Overfill Alarms and Tank Safety Equipment: What Your Fuel Tank Setup Is Missing

You have a fuel tank on site. Maybe it is a self-bunded diesel tank from PETRO Industrial, or an old drum you have been using for years. Either way, the moment you start refuelling, you are handling a product that can spill, contaminate the ground, and land you in hot water with the EPA. The standard setup – a pump, a hose, a nozzle – is not enough to guarantee that you never overfill.

Overfill alarms and tank safety equipment close that gap. They tell you when the tank is full so you can stop the flow before fuel escapes. Without them, you rely on guesswork, a visual check, or someone standing at the tank watching an open port. For the cost of a few litres of lost fuel, you can install a simple battery-operated alarm that removes the guesswork. This article explains what overfill alarms do, which PIUSI models suit your fuel type, and how to pair them with level gauges and other monitoring gear to fully protect your site.

What Is an Overfill Alarm and Why Do You Need One?

An overfill alarm is a sensor that sits inside the tank, near the top, and sounds an audible or visual alert when the liquid level reaches the full point. It connects to a controller or a standalone horn. Most units are battery operated, so you can install them without running mains power to the tank.

For diesel, fuel oil, and similar petroleum products, the device must be ATEX or intrinsically safe (IS) to avoid igniting vapours. For AdBlue (DEF), the material compatibility shifts because urea degrades certain metals and plastics. PIUSI manufactures specific models for each fluid type.

You need an overfill alarm because Australian Standard AS1940 (the flammable liquids storage code) effectively requires one for many stationary tanks, especially in commercial and industrial settings. Even if your tank is exempt, the cost of a spill – cleanup, fines, lost product, downtime – dwarfs the price of an alarm. It is one of the cheapest pieces of safety equipment you can add to your fuel setup.

Overfill Alarm Options from PIUSI

PIUSI offers three battery-operated overfill alarms, each built for a specific liquid. They all use a float switch that triggers a high-decibel alarm (around 90 dB) when the liquid reaches the sensor. The controller box mounts outside the tank, and the sensor cable is typically 2–5 metres long, depending on the model.

The standard PIUSI Overfill Alarm (battery operated) works for most diesel and petrol applications. If your tank is in a classified hazardous zone (Zone 0, 1, or 2), you need the LOA IS model because it carries full intrinsic safety certification. For AdBlue, never use a petroleum alarm – the urea attacks standard seals and the float may not function correctly.

How Do Overfill Alarms Fit into a Complete Tank Safety Ecosystem?

An overfill alarm is one component. To meet AS1940 and to run a safe, efficient site, you should pair it with other monitoring equipment:

• Tank level gauges – The PIUSI Ocio gauge (available in standard and 4-20mA versions) measures the remaining fuel level in the tank. It tells you when you need to order a delivery. Combined with an overfill alarm, you get both low-level and high-level awareness.

• Fuel management systems (FMS) – The iPETRO range (including the iPETRO Lite FMS) automatically authorise users, record every litre dispensed, and can integrate with tank level data. When the tank is nearly full, the FMS can shut off the pump remotely.

• PETRO Industrial self-bunded tanks – Many of these tanks come pre-fitted with bungs and mounts for overfill alarms and gauges. If you are buying a new tank, spec it with the alarm from day one. Retrofitting is still easy – the PIUSI alarms use standard tank openings.

The upshot: an overfill alarm by itself is good. An overfill alarm plus a gauge plus an FMS is a complete system that prevents spills, tracks fuel usage, and keeps you compliant.

Which Overfill Alarm Should You Choose?

For a standard diesel tank in a workshop or farm, not in a classified zone: Choose the PIUSI Overfill Alarm (Battery Operated). It is simple, effective, and affordable. It runs on a 9V battery with a 12V backup if you have power nearby.

For a diesel tank located inside a hazardous area (e.g. an underground mine, a fuel depot, or a site with strict explosion-proof requirements): Choose the PIUSI High Level Alarm LOA IS (Battery Operated). It is ATEX/IECEx certified, so it will pass any safety audit.

For an AdBlue/DEF tank (urea solution): Choose the PIUSI AdBlue/DEF Overfill Alarm (Battery Operated). Do not use a petroleum alarm on AdBlue – the chemical attack will cause the float to stick and the housing to crack over time.

If you are setting up a complete refuelling station, pair the alarm with a PIUSI tank gauge and consider the PETRO Industrial self-bunded tank system. That combination gives you storage, monitoring, and overfill protection in one package.

Need help choosing the right setup? Contact the PIUSI Shop team or call 1300 987 789 for advice on your site’s specific requirements.

FAQ

Can I install an overfill alarm on an existing tank?

Yes. All PIUSI battery-operated overfill alarms come with a float sensor that fits into a standard 2-inch (50mm) bung or tank opening. If your tank does not have a bung at the top, you may need to drill and fit one – or use an adapter. The wiring to the controller is straightforward and does not require an electrician for the battery-only models.

What does intrinsically safe (IS) mean for an overfill alarm?

Intrinsically safe means the electrical energy in the device is limited so it cannot create a spark hot enough to ignite flammable vapours. The LOA IS model carries ATEX and IECEx certification, making it suitable for installation in Zone 0, 1, and 2 hazardous areas. Standard overfill alarms are not IS and must be kept outside any classified zone.

How loud is the alarm, and can I hear it from a distance?

All three PIUSI models produce an audible alarm of around 90 dB at 1 metre. That is about as loud as a lawnmower or a heavy truck engine. In a typical workshop or depot with background noise, you will hear it within 30–50 metres. For larger sites, you can install multiple alarms or connect the controller to a central monitoring system via the auxiliary outputs (available on some models).

Does the AdBlue/DEF overfill alarm need special wiring or power?

No. It uses a standard 9V battery as its primary power source, with a 12V DC backup input if your site has a nearby supply. The sensor is chemically resistant to urea, so you do not need stainless steel fittings – the housing is made from polypropylene and the float from PTFE-treated materials.

Can I use one overfill alarm for multiple tanks?

Each alarm is designed for a single tank because the float sensor must be located inside the tank it is monitoring. If you have two separate diesel tanks, you need two individual alarm kits. PIUSI does not offer a multi-tank controller for overfill alarms, but you can wire multiple alarms to a central annunciator or building management system if required.