© 2019 Department of Petroleum Resources. All rights reserved Department of Petroleum Resources (DPR) PROCEDURE GUIDE

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hydrometer/densitometer shall be used as the test liquid. The secondary standard
hydrometer/densitometer to be used in the exercise shall have a valid certificate of its prior
calibration against a primary standard hydrometer/densitometer which shall be issued by a
recognized bureau of standard.
2.2.6 Presentation of Results
A report of the calibration exercise shall be submitted to the Department of Petroleum
Resources for approval before the hydrometer/densitometer can be used.
This report shall be accompanied by a copy of the certificate of the calibration of the
secondary standard hydrometer/densitometer that has been used as reference during the
exercise.
2.3 Calibration of Pressure and Differential Pressure Measuring Devices
2.3.1 Accreditation
Only companies or Institutions that possesses a current Petroleum Resources registration
permit as an equipment calibrator shall be eligible to carry out Pressure and Differential
Pressure Measuring instrument calibration with participation of representative(s) of The
Department of Petroleum Resources.
2.3.2 Principle
Pressure and Differential Pressure Measuring devices shall be calibrated by a pressure
calibrator that is certified as intrinsically safe. The Pressure Calibrator shall have the ability
to apply pressure to a pressure transmitter or pressure switch while simultaneously
measuring the mA signal or switch contacts.
2.3.3 Frequency of Calibration
All Pressure and Differential Pressure Measuring devices shall be calibrated and certified in
the presence of DPR official before being put to use and thereafter annually.
2.3.4 Applicable Standard
Calibration method shall be as outlined in latest applicable ASTM and American Petroleum
Institute Manual of Petroleum Measurement Standard (API MPMS).
2.3.5 Verification and Calibration
2.3.5.1 All new Pressure and Differential Pressure Measuring devices shall be deemed
calibrated before use and annually thereafter. Certificate of calibration issued by the
manufacturer shall be acceptable as evidence of calibration.
2.3.5.2 If a Pressure and Differential Pressure Measuring device calibration error exceeds
one-half of the scale division, error correction shall be applied whenever the
instrument is used.

2.3.6 Presentation of Results
A report of the calibration exercise shall be submitted to the Department of Petroleum
Resources for approval before the Pressure and Differential Pressure Measuring device can
be used.
This report shall be accompanied by a copy of the certificate of the calibration of the
secondary standard Pressure and Differential Pressure Measuring device that has been used
as reference during the exercise.