O リングのサイズを正確に測定する方法は?

O リングのサイズを誤って測定すると、漏れ、ダウンタイム、製品の故障につながる可能性があります。機器に適したサイズを見つけるのに苦労していませんか?

Knowing how to measure an O‑ring size accurately is essential to ensure proper sealing, reduce replacements, and avoid costly mismatches. Here’s a practical guide to help you do it right.

What are the key O‑ring dimensions you should measure?

O‑rings aren’t one‑size‑fits‑all—they need three critical measurements:

1. 内径（ID）
2. 外径（OD）
3. Cross‑Section (CS)

How do you measure O‑ring size step by step?

Over the years, I’ve taught many customers how to avoid seal mismatches by measuring correctly. Here's how to do it:

Best tools and measurement techniques for O‑rings

Step-by-step guide:

1. 測定 ID using caliper across the ring inside.
2. 測定 CS by laying the ring flat and measuring wall thickness.
3. Calculate 外径 as ID + 2 × CS, or measure directly if accessible.

Pro tips:
• Don’t stretch the ring.
• Measure at room temperature.
• Compare with a new sample from an o‑ring assortment kit for worn rings.

Real-world example:
An automotive client misread OD and used 24 mm rings instead of 22.5 mm. Switching to our measured-grade FKM O‑rings and using groove gauges reduced leakage by 87%.

Why are accurate O‑ring measurements critical for performance?

Even a 0.5 mm mismatch can cause:

• 液漏れ
• Seal fatigue
• 圧力不均衡
• Safety risks or recalls

Always verify dimensions before ordering. Refer to size charts like this:
Oil Seal & O‑Ring Size Reference Chart

How to distinguish metric vs inch O‑ring sizes?

Units and standards differ:

Swapping standards without checking can break sealing. Learn more in our guide:
Metric vs Inch O‑Ring Kit Guide

What should you do if your O‑ring is deformed or swollen?

If a ring looks warped, measure the groove dimensions instead. Compare with online charts or reach out for a custom replacement.

How to measure O‑rings already installed in a groove?

使用 depth gauge to get the groove’s depth (matching CS), and a caliper to measure ID across the groove. This ensures accurate sizing without removal.

Best practices for measuring worn or used O‑rings

• Always cross-check ID and CS
• Avoid direct surface scratches
• Use calibrated tools regularly
• Replace rings showing deformation
• Double-check units—mm vs inches

結論

Getting O‑ring measurements right means better sealing, longer service life, and fewer replacements.

Still unsure about O‑ring dimensions?

Contact our sealing experts—they’ll help you find or customize the exact size you need:

📧 メールアドレス: お問い合わせ
📱 ワッツアップ: +86 176 2297 9498

Related topics

O‑Ring Assortment Kit Guide
FKM O‑Rings for High‑Temp Sealing
Metric vs Inch O‑Ring Kit Comparison

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