API Spec 1582 pdf download SPECIFICATION FOR SIMILARITY FOR API/IP 1581 AVIATION JET FUEL FILTER/SEPARATORS
2.4.2 End-opposed classes
(a) Vertical systems having elements in the end- opposed layout populate different classes (Figure 4) when the flow is 1) opposed to and 2) aligned with the attraction of gravity.
(b) Systems having a single, non-cylindrical-shaped (or “basket”) separator (Figure 5) populate a different class than systems having cylindrical- shaped separators. Figure 5 – End-opposed classes of element layout: Non-cylindrical separator
2.5 RATED FLOW The candidate system shall have a rated flow equal to or less than the flow of the qualified system.
2.6 MODEL TYPE The filter/coalescer and separator elements shall be the same models in both candidate and qualified systems. Elements shall be identical with respect to construction and media but may vary in length and end-cap type (open-ended/threaded base). The outside diameter of separator elements may vary. The length-to-outside-diameter ratio of the separator elements (each stack of separator elements when stacked) in the candidate system shall not exceed that of the qualified system.
2.7 MEAN LINEAR FLOW RATE The mean linear flow rate of the filter/coalescer elements of the candidate system shall not exceed that of the qualified system.
2.8 LIQUID ENTRANCE VELOCITY The liquid entrance velocity (m/s) at the outer surface of the separator elements in the candidate system shall not exceed that of the qualified system. The velocity can be calculated from the following equation (in SI units):
2.9 ELEMENT/VESSEL RATIOS The void volume ratio of the candidate system shall not be less than the qualified system. In addition: (a) For the side-by-side general flow pattern: ΣS Ae /A cv shall not exceed that of the qualified system. (b) For the end-opposed general flow pattern: ΣA e /A cv shall not exceed that of the qualified system. 2.10 SIMPLIFIED FLOW MODEL Candidate systems that meet 2.2 – 2.9 qualify as meeting API/IP 1581 by similarity. An alternative qualification is permitted for candidate systems that would otherwise fail because they do not meet all of 2.2 (c), 2.2(d), 2.3 and 2.4. If the candidate system meets 2.2 (a), 2.2 (b), 2.5 – 2.9, 2.10 (a) and 2.10 (b) then it shall qualify as meeting API/IP 1581 by similarity. (a) The maximum internal flow velocities of the candidate system shall not be greater than the qualified system.
(b) The residence times in the candidate system shall not be less than the qualified system. Compliance with 2.10 (a) and (b) may be demonstrated by application of the Simplified Flow Model, defined in Section 3, or by agreement between supplier and purchaser using any equivalent or more rigorous flow model.