Metal Tube Float Flowmeter
The Metal Tube Float Flowmeter is a variable area flow measurement instrument composed of a measuring tube, float, indicator, and process connections.
With its compact structure, wide measuring range, and easy installation, it has been widely applied in industrial process control systems for the measurement of liquids, gases, and steam, especially in low flow velocity and small flow rate applications.
The metal tube float flowmeter is available in local indication type and intelligent remote transmission type.
-
Local type provides pointer indication for instantaneous flow measurement.
-
Intelligent type features pointer indication combined with an LCD display, showing instantaneous flow and totalized flow, and supports high and low limit alarm outputs, pulse output, standard two-wire 4–20 mA current output, and HART communication protocol.
Flow Meter Description
Metal Tube Flow Meter-Features
-
Simple and Robust Design – The metal tube rotameter features a compact structure with excellent stability and long-term reliability, ensuring consistent performance in demanding industrial environments.
-
Independent of Medium Properties – Accurate flow measurement is maintained regardless of the medium’s conductivity, dielectric constant, or other physical and chemical properties.
-
Versatile Application – Suitable for a wide range of media, including corrosive, toxic, and explosive substances, making it ideal for diverse industrial processes.
-
Multi-Media Measurement – Capable of measuring interfaces or levels of two different media with varying densities, providing flexible process monitoring.
-
Advanced Signal and Display Options – Supports two-wire 4–20 mA output and digital LED display (0.56” or 0.8”), enabling local reading and easy integration with automated control systems.
Metal Tube Flowmeter-Applications
With its excellent performance, high reliability, and cost-effective solution, the metal tube float flowmeter is widely used in:
-
Petroleum and chemical industries
-
Steel and metallurgical processes
-
Power generation and energy systems
-
Light industry and food processing
-
Pharmaceutical production
-
Water and wastewater treatment
By selecting different wetted materials, the flowmeter is suitable for non-corrosive, corrosive, and highly corrosive media, meeting the demands of various industrial applications.
Flow Meter Parameter
| Measuring range | Water:1-150000L/H(20℃) |
| Air: 0.7~3000m3/h (20℃, 0.1013MPa) | |
| Measuring range proportion | Standard: 10:1 |
| Accuracy class | Standard:1.5, 2.5; Special: 1.0 |
| Pressure rating | Standard & sanitary one:DN15~DN50≤4.0MPa; DN80~DN200≤2.5MPa |
| Special one:DN15~DN25≤42MPa;DN50~DN100≤16MPa | |
| Jacket one: 1.6MPa | |
| Pressure loss | 7kPa~70kPa |
| Medium temperature | Standard:-70℃~+180℃; PTFE:-50℃~+100℃(Change frequently is not allowed) |
| Environment temperature | Remote type: -40℃~+85℃ (LCD display: -35℃~+70℃) |
| Local needle indicator: -40℃~+100℃ | |
| Connection type | Flange; Sanitary tri-clamp |
| Jacket connection | DN15/PN1.6MPa or 1/2” ANSI 150LB RF or φ12mm tube |
| Flange Standard | Standard: GB/T 9119-2010, HG20592, ASME/ANSI B 16.5, DIN2501, SH3406 |
| Food type: SMS, DIN 11851, Tri-clamp | |
| Wiring connection | M20×1.5; 1/2NPT female thread |
| Power supply | Standard: 24VDC two-line 4~20mA(12VDC~32VDC) |
| AC type:85~260VAC | |
| Battery type:3.6V lithium battery(2-3 years lifetime) | |
| Loading resistance feature | Two-line: max loading resistance 500Ω(24VDC) |
| Multi-line: max loading resistance 500Ω | |
| Warning signal output | Reed pipe warning switch output, upper limit and lower limit flow warning(contact capacity 250V 0.05A or 24VDC 0.2A) |
| LCD display | Instant flow display scope:0~99999 |
| Total flow display scope: 0~99999999 | |
| Protection grade | IP65, IP67 |
| Explosion-proof grade | Exia II CT6Ga Exd II BT6Gb |
| Installation Height: | Standard height: 250mm for DN15-DN200; High pressure type: 300mm for size > DN80 |
Instrava OEM/ODM
Tailored Sourcing & Customization: Getting You the Exact Product You Need
As your trusted supplier and sourcing partner, we bridge the gap between your custom requirements and China’s vast manufacturing capabilities.
Finding the right product in a massive supply chain can be challenging. That is where we step in.
As a curated industrial supplier, our core value is simple: we stand in your shoes to help you procure the most optimal products. Whether you are an EPC contractor needing specialized technical compliance, an OEM equipment manufacturer looking for custom branding, or an industrial distributor/trader seeking competitive edge, we customize and tailor products to fit your exact procurement needs.
How We Customize to Fit Your Procurement Needs
For EPC Contractors & Engineers: We custom-configure instruments and devices to match your precise datasheets—tailoring process connections, exotic materials, signal protocols, and managing third-party calibration and testing so you get project-ready solutions.
For OEM Equipment Manufacturers: We provide comprehensive OEM/ODM customization, including custom housing, labeling, branding (private labeling), and tailored technical specifications to seamlessly integrate with your machinery.
For Industrial Distributors & Traders: We offer flexible customization in packaging, product ranges, and technical parameters, helping you differentiate your portfolio and win more local bids.
Why Partner with Us for Custom Sourcing?
