Custodial measurement is considered one of the most important technical and regulatory pillars for sectors such as sugar and ethanol, oil and gas, biofuels, energy, mining, and petrochemicals. It ensures precision, traceability, and reliability in commercial transactions of liquid products and industrial fluids. In an increasingly regulated environment, investing in reliable systems makes a direct difference to companies' revenue. See how it works.
What is custody measurement?
Custodial measurement is the technical and regulated process of accurately measuring the volume, mass, and operational variables of liquid or gaseous products. This measurement is crucial in purchase and sale transactions, tax audits, inventory control, and property transfers. In practice, it ensures that buyer and seller agree on the quantity actually transferred, guaranteeing transparency and avoiding discrepancies.
in the sector of oil In the case of gas, for example, custody transfer occurs every time the product changes hands along the logistics chain. This happens in pipeline transport, terminal storage, ship loading, arrival at refineries, and multiple other stages. Each transfer requires extremely precise measurements, as the commercial value is directly determined from these quantities. In biofuels, chemicals, and liquid foods, the principle is the same: quality and quantity need to be reliably measured to avoid losses, contamination, tax errors, and commercial disputes.
Custody measurement also plays a crucial role in the sugar and ethanol industry. Hydrated and anhydrous ethanol need to undergo high-precision measurements at every stage of the chain, from the tanks at the mills to shipment to distribution centers. Because the product involves a large volume of movement and has a direct impact on revenue, any minimal variation can lead to tax discrepancies, financial losses, and commercial disputes. Therefore, this procedure is also crucial in the sector, as it ensures transparency, traceability, and regulatory compliance.
The importance of custody measurement increases even further when considering the high added value of the commodities involved. A small difference of tenths of a percent can represent hundreds of thousands of reais in a single large tank. Therefore, the measurement must follow strict norms and international standards that ensure legal validity and complete auditability.
Why is custody measurement important?
Custody measurement plays a fundamental role for financial, regulatory, and operational reasons. In financial terms, it accurately determines the monetary value involved in the transaction. A seemingly small error can represent improper billing, incorrect charges, or loss for one of the parties. In operations repeated daily, any recurring inconsistency translates into accumulated financial loss.
From a regulatory standpoint, sectors like oil and gas must adhere to strict standards established by the ANP (National Agency of Petroleum, Natural Gas and Biofuels), Inmetro (National Institute of Metrology, Quality and Technology), and international organizations. These rules define everything from the type of instrument to be used to acceptable calculation methods and tolerances. Companies that fail to meet these standards may face sanctions, operational blockages, and enormous legal difficulties.
From an operational perspective, accurate measurement prevents disputes between agents, reduces the time required to close transactions, and increases the reliability of internal processes. Precise equipment and modern systems reduce the risk of human error and standardize routines, leading to greater predictability and efficiency.
Another essential point is safety. Historically, tank measurements were performed with a tape measure or ruler, requiring operators to climb to the top of the tank. Besides being inaccurate, this method exposed workers to falls, flammable fumes, and the risk of sparks when touching the product. Modern automation completely eliminates this scenario, removing the need for manual measurements and drastically reducing the likelihood of accidents.
How does custody measurement work?
Measurement can occur in continuous flow, common in pipelines, refineries, and terminals, or in stationary tanks where the product remains stored. In both cases, the principle is the same: to measure variables such as flow rate, temperature, pressure, density, and level to determine the actual quantity of product under reference conditions.
Continuous flow measurement
In flow systems, devices such as ultrasonic, mass, turbine, or differential pressure flow meters collect data in real time. These instruments send all the information to a flow computer, which is responsible for applying corrections stipulated in technical standards, such as compressibility factors, thermal expansion, base density, and other variables that influence the final quantity. These corrections are essential because the density and volume of fluids vary with temperature and pressure. Without standardization, it would not be possible to compare values between different locations and operating conditions.
