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Onicon F 300 Flow Meter Operation for Chilled Water Systems
Quick Answer: The F 300 inline vortex flowmeter measures chilled water flow with no moving parts and gives 4-20 mA HART, pulse, or Modbus output. It suits DN25 to DN200 pipes, handles water and glycol from 0 to 50 degrees Celsius, and needs 15D straight run upstream. Send your pipe size DN, flow range, pressure in bar, temperature, and output signal to Silver Instruments for a compatible model and quote.
What the F 300 Flow Meter Does on a Chilled Water Line
Most district cooling plants and building HVAC systems run flow meters on primary and secondary chilled water loops. You need to know how much chilled water reaches each building or heat exchanger. The Onicon F 300 inline vortex flowmeter is one common device for this task. Silver Automation Instruments supplies inline vortex flowmeters for chilled water systems. We size the meter to match the pipe diameter and the temperature of your loop.
Chilled water is not a difficult fluid for a vortex meter. The temperature is usually between 0.5 and 15 degrees Celsius. Pressure stays within PN16 on most loops. But there is one issue. Cooling plants often add glycol to prevent freezing. A chilled water flow meter has to keep its accuracy when the glycol percentage changes from 0 to 40 percent. We ask for the glycol type and concentration before configuration.
Operating Principle of an Inline Vortex Flowmeter
An inline vortex flowmeter uses a bluff body inside the pipe. As water passes the body, vortices form downstream. The frequency of these vortices is proportional to flow velocity. A sensor behind the bluff body detects the passing vortices and converts the frequency into a flow reading. No moving parts sit in the flow path. That means no bearings to fail and no filter requirement under normal conditions.
In practice, the output signal is more useful than the raw frequency. The F 300 flow meter converts the vortex frequency into a 4-20 mA signal with HART. Many plants also use pulse output for batching or energy calculation. A chiller plant in Bangkok may send pulse signals to a BTU meter. A building management system in Dubai may read the 4-20 mA signal. Silver Instruments can supply the same signal type as your existing Onicon F 300. So the control loop does not change.
Installation and Wiring Notes That Prevent Field Errors
Most engineers skip this part and regret it later. Vortex meters need a straight pipe run to produce stable vortices. We recommend 15D upstream and 5D downstream for inline installations. If you install the meter after a control valve or a pump, add more upstream straight length. A rule of thumb from field work is 30D after a control valve. This reduces swirl and keeps the meter within its accuracy spec.
Mount the F 300 flow meter in a location where the pipe is full at all times. Do not install it at the highest point of a chilled water loop where air can collect. Air bubbles create false pulses and unstable readings. For horizontal lines, the meter can be installed with the electronics head to the side or on top. Because condensation can enter the housing, avoid downward flow with the electronics below the pipe.
Wiring follows the standard for 4-20 mA HART instruments. Use a shielded twisted pair for the analog output. Keep signal cable away from variable frequency drive cables. VFD noise is a common cause of pulse dropouts on chilled water pumps. We have seen this on customer sites many times. Ground the shield only at the control panel end. That single change often removes the noise.
F 300 Flow Meter Specifications for Chilled Water Systems
The Silver Instruments inline vortex meter for chilled water comes in DN15 to DN300 sizes. For most building flows, DN25 to DN200 co
Temperature range is minus 20 to 120 degrees Celsius. Chilled water at 5 degrees Celsius sits well inside this range. Pressure rating options are PN16, PN40, or ANSI Class 150 or 300. Wetted parts can be 304 stainless steel or 316L stainless steel. Output options include 4-20 mA with HART, pulse, and RS485 Modbus RTU. Power is 24 V DC. The local display shows flow rate, total flow, and alarm status.
Onicon F 300 Replacement Without Rebuilding the Pipe
Several maintenance teams ask us to replace a failed Onicon F 300 on an existing chilled water line. The original meter may be old, the display may be dead, or the pulse output may have drifted. A full pipe rebuild is expensive and shuts down the cooling loop. We match the flange standard and face to face dimension so the replacement meter drops into the same space. Most Onicon F 300 installations on chilled water use ANSI 150 flanges or PN16 flanges. We confirm the bolt pattern and the insertion length before shipping.
A district cooling plant in Manila replaced two failed Onicon inline vortex flowmeters on a DN150 chilled water return header. The plant sent us the pipe size, the flow range, and a photo of the old nameplate. We supplied two inline vortex meters with 316L bodies and Modbus output. The plant installed them during a weekend shutdown and the system came back online without retuning the building management system.
Price and Quote Data We Need From You
We do not publish fixed prices because each chilled water application has different flanges, outputs, and temperature ranges. Send us the following data for a quote. Pipe size DN, flange standard, flow range in cubic meters per hour, pressure in bar, fluid temperature in degrees Celsius, glycol percentage if any, and the output signal your control system needs. Also tell us your country and the quantity. We will return a price and a lead time within one business day.
As a flow meter manufacturer and supplier, Silver Instruments keeps common chilled water sizes in stock. Contact us by phone at +86-25-68650347, by Whatsapp at +86-25-52155837, or by WeChat at +86 15365082610. For email, visit flow-meter.com.au and use the contact page.
Five Questions Engineers Ask Before Ordering an F 300 Flow Meter
1. Can this meter measure chilled water with 30 percent glycol
Yes. We configure the meter for the glycol concentration you specify. Accuracy may shift slightly if the glycol percentage moves more than 5 percent from the configured value.
2. Does an inline vortex meter need a straight run
Yes. We recommend 15D upstream and 5D downstream for normal piping. Install a straightening vane or add more upstream length after pumps and control valves.
3. What output works with a building management system
Most sites use 4-20 mA HART. If your BMS reads Modbus RTU, we also supply RS485. Pulse output is common for energy meters and totalizer panels.
4. Can the F 300 flow meter be installed on a vertical chilled water pipe
Yes. The flow direction must be upward in most cases. This keeps the pipe full and prevents air from collecting at the sensor.
5. How do we know the replacement will fit our existing flanges
Send a photo of the nameplate and measure the flange standard and face to face length. We will match those dimensions before shipping.
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