Rotameter Flow Meters and Variable Area Systems for Gas and Liquid

Quick Answer: For local gas and liquid flow indication, a rotameter is a simple visual indicator and often the lowest cost variable area flow meter. Silver Automation Instruments supplies metal tube and plastic tube rotameters for water, air, nitrogen, chemicals, and fuel oil. Send your fluid name, flow range, pressure, temperature, and pipe size for a quote.

Many engineers call these devices rotameter flow meters or variable area systems. For gas and liquid lines they are simple visual indicators that need no external power. A float moves inside a tapered tube. Higher flow lifts the float higher. You read flow rate from the scale next to the float. In a metal tube rotameter, a magnetic coupling drives an indicator outside the tube.

Silver Automation Instruments is a flow meter manufacturer and supplier. We keep standard DN15 to DN50 rotameters in stock and build larger sizes to order.

Metal Tube vs Plastic Tube Rotameters

Plastic tube rotameters fit low pressure water and air lines. Typical limits are 10 bar and 60 °C. They work well for purge flows and cooling water circuits. Prices are low and installation is direct in PVC or PP lines.

Metal tube rotameters handle higher pressure and temperature. Common ratings are 16 bar to 40 bar and up to 200 °C. Materials include SS316, PTFE lining, and Hastelloy C floats. These units are used for hot water, steam condensate, diesel, solvents, and light chemicals.

Output Options and Hazardous Area Versions

A basic rotameter gives local indication only. Many customers add a 4-20 mA HART transmitter for remote totalization or SCADA. Switch outputs are available for high flow or low flow alarms. Silver Automation Instruments stocks ATEX Zone 1 and Zone 2 versions for gas and solvent lines in the Middle East and Latin America.

Optional PT100 temperature sensors and LCD indicators can be built into the same housing. This reduces the number of devices on a skid. A water treatment contractor in Malaysia recently ordered 20 metal tube rotameters with 4-20 mA HART and low flow switches for chemical dosing skids.

Key Sizes and Accuracy

We supply sizes from DN15 to DN150. Accuracy for standard models is 1.6% to 2.5% of full scale. A standard rotameter is not a custody transfer device. A rotameter works well for process monitoring, purge gas, seal water, and burner fuel control. Specify your normal flow and maximum flow by kg/h, L/h, or m3/h.

For liquids above 50 cP, variable area flow meters become less accurate. Tell us the viscosity value if you are not sure. Our engineers can check the correction factor before you order.

Industries That Use These Flow Meters

Common installations include nitrogen blanketing lines in chemical plants, diesel consumption on generator sets, boiler fuel oil loops, cooling water circuits, and small dosing systems. A food processor in Chile uses plastic tube rotameters for clean water flow indication. An oil and gas workshop in Nigeria uses metal tube rotameters for diesel fuel measurement at generator day tanks.

Last year a customer in Vietnam asked us for a rotameter to measure diesel return flow on a generator test bench. We supplied a DN15 metal tube unit with a 4-20 mA HART transmitter. The local scale was calibrated in L/h and the output went to a PLC.

How to Get a Quote

Send us your fluid name, normal and maximum flow rate, operating pressure in bar, temperature in °C, pipe size in DN, and required output. We will reply with a model recommendation, accuracy, delivery time, and price. You can reach Silver Automation Instruments by Tel: +86-25-68650347, Whatsapp: +86-25-52155837, or WeChat: +86 15365082610.

Rotameter Flow Meter FAQ

Question 1. Are a rotameter and a variable area flow meter the same thing?
Yes. Rotameter is a common trade name for a variable area flow meter. The operating principle is the same.

Question 2. Can one rotameter measure both gas and liquid?
No. Each unit is calibrated for one fluid and one set of process conditions. Gas and liquid densities differ too much for one calibration to work for both.

Question 3. What accuracy can I expect?
Standard accuracy is 1.6% to 2.5% of full scale. For a 100 L/h meter, a 2.5% FS error means a 2.5 L/h uncertainty across the range.

Question 4. Do you supply ATEX versions?
Yes. We supply ATEX Zone 1 and Zone 2 metal tube rotameters with 4-20 mA HART and alarm switches.

Question 5. What is the price of a rotameter flow meter?
Price depends on size, material, accuracy, and output. A small plastic tube air rotameter is lower cost. A DN50 SS316 metal tube unit with HART and ATEX costs more. Send your specifications for a firm quote.

Silver Automation Instruments
Web: https://flow-meter.com.au
Tel: +86-25-68650347
Whatsapp: +86-25-52155837
WeChat: +86 15365082610

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