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Water Flow Meter 4-20 mA for Industrial Loop Connected Utility Telemetry Systems
Quick Answer: A 4-20 mA water flow meter sends flow rate as an analog current loop signal to PLC, RTU, or SCADA systems. Silver Automation Instruments supplies electromagnetic, ultrasonic, and vortex water flow meters with 4-20 mA output for pipes from DN15 to DN600. Send your flow range, pipe size, pressure, and temperature for a working quote.
Utility telemetry systems often need flow signals that travel long distances without signal loss. A 4-20 mA loop does this well. The current changes with flow rate. 4 mA usually means zero flow. 20 mA normally means full scale flow. The receiver at the control room reads the current and converts it back to flow units.
Silver Automation Instruments builds water flow meters for these exact field conditions. We have supplied instrumentation to water utilities, desalination plants, and industrial sites in Vietnam, the Philippines, Thailand, Oman, Chile, Mexico, and Nigeria. Many of these projects use 4-20 mA loop powered devices because the wiring is simple and field maintenance is fast.
What 4-20 mA Means for Water Flow Metering
A 4-20 mA flow meter acts as a transmitter. It changes loop current in proportion to measured flow rate. For example, a DN80 electromagnetic flow meter may have a range of 5 to 100 cubic meters per hour. At 5 cubic meters per hour, the output is 4 mA. At 100 cubic meters per hour, the output is 20 mA. A mid flow of 50 cubic meters per hour gives roughly 12 mA.
The low end of 4 mA is not zero current. This is important in utility telemetry. If the loop current drops to 0 mA, the RTU or PLC detects a broken wire, a power loss, or a transmitter fault. Most engineers skip this part, but it matters on site. That simple diagnostic rule saves troubleshooting time on remote water sites.
Which Silver Instruments Flow Meters Output 4-20 mA
Our electromagnetic flow meter series is the first choice for raw water, potable water, and wastewater. It covers DN15 to DN600 line sizes. Liners include PTFE and hard rubber. Electrode materials include stainless steel, Hastelloy, and titanium. Electromagnetic flow meters need a minimum liquid conductivity of about 5 µS/cm for stable readings. The output board provides 4-20 mA, pulse, and RS485. Accuracy is plus or minus 0.5 percent of reading. This series works well for utility flow measurement because there are no moving parts and the straight run requirement is shorter than a vortex meter.
For desalination plant feed lines or brine lines, we often recommend an inline ultrasonic flow meter. It handles high salinity, high pressure, and bi-directional flow. The 4-20 mA output can be configured with HART. A customer in Oman runs DN200 ultrasonic flow meters on brine discharge lines. They send 4-20 mA signals to a central SCADA system across the plant.
Vortex flow meters are used for utility water with higher temperatures and pressures. They work well on steam condensate, hot water, and chiller water. The output is a 4-20 mA signal with pulse. Pipe sizes from DN25 to DN300 are common. For hot water above 120 °C, specify the high temperature sensor option.
Water treatment plants also use our oval gear flow meters on chemical dosing skids. They measure polymer or coagulant flow in liters per hour or kilograms per hour. These meters handle viscosities from 1 cP to over 1000 cP. The 4-20 mA signal goes to the same PLC or SCADA input as the main water flow meter.
Loop Wiring and T
Most utility telemetry systems use either a 2 wire loop or a 4 wire flow meter. A 2 wire loop powered flow meter is easier to wire. The same two wires carry power and signal. A 4 wire flow meter needs a separate power supply but often gives more output options, such as 4-20 mA plus HART, pulse, or Modbus.
Here is the thing. On a remote pumping station, a 2 wire electromagnetic flow meter with 4-20 mA output is often the fastest to install. You connect it to a solar powered RTU. The RTU reads the 4-20 mA input and logs flow total. Telemetry then sends data by radio or cellular modem to the central office.
We have seen this many times on customer sites in Southeast Asia. A water utility in the Philippines replaced old mechanical meters with electromagnetic flow meters on DN100 distribution lines. They ran 4-20 mA cables back to local RTU panels. The site flow data now reaches the main office every 15 minutes.
Key Specifications to Send Before Quote
To get a water flow meter price fast, include the following details in your inquiry. Pipe size in DN or inches. Fluid type, such as potable water, raw water, seawater, or wastewater. Flow range in cubic meters per hour or liters per minute. Pressure in bar. Temperature in °C. Power supply, such as 24 V DC or 220 V AC. Output type, such as 4-20 mA, 4-20 mA with HART, pulse, or Modbus RTU.
You can send these details by email or WhatsApp. Our team responds with a model recommendation, a datasheet, and a quote within 24 hours for standard requests.
FAQ
Can a 4-20 mA water flow meter connect directly to a PLC or RTU?
Yes. The 4-20 mA signal connects to an analog input channel on the PLC or RTU. Set the input range to 4 mA as minimum flow and 20 mA as maximum flow. Some systems also need a 250 ohm resistor to read HART signals.
What is the difference between active and passive 4-20 mA output?
Active output means the flow meter sources the loop current from its own power supply. Passive output means the loop current is powered by an external supply. For most utility telemetry systems, a passive 4-20 mA output can be used if the RTU already provides loop power. Silver Instruments flow meters can be ordered with active or passive output.
Which Silver Instruments water flow meter is best for raw wastewater?
For raw wastewater, we recommend an electromagnetic flow meter with hard rubber liner and stainless steel electrodes. It handles solids, sludge, and low conductivity fluids. Choose a DN50 to DN300 size based on pipe diameter and flow range.
Do you supply 4-20 mA flow meters for ATEX Zone 1 areas?
Yes. Some electromagnetic and vortex flow meters from Silver Automation Instruments are available with ATEX Zone 1 certification. Specify the gas group and temperature class when you send the inquiry.
What details do you need to quote a water flow meter with telemetry?
Send us your pipe size in DN, fluid type, flow range, pressure in bar, temperature in °C, power supply, and output signal. If the site is in a hazardous area, include the zone classification.
Contact Silver Automation Instruments for water flow meter 4-20 mA pricing and telemetry support.
Tel: +86-25-68650347
Whatsapp: +86-25-52155837
WeChat: +86 15365082610
Send us your pressure in bar, temperature in °C, pipe size in DN, and flow range in cubic meters per hour. We will propose a suitable water flow meter with 4-20 mA output for your utility telemetry system.