Q.Please tell me the key points in how to perform daily inspection and periodic inspection of balances.
1. Daily inspection and periodic inspection
- The three main inspections to be performed on a daily basis or before using a balance are (1) Check to see if the balance's pan or surroundings are dirty. (2) Check to see if the reading is fluctuating. (3) Check to see if the weighing capacity is correct.. To inspect the weighing capacity, place a weight of known mass on the pan, and make sure that the difference with its indicated value is within the criteria (numerical value determined by the user himself). Remedies for when criteria are exceeded must be pre-determined in a Procedures Manual. So, determine in advance procedures such as whether to re-adjust the balance to make sure it is within these criteria or send the balance back for repair.
- For periodic inspection, inspection items are generally increased and the following are added to the daily inspection items mentioned above: (4) Repeatability, (5) Eccentric error, and (6) Linearity. The hysteresis and drift inspections also can be added on, as necessary. Periodic inspection once per year is generally considered to be sufficient. However, once every two years is sufficient when the balance is used less frequently. Your Shimadzu service representative can perform periodic inspection and calibration for you using JCSS weights for a fee.
2. JCSS weights
- Equipment used for calibrating instruments is required to have traceability to national standard equipment. The equipment used for calibrating balances is weights, and the most commonly-used weights that have obtained traceability are JCSS weights. JCSS weights come with a certificate that clearly states measured value (conventional mass) and its confidence interval (uncertainty). The conventional mass is used as the mass of the weight.
3. JCSS weight expiration date
- JCSS certificates have no expiration dates. However, since weights become scratched or dirty over prolonged use, their mass values might vary, so we recommend that they are calibrated every 2 or 3 years (i.e. re-calibrated by a JCSS calibration organization).