Calibration Procedure For Dead Weight Tester

 
(A) Check followings before calibration of Dead Weight Tester
 
 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.
 
(B) Calibration of Dead Weight Tester
 
   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.
 
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.
 
DWT Weight Used Pressure in DWT Under Test in (A) in KG / Cm2 REading in Ametek PPC 35/200/700 Bar (B) in Kg/cm2 Error
(A-B) in Kg/cm2
Accuracy in % of Span
(A-B) / Spam *100
 
 
Calibration Procedure For Pressure Gauge

 
(A) Check followings before calibration of Pressure Gauge
 
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.
 
(B) Calibration of Dead Pressure Gauge
 
  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.
 
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.
 
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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