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

Page 29 of 114

28 | P a g e

3.1 Quality parameters for Fiscal Measurement
3.1.1 Relative Density (Specific Gravity)
This is defined as the ratio of the mass of a given volume of liquid at a given temperature
to the mass of an equal volume of pure water at the same temperature.
3.1.2 API Gravity
This is a special function of relative density (Specific Gravity) at 60/60˚F represented by API
Gravity = (141.5/specific Gravity @60/60˚F) – 131.5.
3.1.3 Base Sediment and Water (BS&W)
This is a measure of the percentage of solid impurities and water content of a petroleum
and petroleum product sample. This parameter is used to deduce the quantity of net
petroleum and petroleum product in a batch or cargo.
3.1.3.1 The Base Sediment & Water (BS&W) in percentage (%) obtained from automatic
sampler as composite samples shall not exceed 0.50% for all export crude oil cargo.
However, when the prescribed parameter of 0.50% BS&W is exceeded consecutively more
than three times, outturn verification shall be mandatory, and company shall ensure that
the Department witnesses the exercise.
3.1.3.2 If the cause of frequent off-specification cargo of high BS&W% is a characteristic
nature of the petroleum and should the abnormal source of the above challenge remain
the same, the company shall apply to the Director, Petroleum Resources for an approval
for a specific period to continue the export of those cargo enumerating their peculiar
situation.
3.2 Procedure for Determining Relative Density (Specific Gravity)
In carrying out the measurement of the specific gravity of a petroleum and petroleum
product sample for fiscal measurement purpose, the standards and procedures outlined in
ASTM D1298/API MPMS Chapter 9 shall generally be followed.
3.2.1 Equipment Specification
3.2.1.1 Thermometer: Shall conform to the type IP 64F or ASTM E 100 No. 12F and shall be
of range -5˚F to 215˚F interval 0.5ᵒF and a scale error of not more than ±0.25F. Its calibration
shall be supported with a certificate issued by an approved authority which is recognized
by the Department of Petroleum Resources and shall be periodically calibrated as specified
in this guide under part III
3.2.1.2 Hydrometer: Shall be glass type, graduated preferably in units of API gravities. Shall
conform to the type BS718: 1960 L50 SP with meniscus correction of ±0.0007, M50 SP with
meniscus correction of ±0.0007 to ±0.0014, for hydrometers of the SG type or of type ASTM
E100 Nos. 1H or 10H long and plain for API Gravity hydrometers. The accuracy of the
instrument shall be confirmed by a certificate issued by a standardizing authority which is
recognized by the Department of Petroleum Resources.
3.2.1.3 Constant temperature Bath: This shall be a thermostatically controlled water bath to
be maintained at about 60˚F with a maximum temperature fluctuation of ±5˚F.