How to Calibrate a Manual Calibration Lab Balance

How to Calibrate a Manual Calibration Lab Balance

At its most basic level, calibration involves comparing a mass reading against a standard weight. In the case of a lab balance, standard weights are graded according to class, which is a specification describing the accuracy of the weight. There are four ASTM weight classes (1-4), with class 1 being the most accurate, and class 4 being the least. The class of weight to be used corresponds to the accuracy of the balance. For lab balances, Class 1 and 2 weights are most commonly used.

To calibrate a balance, you need to set up a base point (ZERO) and establish the instrument's full capacity weight. This way, you have determined two precise extreme points, between ZERO and the maximum weight. It is now possible to determine all weights in-between with an acceptable degree of precision. There may be applications where the maximum capacity of the balance is unlikely to ever be reached. Some manufacturers offer the capability of calibrating the balance in stages, so that the user can choose the upper limit according to the heaviest substance he is likely to weigh. Why should he do this? Because calibration within a reduced range results in greater accuracy.

To set about calibrating your balance, you will need a calibrated weight corresponding to the maximum value. It is recommended that you purchase the calibration (external) weight along with the balance. The actual procedure for calibrating a balance will often depend on the brand and model. The examples given below are for analytical balances manufactured by Kern.

All balances have an auto-check feature which comes on when the balance is switched on, at the end of which the reading is set at zero. However, this is not to be confused with calibration. First we need to recall a few basic facts of physics. The acceleration due to gravity on a mass is not the same at every location on earth and, although this variation is not significant enough to affect many other types of equipment, it does matter when you are measuring very small masses to an accuracy of 0.1 mg. Hence, a lab balance needs to be recalibrated whenever it is shifted to another location. Temperature fluctuations, too, play a role. Also, calibration requires a stable environment and this is achieved by allowing the balance to warm up for 1 to 4 hours after it is switched on.

The ABS series of lab balances manufactured by Kern uses an external adjusting weight, whereas the ABJ and ABT series rely on an internal adjusting weight to check the accuracy of the balance and make fine adjustments, if required. Care should be taken that the weighing pan is entirely free of extraneous matter.

The precise steps to be followed for calibration are described in detail in the included operation manuals. When you purchase a balance with external calibration ask whether the calibration weight is included or must be ordered separately.

POST COMMENT

Company Formation Process in UK The Ten Commandments KJV - What are the Ten Commandment? Who Wants to be an Etycoon? How to Fix Blue Screen of Death BSOD - 5 Simple Steps Federal Prison "One Day at Club Fed" Going to Pattaya Athlean X workout Plan Water Leak Problems In Portland Chardham Yatra Revitalizes Mind & Soul during Chardham Yatra Packages Essay: Conjugal Visitations Visitor's Guide to PageRank Essay: Conception of Liberty Can Fasting Help You Live Longer?