Current position > News detail
『Bi Directional Ultrasonic Flow Meter: Sourcing Forward and Reverse Acoustic Probes』Related information(v cone flow meter|rotary gas meter|gallon meter|gear meter|metal tube rotameter|glass tube rotameter|nutating disk meter|transit time ultrasonic flow meter|wedge flow meter|pd meters|hydraulic flow meter|ultrasonic water flow meter|water flow meter|air flow meter|magnetic water flow meter|oxygen flow meter|gas flow meter|argon flow meter|air velocity meter|gasoline flow meter|fuel flow meter|ultrasonic water meter|digital water meter|nitrogen flow meter|solid flow meter|Oxygen tank flow meter|digital water flow meter|diesel fuel flow meter|steam flow meter|02 flow meter|compressed air flow meter|oil flow meter|liquid flow meter)
Bi Directional Ultrasonic Flow Meter Sourcing Forward and Reverse Acoustic Probes
Quick Answer: For bidirectional ultrasonic flow meters, forward and reverse acoustic probes must be ordered as a matched pair from one manufacturer. Check frequency, probe angle, cable length, temperature rating and hazardous area certification before you buy. Send Silver Automation Instruments your pipe size, wall thickness, fluid type, temperature and flow range to get a probe set that holds stable reverse flow totals.
Most flow meter sourcing mistakes happen before the order is placed. A buyer sees a cheap replacement probe online and thinks any 1 MHz probe will work. In a bidirectional ultrasonic flow meter the forward and reverse probes switch roles hundreds of times per second. If the two probes do not have the same electrical and acoustic response the meter will show a zero flow offset or unstable reverse flow.
Why Bidirectional Probe Sets Need to Be Matched
A bidirectional ultrasonic flow meter measures transit time difference. In forward flow the upstream probe fires and the downstream probe receives. In reverse flow the sequence flips. Because the same pair handles both directions the two probes must have near identical resonance frequency, beam angle, capacitance and cable length. A 2 percent difference in crystal impedance can create a 0.4 percent span error in reverse flow. That is enough to fail a custody transfer audit or a batch recipe.
We have seen this on customer sites many times. A water utility in the Philippines replaced one damaged probe on a DN600 cement lined steel pipe. The flow meter worked in forward direction but the reverse totalizer drifted by 3.1 percent at night when flow dropped to 0.15 m/s. The old probe was from a different batch. We supplied a matched 1 MHz clamp on pair with stainless steel brackets. The reverse flow error fell to 0.6 percent of reading.
Forward and Reverse Acoustic Probe Parameters That Engineers Check
Frequency is the first filter. For DN15 to DN50 use 2 MHz probes. For DN65 to DN250 use 1 MHz probes. For DN300 and above use 0.5 MHz probes. Pipe wall material and lining also matter. A thick asphalt lining on a steel pipe can force you to drop from 1 MHz to 0.5 MHz because the acoustic signal loses too much energy.
Probe angle is next. Common angles are 30 degrees, 45 degrees and 60 degrees. Smaller angles give a longer acoustic path and better resolution on small pipes. Larger angles are easier to install on large pipes but may reduce signal strength. Always ask the supplier to calculate the installation gap for your pipe schedule and lining. If the gap calculation is wrong the meter will not pick up a clean signal.
Cable length is often ignored. In practice most engineers skip the cable length check and then wonder why the meter reads a small negative flow at zero flow. Probe cables are part of the tuned circuit. If the forward probe uses 5 m cable and the reverse probe uses 20 m cable the phase shift can pull the zero point. Order both with the same cable length or use the factory supplied cables. For hazardous areas request stainless steel armored cable and state the ATEX or IECEx zone.
Installation Style and Process Conditions
Clamp on probes work well for clean water, seawater, chemicals and light oils. They do not touch the fluid and are easy to install on existing pipes. Insertion probes are better for dirty water, wastewater and fluids with suspended solids. A wastewater plant in Vietnam needed bidirectional flow measurement on a DN500 ductile iron sludge line. Clamp on probes could not hold a signal at 2.5 percent solids. We supplied insertion probes rated for
For food and beverage lines check the wetted material. Probe faces can be PFA, PVDF or stainless steel 316L. For aggressive chemicals a PTFE face may be needed. For high temperature above 120 °C use high temperature probes with heat resistant backing. For low temperature LNG or chilled water lines mention the temperature range because standard probes can crack at minus 40 °C.
Application Examples from Customer Sites
Last year a paint manufacturer in Southeast Asia ran resin batching on a 25 mm stainless steel line. The fluid viscosity was 45 cP at 60 °C. They ordered a 2 MHz clamp on pair from a local supplier but the reverse batching total was unstable. One probe had a different backing material and the beam angle was not matched. We provided a matched forward and reverse probe set with PTFE faces, 10 m cables and ATEX Zone 1 certification. The reverse batching error moved to within plus or minus 0.5 percent.
An offshore platform in the Middle East needed replacement probes for a bidirectional diesel transfer meter. The pipe was DN100 schedule 80 carbon steel. The line had fast reversing flow during tank switchover. Standard probes worked but the cable jacket degraded near salt spray. We supplied IP68 probes with marine grade cable glands and stainless steel mounting rails. The meter now holds stable forward and reverse totals at up to 8 m/s.
Data to Prepare Before You Ask for a Quote
Do not send a one line request for a bidirectional ultrasonic flow meter probe set. Send the pipe size in DN or inches, pipe material, wall thickness, lining material, fluid type, density or viscosity if known, temperature range, pressure range, flow range in both directions and hazardous area classification. Also state whether the meter is clamp on, insertion or inline. If you have the existing flow meter model or serial number include that too.
Silver Automation Instruments supplies bidirectional ultrasonic flow meter probes for forward and reverse measurement in water, wastewater, oil and gas, chemical, food and beverage and marine applications. For a specific quote contact Tel: +86-25-68650347. Whatsapp: +86-25-52155837. WeChat: +86 15365082610. Send us your pipe size, wall thickness, fluid, temperature, pressure and flow range. We will return a probe model, installation gap and price within 24 hours.
FAQ
Can I use different forward and reverse acoustic probes on one bidirectional ultrasonic flow meter? No. The two probes must be a matched pair from the same batch or the reverse flow reading can drift and create zero offset.
What frequency of acoustic probe do I need for my pipe size? DN15 to DN50 typically uses 2 MHz. DN65 to DN250 uses 1 MHz. DN300 and above uses 0.5 MHz. Pipe wall and lining can change this choice so send full pipe data.
How do I order replacement probes if I only know the flow meter model? Send a photo of the probe face, the cable label, the meter serial number and your pipe dimensions. Silver Automation Instruments can match an equivalent probe set for most ultrasonic flow meters.
Do you supply hazardous area probe sets for ATEX or IECEx zones? Yes. We supply Ex Zone 1 and Zone 2 probe sets with stainless steel housing and armored cable. State the zone and gas group when requesting a quote.
What is the delivery time and price for forward and reverse acoustic probes? Stock clamp on probe sets ship in 5 to 7 days. Custom insertion probes take 10 to 15 days. Price depends on DN, frequency, cable length, temperature rating and Ex rating. Send your process data for a firm quote.