Coriolis flow meters produce a pulse signal that corresponds to the measured mass or volume flow. The Pulse Scaling Factor (PSF) is a quantity that tells you how many pulses there are for every unit of flow. The PSF must be set up very carefully so that the meter’s output frequency stays within the working limits of both the flow meter and the receiving device, which might be a SCADA system or a PLC.
The Micro Motion® 1000, 2000, and 3000 Series are examples of Coriolis transmitters that can only send signals up to 10,000 Hz. Exceeding this frequency may result in communication failures, loss of signal fidelity, or incompatibility with receiving systems. So, it’s vital to figure out the highest PSF that will maintain the output frequency below this level.
This calculator below helps determine the maximum Pulse Scaling Factor (PSF) for a Coriolis flow meter to ensure its output frequency does not exceed 10,000 Hz. Use it to safely configure pulses per unit flow based on the meter’s maximum flow rate, ensuring compatibility with control systems like PLCs or SCADA.
What is PSF (Pulse Scaling Factor)?
The Pulse Scaling Factor (PSF) is a setting that the user chooses that shows how many pulses are made for every unit of measured mass or volume. The PSF in Coriolis meters can be changed to fit the needs of the transmitter and the system it is attached to. This is different from mechanical meters, which have fixed K-factors.
If you set the PSF too high, the frequency output could go over 10,000 Hz when the flow is high, which could overload electronics downstream.
Why Calculate the Maximum PSF of Coriolis Flow Meter?
The maximum PSF calculation is done to find the highest number of pulses per unit that can be employed without the frequency output going over 10,000 Hz, especially when the flow rate is at its highest.
This is very important during:
- New flow meter installations
- Commissioning and loop testing
- SCADA or PLC configuration
- Meter retrofitting or transmitter upgrades
Formula for Maximum PSF of Coriolis Flow Meter
To find the maximum PSF, use this formula:
Where:
- Maximum PSF is the most pulses that can be sent via a unit of flow (for example, pulses per barrel or pulses per pound).
- The transmitter may only send out a maximum of 10,000 times per second, or Hertz.
- To change units of time, you can use 3600, which is the amount of seconds in an hour.
- Maximum Flow Rate is the largest flow rate that is expected to go through the meter, and it is measured in units per hour, like barrels per hour or pounds per hour.
Example Calculation: Maximum PSF
A Coriolis flow meter should be able to monitor a flow of up to 60,000 barrels per hour. To find the highest PSF that is allowed:
The PSF should be set to 600 pulses per barrel or less in this situation to make sure the output frequency doesn’t go over 10,000 Hz.
Key Considerations
- Safety Margin: It is a recommended practice to tune the PSF slightly below the calculated maximum to provide a margin of safety in case of flow spikes.
- Resolution vs. Frequency: A higher PSF gives you more resolution, but it also makes the output more frequent. Always weigh these factors against what the system can do.
- Compatible with Devices: Check that the receiving device (SCADA, PLC, or flow computer) can handle the pulse frequency that the meter sends out.
- Flow Units: If you use barrels per hour, for example, PSF should be in pulses per barrel.
Refer the link for Coriolis Flow Meter Installation: Best Practices for Accuracy
Practical Applications of Maximum PSF Calculator
- When integrating a Coriolis flow meter into a legacy control system that has limited frequency input capacity.
- When troubleshooting or verifying configuration of an existing flow meter setup.
- When configuring new transmitters during system upgrades or expansions.
Coriolis flow meters will work within their frequency output limits if you set the maximum PSF correctly and calculate it correctly. This stage is very important for the long-term reliability and performance of systems that measure and control things in factories. Use the offered method as a quick and effective way to establish your ideal configuration during design, installation, or maintenance tasks.
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