LimsPulse
Analytical balance · Calibration procedure

Accuracy

Weighs a calibrated test weight near the top of the range and compares the reading with its certified value. Also called a sensitivity test.

Photo of a Analytical balance
Photo: Karelj, Public domain (cropped), via Wikimedia Commons
PURPOSE

Why this is checked

Confirms the balance's calibration (its sensitivity) is correct, so that readings across the range are true and not only precise.

Frequency

Typically every 6 or 12 months, and after repair, relocation or a failed daily check, as defined in your calibration SOP.

Learn how the Analytical balance works
YOU WILL NEED

Standards & tools

  • Calibrated test weight between 5% and 100% of capacity, e.g. 200 g OIML class E2 for a 220 g balance, with certificate
BEFORE YOU START

Prerequisites

  • Balance level, clean and warmed up
  • Weight at room temperature and handled with forceps
PROCEDURE

Step by step

  1. 1Zero the balance with the doors closed.
  2. 2Place the test weight centrally and record the stable reading.
  3. 3Remove the weight and confirm the reading returns to zero.
  4. 4Repeat the measurement as many times as your SOP asks (often three) and use the mean.
  5. 5Compare the reading with the certified (conventional) mass of the weight.
RECORD

Example observation table

Certified value (g)Reading 1 (g)Reading 2 (g)Reading 3 (g)Mean (g)% error
200.0000200.0003200.0004200.0005200.0004+0.0002%
CALCULATION

How to calculate the result

% error = (Mean reading − Certified value) ÷ Certified value × 100
  1. Mean reading = (200.0003 + 200.0004 + 200.0005) ÷ 3 = 200.0004 g
  2. Difference = 0.0004 g
  3. % error = 0.0004 ÷ 200 × 100 = 0.0002%
ACCEPTANCE CRITERIA

Pass if

  • Reading within 0.10% of the test weight value (USP <41>). Many SOPs also apply a tighter internal limit.
IF IT FAILS

What to do

  • Run the balance's adjustment (internal or with an external weight) and repeat.
  • If it still fails, label it 'Out of calibration' and call service.
  • Assess the impact on results since the last passing calibration.
MORE

Other Analytical balance calibrations

In LimsPulse · Calibration Management

LimsPulse schedules this calibration, records the result against limits, and blocks the instrument everywhere if it fails or goes overdue.

See how