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General Information
Environmental Corrections 1
1-3
When the gas pressure within the system balances the combined downward force of the
piston and weights, the piston and weights will float freely and the system is in
equilibrium.
The design of a Piston/Cylinder Unit (PCU) fitted to a deadweight tester allows for a very
small clearance gap between the piston and cylinder. This is required to allow the gas to
pass between the components, providing a lubricating film, and preventing
metal-to-metal contact.
Operating & Storage Specification
Temperature and relative humidity ranges for operation and storage of the deadweight
tester.
Table 1-2. Operation and Storage Specifications
Operation Storage
Temperature 18 °C to 28 °C
64 °F to 82 °F
10 °C to 50 °C
50 °F to 122 °F
Relative Humidity
(Non-Condensing)
20 % to 75 % 0 % to 90 %
Environmental Corrections
The deadweight tester has been calibrated to the Gravity, Temperature, and Air Density
stated on the certificate.
Equations and factors are given on the certificate to adjust for any variations in these
environmental conditions.
Gravity
Gravity varies greatly with geographic location, and so will the deadweight tester reading.
Due to the significant change in gravity throughout the world (0.5%), ensure that the
tester has either been manufactured to your local gravity, or that you have applied the
correction from the calibrated gravity.
Example:
Deadweight Tester calibrated gravity 980.665 cm/s²
(980.665 cm/s² is the International Standard Gravity)
Gravity at site 981.235 cm/s²
Indicated Pressure 250 psi
250
665.980
235.981
xPRESSURETRUE =
psiPRESSURETRUE 1453.250=
The ability to determine the local gravity value will depend on the data available in the
country that the instrument is to be used in. Some countries have geographic/geological
survey/mapping organizations that have the data readily available. If not, the countries’
National Standards Laboratory may be able to recommend a source of suitable
information.
Temperature
1.888.610.7664 sales@GlobalTestSupply.com
Fluke-Direct.com
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