『Laser Flow Meter: Non-Contacting Optical Open Channel Wastewater Level Senses』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)
Laser Flow Meter: Non-Contacting Optical Open Channel Wastewater Level Sensing
Quick Answer: A laser flow meter measures surface velocity in an open channel without touching the wastewater. It works with a non-contacting ultrasonic or radar level sensor to calculate flow rate from velocity and level. Silver Instruments supplies this open channel monitoring package for wastewater plants and industrial discharge points.
What a Non-Contacting Optical Laser Flow Meter Does
A laser flow meter uses a low power optical beam pointed at the water surface. The sensor reads surface velocity by detecting light scatter from particles, bubbles, or small ripples. It does not sit in the flow. This matters a lot in wastewater because grease, rags, and sludge can foul contact sensors.
In practice, most engineers choose this meter for effluent channels, plant outfalls, and partially full pipes. The laser sensor mounts above the channel on a bracket or rail. One technician can install it without stopping the flow. No flume or weir is required, so it suits existing concrete channels.
Open Channel Wastewater Level Sensing Without Contact
A laser velocity sensor alone cannot give flow rate. You also need water level. The standard package pairs the laser sensor with an ultrasonic level transmitter or a radar level transmitter. The flow calculator uses channel geometry and the measured level to compute wetted area. It then multiplies area by mean velocity.
Here is the thing. Mean velocity is not the same as surface velocity. The flow calculator applies a velocity coefficient from 0.85 to 0.93 for most channels. Silver Instruments preconfigures this coefficient based on channel width, roughness, and flow depth. For a 1.2 m wide concrete effluent channel in a Vietnamese seafood plant, the coefficient was 0.89.
Typical Specifications and Outputs
The laser velocity sensor usually covers 0.1 m/s to 6 m/s. Level sensors can cover 0.15 m to 8 m depending on the model. Flow accuracy is often within 2 percent to 3 percent of reading when installation is correct. Output options include 4-20 mA HART, RS485 Modbus, and pulse output for totalizer integration.
Power supply is normally 24 V DC. The sensor housing can be IP68 for outdoor and wet weather use. Operating temperature range is -20 °C to 60 °C. Some customers ask about ATEX Zone 1 areas. For wastewater plants this is rare, but we can supply an Ex version if the channel carries solvent laden effluent.
Silver Instruments does not sell a bare laser sensor with no support. We supply the sensor, level transmitter, mounting bracket, and a prewired signal converter. You get a test report with your serial number and calibration data.
Where Customers Use Laser Flow Meters for Wastewater
We have seen this setup on customer sites in Vietnam, Indonesia, Chile, Nigeria, and Saudi Arabia. One customer in Vietnam used a laser flow meter on a 0.8 m wide cant
_600x400.jpg)
A distributor in Mexico asked us for a non-contacting solution for a dairy plant. The effluent channel had high fat content. The laser sensor stayed clean because nothing touched the water. The ultrasonic level sensor was installed on the same rail about 0.4 m above the channel.
Most engineers skip this part. They focus only on the laser velocity sensor and forget level measurement. If you already have a working level sensor, you can send its 4-20 mA signal into our flow calculator. Silver Instruments can integrate with your existing level transmitter.
Installation Notes for Open Channel Monitoring
The mounting point should have a straight channel section upstream. Ten times the channel width is a good benchmark. Avoid dropping the sensor above hydraulic jumps, bends, or gates. Surface foam and heavy floating debris can interfere with the optical signal. In that case, a radar velocity sensor may be a better fit.
For partially full pipes, mount the laser sensor on a manhole frame. The level sensor works alongside it. The system calculates flow based on pipe diameter and wetted level. This substitutes for a magnetic flow meter when the pipe is not always full.
How to Request a Quote
Send us your channel width in mm, pipe size (DN) if applicable, minimum and maximum flow in m3/h, wastewater type, and site country. Tell us if you need a local display or data logging. The technical team at Silver Automation Instruments will select the right laser velocity sensor and level transmitter. You can also visit flow-meter.com.au and browse the open channel flow meter category for data sheets.
Tel: +86-135-1213-1526
WhatsApp: 86-135-12131526
WeChat: +86 13512131526
Frequently Asked Questions
Can a laser flow meter measure wastewater at night? Yes. The laser sensor uses its own optical source, so ambient light does not stop measurement. Rain and humidity matter more than darkness.
What is the minimum flow depth for a laser flow meter? The level sensor typically needs at least 150 mm depth for reliable area calculation. Very shallow flow below 100 mm may require a smaller channel section or a different sensor.
Does oil film on the water surface block the laser reading? A thick oil or foam layer can reduce the signal. A thin oil film usually still works because the laser reads surface ripple and particle movement.
Can this system replace a flume or weir? Yes, it can. The non-contacting method does not need a primary element. This saves civil work and avoids head loss in the channel.
What signals can go to my SCADA or PLC? Standard output is 4-20 mA HART. RS485 Modbus is available. Some systems also provide pulse output for a remote totalizer.
Hot Product
Related AD
