Zoro Select Square Profile Buna-N O-Ring Dash 139 PK25
Pack of 25 rectangular Buna-N O-rings, dash 139, 70A durometer, rated from -40 to 250 °F
- Buna-N material resists oil and fuel
- Square cross-section improves sealing under pressure
- Dash 139 size fits standard grooves
- Pack of 25 covers multiple repairs
- Operating range from -40 to 250 degrees F
Zoro Select Buna-N O-Ring Dash 139
This pack contains 25 square-profile Buna-N O-rings in dash size 139. They suit maintenance teams and technicians who need inch-measurement seals for hydraulic or pneumatic assemblies. The rectangular cross section and medium-hard durometer fit standard grooves that call for this dash number. Buyers who require metric sizing or a different durometer should look elsewhere.
Metal-detectable seal material
Each ring is metal detectable but not X-ray detectable, helping quality-control lines spot contamination in food or pharmaceutical equipment. The Buna-N compound handles temperatures from -40 to 250 degrees F and carries a 70A durometer rating. The material is not FDA compliant, so it cannot be used in direct food-contact zones.
Verify groove dimensions before ordering
Confirm the groove calls for a 2.1 inch actual inside diameter and a 0.103 inch actual width. The nominal outside diameter is 2 3/8 inch with an actual outside diameter of 2.381 inch. Cross-reference the dash 139 designation on your engineering drawing to ensure the rectangular profile matches the gland design.
How it compares
Measured against everything we stock in Threadlockers & Sealants, at today’s prices. Recalculated every night.
- Price $9.99
- Cheaper than about 70% of the 147 comparable items (median $11.99).
Specifications
| Product | |
|---|---|
| Brand name | ZORO SELECT |
Questions about this item
When should I replace the Buna-N material in these dash-139 rings?
Plan replacement when the material hardens, cracks or loses elasticity after prolonged exposure to temperatures near the 250 °F upper limit or aggressive fluids.
What is the first limit reached when these rings operate continuously at high temperature?
The 250 °F maximum service temperature is the primary limit; exceeding it accelerates degradation of the 70A durometer Buna-N compound.
How much heat do the rings transfer to surrounding parts during all-day operation?
The rings themselves generate no heat; they simply conduct ambient temperature up to their 250 °F rating while maintaining seal integrity.
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