#228 Nitrile O-Rings (10 Pack) - Buna-N NBR 70A - 2-1/4" ID x 2-1/2" OD x 1/8" CS

#228 Nitrile O-Ring (Buna-N NBR, 70A) - 2-1/4" ID x 2-1/2" OD x 1/8" CS Standard AS568 dash size #228 nitrile O-ring - the exact size used across faucets, pumps, filters, and fittings worldwide. Sold as a pack of 10 so you have spares on hand for every rebuild. Specifications AS568 Dash Number: -228 Inside Diameter: 2-1/4" nominal (2.234" / 56.74 mm actual) Outside Diameter: 2-1/2" Cross Section (Width): 1/8" (0.139" / 3.53 mm) Material: Nitrile rubber (Buna-N / NBR) Hardness: 70A durometer Temperature Range: -40°F to 250°F Color: Black | Pack of 10 Material - Why Buna-N Nitrile Buna-N is the workhorse O-ring compound: excellent resistance to petroleum oils, fuels, hydraulic fluids, water, and silicone greases, with good abrasion and tear resistance. Not recommended for ozone/direct sunlight exposure, brake fluid, ketones, or strong acids - for those, use EPDM or Viton. Common Applications Pool and spa pump unions, chlorinator lids, filter housings, large plumbing unions. How to Measure an O-Ring Measure the inside diameter (hole to hole) and the cross-section thickness of your old ring, or measure the groove: groove inner diameter = O-ring ID, groove width slightly wider than the cross section. Match both numbers to the chart below - the dash number takes care of the rest. AS568 O-Ring Size Chart - Sizes We Stock Dash # Inside Dia. Outside Dia. Cross Section Metric ID #010 1/4" (0.239") 3/8" 1/16" (0.070") 6.07 mm ID #011 5/16" (0.301") 7/16" 1/16" (0.070") 7.65 mm ID #017 11/16" (0.676") 13/16" 1/16" (0.070") 17.17 mm ID #121 1-1/16" (1.046") 1-1/4" 3/32" (0.103") 26.57 mm ID #228 (this size) 2-1/4" (2.234") 2-1/2" 1/8" (0.139") 56.74 mm ID #230 2-1/2" (2.484") 2-3/4" 1/8" (0.139") 63.09 mm ID #238 3-1/2" (3.484") 3-3/4" 1/8" (0.139") 88.49 mm ID #357 5-1/2" (5.475") 5-7/8" 3/16" (0.210") 139.07 mm ID Installation Tip Wipe the groove clean and apply a thin film of silicone grease before seating the ring - it prevents pinching and doubles seal life on anything that gets opened regularly, like filter housings. Why Buy From Rubberfeetwarehouse Genuine 70A Buna-N, ships fast from our South Carolina warehouse. Need a different size or larger quantity? Contact us.