Aerospace O-ring family, ethylene propylene, phosphate-ester fluid
NAS1611 O-rings: ethylene propylene to NAS1613 for phosphate-ester hydraulic fluid
NAS1611-XXX is an ethylene propylene (EPDM) O-ring for phosphate-ester hydraulic fluid, in the standard AS568 size the dash names, and NAS1612-YY is the same material in the straight-thread boss sizes. NAS1613 is the material document behind both. All three are Aerospace Industries Association standards, bought from AIA rather than DLA; manufacturers build the suffixed NAS1611-XXXA part to NAS1613 Revision 6.
- Polymer
- Ethylene propylene (EPDM)phosphate-ester fluid
- Durometer
- 80as manufacturers supply it
- Material document
- NAS1613AIA; status: ask with the quote
- QPL
- No DLA QPLAIA document
Specification: documents, status, material
| Item | Value | Source |
|---|---|---|
| Material document | NAS1613, packing, preformed, ethylene propylene rubber, seal element: an AIA standard; a 1995 edition is on record at NTIS; DoD adoption notice dated 1995-09-29; Revision 6 exists (manufacturers build to it); current revision and date: ask with the quote | NTIS, read 2026-09-13; DLA ASSIST adoption notice; manufacturers' cross-references |
| Standard-size drawing | NAS1611, an AIA standard: status, ask with the quote | AIA |
| Boss-size drawing | NAS1612, packing, ethylene propylene, preformed, straight-thread tube fitting boss, phosphate-ester resistant: DoD adoption notice dated 1995-09-29; status: ask with the quote | DLA ASSIST adoption notice |
| Base polymer | Ethylene propylene (EPDM) | document titles |
| Durometer | Manufacturers supply this family at 80 (Parker® ORD 5700 (2021) Table 8-4 lists its Revision 5 compound in the 75 to 85 band); confirm the durometer against your print | Parker ORD 5700 (2021) |
| The -A suffix | NAS1611-XXXA and NAS1612-YYA: as manufacturers use it, a compound qualified to NAS1613 Revision 6, while the unsuffixed part is the Revision 2 compound; NAS1613 itself governs | manufacturers' cross-references |
| Classes | NAS1613 defines classes by phosphate-ester fluid compatibility; confirm the class against the AIA document | a reseller's abstract of NAS1613 |
| Boss variant | NAS1612-YY, mapping to AS568-9YY | manufacturers' cross-references |
| QPL | No DLA qualified products list (AIA document); ask with the quote whether an industry list applies | DLA ASSIST and SAE Mobilus, read 2026-09-06 |
| Service | Phosphate-ester hydraulic fluid (the NAS1612 title; Parker ORD 5700 (2021) Table 8-4 reads phosphate ester resistant beside NAS1613) | document title; Parker ORD 5700 (2021) |
| Tolerance note | One manufacturer's 2024 cross-reference flags NAS1611 and NAS1612 parts above 0.500 in inside diameter as tight tolerance, tighter than plain AS568; the drawing governs | manufacturers' cross-references |
| Compounds manufacturers pair with this document | Parker ORD 5700 (2021) Table 8-4 pairs E0515 with NAS1613 Revision 2 and E1267-80 with NAS1613 Revision 5; no Revision 6 pairing is on record | Parker ORD 5700 (2021) |
Status strings are quoted as DLA ASSIST and SAE Mobilus print them (Canceled is ASSIST's spelling; Inactive means inactive for new design; Withdrawn is SAE's word). Conquest Seal is a distributor and is not itself listed on any qualified products list.
Designator to AS568 size
NAS1611-XXX is the AS568-XXX size and NAS1612-YY the boss size AS568-9YY, per the manufacturers' cross-references. The drawing's tolerances can be tighter than AS568 on the larger inside diameters, so the drawing governs. The -A suffix changes the compound revision, never the size.
| NAS1611 | With -A suffix | AS568 dash | ID in | W in | ID mm | W mm |
|---|---|---|---|---|---|---|
| NAS1611-006 | NAS1611-006A | AS568-006 | 0.114 | 0.070 | 2.90 | 1.78 |
| NAS1611-010 | NAS1611-010A | AS568-010 | 0.239 | 0.070 | 6.07 | 1.78 |
| NAS1611-012 | NAS1611-012A | AS568-012 | 0.364 | 0.070 | 9.25 | 1.78 |
| NAS1611-112 | NAS1611-112A | AS568-112 | 0.487 | 0.103 | 12.37 | 2.62 |
| NAS1611-114 | NAS1611-114A | AS568-114 | 0.612 | 0.103 | 15.54 | 2.62 |
| NAS1611-116 | NAS1611-116A | AS568-116 | 0.737 | 0.103 | 18.72 | 2.62 |
| NAS1611-210 | NAS1611-210A | AS568-210 | 0.734 | 0.139 | 18.64 | 3.53 |
| NAS1611-214 | NAS1611-214A | AS568-214 | 0.984 | 0.139 | 24.99 | 3.53 |
| NAS1611-222 | NAS1611-222A | AS568-222 | 1.484 | 0.139 | 37.69 | 3.53 |
| NAS1611-325 | NAS1611-325A | AS568-325 | 1.475 | 0.210 | 37.47 | 5.33 |
Millimeter values are converted from the inch table. The dash is a size lookup and never a material; the same dash on another family on the mil-spec hub is the same size in a different document. Full chart: AS568 size chart.
