M83248 O-Rings

M83248 is the part-number family for fluorocarbon (FKM) O-rings originally specified by MIL-R-83248, the military specification for high-temperature, fluid-resistant, compression-set-resistant fluorocarbon rubber used in aircraft fuel, lubricant and hydraulic systems. Parts are called out as M83248/1-XXX (Class 1, 75 Shore A) and M83248/2-XXX (Class 2, 90 Shore A), where the three-digit dash number is the AS568 size. The military document was cancelled in 2001 and superseded by four SAE documents, but the part numbers remain in daily use on drawings and purchase orders, and the live material specification behind an M83248/1 O-ring today is SAE AMS7276. This guide decodes the callout, gives the document lineage as it stands in the government and SAE records, and says what an RFQ needs to state.

What does an M83248 part number mean?

Document lineage: what is cancelled, what replaced it

Statuses and supersession below are read from the DLA ASSIST document records and the SAE Mobilus standard pages, read 2026-09-06. A cancelled document is still a live part number: buyers keep ordering M83248/1 by that number, and the right answer is which current document governs, never that the part does not exist.

A prefix change is not a new document: a print that reads MIL-R-83248 refers to the same cancelled record whatever letters it carries. Trailing letters on the document (AMS7276J, AS83248/1A) are revisions; a trailing letter inside a part number is not.

What material is it, and what can it take?

Both classes are fluorocarbon (FKM) rubber, the family covered in the Viton® guide. The Parker O-Ring Handbook (ORD 5700) rates standard FKM compounds for continuous service from -26 C (-15 F) to 204 C (400 F), with low-temperature grades to -46 C (-51 F) and short excursions above 204 C; the qualified compound's own sheet governs. The specification titles describe the service, high-temperature fuel and oil resistance with low compression set, and a specification is not a temperature: the Parker handbook's own caution is that spec temperature limits do not necessarily represent operating limits. Class 1 (75 A) is the general aerospace fuel and lubricant seal; Class 2 (90 A) is for high pressure and extrusion resistance. The company's former compound chart carried a 75 A compound listed against AMS-R-83248, AMS7276, AMS7278 and AMS7280 together, and a 90 A compound against MIL-R-83248 Class 2, AS3581 and AMS7259, which is typical: one qualified compound often serves several of these documents.

Related callouts you will see on the same drawings

The mil-spec O-ring chart lists the full set and the AMS7276 guide covers the live material specification.

What should the RFQ state?

The full part number (M83248/1-214, or the AS3209-214 or AS83248/1-214 equivalent), the quantity, whether the print allows the SAE equivalent when it names the MIL number, and the documentation required: a certificate of conformance to the specification, the manufacturer's test report if the program needs it, and lot traceability. If the drawing carries a revision letter, quote it; if it carries a compound number as well, quote that too. A drawing that names MIL-R-83248 with no revision and no "or equivalent" is still answerable: the current document is AMS7276 (or AMS7259 for Class 2), and the certificate names both.

How Conquest Seal supplies it

Parts to these documents are made by manufacturers on the relevant qualified products list, where the document has one; Conquest supplies them as a distributor and provides the certification paperwork (certificate of conformance naming the specification and, where the manufacturer issues one, the test report). Conquest's quality management system handles the order and the paperwork; it is not a product qualification and is unrelated to any QPL. See aerospace and defense sealing.

Viton is a trademark of The Chemours Company. No affiliation or endorsement is implied.

Sources

1. Parker O-Ring Handbook ORD 5700, section 2.2.7 (fluorocarbon heat and cold figures), read 2026-09-14
2. DLA ASSIST document records for MIL-R-83248, MIL-R-83248/1 and MIL-R-83248/2, read 2026-09-06
3. SAE Mobilus records for AMS7276, AMS7259, AMS3216, AMS3218, AMS-R-83248, AS83248/1, AS3581, AS3208 and AS3209, read 2026-09-06
4. AMS7278, AMS7280, AMS-R-83485, AMS-R-25988, AS3084, AS3085, MS28775 and MIL-PRF-25732, named as callouts
5. Conquest Seal's former compound chart (compound and specification pairings only)

Reviewed by Grant Midstokke, Conquest Seal Corporation. Last updated September 2026. Spec values in this guide are drawn from the sources listed above; the compound datasheet and your application conditions govern the final choice.