Tank Overfill Protection Systems: The Complete Guide

Tank overfill protection systems prevent hazardous liquids from overflowing when loaded into storage tanks. Despite their importance, they can lead to issues if mishandled. Continue reading to learn about overfill system troubleshooting and how to handle these systems properly.

What Is an Overfill Gas Tank Protection System?

Overfill prevention devices are designed to quickly and efficiently shut off flows when spillage is detected in storage tanks. These monitoring safety systems are ideal for both top-loading and bottom-loading tank trucks equipped with sensors.

While a bottom tank device, known as a retain sensor, warns truckers that their tank is getting low and needs fuel, the top tank device, known as an overfill sensor, alerts them to stop filling to prevent overflow. Both sensors work collaboratively to ensure systems operate smoothly and safely.

Applications of Overfill Protection Systems

Fuel tank overfill protection systems are commonly utilized on tanker trucks to detect the overfilling of:

  • Petroleum products
  • Water and wastewater
  • Food-grade dry and liquid bulk

Elements of Overfill Protection Systems

Overfill protection systems typically involve four essential components: an electronic sensor, bottom sensors, an electric socket, and a rack monitor.

Typically attached to manhole covers, electronic sensors detect dry or wet conditions at the top of a storage tank. The bottom retain sensors of an overfill protection system are used to recognize when a tank is empty or near empty. Electronic sockets are installed on the exterior base of tankers. They are electronically connected to the interior sensors and include a physical grounding for the prevention system. Lastly, cables connect the rack monitor component to the tanker socket.

Having trouble with your overfill gas tank protection system? Contact White Tank & Truck Repair for our testing and diagnostic services.

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Overfill Gas Tank System Troubleshooting

There are several reasons compartments can overfill, including:

  • Terminal Fault

    • Terminal fault is commonly blamed for fuel tank overfill protection errors; however, it is rarely the cause. If you believe terminal fault is the cause of any issues, you should contact the terminal directly.
    • If you or your drivers can’t get the green light needed to begin filling, it could be faulty monitors, flooded probes, sockets the rack plugs into, or wiring issues. Finding a repair shop with experienced technicians who use a sophisticated testing system and run diagnostics is a great way to narrow down the cause of the problem quickly.
    • Top probes, monitors, and sockets used by loading rack equipment are easily worn or loosened from the weight of rack plugs. Insufficient voltage to monitors is another problem testing can pinpoint the cause of. If testing and diagnostics identify failed components, professionals can replace them quickly.

  • Metering Device

    • If a metering device is the source of your fuel tank overfill protection system’s problems, several likely causes exist. Often, a meter issue arises from losing connectivity to the truck cab’s printer, losing constant power to the system, or memory failure on a control board.
    • If connectivity to the printer is the problem, tickets in the meter are likely shown as needing to be printed. This error stops the system because tickets are caught and must be cleared out. The simple solution is fixing the wiring to the printer. Though less common, mechanical problems are also possible. Mechanical issues include checking valves, malfunctioning air eliminator parts, and leaking diaphragm solenoids.

  • Pump Failure

    • Pump failures, whether PTO or hydraulically driven, can be diagnosed. A common problem that leads to pump failure is bypass reliefs from adjustment. This causes the bypass to “back itself off” and triggers the pump to relieve pressure and bypass back into the pump.
    • Another pump failure cause is leaking mechanical seals. Vanes can be worn, and housing can be grooved if a large amount of grit is not caught by a screen and pumped out. While vanes can be repaired, badly grooved housing may need to be replaced. If the pump runs too fast with no product to lubricate the vanes, there’s a good chance a PTO was engaged while driving. In most cases, this leads to grooved housing or overheating bearings. The pump has to be disassembled to determine if it is repairable.

  • Verified Outage Complications

    • Virtually all loading racks require a tank to have a verified outage point. This ensures there is enough room in the compartment and that it doesn’t cause a spill. The typical outage is 60 gallons. That’s because tanks fill so quickly that 60 gallons are needed for a tank overfill protection system’s electrical signal to shut down the valves at the loading dock.

  • Partial Loads in Tankers

    • Most carriers have not adopted the “retain” portion of the loading system. The probes of a tank overfill protection system relay if a partial load is still on the bottom of the tank. Often, carriers don’t utilize this adoption because of the maintenance costs associated with caring for a second system that loading facilities don’t require.

  • Electrical Failure and Voltage Issues

    • Ideally, this is the first thing to confirm with any electrical component on a truck or trailer. Fuel tank overfill protection systems are susceptible to voltage going out of the ECU and the probes. They are built to operate with less than 12 volts, but a steady power as close to 12 volts is always a target to consider when diagnosing electrical failures.

The Benefits of Preventing Gas Tank Overfill for Your Fleet

Overfill prevention systems play a critical role in fuel tank safety. These systems prevent hazardous overfills and spillage in storage tanks. This safeguards people, vehicles, and the cargo they transport and reduces the risk of accidents and associated liabilities.

They also streamline commissioning processes, saving time and money during installation and setup. Ongoing maintenance costs are minimized as the risk of costly repairs caused by overfills is significantly reduced.

Prevent Overfill in Gas Tanks by Partnering With White Tank & Truck Repair

For over 30 years, White Tank & Truck Repair has been the go-to source for tank and truck services in Missouri, Kansas, and southern Illinois. From pump failures to terminal faults, there’s no issue too complicated or complex for our experienced technicians. We can efficiently diagnose and repair issues with your tank overfill protection system. Reach out today to schedule an appointment and get your truck back on the road with minimized downtime.

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