HNF50 Metal Tube Rotameter for Liquids & Gases, DN15–DN150

All-metal variable-area rotameter for liquids and gases. DN15–DN150, liquid to 150,000 L/h, gas to 3000 m³/h, ±1.0–1.5% FS, 4–20 mA/HART/RS485, IP65.

HNF50 Metal Tube Rotameter for Liquids & Gases

The HNF50 all-metal tube float flow meter — also called a metal float flowmeter, metal tube rotameter or variable-area flow meter — measures both liquids and gases. As flow increases, the float rises inside a tapered measuring tube; its position is read on the scale and transferred by a magnetic coupling, so the indicator stays fully sealed from the medium and signal transmission remains stable. The sturdy all-metal design uses an independent modular measuring-tube/indicator concept, with 304, 316, 316L, Hastelloy B/C, titanium or PTFE-lined measuring tube and float for corrosive service, and IP65 protection.

INQUIRY

Variable-Area Measurement for Harsh Process Service

Available in pointer, electric remote, corrosion-resistant, high-voltage, jacket and explosion-proof versions, with analog output, local indication, totalization, digital communication, on-site parameter modification and multiple supply options, plus magnetic filters and special specifications. It serves petroleum, chemical, power generation, pharmaceuticals, food and beverage, water treatment, corrosive acid/alkali media, high-temperature processes, sanitary dairy lines, gas purging and dosing lines in complex and harsh environments.

Good fit: petroleum, chemical industry, power generation, pharmaceuticals, food & beverage, water treatment, corrosive acids and alkalis, high-temperature processes to 350 ℃, sanitary food and dairy lines, gas purging and dosing lines, complex and harsh process environments.

Is HNF50 Suitable for Your Application?

Choose HNF50 when:

You need a rugged variable-area meter for liquid or gas, with local indication and optional remote transmission.
The medium is corrosive, high-temperature, high-pressure or sanitary, requiring stainless, Hastelloy, titanium or PTFE-lined wetted parts.
You want 4–20 mA, HART, RS485/RS232, pulse or relay alarm output, with DC, AC or battery supply.

Confirm with us first when: viscosity exceeds the DN-specific limit, the process pressure/temperature is outside the standard rating, a sanitary or jacketed connection is required, or an explosion-proof version is needed.

Working Principle

On the variable-area principle, flow through the tapered tube lifts the float until the annular gap balances the float weight against flow force. The float position is transferred through the magnetic coupling to the sealed indicator, which shows the flow on the scale and drives the output electronics. Full digital processing gives strong anti-interference, reliable measurement and high accuracy; the low-pressure-loss design and vertical or horizontal installation suit different layouts.

Technical Specifications

Model	HNF50 — Metal tube float (variable-area) flow meter
Measurement medium	Liquid and gas, compatible with the selected contact material
Accuracy	≤±1.5 % FS typical; ≤±1.0 % FS highest (including nonlinearity, hysteresis and repeatability)
Nonlinearity (BFSL)	≤±0.3 % FS
Hysteresis / repeatability	≤±0.1 % FS
Thermal drift	Zero and full range ≤±0.1 % FS/10K typical, ≤±0.2 % FS/10K maximum
Range ratio	10:1; 20:1 customized
Nominal size	DN15, DN25, DN50, DN80, DN100, DN150; customized; caliber range DN10…DN2600
Pressure rating	DN15/25/50: 4.0 MPa; DN80/100/150: 1.6 MPa
Measuring range	Liquid 1.0–150,000 L/h; gas 0.05–3000 m³/h
Medium temperature	Standard −30…+120 ℃; high-temperature 120…350 ℃; PTFE lining up to 80 ℃
Supply	24 VDC (12–36 VDC); 220 VAC; 3.6 V lithium battery
Output signal	Two-wire 4–20 mADC, 4–20 mA + HART; three-wire MODBUS RTU; accumulated pulse (24 V, 50 % duty); optional relay alarm, contact 250 VAC 3 A
Output load	500 Ω (when powered by 24 VDC)
Ambient temperature	Local type −40…120 ℃; remote type −30…70 ℃; storage −40…85 ℃, humidity ≤85 %
Connection	Flange to GB/T 9119-2000; clamp and sanitary connections; sanitary surface roughness <0.8 Ra
Protection rating	IP65
Viscosity limit	DN15 η<5 mPa·s; DN25 η<250 mPa·s; DN50–DN150 η<300 mPa·s
Tube / float material	R1 304 (0Cr18Ni9); R0 316 (0Cr18Ni12Mo2Ti); RL 316L (00Cr17Ni14Mo2Ti); H Hastelloy B/C; Ti titanium / titanium alloy; Rp PTFE lining

