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Greyline Pulsar Non-Contacting Area Velocity Sewer Monitor: Get Flow Data Without Sensor Contact
Quick Answer: The Greyline Pulsar uses an ultrasonic Doppler sensor mounted above the water surface to measure flow velocity, combined with a submerged pressure transducer for level. No sensor parts touch the wastewater. This non-contact design avoids fouling, debris hang-ups, and sensor corrosion. You get accurate flow data in partially full pipes, open channels, and surcharged sewers with almost zero maintenance.
Why a Non-Contact Flow Meter Matters in Real Sewer Conditions
In most sewer applications, the flow stream carries rags, grease, solids, and corrosive gases. Contact sensors like magnetic flow meters or inline ultrasonics foul quickly. Cleaning is frequent and unpleasant. The Greyline Pulsar side-steps all this. A velocity sensor clamps to the top of the channel or pipe wall, never touching the water. Below the surface, a small submerged pressure transducer measures level. That simple combination gives area-velocity flow rate even when the pipe runs partially full, which happens daily in most sewer networks.
We have seen plants in Malaysia, the UAE, and Chile dealing with rag buildup on paddlewheel flow meters after just two days. The Pulsar solved that problem completely. It is a practical choice for raw sewage, stormwater, industrial effluent, and any liquid you would rather not handle.
How the Pulsar Measures Flow Without Contact
The velocity sensor works on an ultrasonic Doppler principle. It sends a 640 kHz ultrasonic signal through the air, off the water surface, and into the flow stream. Particles and bubbles in the water reflect the signal back. The frequency shift gives velocity. Because the sensor is mounted above the wastewater at a known angle, the unit calculates average velocity reliably. The pressure transducer reads liquid depth. With pipe or channel dimensions entered, the meter outputs flow rate continuously.
Installation is fast. You do not need to drain the channel or build a weir. The velocity sensor mounts on a stainless steel bracket, and the pressure sensor drops to the bottom using a stilling well or a simple mounting ring. In practice, most engineers treat the setup as a one-day job.
Where the Pulsar Fits: Pipe Sizes, Shapes, and Industry Examples
The Greyline Pulsar works on pipe diameters from 150 mm (6 inches) up to large box culverts. It handles circular, rectangular, trapezoidal, and egg-shaped channels. A few installations we have followed closely:
A wastewater plant in Surabaya, Indonesia needed flow monitoring in a 900 mm diameter partially filled concrete pipe. Their old magnetic flow meter failed repeatedly due to slime coating. The Pulsar, installed in two hours, has been running for 11 months with zero maintenance.
An edible oil refinery in Durban, South Africa uses it on a rectangular effluent channel with high temperature and fat content. No sensor contact means no cleaning crew exposure to hot, greasy water.
In a Chilean copper mine, the Pulsar monitors pro
Output Options and Integration
The Pulsar offers a 4-20 mA signal for flow rate, two relays for alarm or totalizer, and RS-232/RS-485 Modbus. This fits directly into most SCADA systems. We often supply the model with an onboard data logger and USB download if the site lacks telemetry. There is also a built-in display showing flow, velocity, level, and total. Engineers like the ability to check readings locally without a laptop.
Common Questions from Our Customers
Q: Does the velocity sensor work if the water surface is foamy or covered in scum?
Yes, in most cases. The 640 kHz signal penetrates thin foam and grease layers. Very thick floating scum can reduce signal strength. In those rare situations, a small deflector or manual cleaning once a week fixes it. We have seen this in a dairy plant in Mexico, and deflector plates solved it for good.
Q: What pipe materials cause measurement issues?
The velocity sensor mounts above the surface, so pipe material does not affect the ultrasonic signal. Only the submerged pressure transducer touches the water, and it works with concrete, steel, HDPE, and brick sewers. No special liners needed.
Q: Can it measure flow in a surcharged pipe?
Yes. The pressure transducer measures level up to full-bore conditions. When the pipe runs full and under pressure, the area-velocity method still works. There is a slight accuracy drop at very high surcharge levels, but operators still get reliable trend and total data. In one site in Auckland, New Zealand, the Pulsar operated under surcharge for 48 hours during a storm with no issues.
Q: What accuracy can I expect?
Typical accuracy under stable flow is plus-minus 2% of reading. In highly turbulent flows with uneven velocity distribution, the reading may show a bias. That is why Greyline recommends profiling the channel once and applying a correction factor if needed. In most sewers, 2 to 5 percent is realistic and more than enough for billing or process control.
Q: Do I need calibration after installation?
Not in the traditional sense. The meter ships pre-configured for the pipe size and shape you provide. You only enter the channel dimensions and mounting angle. There is no sensor zero or span to adjust. Some sites do a one-point velocity check with a dye test or portable flow meter to verify, but it is not mandatory.
Get a Quotation for the Greyline Pulsar Flow Meter
If you are dealing with dirty flow streams where contact sensors fail too often, the Pulsar could be the right tool. Send us your pipe or channel dimensions, material, flow range, and whether you need data logging or Modbus output. We will return a price and delivery lead time within one working day.
Silver Automation Instruments
Email: [email protected]
Tel: +86-135-1213-1526
Whatsapp: 86-135-12131526
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Web: flow-meter.com.au