower limit instantaneous flow alarm;
Switch quantity alarm;
Relay output;
LCDInstantaneous flow rate display value range: 0-50000 (with decimal point)
Accumulated flow display value range: 0-99999999 (with decimal point) automatic reset
Protection levelIP65

Oval Gear Flow Meters

ModelSI-3601-ASI-3601-ESI-3601-B
Categorycast ironcast steelstainless steel
Nominal pressure MPa1.0  1.62.5  4.0  6.41.0  1.6
Medium viscosity2~200 mpa.s
Medium temp.-20℃~+100℃
Flow
rate range  (m3/h)
SI-3601-ASI-3601-ESI-3601-B
Nominal diameterClass 0.5Class 0.2Class 0.5Class 0.2Class 0.5Class 0.2
100.08~0.50.1~0.50.08~0.40.1~0.40.1~0.50.1~0.5
150.25~1.50.3~1.50.25~1.50.3~1.50.3~1.50.3~1.5
200.5~30.6~30.5~30.6~30.6~30.6~3
251~61.2~61~61.2~61.2~61.2~6
402.5~153~152.5~153~153~153~15
504~244.8~244~244.8~243~204~20
LA504~244.8~24////
658~5010~508~5010~5012~6012~60
LA656~408~40////
8010~6012~606~6012~6012~6012~60
LA808~5010~50////
10016~10020~10016~10020~10020~10020~100
15032~19038~19032~19038~19038~19038~190
20056~34068~34034~34068~34068~34068~340

Order Guide

When selecting a mechanical water flow meter, several specifications are crucial:

  • Flow Range: The minimum and maximum flow rates the meter can accurately measure.
  • Size: For example, a mechanical water flow meter 2 inch is suitable for larger pipes and higher flow rates.
  • Accuracy: Usually expressed as a percentage of reading, important for precise water measurement.
  • Pressure Rating: The maximum pressure the device can withstand without malfunction.
  • Material: Commonly brass, stainless steel, or plastic, depending on water quality and environment.
  • Mechanical Water Meter Price: Varies based on size, accuracy, and features, with mechanical water flow meter price ranging from affordable models to high-precision industrial units.

Understanding these mechanical water flow meter specifications ensures optimal performance and longevity in your water measurement applications.

Measuring hot water requires a mechanical flow meter that can withstand elevated temperatures and pressures. These meters are constructed with materials resistant to thermal expansion and corrosion, such as stainless steel or specialized plastics.

When selecting a mechanical water flow meter for hot water, consider:

  • Temperature limits specified by the manufacturer. For example, an oval gear flow meter can withstand up to 280°C, while a metal rotor flow meter can withstand up to 450°C.
  • Compatibility with the piping system.
  • Calibration for hot water conditions to ensure measurement accuracy.
  • Pressure rating. For example, a standard water flow meter withstands 1.6 MPa. Custom-made meters can meet pressures of 2.5 MPa, 4 MPa, etc.

Using the right mechanical water meter for hot water applications guarantees reliable readings and durability over time.

Converting a steady water flow into a pulsed signal can be useful for various monitoring and control applications. Some methods include:

  • Flow Modulation Devices: Installing valves or flow restrictors that intermittently open and close to create pulsed flow.
  • Electronic Interfacing: Using sensors attached to the mechanical water flow meter that generate pulse signals corresponding to flow increments.
  • Mechanical Modulation: Employing mechanical devices like rotary or oscillating components that naturally produce pulsed outputs as water flows.

Understanding how to measure water flow rate and manipulate flow characteristics allows for better integration with automation systems and data logging devices, enhancing water management efficiency.

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In summary, mechanical water flow meters are essential tools for accurately measuring water consumption in various environments. By understanding their types, working principles, specifications, and applications (including hot water measurement and flow regulation), you can make informed decisions to optimize water resource management and ensure reliable operation. Whether you’re interested in a 2-inch mechanical water flow meter or want to learn about pricing options, feel free to contact us!

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