Measurement Process

Mass Measurements
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e. Measurement Process.

(1) Zeroing. When the balance is released at zero, the output voltage VO from the

LVDT is converted to a frequency fO by the V/F converter. This frequency is

measured for 0.2 seconds and the count is stored in the Z-register when the ZERO

button is operated. (Momentary contact).

(2) Ranging (calibration). Without changing the zero, a standard one gram weight

is placed on the pan. The output voltage VR from the LVDT is converted to

frequency fR and measured for 0.2 seconds. The zero count obtained in e.(1) is

subtracted from this count and the difference is stored in the R-register as R-Z.

(3) Measuring. The output of the LVDT during a measurement will be a voltage

between VO and VR. This voltage is converted to a frequency fx by V/F converter

and counted for 0.2 seconds. The number in the Z-register obtained in e.(1) is

subtracted from this count and the difference is stored as X-Z in the X-Z register.

(1) Zero. The balance is zeroed by releasing the beam with the pan empty, waiting

until the reading is steady and depressing the ZERO button momentarily. In

approximately 3 seconds, the balance indication will be .000-IN RANGE.

If there are disturbances to the pan, the indication may vary 1 digit and the

number displayed may be .XXX-UNDER; .000-IN RANGE; .001-IN RANGE. In

the case of minus indications (.XXX-UNDER) the digits are not significant.

g. Weighing Technique.

(1) Some basic principles fundamental to all types of precision weighing must be

observed in order to achieve the high precision of which the Voland Jupiter

J5000S is capable. Maximum precision is achieved when the balance and the

weights under test are at temperature equilibrium and the air inside the case is free

of convection currents. Weighing should be made as quickly as possible.

Disturbing elements which interfere with either of these will detract from

precision. To assure maximum precision the following procedure should become

standard operating procedure in any weighing sequence.

(2) To ascertain that the temperature of the weights is the same as the temperature

of the balance, it is best to store the sample and standard weights within the

balance chamber for at least one hour for the larger weights. With the door of the

balance closed, the weights, and balance can come to equilibrium together.

(3) Setting of Dial-Operated Weights.

The value of the weight under test must be dialed into the digital display in order

for the weight to be on-scale. In the case of metric weights, the indicated value of

the weight can be set directly on the dials. For instance, if the weight to be tested

is a 2 kg weight, merely set the 1 kg knob until the indicator (16) reads 2000. In