Ametek PK II, Operating Instructions Manual, Page: 8 / 28

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Temperature
If the coefficient of expansion of the ball and nozzle is positive, the effective area will
increase with increasing temperature resulting in a corresponding decrease in pressure.
Corrections can be made using the following formula:
Where:
P
G
= tester output pressure corrected only for gravity
P
T
= tester output pressure corrected for gravity and temperature
T = ambient temperature ( ° C)
Air Head
When pressurized, a correction is required only when the gauge height or reference plane
of the unit being calibrated is either higher or lower than that of the pneumatic tester. The
reference plane of the tester is at the top of the nozzle. Heights above the reference plane
are negative, while heights below the reference plane are positive. Corrections can be
made using the following formula:
Where:
H = air head (Inches)
P
T
= tester output pressure corrected for gravity and temperature
P
A
= tester output pressure corrected for gravity, temperature and air head
P
T
=
P
G
1 + 1.67 x 10
-5
(T - 23 ° C)
P
A
=
P
T
(1 + H x 2.84 x 10
-6
)