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Q1: How to quickly decide between static and dynamic seals?
First, clarify the relative motion state of the sealing surfaces: select static seals (O-rings, gaskets, face seals) when there is no relative motion between sealing faces; select dynamic seals when there is relative sliding or rotation. Dynamic seals also require distinguishing reciprocating motion (hydraulic cylinder piston seals, rod seals) from rotary motion (radial shaft seals, PTFE rotary seals, mechanical seals). If uncertain, provide the equipment type and photos of the sealing location, and our engineers will provide a recommendation.
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Q2: How to choose O-ring hardness?
For general applications, 70 Shore A is recommended, balancing sealing performance and installation convenience. For low pressure (<5 MPa), 60 Shore A can be selected for better low-pressure sealing. For high pressure (>10 MPa) or large extrusion gaps, select 80–90 Shore A for improved anti-extrusion capability. For dynamic seals, 70–80 Shore A is recommended—too hard accelerates shaft wear, too soft tends to extrude and fail.
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Q3: How to choose between NBR and FKM?
NBR (Nitrile Rubber) is low-cost with excellent resistance to mineral and hydraulic oils, temperature range -40~120°C, and is the top choice for most general industrial oil seals. FKM (Fluoroelastomer) has a wider temperature range (-20~230°C) and significantly superior resistance to fuels, acids/alkalis, and oxidizing chemical media. In short: use NBR for general hydraulic/lubricating oil applications, use FKM for high-temperature/fuel/chemical applications. For non-oil media (water, steam), neither is suitable—select EPDM instead.
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Q4: The seal leaked soon after installation. What are the common causes?
The three most common causes of early leakage: (1) Installation damage—surface scratches from dry installation, passing sharp edges without a guide sleeve, O-ring twisted during installation; (2) Clearance/extrusion—excessive groove clearance causing the seal to be extruded into the gap under pressure and damaged (add backup rings or reduce clearance); (3) Material incompatibility—media causing seal swelling or shrinkage, dimensions correct at installation but changed after operation leading to leakage. Recommended troubleshooting sequence: first check installation marks → then measure dimensional changes → finally verify material compatibility.
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Q5: The shaft surface under the oil seal is worn. Does the shaft need replacing?
Not necessarily. If the wear groove depth is ≤0.5mm, you can use an AIINDUSTRY Shaft Repair Sleeve—an ultra-thin-wall stainless steel sleeve that slides directly over the worn area to provide a fresh sealing mating surface for the oil seal, without removing the shaft. This can save over 80% in downtime and repair costs. Only when wear is severe or the shaft structure won’t permit sleeve use should you consider weld repair or shaft replacement.
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Q6: Why do seals of the same specification have such different service lives?
Seal life is affected by multiple coupled factors: operating parameters (higher temperature, pressure closer to limits, and faster speed all shorten life), installation quality (damage, misalignment), media conditions (corrosiveness, lubricity, particulate contamination), and equipment condition (shaft surface quality, vibration, eccentricity/runout). AIINDUSTRY’s Smart Services platform records full-lifecycle data for each seal, helping customers analyze the key factors affecting service life and continuously optimize sealing solution selection.