OfiTE 112-00 - Calculations - Lubricity Coefficient

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Lubricity Test
Calculations - Lubricity
Coefcient
The Lubricity Coefcient is a more accurate measure as it considers the
variance (Correction Factor) the machine registers when calibrated against
deionized water.
Correction Factor
The Coefcient of Friction value for deionized water would be a constant if
the metallurgical structures of all rings and test blocks were the same, and
the same area between the two objects came into contact each time. At 60
rpm and 150 in-lb of load, the torque meter reading should be 34, resulting
in a Coefcient of Friction of 0.34. However since every ring and test block
is different a correction factor is required to achieve accurate results. To
calculate the correction factor, divide the standard meter reading for water
(34) by the actual meter reading, which you recorded in the lubricity test.
Correction Factor =
Meter Reading × Correction Factor
100 Pounds
Lubricity Coefcient =
Percent Torque Reduction
The percent of torque reduction is based upon the torque reading of a sample
that has been treated with a lubricant, relative to the same sample untreated.
Percent (%) Torque Reduction at a Given Load = × 100
Where:
A
L
= Torque reading of untreated mud under the same force as B
L
B
L
= Torque reading of treated mud under the same force as A
L
Standard Meter Reading for Deionized Water
Meter Reading Obtained in Deionized Water Calibration
=
34
Meter Reading (32 to 36)
A
L
-B
L
A
L