In the fascinating and fundamental field that is industrial fluid filtration, there exist many types of filter elements and many different types of media. In this article, we will briefly cover filter elements and the most common types of media they're made up of. The medias featured below include: cellulose, glass, wire mesh and water removal, coalesce and resin.
Large paper mills rely on continuous production to be profitable, thus unplanned down time is a huge financial burden. When unplanned downtime does occur and equipment must also be either repaired or replaced, the damages can feel exponential.
Throughout the first three entries in this series (find parts one, two and three), we've discussed the difference in two filter element testing methods, ISO16889 and DFE. We've also illustrated how many elements fall short of their stated beta ratio under dynamic flow conditions. Today we'll wrap it up with simulated cold-start tests.
DFE Multi-Pass: Cold Start Contamination Retention
Once the element has captured enough contaminant to reach approximately 90% of the terminal ΔP (dirty filter indicator setting), the main flow goes to zero and the injection system is turned off for a short dwell period. Then the main flow goes to maximum element rated flow accompanied by real-time particle count to measure retention efficiency of the contaminant loaded element. The dynamic duty cycle is repeated to further monitor the retention efficiency of the filter element after a restart.
Last week we covered the differences between the ISO16889 Filter Test Procedure and the DFE Filter Test Procedure. This week we illustrate the difference between elements engineered to retain particles during dynamic flow conditions and those that are engineered only to pass the ISO16889 test. (Looking for previous posts? Find parts one, two and four.)
Last week, in part one, we briefly discussed how filter elements are rated by manufacturers. This week we're discussing the industry standard ISO16889 multi-pass test and Hy-Pro's standard, the DFE test. (Already read part two? Read parts three and four.)
Current Filter Performance Testing Methods
To understand the need for DFE, it is important to understand how filters are currently tested and validated. Manufacturers use the industry standard ISO16889 multi-pass test to rate filter efficiency and dirt-holding capacity of filter elements under ideal lab conditions.
Figure 1 depicts the test circuit where hydraulic fluid is circulated at a constant flow rate in a closed-loop system with on-line particle counters before and after the test filter. Contaminated fluid is added to the system at a constant rate. Small amounts of fluid are removed before and after the
The Dynamic Filtration Efficiency (DFE) Test is Hy-Pro's standard for testing filter elements. Throughout this four-part
First, let's start with the basics.
Why are filters used? How are they rated?
All hydraulic and lube systems have a critical contamination tolerance level that is often defined by -- but not limited to -- the most sensitive system component such as servo valves or high-speed journal bearings. Defining the ISO fluid cleanliness code upper limit is a function of component sensitivity, safety, system criticality and ultimately getting the most out of hydraulic and lube assets.
Choosing the best filter element size and media for a specific application can be tricky. You want media that is tight enough to help you reach your target ISO code. However, if you choose a media that is too tight for your application, the element differential pressure (Delta P or ΔP) will rise too quickly and you will be replacing elements far too frequently.
To prevent these situations you should always calculate clean element Delta P whenever changing the filter media or manufacturer.
Changing a filter element can cause massive contamination ingression if the proper precautions are not taken and the proper procedures followed. We have compiled a step-by-step guide to minimize contamination ingression while changing out elements. Check out how to change out a filter element below
Do you know what the 3 different types of water contamination are? What about the 4 methods to remove water from your fluid? Watch our short video for a thorough explanation of each.
Most people have at least heard the term control valve, even if they don't know exactly what it does. For those of you caring for hydraulic systems, you likely work intimately with these parts. Did you know that if you're not using proper filtration in front of said control valves that you're likely doing your operation a disservice? (It's true.)