Representative Flow Ranges by Size

Nominal size	Water / oil (L/h)	Air (m³/h)
DN15	2.5–630	0.07–16
DN25	100–4,000	3–110
DN40	500–6,000	12–160
DN50	630–16,000	18–400
DN80	2,500–40,000	60–800
DN100	6,300–63,000	100–1,000
DN150	20,000–100,000	600–3,000

Each size offers A–H sub-scales; the exact water/oil and air range and pressure loss for a sub-scale are listed in the datasheet range comparison table.

Selection Code

Code segment	Code	Description
Type	A	Sanitary type
Type	B	Standard type
Flow range	X	Note the maximum flow rate corresponding to 20 mA after X
Nominal size	10	DN10
	25	DN25
	50	DN50
	100	DN100
	200	DN200
	X	Write the diameter directly after X, max 2200 mm
Accuracy	A	1 % FS
Accuracy	B	1.5 % FS
Signal output	M	4–20 mA
	MH	4–20 mA with HART
	P	Pulse output
	R2	RS232 output
	R4	RS485 output
Rod structure	A	Down in, up out
	B	Right in, left out
	C	Left in, right out
Float material	L	316L
	O	PTFE
	T	Titanium
Shell material	1	Carbon steel
Shell material	2	Stainless steel
Measurement medium	A	Water
	B	Air
	C	Oil
Pressure / temperature	A	Standard
Pressure / temperature	B	High temperature and high pressure
Supply voltage	1	DC 24 V
	2	AC 220 V
	3	3.6 V lithium battery
Explosion-proof	1	Non-explosion-proof
Explosion-proof	2	Explosion-proof type

Installation Notes

Vertical and horizontal mounting are supported; match the rod structure code (down-in/up-out, right-in/left-out, left-in/right-out) to the piping orientation.
For liquid service install to avoid gas entrainment; for gas service avoid liquid slugging; a magnetic filter can be fitted where required.
Match tube, float and seal materials to the medium; choose PTFE lining or Hastelloy/titanium for corrosive service.
Confirm viscosity against the DN-specific limit before ordering.

Typical Applications

Process industry: petroleum, chemical, power generation, water treatment.
Sanitary and food: pharmaceuticals, food and beverage, dairy lines with <0.8 Ra finish.
Corrosive and high-temperature: acids and alkalis, processes up to 350 ℃, jacketed service.
Gas and dosing: gas purging and dosing lines, compressed-air and fuel-gas measurement.

What to Send Us for Selection

Send: medium (water/air/oil or other), flow range and normal operating flow, nominal size and connection, required output, supply, wetted/float material, pressure and temperature, sanitary or jacketed requirement, and whether explosion-proof is needed. We will confirm the size and selection code before quoting.

Frequently Asked Questions

Can one rotameter measure liquids and gases?

Yes. The HNF50 variable-area meter measures both liquids and gases; the medium and sub-scale are selected in the code, with liquid to 150,000 L/h and gas to 3000 m³/h.

Which wetted materials resist corrosive process fluids?

The measuring tube and float can be 304, 316, 316L, Hastelloy B/C, titanium or PTFE-lined. Send the chemical and concentration so we can match the material; PTFE lining is limited to 80 ℃.

Does it support horizontal installation?

Yes. Vertical and horizontal installation are supported; choose the rod structure code that matches inlet/outlet orientation (down-in/up-out, right-in/left-out, left-in/right-out).

How does magnetic coupling isolate the sealed indicator from the measured medium?

The float position is transferred to the indicator through a magnetic coupling, so the indicator is fully sealed from the medium; this keeps signal transmission stable and protects the electronics from aggressive process fluids.

What output and battery options are available for remote flow monitoring?

Outputs include two-wire 4–20 mA and 4–20 mA+HART, three-wire MODBUS RTU, accumulated pulse and optional relay alarm; RS232/RS485 are also selectable. Supply can be DC 24 V, AC 220 V or a 3.6 V lithium battery for locations without mains power.