The MTS 225-piece Metric O-Ring Assortment is a comprehensive repair kit containing a wide variety of circular sealing gaskets. These O-rings are made from Nitrile Rubber (NBR), also known as Buna-N, which is the industry standard for resistance to petroleum-based oils, fuels, and hydraulic fluids.
Contents & Sizes
This kit is organized in a compartmentalized plastic case, featuring 18 of the most common metric sizes. The set typically ranges from small internal diameters (3 mm) to larger industrial sizes (22 mm), with varying cross-sectional thicknesses (usually 1.0 mm to 4.0 mm).
Commonly included sizes (Internal Diameter x Thickness):
- 3 x 1 mm / 4 x 1 mm / 4.5 x 2 mm
- 5 x 2 mm / 6 x 2 mm / 6 x 2.5 mm
- 6 x 3 mm / 7 x 2 mm / 8 x 2 mm
- 9 x 2 mm / 10 x 2 mm / 12 x 3 mm
- 13 x 3 mm / 14 x 2.5 mm / 17 x 2.5 mm
- 18 x 4 mm / 20 x 2 mm / 22 x 2 mm
Key Features
- Oil & Fuel Resistance: NBR material is specifically designed to withstand degradation when in contact with engine oil, diesel, gasoline, and grease.
- High Temperature Stability: Generally rated for operation between -40°C and +120°C.
- Compression Set Resistance: These O-rings are designed to "spring back" after being compressed, maintaining a tight seal over long periods of mechanical vibration.
- Universal Application: Suitable for both static seals (where parts don't move) and dynamic seals (like a reciprocating piston or rotating shaft).
Common Applications
- Automotive: Sealing fuel injectors, oil filter housings, air conditioning lines, and cooling system sensors.
- Hydraulics & Pneumatics: Repairing leaky floor jacks, air compressors, and pneumatic nail guns.
- Plumbing: Fixing dripping taps, showerheads, and garden hose connectors.
- Industrial: Sealing gearboxes, pumps, and valve stems.
Usage Tips
- Lube Before Install: Always apply a small amount of clean oil or Silicone Grease to the O-ring before installation. This prevents the rubber from tearing or "bunching up" as you tighten the components.
- Avoid Sharp Tools: Never use a screwdriver or sharp pick to stretch an O-ring into place, as a single tiny nick will cause the seal to fail under pressure.
- Check Compatibility: While NBR is great for oil, it is not recommended for use with brake fluid (which requires EPDM rubber) or high-concentration acids.
- The "Squish" Rule: An O-ring seals by being compressed. If the O-ring you select is loose in the groove or doesn't protrude slightly above the surface before assembly, it will likely leak.
