The DFE Multi-Pass Testing Method

DFE multi-pass enhances the industry standard by inducing dynamic conditions (duty cycle) and measuring the effects of the duty cycle in real time instead of looking at normalized numbers over a time weighted average. DFE also quantifies retention efficiency in real time in order to identify a filter’s ability to properly retain previously captured contaminant and the degree to which it unloads captured contaminant back into the system. For an easy comparison, think of it as a sneeze that releases a rush of contamination to levels that are well above the upper limit of fluid cleanliness then fades as the flow rate normalizes.

In the DFE test, flow rate is truly dynamic in that rapid changes can be made while maintaining full system flow through the test filter. The raw data is continuously collected and organized so filter efficiency can be reported for variable flow conditions including time weighted averages and isolated moments to reveal true filter performance during hydraulic stress conditions – exactly when you need the filter to perform at its best.

At the end of the initial test when the filter element is loaded with contaminant, it is subjected to a restart test in which the flow goes from zero to max flow in milliseconds, replicating a hydraulic or lube system restart. Through rapid particle counting with precise control, this dynamic flow change allows Hy-Pro to analyze the amount of particles released and understand both the capture and retention efficiencies of each and every filter tested.