Calibration weighted

What is the minimum density of a substance necessary to keep the buoyancy correction to less than 0.01% when using brass calibration weights with a density of 8.40 g/cm ... 

Instrumental and reagent errors. These arise from the faulty construction of balances, the use of uncalibrated or improperly calibrated weights, graduated... 

WEIGHT.dat Thirty high-precision calibration measurements carried out on each of two analytical balances (LSD 0.01 mg) in the course of less than one hour using the calibration weight 30 g , cf. Ref. 25. 

If, as is usual, the sample has a lower density than the stainless steel balance calibration weight, the buoyancy effect of air on the sample mass means that a litre of water would indicate a weight of 1.05 g less than expected. Where weights of sample components are expressed as percentages or ratios, this error almost reduces to zero. This correction is usually ignored and considered well within acceptable experimental error (Jeffery et al., 1989, p. 76). 

Between periods of servicing of the balance, it is wise to check the accuracy with a calibration weight. Some balances incorporate a self-calibration facility. 

Fifty (50 mg) calibrated weight standard or whatever is recommended by the instrument manufacturer... 

The shock sensitivity of materials are also frequently evaluated in a drop weight test. A variety of drop weight testers have been developed, but the standard device used to evaluate the sensitivity of liquid propellants is test No. 4 of the Joint Army-Navy-Air Force Panel on Liquid Propellants (2). A sample of material (usually less than 0.1 gram) is confined in an enclosed volume, and a calibrated weight is allowed to... 

A calibrated weight obtained from the National Bureau of Standards had a value of 10.000 g. When it was used on a student s top loading balance, the balance showed the following readings 9.503, 9.499, 9.500. Comment on the balance s accuracy and precision. 

Balances can be calibrated or verified for accuracy with special weights, called calibrated weights, whose specific mass is known. Calibrated weights vary in quality and tolerance. They are classified by type, grade, and tolerance All calibrated weights are compared directly or indirectly to the international prototype one-kilogram mass to verify their accuracy. 

Calibrated weights are verified to weigh what they say they do within a given tolerance. The smaller the tolerance of a calibrated weight, the better the quality and the more expensive it will be. 

These parameters are discussed further in the section on calibrated weights (see Sec. 2.4.13). 

The greater the accuracy of a balance, the closer the balance will read the nominal weight of a calibration weight. If the calibration weight reads 10 mg, the balance should read 10 mg. If, for example, the balance reads 10.5 mg, it has less than desirable accuracy, and if it reads 12 mg, it has poor accuracy. 

Never handle a calibration weight with your fingers. Even if the toler-... 

The lever arm balance compares the mass of an object to the mass of calibrated weights. There are two major types of lever arm balances. The equal arm balance [see Fig. 2.23(a)] works by directly comparing a known weight to an unknown weight, both of which are placed an equal distance from the fulcrum. Once in balance, there is a one-to-one ratio (of the weights) between the unknown and known weights. A well-made balance of this type is capable of high accuracy and preci-... 

The unequal arm balance [see Fig. 2.23(b)] compares an unknown weight to the distance a known weight is to the fulcrum. When weighing an object, the further the balance weight is moved from the fulcrum, the heavier the object. The primary advantage of the unequal arm balance is that it needs only a limited number of calibrated weights. The disadvantage of this type of balance is that its accuracy is limited by how many divisions can accurately be defined between the units on the balance arm. 

Calibration weights should only be used to calibrate or verify the accuracy of a balance. Calibration weights should never be used to make weight determinations. They should never be handled directly with hands, and they should be stored in safe locations away from environmental dangers. 

A balance should be verified using the same calibrated weight each time. Because calibrated weights have expected variations in tolerance, using different weights may yield varying test results and could lead you to believe your balance requires constant (minor) recalibration when, in fact, no such calibration is required. 

However, this requirement may not have to be interpreted in an as stringent way as it would seem at first sight, and it could be fulfilled in some instances in a rather easy way. In utilising calibration weights provided by the manufacturer of the respective balance the test facility could rely on the certification of the manufacturer who had calibrated them against the national standard. For temperature determinations, the respective thermometers or... 

We might consider the topic of calibration as a good example on which these distinctions can be demonstrated. Calibration of a balance may not involve more than just the placement of the correct calibration weight on the balance and to read off the respective value indicated. Thus, the respective SOP can be kept rather simple. Calibration of an HPLC apparatus for the quantitative determination of test item in a biological matrix will involve, however, more complex and delicate manipulations, so that a much more detailed description of the whole procedure should certainly be advisable. 

The sample mass determination and the sample temperature measurement of the TGA has to be calibrated using calibrated weights and the ferromagnetic transition (Curie) temperatures of calibration metals. 

Strain gauges require frequent calibration and are sensitive to temperature variations to be accurate the body part must pull or push against the gauge in the same line that the calibration weights were applied unfamiliar to most clinicians not commercially available difficult to interface the device comfortably with the subject... 

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