Crude oil assumes a definite value for producing company.Crude oil must be tested for quality and quantity in other to ascertain its economic value.A pipeline company employee known as a GUAGER or LEASE OPERATOR measures samples and test the crude oil to determine its quality
and quantity.This operation are referred to the industry as GUAGING.

The guager applies rules which have their basis in long standing experience and experimentation.These rules have been specified by a body  called American Petroleum Institute(API),American Standard for testing Materials(ASTM)

Though individual pipeline companies usually furnish supplementary instructions.Most crude oil and its products are measured in tank and barrels, and when measuring ,sampling and testing ,the guagers responsibility includes

1. Guaging(measuring the depth of the oil in the tank)

2.Tank temperature(via the thermometer)

3.Sampling and testing for API gravity and thermometer variation using either hydrometer or density bottle

4.Sampling and testing for BS and W in suspension

5.General Inspection of tank or tank battery

6.Checking valves for leaks and faulty seals

7.Starting and completing the run ticket.

With the effort of the guager in maintaining the quantity and quality of crude petroleum acceptable in the world market, some factors influencing his accuracy are:Temperature,BS&W,,weight,viscosity and sampling.

Quantity, volume is affected by temperature changes above or below the bases of 60 degree Fahrenheit, which is the oil industry standard temperature for a net barrel of oil,equivalent to 42 us gallon.On the other hand quality is based on the gravity of the crude oil at indicated temperature, and the percentage of foreign matter (impurity) within the crude oil is known as BS&W


May be considered as the act of taking a representative quantity of a substance for the purpose of testing the quality of the substance.
Therefore any equipment which by design is employed in carrying out sampling could be registered as a sampling equipment.
Two type of sampling are done in the oil industry: static and dynamic sampling techniques.The former is done more or less on a static fluid while the letter is done on a flowing fluid because of these significant difference the both methods different equipment are used.

During tank fiscalization (under static method) a process for the measurement of the liquid level and withdrawing of samples from the tank is done with an instrument or equipment called "thief can"
This is made of brass material with a weighted bottom for easy sinking

The can is often lowered into the tank at a predetermined depth.the sample withdrawn is transferred to another container known as the sample can which is made of either a metallic or plastic material.The sample in a metallic container suffers relative temperature losses due to its good nature of conductance , and it is therefore not the best in most cases.

The sample can is first watched off all foreign matter in its internal walls.Then it is labelled according to the information on the tank from which sample is to be collected and then rinsed with the liquid to be put into it,and then the sample can is filled with the liquid
For the dynamic method,some of the ready sampling equipment includes the automatic sampler. the ultrasonic tape, the sample can and the sample probe.
The automatic sampler is a metallic container installed along pipeline in the meter bank unit in terminals for sampling crude oil during loading.It operates on the principle of positive displacement,that is a given volume of sample is discharged into the container for every known predetermined rate of discharge.Some are capable of holding up to five liters of sample while others take more or less depending on the design.

The ultrasonic tape is contained in a housing with contains batteries.At the tip is an electronic unit which is capable of sending electrical pulse through the transmitter to the meter unit where the pulse are converted to metric unit.

It actually samples the required temperature level relative to the total liquid height in the tank and also determines oil water interface.

This is achieved when the tape makes breaking noise.
The ultrasonic sampling has the same description with the former.The only discrepancy that exist is the ability of the tape to measure temperature values at desired depth.The ultrasonic equipment has a brass cut for picking samples as it travels along the liquid column


Generally, it is a concept of comparison, a rule that is to be used as a basis for judgement and determination.This is handled by specified bodies e.g the API, ASTM and OCMA to mention but a few.This is to serve as a clearance between the oil industries and the consumers of their products.In this agreement, it is stipulated that all oil delivered to pipeline is subject to testing and must attain certain quality.

In order to access the quality and quantity determination of crude oil sample, a set standard is necessary.

Without a set standard,negotiations and transactions would be highly impeded between the producer and the purchaser.Through the knowledge of a set standard,experience has shown that temperature affect crude oil (shrinkage) and if not considered carefully will lead to loss of purchasers.


BS&W determination is one of the various  test carried out in the laboratory to ascertain their international market value.
Crude oil is produced from the reservoir with lots of impurities especially water and sludge
In actual practice,it is totally inconceivable to remove all the impurities from crude but can be reduced a great deal.International BS&W value is 1%.
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