Where the documents stand
NAS1613, NAS1611 and NAS1612 are published by the Aerospace Industries Association, which is why they behave differently from every MIL and SAE family on this site: DLA adopted NAS1613 and NAS1612 for DoD use (the adoption notices are dated 1995-09-29; no NAS1611 notice was seen) but does not maintain them, and their current revisions are bought from AIA. A 1995 edition of NAS1613 is on record at NTIS. NAS1613 has been revised since; Revision 6 exists, and manufacturers' cross-references build the suffixed NAS1611-XXXA part to Revision 6 and the unsuffixed part to Revision 2. Parker ORD 5700 (2021) still pairs compounds with Revision 2 and Revision 5.
This page does not state whether the current AIA revision is 6 or later, nor what the standard itself says the -A suffix and the classes mean; the AIA document governs. Send the print's exact callout, suffix included, and we quote to it.
The base polymer
The polymer behind this family is ethylene propylene (EPDM). The Parker O-Ring Handbook ORD 5700 family range on file for EPDM is -57 C to 150 C; that is the polymer family's range, not this document's requirement, and the compound sheet for the qualified grade governs. Parker notes that specification temperature limits do not necessarily represent operating temperature limits.
Material page: Ethylene propylene (EPDM) O-rings. Temperature ranges by family: O-ring temperature ranges.
How we quote this family
Send the designator exactly as printed, including any -A suffix, for example NAS1611-XXX or NAS1611-XXXA, with the dash, the quantity and the certification the order needs. We quote it supplied against NAS1611 or NAS1612 with NAS1613 as the material document, in the ethylene propylene compound qualified to the revision the suffix calls for, with a certificate of conformance and lot traceability. If your print states the NAS1613 revision or a class, include it.
Related pages
Other families: MS28775, M83461/1, M83248/1 and M83248/2, M83485/1, M25988/1, /2, /3 and /4, MS29513 and MS29512, AS3582, AS9386 and AS9385, AS3209 and AS3208.
Frequently asked
What does NAS1611 specify and what compound is NAS1613?
NAS1611 is the standard-size O-ring drawing for phosphate-ester hydraulic fluid service, and NAS1613 is the ethylene propylene (EPDM) seal-element material document it calls out; NAS1612 is the boss-size drawing on the same material. All three are AIA standards. Manufacturers supply the family at 80 hardness; Parker ORD 5700 (2021) pairs E0515 with NAS1613 Revision 2 and E1267-80 with Revision 5.
What is the difference between NAS1611 and NAS1612?
Size series. NAS1611-XXX carries the standard AS568 sizes with a three-digit dash, and NAS1612-YY carries the straight-thread tube-fitting boss sizes with a two-digit dash that maps to AS568-9YY. Both are the NAS1613 ethylene propylene material.
What does the A suffix on NAS1611-XXXA mean?
As manufacturers use it, a compound qualified to NAS1613 Revision 6; the unsuffixed NAS1611-XXX is the Revision 2 compound. Treat this as manufacturer usage; NAS1613 itself governs, so quote the suffix exactly as the print shows it.
What O-ring should I use for phosphate-ester hydraulic fluid?
The NAS1611 family, ethylene propylene to NAS1613, is the aerospace callout for the phosphate-ester hydraulic fluids used in aircraft hydraulics. Ethylene propylene is chosen for these fluids where nitrile and fluorocarbon are not, and the print or the system specification names the revision. The choice belongs to your print or your system specification; send the callout it names and we quote that part.
Is there a QPL for NAS1611 or NAS1613?
Not a DLA one: NAS documents are published by the Aerospace Industries Association, so they are not in DLA's Qualified Products Database. Ask with the quote whether an industry qualified list applies to your NAS1613 revision. Manufacturers certify their compounds to the NAS1613 revision, and we supply the part with that certificate of conformance.
Related guides
Sources
NTIS National Technical Reports Library record for NAS1613 (1995 edition), read 2026-09-13; DLA ASSIST adoption notices for NAS1612 and NAS1613 (1995-09-29), read 2026-09-06; Parker O-Ring Handbook ORD 5700 (2021), Table 8-4, for the compound pairings; Manufacturers' aerospace cross-references (2024) for the Revision 6 build, the -A suffix usage and the tolerance note; AS568 dimensions from this site's size chart. Facts are stated in our own words and our own arrangement; no standard's text or table and no manufacturer's cross-reference table is reproduced. Compound pairings are the named manufacturer's published statements, not qualified products list entries.
Parker is a trademark of Parker Hannifin Corporation. No affiliation or endorsement is implied.
Need NAS1611 and NAS1612 with certification?
Send the designator as the print reads it, the dash, the quantity and the paperwork the order needs. A Conquest representative replies with the part quoted against the document.
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