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

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2.4.5 Sampling Procedure
2.4.5.1 To conduct the sampling exercise, the “thief-can” to be used is selected and after
securing the cork on it properly, it is gently lowered to the desired level through the dip
hatch and by counting the number of knots used to graduate the cord or reading directly if
a graduated tape is used. On reaching the level, the thief-can is opened by gently jerking the
cord to allow oil to flow in. The thief-can is then allowed to stay at this depth for a minimum
of fifteen seconds for it to be filled up. Thereafter, it is gently withdrawn to the surface for
tank temperature measurement.
2.4.6 Sampling using Portable Manual Sampling Unit (PSU)
2.4.6.1 The portable manual sampling unit (PSU) is designed to obtain samples under closed
or restricted system conditions and to be compatible with vapor control valves fitted on
vessels. The use of such equipment shall generally conform with provisions of API MPMS
Chapters 8.1 and 17.2.
2.4.7 Determination of Tank Temperature
2.4.7.1 Equipment
The approved equipment shall be the mercury-in-glass thermometer of the ASTM type as
specified in API MPMS Chapter 7. It shall be either the cup case or flushing case model of a
suitable range and an accuracy of ±0.25˚F
2.4.7.2 Tank Temperature Measurement
2.4.7.2.1 The sample can after being filled up at the desired level is gently moved up and
down in the petroleum or petroleum product’s column for about two (2) minutes to allow
its content to reach a temperature equilibrium with the petroleum or petroleum product in
storage. Thereafter, the can is withdrawn and held just below the shelter of the gauge hatch
and the thermometer is inserted into it. As soon as equilibrium is reached, at which time the
thermometer reading becomes constant, the indicated temperature is observed and
recorded as the tank temperature at the level of sampling.
2.4.7.2.2 This procedure is followed for the samples withdrawn from other levels of the tank
and an average of the temperatures recorded for all the sampled levels shall be noted as
the applicable tank liquid temperature to be used for volume correction factor (VCF)
determination. For the UTI, the temperature can be read at different levels as describe
under section 2.5.3
2.4.7.2.3 Similarly, the reading on the back-up device installed on the tank for measuring
tank temperature shall be noted for comparison.
2.4.7.2.4 The back-up device shall either be of mercury-in-glass type of the same range or
the electrical resistance type as specified in API MPMS Chapter 7.
2.4.7.2.5 Thereafter, a “cocktail” of the samples withdrawn from the prescribed levels of
the tank is formed by transferring all the samples from the can into a sample container
which is properly labeled to indicate:
(a) Date of sampling and name of sampler.
(b) The tank number and depth(s) at which sample was obtained.
(c) Grade of oil sampled.
(d) Gross quantity of oil represented by sample.