#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-Rings (10 Pack) - Buna-N NBR 70A - 2-1/4" ID x 2-1/2" OD x 1/8" CS is backordered and will ship as soon as it is back in stock.
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#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.
Delivery and Shipping
Delivery and Shipping
Usually Ships Within 24 Hours. All Orders Are Shipped With Tracking Numbers.
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