Originally Posted By: ARCOgraphite
I haven't read the 4548-12 spec - is that multipass?
From FRAM's website in thier FAQ section:
http://fram.com/learn_more/frequently_asked_questions
Q: How are filters tested?
A: Filter Engineering Measurements. Measuring efficiency must be based on the premise that the filter is present on the engine to remove harmful particles and thus protect the engine from wear. Filter efficiency is the measurement of the filter’s performance in preventing harmful particles from reaching the wearing surfaces of the engine. The most widely used method of measurement is Multi-Pass Efficiency test developed by the ISO (International Standards Organization). This and other standard industry tests used to evaluate filters are described below.
1.Multipass Efficiency. This procedure is specified in ISO 4548-12 and is the most recently developed. It involves a newer test technology in that automatic particle counters are used for analysis instead of simply weighing the dirt. The advantage of this is that the particle removal performance of the filter can be found for different size particles throughout the filter’s life. The efficiency determined in this test method is an "instantaneous" efficiency, because the number of particles before and after the filter are counted at the same instant. These numbers are then compared to generate an efficiency measurement.
2.Filter Capacity is also measured in a the ISO 4548-12 test method. To create a successful filter, a balance must be found between high efficiency and long life. Neither a long life filter with low efficiency nor a high efficiency filter with short life is useful in the field. The contaminant holding capacity as defined in ISO 4548-12 is the amount of contaminant removed and held by a filter from the oil during a constantly recirculating flow of contaminated oil. The test is terminated when a predetermined pressure drop across the filter is reached, typically at 8 psid. This pressure drop is associated with the setting of a filter by-pass valve.
3.Mechanical and Durability tests. Oil filters are also subjected to numerous tests to assure the integrity of the filter and its components during vehicle operating conditions. These tests include Burst Pressure, Impulse Fatigue, Vibration, Relief Valve and Anti-Drainback Valve operation, and Hot Oil Durability specified in other ISO and SAE test methods.
