| An analytical balance is used to measure mass to a | | | | scales. |
| very high degree of precision and accuracy, because | | | | Chemical analysis is an area where these balances are |
| unlike spring scales their accuracy is not affected by | | | | often used, since it is designed for great precision |
| differences in the local gravity. A change in the | | | | which is useful in quantitative chemical analysis. |
| strength of the gravitational field caused by moving | | | | Top-loading balances, which can measure objects up |
| the balance will not change the measured mass, | | | | to 200 g, are less expensive but also offer less |
| because the moments of force on either side of the | | | | resolution than do some other types of balance. A |
| balance beam are affected equally by the pull of | | | | top-loading balance is considered to be a semi |
| gravity. | | | | analytical balance, with a readability of up to three |
| The weighing pans of a high precision (.01 mg or | | | | decimal places (up to.001 g). A precision balance has a |
| better) balance are inside a transparent enclosure | | | | readability of 0.01 g. It produces steady readings in a |
| with doors so that dust does not collect and so any | | | | wider range of environmental conditions than an |
| air currents in the room do not affect the balance's | | | | analytical model, being less sensitive to temperature |
| operation. The use of a vented safety enclosure with | | | | fluctuations. |
| an analytical balance which has uniquely designed | | | | Microbalances and ultra-microbalances are used to |
| acrylic airfoils, allows a smooth, turbulence-free | | | | weigh the smallest samples. They offer a capacity of |
| airflow that allows weighing of masses of as little as | | | | up to 6 g with readability up to seven decimal |
| 1 micro gram without fluctuations or loss of product. | | | | (.0000001 g). Electronic scales and balances can |
| Samples should be at room temperature to prevent | | | | provide weights in more than a dozen units, including |
| natural convection from forming air currents inside | | | | grams, kilograms, pounds, newtons, grains, and |
| the enclosure, which could affect the weighing | | | | ounces. |
| process. | | | | Many things can affect the precision of an analytical |
| Analytical precision is achieved by maintaining a | | | | balance. The environment of the lab, operating |
| constant load on the balance beam, by subtracting | | | | temperature, humidity, vibration and ventilation |
| mass on the same side of the beam to which the | | | | currents can all affect performance. Consequently, it |
| sample is added. The final balance is achieved by | | | | is important to keep the balance inside an enclosed |
| using a small spring force, rather than subtracting | | | | space, keep it clean and make sure it is leveled |
| fixed weights. This allows the weight to be added as | | | | correctly. It is equally important to make sure it is |
| a fine adjustment. | | | | regularly maintained and serviced. There are also |
| An analytical balance or scale used in laboratories may | | | | personnel considerations that need to be observed. It |
| be in various shapes and sizes. Although often used | | | | is useful to know who will be operating and |
| interchangeably, scales and balances have different | | | | maintaining the device and the type of training they |
| uses. A balance compares the mass of two sets of | | | | have received. |
| objects, while a scale determines the mass of an | | | | Finally, it is best to always follow the manufacturer's |
| object or set of objects. The most common types in | | | | operating instructions, calibration frequency and |
| use today are beam balances, spring balances, | | | | maintenance recommendations for the analytical |
| top-loading balances, analytical balances and precision | | | | balance. |