Standby generators provide energy in the instance of a power outage and are excessively helpful in situations where lack of power – even if temporarily – can cause human or financial loss.

However, if the fuel tank is too small to meet your energy needs or is not the right type for the application, it’s of no use. That’s why it’s essential to learn about the types of generator fuel tanks and to determine their capacities for your particular requirements.

How To Determine The Required Capacity Of Generator Fuel Tanks?

First off, you need to know how much fuel a generator can house. It will give you an idea about the generator’s duration of the operation. Here are three important considerations in this regard:

Emergency Stock: You have to measure the amount of fuel you’ll need in excess if there’s a delay in supply or your consumption increases.
Lead-Time: How much time does it take for you to buy the fuel and get it to the site of the generator?
Lean Time Stock: While you’re bringing the fuel from the seller to the generator, the generator needs to be operational to ensure uninterrupted workflow. How much fuel do you need for the generator to run during this time?

Once you’ve figured out these things, you can use this formula to calculate the fuel capacity you need.

Minimum Capacity = Lead Time Stock + Emergency Stock

What Is The Best Capacity For You?

It depends on the frequency of power outages and how long they last. If you experience frequent power cuts that go on for hours, you need a generator with a higher capacity.

For infrequent power outages, you can opt for a smaller generator. However, keep in mind that you’ll have to refill it more often. Although the upfront cost will be lower, the delivery charges on refills will be higher.

If you’re purchasing a generator for a commercial setting, it must have a larger storage tank. Do note that these generators have a higher maintenance and upfront cost. But they reduce the delivery charges since you don’t have to order fuel so frequently.

Apart from the capacity, fuel tanks are also available in two types with a slight difference between both.

Single Wall: interior. Since they’re simple to make, you’ll commonly find them in generators. Single-walled fuel tanks only have one metal wall separating the exterior from the interior.
Double Wall: On the contrary, double-wall generators have two walls. The inner wall is there to retain a leakage, in case there’s one. These fuel tanks are less common, but they’re good for the environment since they prevent pollution.

Tank Calculator

If you have a generator but are uncertain about its tank capacity, you can use the Tank Calculator to measure how much fuel the tank can store.

All you have to do is measure the diameter and length of the tank. Then, you need to choose the type of tank:

Horizontal
Rectangular
Vertical

With this information, the calculator will tell you the amount of fuel needed to fill the tank. You can convert the results into different units:

Meters cube
Feet cube
Gallons
Barrels

The tool also has a Volume Converter that you can choose to convert the units to six different options, depending on the standard in your country.

Types Of Generator Fuel Tanks

When it comes to generator fuel tanks, it’s hard to find one option that fits all industries and requirements. Thus, you have to consider your specific needs to choose the right fuel tank type. Here’s a short description of each type.

Sub Base Tanks

These tanks are overground, but they are below the generator set’s base. They may have double walls for added protection against fuel spillage and are normally rectangular. Moreover, the following attachments accompany these fuel tanks:

Air vent
Pressure relief valve for emergencies
Fuel supply
Fuel return
Fuel alarms (for when the fuel level is too low to too high)

These fuel tanks prevent spillages during leakages and have an inlet valve that closes automatically as the tank reaches its capacity – near 95%.

Furthermore, sub base tanks are smaller than other types and are the perfect choice for people who need to house 100 gallons. The height of a sub base tank can be as high as 40 inches – sometimes even longer than the generator itself – to accommodate the required amount of fuel.

On the flip side, some tanks are only eight inches in height. Among all types of generator tank fuels, these are the most common ones.

Underground Tanks

Underground tanks, as per their names, are under the ground. Although they are more expensive, these tanks are worth the cost because they’re protected from environmental factors.

These tanks are made of steel – that has been protected by cathodes – or plastic with fiberglass reinforcement. Unlike sub base tanks, they don’t come with spill prevention mechanisms, and this additional equipment has to be installed as underground spills can be very problematic.

Concrete walls and floors surround underground tanks.

Above Ground Generator Tanks

Finally, above ground tanks are much similar to underground tanks in terms of construction. However, their installation process differs quite a bit since they are over the ground.

When installing these tanks, you have to make sure they’re a considerable distance from all other human-occupied areas in the area since they’re a fire hazard.

Moreover, they do not have double walls or any other spill prevention mechanisms. Instead, you have to build dikes around above ground tanks to contain spills.

Make sure the volume of the dike is more than the total capacity of the tank – up to 110%. Also, these tanks are exposed to environmental factors, so they need protective covers or similar structures.

Conclusion

Since they’re a hefty and long-term investment, it’s crucial to be well-informed about generators before making a purchase. In this guide, we discussed the types of generator fuel tanks and how you can determine the fuel capacity you need for your facility.

If required, make sure to get professional consultation since modern generator sets come in different customizations, and a pro’s insight will help you make an informed decision.