What is the function of gauges placed before and after the prefilter?

The function of gauges placed before and after the prefilter is primarily to monitor pressure. This monitoring is crucial in ensuring that the prefilter is functioning correctly and efficiently. By checking the pressure readings, healthcare professionals can determine if the prefilter is becoming clogged or is operating under normal conditions. A significant difference in pressure readings before and after the prefilter could indicate that it requires maintenance or replacement, allowing for timely intervention to ensure the quality of the water used in dialysis.

While flow rates are indeed important in the context of overall system performance, the primary role of the gauges in this scenario is pressure monitoring, which directly impacts the filtration process. Thus, this choice accurately identifies their purpose in the workflow of hemodialysis preparation.