What does the frequency pen on a magnetic flow meter recorder indicate?

The frequency pen on a magnetic flow meter recorder primarily indicates the cumulative flow rate of the fluid passing through the meter. In a magnetic flow meter, the flow of conductive fluid generates a signal that is proportional to the velocity of the fluid. This velocity is then translated into a frequency signal, which can be recorded and monitored.

The cumulative flow rate is essential for various applications in industries where measuring the total volume of fluid processed is critical for operational efficiency and regulatory compliance. Therefore, the frequency of the signal reflects how much fluid has passed through the meter over time, making it a vital component for flow monitoring.

Other options may relate to flow measurements and conditions but do not accurately describe what the frequency pen directly indicates. Magnetic field strength and fluid temperature are important factors in the functioning of a magnetic flow meter but are monitored through different parameters or indicators. Legal speed of flow is also not typically indicated by the frequency pen; instead, it requires a separate calculation or regulation compliance check.