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『Krohne Clamp On Ultrasonic Flow Meter Setup: Fluxus Transducer Spacing Calculations for Steel Pipes』Related information(clamp on meter|electromagnetic meter|venturi meterrotameter|orifice meter|ultrasonic flow meter|mass flow meter|coriolis mass flow meter|coriolis flow meter|magnetic flow meter|magmeter flow meter|magflow flow meter|mag meter flow meter|electromagnetic flow meter|vortex flow meter|turbine flow meter|thermal mass flow meter|thermal flow meter|rotameter flow meter)
Krohne Clamp On Ultrasonic Flow Meter Setup Fluxus Transducer Spacing Calculations for Steel Pipes
Quick Answer: For steel pipes, the Krohne Fluxus clamp-on flow meter calculates transducer spacing after you enter measured pipe OD, wall thickness, pipe material, liner, fluid, and fluid temperature. Mount the transducers in V mode or Z mode depending on pipe size and signal quality. Always check the spacing value on the Fluxus display before you apply couplant.
What the Fluxus Spacing Calculation Uses
Most engineers do not calculate transducer spacing by hand. The Fluxus transmitter stores sound speed data for common pipe materials, including carbon steel and stainless steel. You measure the pipe OD and wall thickness at the mounting point, enter the fluid and temperature, and the transmitter gives you a spacing in millimetres. This value is measured between the reference marks on the transducer blocks.
On steel pipes, wall thickness changes the spacing more than pipe OD changes it. A DN100 Schedule 40 carbon steel pipe has an OD of 114.3 mm and a wall of 6.02 mm. A DN100 Schedule 80 pipe has the same OD but an 8.56 mm wall. The transmitter uses the shear sound speed of the pipe material, close to 3250 m per second for carbon steel. A thicker wall changes the shear wave path and the final transducer position.
V Mode W Mode and Z Mode on Steel Pipes
For clean steel pipes from DN15 to DN100, V mode is the standard first choice. The transducers sit on one side of the pipe and the signal bounces once off the far wall. W mode uses more reflections and works well on small pipes below DN50 or when the flow velocity is low. Z mode places the transducers on opposite sides of the pipe. This mode is common above DN200, on corroded steel pipes, or on fluids with gas bubbles and suspended solids. A 2 MHz transducer pair often works for DN50 to DN200 steel pipes.
In practice, a clean DN150 carbon steel pipe with water at 20 degrees Celsius usually runs well in V mode. If the signal drops because of scale or aeration, switch to Z mode and check the signal gain on the Fluxus display. The calculated spacing changes with the mode, so do not reuse the previous V mode distance after switching.
Step by Step Setup for a Steel Pipe
First, find a straight run with at least 10 pipe diameters upstream and 5 diameters downstream. Clean the steel surface with a grinder or file until you see bare metal. Remove paint, rust, and high spots. Measure the OD with a pipe tape or calliper. Measure the wall thickness with an ultrasonic thickness gauge. Do not trust the pipe schedule table if the pipe is old or has internal scale.
Then enter the parameters into the Fluxus menu. Key inputs are pipe OD, wall thickness, pipe material as carbon steel or stainless steel, lining as none for bare steel, fluid type, fluid temperature, and transducer frequency. The transmitter calculates the spacing. Mark the pipe using the reference marks. Apply a thin layer of acoustic couplant and fix the transducers with straps or magnetic holders. Use a water-based couplant for temporary tests and a grease-based couplant for permanent installations.
Rusted Coated and Lined Steel Pipe
We have seen this on customer sites many times. A steel pipe in a wastewater plant looks fine on the outside but has 3 to 5 mm of scale inside. The Fluxus transmitter thinks the pipe wall is the value you entered. If the real wall plus scale is thicker, the signal path shifts and the reading becomes unstable
Common Setup Mistakes
One mistake is using nominal pipe size instead of the measured OD. A DN80 steel pipe may have an actual OD of 88.9 mm, but rough field tape measurement can be 90 mm if paint remains. Clean first and measure twice. Another field issue is couplant application. A thin layer is enough, and too much paste can trap air bubbles between the transducer and the steel surface. A separate problem comes from entering fluid temperature at the control room value instead of the pipe surface temperature. Sound speed changes with temperature, so the spacing changes.
Some engineers also mount the transducers on a pipe section with internal pitting. The signal bounces in an unexpected way. Move the mounting point one pipe diameter away and check the signal strength again.
Silver Instruments Clamp-On Flow Meters for Steel Pipes
Silver Automation Instruments supplies fixed and portable clamp-on ultrasonic flow meters for steel pipes in Southeast Asia, Oceania, Latin America, Africa, and the Middle East. The setup logic is similar to the Krohne Fluxus series. You send pipe OD, wall thickness, pipe material, fluid, temperature, pressure, and flow range, and we recommend a meter with the right transducer frequency and mounting mode.
Last year a customer in Vietnam replaced a rented Krohne Fluxus unit with a fixed clamp-on meter from Silver Instruments on a DN200 stainless steel seawater line at 4 bar and 30 degrees Celsius. They sent the measured OD and wall thickness, and we matched the transducer frequency and mounting recommendation.
If you need a price for a clamp-on ultrasonic flow meter on a steel pipe, send us your pipe OD in mm, wall thickness in mm, pipe material, fluid name, temperature in degrees Celsius, pressure in bar, and flow range in m3/h. Tell us whether the pipe is carbon steel or stainless steel and whether it has a lining. Contact Tel: +86-135-1213-1526, Whatsapp: 86-135-12131526, or WeChat: +86 13512131526. You can also visit flow-meter.com.au for product data and application notes.
Frequently Asked Questions
How is transducer spacing calculated for a Krohne Fluxus on a steel pipe? The Fluxus transmitter calculates the spacing after you enter measured OD, wall thickness, pipe material, lining, fluid, fluid temperature, and transducer type. Read the value in millimetres from the display. You do not need to calculate by hand.
What mounting mode should I use for a DN150 steel pipe? V mode normally works on a clean DN150 carbon steel pipe with water. If the signal is weak because of scale or entrained air, use Z mode and check the signal gain.
Does pipe schedule affect transducer spacing? Yes. Two pipes with the same OD but different wall thickness need different spacing. Always enter the measured wall thickness at the transducer location.
Can transducers be mounted on painted steel pipe? No. Remove paint, rust, and loose material down to bare steel. A clean contact area improves the acoustic coupling and signal strength.
What details does Silver Instruments need for a clamp-on ultrasonic flow meter quote? Send pipe OD, wall thickness, pipe material, fluid, temperature, pressure, flow range, and power supply. Contact us on Tel: +86-135-1213-1526, Whatsapp: 86-135-12131526, or WeChat: +86 13512131526.