SubscribeThe quality of jet fuel on an aircraft is something most people take for granted.
However the overall performance of the aircraft is dependent on the jet fuel’s cleanliness, clarity, and dryness. Contaminated and/or wet fuel in a jet will result in a multitude of problems. In order to prevent these problems, and to provide some level of certainty that the fuel being delivered to an aircraft is of the highest quality possible, the fuel must be filtered at various points in its journey from the refinery to its ultimate destination – the fuel tank of the airplane.
Stringent standards and specifications are therefore applied to the process of jet fuel filtration. These standards are created and maintained by the petroleum/aviation industry, which is comprised of major oil companies, filter manufacturers, airport operators and airlines, among others.
In July 2003 the aviation industry announced a new specification for filter water separators (Fig. 1) for jet fuel filtration. (Filter water separator vessels are the primary defense against dirt and water contamination in fuel.) The specification is “API/IP 1581 5th Edition” (American Petroleum Institute / Institute of Petroleum). This replaces API/IP 1581 3rd Edition, which had been in place since 1989.
Figure 1 ~ Typical Filter/Separator
The key objectives of the API/IP 1581 5th Edition are:
- Raise the level of performance of filter water separators
- Address the military requirements so that the military community can also utilize the specification
- Require development of new products that are more resistant to surfactants
- Change test dust to better simulate field conditions
- Change test protocol to reduce the time needed to qualify new elements
- Address three-stage filter/separators
To meet these objectives three new categories were established. These are:
Category C (Commercial)
This category replaces the previous Classes A, B, & C of API/IP-1581 Third Edition. Velcon’s new coalescer cartridges that meet Category C requirements have been developed to provide better water removal performance of surfactant-laden fuels, and improved filtration efficiency combined with longer life. Category ‘C’ cartridges can be used at any point in the fuel distribution system – from refineries to into-plane fueling. Test fuel in this category is:
- “Commercial” Jet A/A1, tested with Stadis 450, DCI-4A.
Category M (Military)
This is a brand new specification for military fuels, like JP8 (similar to Jet A but containing anti-icing additives). Part of the rationale for creating a new edition was to include specifications for military applications, thereby enabling both military and commercial customers to use API/IP 1581. Test fuel in the category is:
- Military, JP-8/JP-5, tested with Stadis 450, DCI-4A, Di-EGME
Category M100 (Military with+100)
This specification is also for military fuels such as JP8, but it includes a surfactant additive called +100. The ‘+100’ allows fuels to run at higher operating temperatures and reduces maintenance for high performance military jet engines. Test fuel in this category is:
Military w/+100 additive, JP8+100, tested with Stadis 450, DCI-4A, Di-EGME,& Spec Aid 8Q462 Thermal Stability Additive
Other Changes
Another new feature of the 5th Edition is a specification that allows operators to incorporate a third-stage water absorbing cartridge with each category. (See Figure2)
The fifth edition of API/IP 1581 also creates a new description of filter/separators: Type S and Type S-LD. “S” represents significant amounts of water and dirt in the fuel, and “S-LD” represents low dirt. All products that are qualified to Type S are automatically qualified for Type S-LD.
Figure 2 ~ Cutaway Showing 3rd Stage Filter/Separator
Similarity Rules
The API/IP-1581 5th Edition incorporates new rules for similarity calculations, and these are detailed in the new specification, API/IP-1582 (Feb. 2001). The major ones are:
- Maximum flow rate that a vessel can be qualified to is 2500 GPM (~ 9,500 lpm)
- A vessel can only be qualified by similarity if the flow rate is equal to or less than the tested flow rate.
- Category M cartridges/vessel combinations can be qualified by similarity to Categories M and C only.
- Category M100 cartridges/vessel combinations can be qualified by similarity to Categories M100 and M only.
- Filters already installed may be qualified (see Paragraph 4.4.1.2 of API/IP-1581 5th Edition) by meeting similarity criteria (as defined in API/IP-1582) for flow rates above 2500 GPM (9,500 lpm) and up to 5000 GPM (19,000 lpm).
- The similarity calculations will be similar to API/IP 1581 3rd Edition plus additional calculations for void volume and sump volume
Test Dust
A new test dust has been included in the specification. Previously there was a problem with agglomeration of the dust that resulted in clumps being formed during testing. The new mixture is 90% Ultrafine and 10% Red Iron Oxide R-9998. Although this mix is slightly larger in size than the “old” Red Iron Oxide, it does not agglomerate. The new dust also more closely simulates field conditions.
Test Protocol
Previous editions required a single element test run with every full-scale test. This has been eliminated. Instead, only one single-element test is required for any particular model or configuration, thereby reducing the time needed to qualify new elements.
| Here are the current specifications and qualification procedures for Aviation Jet Fuel: | |
| API/IP 1581, 5thEdition | FILTER/SEPARATORS |
| API/IP 1582, 1stEdition | SIMILARITY FOR API/IP 1581 FILTER/SEPARATORS |
| API/IP 1583, 4thEdition | FILTER MONITORS WITH ABSORBENT TYPE ELEMENTS |
| API/IP 1590, 2ndEdition | MICROFILTERS |
In Conclusion
The major impact for the users is that the size of new filter/separator vessels for mobile equipment will be larger in diameter due to the new requirement to test filter/separators for mobile equipment with 3% water in place of ½% water as previously specified.
LINKS:
American Petroleum Institute: http://api-ep.api.org/
For more information on the qualification standards:
Energy Institute (formerly Institute of Petroleum): http://www.energyinst.org.uk/
For aviation related information on this site: http://www.energyinst.org.uk/index.cfm?PageID=170
For a list of aviation publications on this site:
http://www.energyinst.org.uk/index.cfm?PageID=305