Measurement in tanks
In tanks, measurement involves monitoring the liquid level, temperature at different heights, and the density of the product column. These values are fed into algorithms defined by standards such as API MPMS, which calculate the liquid volume and the volume corrected for standard temperature. This correction is fundamental to ensuring fiscal reliability, since environmental variations significantly influence the result.
Manual measurement using a ruler or tape measure, despite being traditional, presents significant variability and puts the physical integrity of operators at risk. Exposure to the top of the tank, flammable vapor, and direct contact with the product creates risks of falls, poisoning, and ignition. Furthermore, manual measurement is performed at a single point, ignoring variations in temperature and density along the height of the tank. This results in inaccurate inventories and tax discrepancies.
Automation solves these problems by performing continuous, multi-point measurements without human intervention. This generates more accurate inventories, increases the reliability of reports, and ensures compliance with international standards.
Standards applicable to custody measurement
Custodial measurement is among the most regulated areas of the industry. In Brazil, the main framework is... Joint Resolution ANP/INMETRO No. 1/2013This establishes mandatory criteria for measuring alcohol, petroleum, and its derivatives, including requirements for instruments, calculation methods, and traceability. Inmetro also certifies equipment and oversees procedures to ensure that systems have a reliable calibration history that adheres to international standards.
Internationally, the API MPMS (Manual of Petroleum Measurement Standards) is a global reference, detailing procedures for measuring level, temperature, density, sampling, and volumetric calculations. For natural gas, guidelines from the AGA (American Gas Association), such as AGA 3, AGA 7, and AGA 9, are widely used. ISO 5167 defines rules for differential pressure measurement, while ISO 6976 establishes calculations for the calorific value of gas.
Together, these standards ensure that the measurement process is technically accurate, legally valid, and auditable. Everything, from instrument installation to data storage, must follow standardized procedures.
Alutal solution for custody measurement.
In this highly technical environment, companies that work with petroleum, derivatives, chemicals, biofuels, and ethanol, especially in transfer and storage operations, rely on specialized suppliers, such as Alutal. The company designs and integrates systems that rigorously follow the standards of ANP, API, AGA, ISO, and Inmetro, ensuring metrological and fiscal compliance at all stages of measurement.
Among the solutions is the work BJLM Servo ATG, replacing the old, manual ruler, which prevents accidents.
The BJLM-80H Series TGS is a modern system designed to provide accurate multipoint level, temperature, density, and oil/water interface measurements. One of its main advantages is performing all these measurements using only one tank nozzle, which drastically reduces the need for mechanical intervention, facilitates installations in older tanks, and lowers infrastructure costs.
In addition to being built for classified areas and operating safely in explosion-risk environments, the BJLM-80H allows for local or remote configuration and can communicate with up to 32 instruments. Joyo software automatically processes all collected data and delivers corrected volume and mass calculations in real time.
The process is fully automated: the displacer floats on the surface, descends measuring temperature and density at multiple points, identifies the oil/water interface, and returns to continue monitoring the level continuously. All this occurs without human contact, preserving operator safety and ensuring complete metrological repeatability.
The system also eliminates the need to climb to the top of the tank, avoiding risks of falls, contact with flammable vapors, sparks, and exposure to chemicals. In addition to safety, automation ensures much more accurate inventories and reduces tax discrepancies, bringing direct benefits to operations.
Custody measurement calculator proves savings.
To demonstrate the equipment's effectiveness, Alutal presents its custody measurement calculator, where the client can clearly visualize the potential savings by adopting high-tech equipment certified by the OIML, such as the BJLM-80H Series TGS JOYO.
By using the calculator, it's possible to see how this lean architecture translates into real savings: less material usage, fewer field interventions, and greater overall process efficiency. This optimization is especially valuable in operations where multiple nozzles are not available or where each intervention represents high costs.
For those seeking a reliable, accurate, and internationally recognized solution, Joyo offers equipment that raises the standard in custody measurement. Try it out! uncertainty calculator clicking here.
Take advantage and explore our universe of Products for Custody Measurement with the Alutal quality seal.
