UFC 3-460-03
21 JANUARY 2003
3.3. Filter/Separators (F/S). F/Ss remove undissolved (free) water and solids from petroleum
products. Very fine water particles pass through coalescer filter elements and grow in size (coalesce)
into larger droplets that collect on a second-stage Teflon screen or treated paper elements and fall to the
bottom of the F/S vessel. The solids in the fuel are trapped in the elements and build up a DP across the
F/S.
Water accumulated in the bottom of the F/S is typically removed manually.
NOTE: Because of environmental problems caused from valve failure, the automatic drain feature
originally installed with pre-1994 systems has been disabled, except for certain receipt F/Ss from barges
or pipelines with histories of excessive water. F/Ss are equipped with the means to measure DP to find
when elements should be changed and a sampling port in the outlet pipe to verify fuel quality. Element
change criteria are outlined in paragraph 10.12.1. The piston-type DP gauge is preferred for fueling
systems. Replace individual gauges with the piston-type as soon as practicable.
3.3.1. F/S Important Notes:
3.3.1.1. All F/Ss should be modified to accept the new API coalescer elements, or replaced with
API F/Ss.
3.3.1.2. Heaters are no longer necessary in F/Ss handling military jet fuel because the fuel
contains a fuel system icing inhibitor (FSII).
3.3.1.3. Where possible, move the sight-glass bottom connection to the bottom of the sump to
show the entire water content and equip the system with a density ball.
3.3.1.4. All F/S vessels require pressure relief protection.
3.3.1.5. Remove the automatic water drain option at the first opportunity, unless on a receipt
vessel that must handle excessive water, or if waived by the MAJCOM fuels engineer.
3.3.1.6. Pressure relief protection should be full ported; no reduction in pipe size is allowed.
3.3.2. Specifications and Qualification Procedures. New F/Ss should be qualified to the current
edition of API Publication (Pub) 1581, Specifications and Qualification Procedures for Aviation Jet
Fuel Filter/Separators, tested to either Category M or M100 requirements. Category M F/Ss are
qualified using JP-8 with an additive package. Category M100 F/Ss, coalescer/separators, and multi-
stage systems are qualified using JP-8 with an additive package that also includes dispersant additives
such as those that enhance thermal stability. Category M100 F/Ss qualify for Category M F/S at the
same flow rate and conditions. Type S F/Ss can be used at filtration points where significant levels of
water and dirt in the product can be expected, such as a receipt F/S. Type S-LD F/Ss (also known as
coalescer/separators) can be used at all filtration points where significant levels of water but minimal
amounts of dirt can be expected in jet fuel (i.e., following a micro-filter). A Type S F/S qualifies as a
Type S-LD for the same category at the same flow rate and condition.
3.3.3. Element Replacement for a Vertical F/S:
3.3.3.1. Drain the F/S completely.
3.3.3.2. Raise the cover. CAUTION: Do not touch the new filter elements or the separator
canisters with your bare hand. The oil on your hand will cause damage to the water-removal
capability of these components.
3.3.3.2.1. Where there is an outer canister, remove, clean (paragraph 3.3.5.1.), and set it aside
for reuse.
3.3.3.2.2. Remove and discard the old elements in an approved manner. Coordinate disposal of
elements with base environmental engineering.
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