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| Calibration Procedure For Dead Weight Tester |
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| (A) Check followings before
calibration of Dead Weight Tester |
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| Check for any
physical damage in dead weight tester.
Weight should not be damage or seriously
corroded. Make sure there is no dirt in
oil. The fall of piston should not be
apparently greater to make use of the
DWT difficult. The DWT can not be make
to operate satisfactorily due to wear or
damage to pump, piping, valve, O-rings &
seals. |
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| (B) Calibration of Dead Weight
Tester |
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Recommended
calibration reference temp. is
27 + 5 'C and relative humidity
not more than 85 % RH.
Calibration area should be
adequately free from dust, shock
and vibration. DWT is calibrated
with using Digital Pressure
Calibrator. (Digital Precision
Pressure Calibrator AMETEK -
JOFRA INSTRUMEMT, DENMARK. +
0.05 / 0.1 % FS accuracy). Mark
Sr. No. on all weights for
separate identification. Check
there is sufficient oil in oil
reservoir. Level the DWT on
strong table base using spirit
level. |
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| Make sure there is no air in the hydraulic system. Connect digital pressure calibrator using suitable adopter on DWT as shown in figure. Apply different pressure in the system till the weight is lifted for certain level. Rotate lifted weight slowly & take pressure reading for all different weights. Tabulate the readings as under and find the % accuracy of DWT. |
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| DWT Weight
Used |
Pressure in
DWT Under Test in (A) in Kg /
cm2 |
Reading in Digital Master Pressure Gauge 35/200/700/1000 Bar (B) in Kg/cm2 |
Error
(A-B) in Kg/cm2 |
Accuracy in %
of Span
(A-B) / Spam *100 |
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| Calibration
Procedure For Pressure Gauge |
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| (A) Check followings before
calibration of Pressure Gauge |
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| Check for any physical damage in
pressure gauge. Make sure there is no
restriction or choking in gauge input
connection. There should not be any
loose parts inside the pressure gauge.
All mounting screws should be fully
tight. |
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| (B) Calibration of Dead Pressure
Gauge |
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Recommended
calibration reference temp. is
27 ± 5 'C and relative humidity
not more than 85% RH.
Calibration area should be
adequately free from dust, shock
and vibration. Accuracy ratio of
master gauge and gauge under
test should be 3, 5 or 10 times
higher depending upon
availability and required
calibration standard. Care
should be taken for oxygen
service pressure gauges (Use no
oil). Pressure gauge is
calibrated with using comparison
test pump and master pressure
gauge. (Digital Precision
Pressure Calibrator. AMETEK
JOFRA INSTRUMENT,DENMARK. + 0.05
/ 0.1 % FS accuracy. |
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| Connect pressure gauge using
suitable adopters on the comparison test
pump as shown in figure. Make sure there
is no air in hydraulic system. Adjust
pointer at zero in the pressure gauge
under test at no pressure in the system.
Apply full scale pressure and check
maximum indication in the pressure gauge
under test, If not adjust the span in
pressure gauge. Repeat zero and span
adjustment till both shows ok. Apply
different pressure using manual screw
pump of comparator. Take 5 to 8 readings
for different value of pressure in
increasing and decreasing order.
Tabulate the reading as under and find
out % accuracy of the pressure gauge. |
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Reading in gauge
under test
(X) t in
Kg/cm2 |
Master Gauge
Reading (Y) in
Kg / cm2 |
Error
(X - Y) in Kg / cm2 |
Accuracy in % of span
(X - Y)/span x 100 |
| Up Scale |
Dn Scale |
Up Scale |
Dn Scale |
Up Scale |
Dn Scale |
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