64
BALANCES
Density Kit/Weights Classification
Determining the density of solids and liquids is an
inseparable part of work of the laboratories.
Traditional method of density determination requires
from the operator many measurements and a lot of
complex calculation. In result the operator ends with
a density determination result which can be saddled
with calculation and systematic
errors. Additionally time that needs to be devoted to
density calculation is long. In case of determining the
density of solids and liquids with application of MRC
density determination kit, the whole procedure is very
much simplified and speeded up. Time till the
operator receives the density measurement is very
short, as all the calculation is performed by the
software of the weighing instrument, & operator’s
activities is limited to:
●
operation of the keyboard of weighing instrument
●
placing the samples on the weighing pans of the kit
●
hanging the plunger
Density determination kit is Optional accessories
offered to MRC laboratory balances. The software for
determination of density has following basic features:
●
simplicity of usage (all activities are described on
the display of the balance)
●
reliability (all calculation is automatically performed
by the balance’s software)
●
fast data processing (result is obtained after
determination of sample mass in water or plunger
mass in liquid)
●
accurate data processing (before every
measurement of mass, display indication is
automatically zeroed, this proves the density
determination result to be reliable and real).
1-beaker base
2-pans suspension
3-plunger
4-beaker
5-thermometer holder
6-thermometr
P0180, Density Kit
Selection of the appropriate test weight for your
balance
A balance can never be more accurate than the
test weight used to adjust it, it depends on its
tolerance.
Accuracy of the test weight: Should correspond to
the readout d of the balance, rather than something
better.
Nominal weight value: This is shown in adjust mode
“CAL” in the balance display. Given the choice, the
heaviest weight is the most suitable for accurate
measurement.
OIML Directive
The key points from the OIML Directive
OIML (Organization International de Metrologies
Legal) has established the exact metrological re-
quirements for weights in verified applications in
approx. 100 states all over the world. The OIML
recommendation Rlll (2004 Edition) for weights relates
to sizes 1mg-50 kg. Statements are made on the
accuracy, materials, geometric shape, marking &
storage of the weights.
Error limits for weights of classes E1 to M3
The error limit classes are in fixed hierarchical levels in
the proportion of 1:3, where El is the most accurate
and M3 is the least accurate weight class. When
testing weights with other weights, the correct test
class is the next highest class.
Error limit classes (= tolerances)
The values given in the table below (tolerances ± ...
mg) are the respective permitted fabrication
tolerances. They are to be equal to the measuring
uncertainty of the weight, if no DKD calibration
certificate is available.
Nominal
Value
OIML Max. permissible errors for
weights=permissible tolerances “Tol ± mg”
E1
E2
F1
F2
M1
1mg
±0.003mg ±0.006mg ±0.020mg ±0.06mg ±0.20mg
2mg
±0.003mg ±0.006mg ±0.020mg ±0.06mg ±0.20mg
5mg
±0.003mg ±0.006mg ±0.020mg ±0.06mg ±0.20mg
10mg
±0.003mg ±0.008mg ±0.025mg ±0.08mg ±0.25mg
20mg
±0.003mg ±0.010mg ±0.03mg ±0.10mg ±0.3mg
50mg
±0.004mg ±0.012mg ±0.04mg ±0.12mg ±0.4mg
100mg
±0.005mg ±0.016mg ±0.05mg ±0.16mg ±0.5mg
200mg
±0.006mg ±0.020mg ±0.06mg ±0.20mg ±0.6mg
500mg
±0.008mg ±0.025mg ±0.08mg ±0.25mg ±0.8mg
1g
±0.010mg ±0.03mg ±0.10mg ±0.3mg ±1.0mg
2g
±0.012mg ±0.04mg ±0.12mg ±0.4mg ±1.2mg
5g
±0.016mg ±0.05mg ±0.16mg ±0.5mg ±1.6mg
10g
±0.020mg ±0.06mg ±0.20mg ±0.6mg ±2.0mg
20g
±0.025mg ±0.08mg ±0.25mg ±0.8mg ±2.5mg
50g
±0.03mg ±0.10mg ±0.3mg ±1.0mg ±3.0mg
100g
±0.05mg ±0.16mg ±0.5mg ±1.6mg ±5.0mg
200g
±0.10mg ±0.3mg ±1.0mg ±3.0mg ±10mg
500g
±0.25mg ±0.8mg ±2.5mg ±8.0mg ±25mg
1kg
±0.5mg ±1.6mg ±5.0mg ±16mg ±50mg
2kg
±1.0mg ±3.0mg ±10mg ±30mg ±100mg
5kg
±2.5mg ±8.0mg ±25mg ±80mg ±250mg
10kg
±5.0mg ±16mg ±50mg ±160mg ±500mg
20kg
±10mg ±30mg ±100mg ±300mg ±1000mg
50kg
±25mg ±80mg ±250mg ±800mg ±2500mg
100kg
±160mg ±500mg ±1600mg ±5000mg
200kg
±300mg ±1000mg ±3000mg ±10g
B
7-plunger string
8-hook
9-upper pan of the set for density
determination of solids
10-pan string
11-lower pan of the set for density
determination of solids
12-additional weight
13-additional stand for set of pans
or plunger.
