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『Flow Meter with Pulse Output Calculation: Converting Raw Sensor Frequencies into Scaled Volumetric Totals』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)
Flow Meter with Pulse Output Calculation: Converting Raw Sensor Frequencies into Scaled Volumetric Totals
Quick Answer: A pulse output flow meter sends a square wave where each pulse represents a fixed volume. To convert raw frequency to flow rate, divide the frequency in Hz by the K-factor. To convert total pulses to total volume, divide the total count by the same K-factor.
Silver Instruments supplies pulse output flow meters for water, fuel, chemicals, steam, and gas. We configure the K-factor at the factory or you set it in your PLC or batch controller.
Pulse Output Basics
A pulse output flow meter does not send a 4-20 mA analog signal. It closes a circuit for each volume increment. The signal is a square wave, often open collector or reed switch. The frequency in Hz is the number of pulses per second.
In practice, a DN25 oval gear meter with a K-factor of 200 pulses per liter will output 200 pulses for each liter that passes through. If the pipe flows 30 liters per minute, the output frequency is 100 Hz. That matters because most PLC counters read frequency, not volume.
Converting Raw Frequency to Scaled Flow Rate
Use this formula: Flow rate = Frequency / K-factor. Keep the time base consistent. For a turbine meter with a K-factor of 450 pulses per liter and a measured frequency of 225 Hz, the flow rate is 0.5 liters per second. Multiply by 60 to get 30 liters per minute.
Most engineers skip this part. If the K-factor is in pulses per gallon, the result will be in gallons per second or minute depending on your time base. Check the meter data sheet before scaling the PLC input.
Converting Total Pulses to Scaled Volume
For totalized volume, use this formula: Total volume = Total pulse count / K-factor. For example, a DN40 electromagnetic flow meter with a K-factor of 100 pulses per liter sends 25,000 pulses during a batch. The accumulated volume is 250 liters.
In batch control, set the PLC totalizer to count pulses and stop the valve when the count reaches a setpoint. Use a pulse value if your controller cannot divide by K-factor. Pulse value equals 1 divided by K-factor.
Meter Types That Deliver Pulse Output
Silver Instruments offers pulse output on oval gear flow meters, turbine meters, electromagnetic flow meters, and vortex flow meters. A DN15 oval gear flow meter for diesel can have a K-factor above 1200 pulses per liter. A DN100 electromagnetic flow meter may output a configurable pulse, for example 0.1 liter per pulse. A vortex flow meter on steam outputs pulses based on shedding frequency, with the K-factor set during calibration.
For gas mass flow, the thermal mass flow meter with pulse output and 4-20 mA HART covers DN15 to DN200. It works for air, natural gas, and biogas at low pressure. A built-in PT100 tracks gas temperature. For hazardous areas, ask for ATEX Zone 1 approval.
Configuring Flow Totalizers and Remote Di_600x400.jpg)
A pulse signal can drive a PLC, a batch controller, or a flow totalizer. Use shielded cable, keep the run below 300 meters, and add a pull-up resistor if the input does not have one. We have seen signal drop on sites with unshielded cable next to variable frequency drives. Use twisted pair cable.
Because the signal is digital, it survives electrical noise better than an analog loop. So for remote totalizing in water and wastewater plants, pulse output is often the first choice.
We have seen a paint manufacturer in Vietnam batch solvents with a DN25 oval gear meter and pulse output. A desalination plant in Saudi Arabia used pulse outputs for permeate flow totalizing. Last year a customer in Chile ordered DN80 electromagnetic meters for a river water intake.
Recommended Silver Instruments Models
For water and wastewater, the electromagnetic flow meter with pulse output works from DN15 to DN600. It needs conductivity above 5 µS/cm. For diesel, fuel oil, and soybean oil, the oval gear meter with pulse output covers DN10 to DN80. Viscosity up to 2000 cP is acceptable on some models. For steam and compressed air, the vortex flow meter covers DN25 to DN300. For low pressure gas, the thermal mass flow meter gives pulse output, 4-20 mA HART, and a built-in PT100.
Send us your flow range in kg/h or L/h, pressure in bar, temperature in °C, pipe size in DN, fluid type, and required pulse value. We will recommend a flow meter and send a quote within 24 hours.
Contact Silver Automation Instruments today.
Tel: +86-25-68650347
Whatsapp: +86-25-52155837
WeChat: +86 15365082610
Website: flow-meter.com.au
FAQ
What is a K-factor on a pulse output flow meter?
The K-factor is the number of pulses the meter sends for one engineering unit of volume. For example, a K-factor of 100 pulses per liter means 100 pulses equals one liter. You store this value in the PLC or flow totalizer.
How do I convert pulse frequency to flow rate?
Divide the measured frequency in Hz by the K-factor. Keep the time base consistent. A frequency of 100 Hz with a K-factor of 200 pulses per liter gives 0.5 liters per second or 30 liters per minute.
Can I use pulse output for batching or dosing?
Yes. Pulse output works well for batching because the totalizer counts fixed volume increments. Set a pulse count setpoint and stop the valve when the count is reached.
Does Silver Instruments offer pulse output on all flow meter types?
Most of our electromagnetic, oval gear, turbine, vortex, and thermal mass flow meters have pulse output as standard or optional. Check your model data sheet or send us your flow range and fluid.
What cable length and pull-up resistor do I need?
Use shielded twisted pair cable. Keep the run below 300 meters for most open collector outputs. If the PLC input does not have a pull-up resistor, add one between 1 kΩ and 10 kΩ depending on supply voltage.