 MSB MkI Calibration and use of formula             # MSB MkI Calibration and use of formula

Each balance is supplied with a calibration standard (a sealed tube containing a solution of MnCl2.6H2O) and a test sheet showing the value of the instrument's balance constant, CBal that is factory set at 1.000 ± 0.020

## Calibration procedure - using a known substance

Mk1 readings for samples in a standard sample tube with an internal diameter of 0.324cm are related to Mass susceptibility Xg, by the formula printed on the instrument top panel Where: CBal is the balance constant that is factory set at 1.0 l, m are the length of sample in the tube, in cm. and sample mass, in gm. R, R0 are the balance readings of the sample and empty tube

Using a substance of known Xg and measurements of the other variables in the formula the value of CBal can be checked.

Note this new value of CBal and use it in all subsequent calculations of susceptibility until the next calibration check.

If no such substance is available and there is doubt about the value of CBal the standard tube can be used as follows.

## Calibration procedure - using MkI standard

Put a clean, empty standard sample tube (internal diameter of 0.324cm) in the balance and use the zero knob to set the display to zero on the x1 range.
Remove the tube and insert the standard. Gently and slowly rotate the tube while it is in the balance and note the extremes of the readings. Note the average of these extremes; this will be R to be used later.
R should be the same as Cstd If it is larger than Cstd then the balance constant has decreased by the factor of Cstd/R
A worked example should make this clear.

 CBal = 1.005 from test sheet Cstd = 1019 from the label on the tube R = 1025 from measurement New CBal = 1.005 x 1019/1025 = 0.999

Note this new value of CBal and use it in all subsequent calculations of susceptibility until the next calibration check.