One-Stop Engineering Alignment: You don’t have to deal with multiple factories. We translate your technical requirements into precise manufacturer blueprints.
Strict Quality & Compliance Safeguard: We oversee the entire customization and production process in China, ensuring the final customized product meets your local standards and certifications.
Our Ultimate Value: We don’t just sell what’s on the shelf. We find, customize, and deliver the most suitable and cost-effective product for your unique application.
Related Product Recommendations
What is the measurement principle of a metal tube float flowmeter and what physical parameters does it depend on?
A metal tube float flowmeter operates on the variable area flow measurement principle, where the flow rate is determined by the equilibrium position of a float inside a vertically mounted, tapered metal measuring tube.
The float reaches a stable position when the following forces are balanced:
-
Upward force generated by fluid flow
-
Gravity acting on the float
-
Buoyancy force of the medium
-
Drag force related to fluid density and viscosity
Therefore, the measurement result directly depends on:
-
Medium density
-
Medium viscosity
-
Flow regime (laminar or transitional)
-
Float geometry and mass
This is why metal tube float flowmeters are factory-calibrated for a specific medium and operating condition, and recalibration or correction is required if the process conditions change.
Under what process conditions is a metal tube float flowmeter technically suitable or unsuitable?
Metal tube float flowmeters are technically suitable for stable, continuous flow measurement under harsh process conditions, but they are not universal instruments.
Suitable Conditions:
-
High pressure systems: up to 25–40 MPa
-
High temperature processes: up to 300–450°C
-
Corrosive fluids: with proper material or lining
-
Steam, gas, and liquid applications
-
Low to medium flow rates with stable flow
Unsuitable or Limited Conditions:
-
Strongly pulsating flow
-
Highly unstable density or viscosity
-
Applications requiring very high accuracy (< ±0.5%)
-
Rapidly changing process conditions
-
Severe vibration without proper damping
From an engineering standpoint, correct application matching is more critical than the flowmeter model itself.
How accurate is a metal tube float flowmeter and what factors influence its measurement accuracy?
The typical accuracy of a metal tube float flowmeter is ±1.0% to ±1.5% of full scale (FS) under rated conditions.
Accuracy Influencing Factors:
-
Medium Density Deviation
Any deviation from the calibrated density will cause proportional flow error. -
Viscosity Change
Increased viscosity increases drag force, causing the float to rise higher than expected. -
Installation Conditions
-
Must be installed vertically
-
Straight pipe lengths upstream improve stability
-
-
Temperature & Pressure Variation
Extreme changes may alter medium properties and affect readings.
In practical industrial applications, metal tube float flowmeters are used for process indication, monitoring, and control, not custody transfer.
How should material selection be handled for different process media?
Material selection directly determines safety, service life, and measurement stability.
Common Material Configurations:
| Process Medium | Recommended Tube Material | Float Material |
|---|---|---|
| Water / Steam | SS304 / SS316 | SS316 |
| Corrosive acids | SS316L + PTFE lining | PTFE / Hastelloy |
| Alkalis | SS316L | Alloy / PTFE |
| Hydrocarbons | SS316 | SS316 |
| High-temperature steam | Alloy steel | Alloy steel |
Incorrect material selection may lead to:
-
Float sticking
-
Chamber corrosion
-
Measurement drift
-
Safety risks
From a procurement perspective, material compatibility confirmation is mandatory before ordering.
How are output signals generated and how reliable are they for control systems?
Modern metal tube float flowmeters use magnetic coupling to transmit float position to external devices without process penetration.
Signal Options:
-
4–20 mA two-wire transmitter
-
Local mechanical pointer
-
Digital LED display
-
Limit switches (SPST / SPDT)
Signal Reliability:
-
No direct contact with the medium
-
Immune to vibration and temperature fluctuations
-
Long-term stability for PLC and DCS integration
Typical applications include:
-
Flow interlocks
-
Low / high flow alarms
-
Simple closed-loop control
Metal tube flowmeters are preferred when signal stability and mechanical robustness are more important than ultra-high accuracy.
What are the most common selection mistakes made during procurement?
Based on field feedback, the most frequent procurement errors include:
-
Selecting flow range too close to maximum operating flow
→ Causes float saturation and poor resolution -
Ignoring medium density and viscosity
→ Results in systematic measurement error -
Using standard materials for corrosive media
→ Leads to premature failure -
Assuming metal tube flowmeters are maintenance-free
→ Periodic inspection is still required in dirty media -
Using them in highly fluctuating flow systems
→ Leads to unstable readings
A properly selected metal tube float flowmeter should operate reliably for 10–15 years with minimal intervention.
Why Trust Instrava?
We select manufacturers from a neutral, impartial standpoint, always with your best interests in mind.
Our very existence depends on helping you source the products that are the perfect fit for your needs.
Based in China, we are able to conduct on-site inspections of production environments and product quality firsthand.
We help you avoid intermediaries posing as factories.
We facilitate smoother after-sales support, eliminating time zone issues and the delays often associated with dealing directly with factories.
Our multilingual team ensures effective communication.
For a trading startup, every interaction with a client is a precious opportunity—a sign that you are willing to place your trust in us and give us the chance to prove ourselves.
In the digital age, while information is easily accessible, misconceptions often cloud the trust between people.
Instrava relies entirely on trust; it is our core philosophy and the foundation of our existence in society. It is the fundamental basis for our long-term growth and our commitment to serving the community.
Please place your trust in us.
