Fluke Calibration P3031, User Manual

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P3031 & P3032
Users Manual
1-4
Temperature and Air Density
Temperature and Air Density variations are less significant than gravity.
Variations should be corrected for when maximum accuracy is required.
Temperature variation example:
Deadweight Tester calibrated temperature
20 °C
Operating temperature 24 °C
Percentage change per °C 0.002%
Indicated Pressure 250 psi
( )
250
100
002 . 0
24 20 250 x x PRESSURE TRUE
− + =
psi PRESSURE TRUE 98 . 249
=
Fluid Head
The piston assembly is liquid-lubricated in this particular model of deadweight tester;
therefore variance in the fluid level within the piston chamber will have an effect on the
pressure within the system.
The deadweight tester has been manufactured to an average fluid height relative to the
bottom of the piston in its mid-operating position.
The change in pressure as a result of variations in the relative fluid level, during normal
operation, will not exceed:
0.0055 psi / 0.00038 bar for oil-lubricated systems.
0.0118 psi / 0.00082 bar for Krytox GPL101 lubricated systems.
The fluid level is not visible in operation; therefore the exact height cannot be ascertained.
However, to ensure best accuracy, fill the chamber to its upper limit and then operate. In
this condition, the fluid level will be 4.5 mm above the calculated average.
If running at this level, reduce the pressure measurement by:
0.0055 psi / 0.00038 bar for oil.
0.0118 psi / 0.00082 bar for Krytox GPL101.
The change in fluid height per minute at maximum pressure for the initial 2 mm is
typically 0.01 mm, which equates to:
0.000012 psi / 0.0000008 bar for oil.
0.0000262 psi / 0.0000018 bar for Krytox GPL101.
The change in fluid height per minute at maximum pressure after the initial 2 mm will
reduce to typically 0.005 mm, which equates to:
0.000006 psi / 0.0000004 bar for oil-lubricated systems.
0.0000131 psi / 0.0000009 bar for Krytox GPL101 lubricated systems.
To ensure accuracy is maintained, the piston and weights must be kept clean and
undamaged.