FKM Fluorocarbon Metric O-Ring, 90A Durometer, 12.4mm ID x 3.5mm CS (0.488" x 0.138") - Precision-Molded Replacement Sealing Ring

FINAL SALE - NO RETURNS. THIS IS A STANDARD CATALOGUE SIZE; CONFIRM YOUR DIMENSIONS AND MATERIAL BEFORE ORDERING.

Because standard sizes are chosen by measurement rather than by machine model, they ship as final sale. If we send the wrong item, or it arrives damaged or defective, we replace it free of charge, and that never changes.

Chasing a leak, a slow drip or a pressure loss you cannot track down? A flattened, hardened or wrong-size o-ring lets fluid weep past the joint, drops pressure, and can damage the parts around it.

This Beaver Island Parts Company o-ring is a standard 12.4mm ID x 3.5mm CS (0.488" x 0.138") size, molded in 90A FKM Fluorocarbon. Its outside diameter is 19.4mm (0.764").

Specifications

What It Fits

This size is used across fuel systems, engines, transmissions, chemical pumps, valves, carburetors and injectors, and high-temperature hydraulic or process equipment. If your manual, parts list or old ring calls for 12.4mm ID x 3.5mm CS (0.488" x 0.138"), this is the part.

Why FKM Fluorocarbon

90A FKM combines fluorocarbon heat and chemical resistance with the extrusion resistance needed in high-pressure hydraulic and fuel systems. Recommended for fuels, oils, aromatic hydrocarbons and many acids at high temperature and pressure. Not recommended for ketones, hot water or steam in continuous service, and phosphate-ester fluids.

You Can Do This Repair

Clean the groove and mating surfaces and check them for nicks or burrs. Lubricate the new o-ring, then roll it into the groove without twisting it; pass it over threads or sharp edges on a piece of tape or a plastic sleeve so it is not cut. Tighten to the normal torque. A correct o-ring seals by squeeze, so more torque is not better.

Pro Tip: A thin coat of Aqua Flex silicone lubricant eases installation, protects the seal on first start-up and extends its life.

Shipping: This part is special-ordered and packed for you. It ships from our facility in about 10 business days, then transits by the carrier service you choose at checkout. The estimated delivery date shown on this page includes that lead time.

Why Buy From Beaver Island Parts Company

• Every dimension published. Size, material, hardness and temperature rating are listed up front so you can confirm fit before you buy, not after.
• Inspected, packed and labeled by us. Each order is checked and repacked in a bag labeled with the part's size and material, so it never gets lost in a parts bin.
• Real people who answer fitment questions. We are an American family-owned and operated small business. Send us your measurements or model number and we will help you confirm the right part.
• Replacement guarantee. If we ship the wrong item, or it arrives damaged or defective, we replace it free of charge.

Frequently Asked Questions

Q: Will this fit my equipment?
A: It fits any groove or fitting that calls for a 12.4mm ID x 3.5mm CS (0.488" x 0.138") o-ring. Size, not brand, determines fit for standard o-rings. Measure the old o-ring's inside diameter and cross-section with calipers, or better, measure the groove, because a used ring stretches and flattens. Match the material to the fluid: the right size in the wrong rubber will still fail.

Q: What is FKM Fluorocarbon good for?
A: It is suited to fuels, oils, aromatic hydrocarbons and many acids at high temperature and pressure. Avoid ketones, hot water or steam in continuous service, and phosphate-ester fluids.

Q: Can I install it myself?
A: Yes. Most o-ring replacements take only a pick tool, a clean rag and lubricant. Release pressure, drain the system if needed, remove the old ring, and follow the installation notes above. If it is your first time, take a photo before you take anything apart.

Q: When will it ship?
A: It ships from our facility in about 10 business days, then transits by the carrier service you choose.