Engineer’s Guide Tank Gauging

McCabe and Sons Blog

Tank gauging is critical to the efficient operation of the petroleum supply chain and is widely used in various industries, including automotive, oil and gas, chemical, and power generation. Its primary goal is to precisely determine the volume of the product in a tank.

This article will discuss the fundamentals of tank gauging, including the special indicator paste products from McCabe & Sons.

What Is Tank Gauging?

Tank gauging is the measurement of liquids in large storage tanks to calculate the volume of the product stored in the containers. The measurement system is determined by the tank type, the kind of liquid, and how the tank is used.

Hand estimation is the traditional tank gauging technique that can only be used on atmospheric tanks. This method uses a custom metallic measurement tape to determine the ullage or the distance from the tank’s reference point to the liquid surface. Then, the product level is calculated by subtracting the ullage from the reference height.

Meanwhile, modern systems automate tank measurements before digitally transferring data to a central station. This station will distribute the information to inventory data users.

Tank gauging is required wherever liquids are stored or preserved in large tanks. These containers are typically found in the following industries:

Distribution terminals
Refineries
Vessels (Transportation)
Fuel depots
Petrochemical industry
Air fueling storage at airports
Chemical storage

Common Tank Gauging Technologies and How They Work

Different tank gauging technologies have emerged over time. Some of the most common techniques and solutions are as follows:

Hand Gauging

Hand gauging is a common technique used on atmospheric tanks. It utilizes a specially designed measurement tape, typically made of stainless steel, and has a weighted bob at the end graded in millimeters or fractions of an inch. A high-quality, newly calibrated tape is necessary for proper and precise hand gauging.

Float Gauging

Float gauging involves having a large float connected to metallic tape inside the tank. A pulley system connects the tape to a spring motor and a mechanical numeric indicator at the lower end of the tank’s exterior. One of its benefits is that it requires no external power because the movement of the liquid level drives the entire mechanism.

Servo Gauging

Servo gauging uses a small displacer instead of a float. The displacer is buoyant but does not necessarily float on the liquid. It is also held up by a thin wire that connects to the servo gauge on top of the tank. Additionally, a weighing system in the gauge detects wire tension and sends signals to the mechanism control, causing the displacer to follow the liquid level’s movements. Finally, an electronic transmitter sends the data to the control room readout via field buses.

Radar Gauging

Radar gauging has no moving parts and requires little to no maintenance. It also does not necessitate direct contact with the liquid to determine the tank’s contents. Consequently, a radar gauge can be used on a wide range of liquids, from heated heavy asphalt to cryogenic liquefied gases.

High-Quality Indicator and Gauging Pastes From McCabe & Sons

For over 80 years, McCabe & Sons has been developing tools to improve and streamline the processes of tank gauging and inventory verification of bulk liquids. The products include McCabe H₂O Plus+ Water Level Indicator Paste and McCabe Gasoline Level Indicator Paste.

The McCabe H2O Plus+ Water Level Indicator Paste is a dark green paste that changes to a dark purple color when it comes into contact with water. This product provides a quick and easy visual solution for determining the presence and depth of water in a storage tank.

The McCabe Gasoline Level Indicator Paste is a tank gauging paste that turns from light blue to dark blue when immersed in petroleum products. While initially designed for light hydrocarbons, the paste also performs well with light crude oil, plant oils, and other petrochemicals.

Partner With McCabe & Sons for Premium Indicator Pastes

McCabe & Sons produces only the highest-quality indicator pastes to help with inventory control and tank gauging of petroleum products! We are committed to providing our customers with quality products, which has earned us a solid reputation and direct involvement with various sectors, including petroleum terminals, refining facilities, service stations, the inspection industry, and the barge and shipping areas.