How to Verify a Friability Tester: Drum Speed, Revolution Count and Drum Dimensions (USP <1216>)

A friability result is one line of arithmetic, so labs rarely suspect the instrument when a batch fails. But the result depends on the drum turning at the right speed for the right number of revolutions, in a drum of the right size. If any of those is off, the weight loss changes and the record cannot explain why.

This guide covers what to verify on a friability tester, in the order most labs do it, using the CJY-300E as the example. The current USP <1216> and your own procedure define the acceptance limits.

What the compendial method fixes

• Rotation speed: 25 ± 1 rpm
• Revolutions: 100, which takes about four minutes at 25 rpm
• Drum geometry: inside diameter 283 to 291 mm and depth 36 to 40 mm, with a curved projection that lifts and drops the tablets about 156 mm

The CJY-300E drum measures 286 mm inside diameter and 39 mm deep, inside that window. Its speed is adjustable from 20 to 100 rpm and the counter runs from 1 to 1,000 laps, so verification means confirming the displayed value at the speed you actually run, 25 rpm for the standard method.

The checks

1. Drum speed. Hold a digital tachometer to the rotating drum or shaft and compare the measured speed with the displayed speed at your working setting. Record several readings. A tester can display 25 rpm while turning noticeably faster or slower, and the difference changes the impact profile on the tablets.

2. Revolution count. Confirm that the counter reaches 100 revolutions when it stops. One way is to mark the drum and count a full run by eye once, comparing it with the counter. If you use timer mode, which on the CJY-300E allows a preset time up to 9 hours 59 minutes 59 seconds, check the elapsed time against an independent calibrated timer.

3. Drum dimensions. With a 300 mm digital caliper, measure the inside diameter and the depth of the drum and compare them with the compendial limits. Take a few readings around the drum, since a worn or deformed drum can differ from one position to another.

4. Drum condition. Inspect the inner surface and the curved projection for wear, scratches, cracks or residue, and confirm the projection sits where the compendial drawing places it. A damaged surface changes how tablets tumble.

5. Rotation direction and stability. Run the drum and confirm it turns smoothly without wobble, and that clockwise and counter-clockwise operation both work if your procedure uses them.

6. The balance used for weighing. The weights in the friability formula come from a balance, so make sure it is calibrated under its own schedule and used consistently. This is outside the friability tester itself but inside the friability result.

Our KIT-FRB-001 friability calibration kit contains a tachometer and a 300 mm digital caliper, which cover checks 1 and 3, with the revolution count and drum condition checked by observation and your timer. Each measuring tool ships with a third-party calibration certificate from a laboratory holding ILAC-MRA and CNAS accreditation. The kit applies to the CJY-300E and to the friability function of the SY-6DN.

Why the CJY-300E has no data output, and what that means for records

The CJY-300E is visual observation only. It does not export data or print records, and weighing and drum emptying remain manual. This is a deliberate design choice: the vibration from a running drum can disturb a precision balance, and an automated emptying mechanism adds positioning error, so independent manual weighing is the more reliable route. The consequence is that your handwritten or typed record is the original record, so the SOP should say exactly what is recorded and who signs it. Labs that need electronic data export can look at the SY-6DN. See also our guide to why labs fail friability audits and our free friability calculator.

What the SOP should record

• Instrument ID, location, date and who performed the verification
• Each tool used, its ID, and certificate number and expiry
• Speed readings at the working setting against the limit, with pass or fail
• The revolution-count check and the timer check if used
• Drum dimensions against the limits, and the drum condition
• Corrective action if anything fails, and the date of the next check

Set the interval in your SOP, with event triggers such as repair, drum replacement, relocation, or an unexplained change in friability results.

What we would ask before suggesting a kit

• Which friability tester you run
• Whether your auditors expect third-party certificates on the measuring tools
• Whether you also need calibration for hardness, disintegration or dissolution equipment

Send those details through our contact page. Our testers are in the friability tester collection.

Frequently Asked Questions

What should be verified on a friability tester?
Drum speed, the revolution count, and the drum dimensions and condition, plus the balance used for the weighings.

Is the displayed speed enough?
No. Check it with an independent tachometer at the speed you actually run.

How often should a friability tester be verified?
There is no fixed interval in the pharmacopoeia, so set it in your SOP based on risk. Many labs calibrate every 6 to 12 months and add a check after repair, relocation, drum replacement, or an unexplained change in results.

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