diesel storage tanks for backup generators

Diesel Storage Tanks for Backup Generators

You do not need to be a generator engineer or a fuel technician to understand that a backup generator needs fuel to operate. This is especially important during an emergency when it is crucial for facilities to provide an uninterruptible power supply. During an extended power outage is the worst time to discover an issue with your tanks or fuel. There are specific facts about diesel storage tanks for backup generators of which every manager needs to be aware. Additionally, individual states may dictate additional regulations above federal guidelines.

Three Types of Fuel Tanks

1. Sub-Base Tanks

For facilities that store less than 1,000 gallons of fuel, sub-base tanks are the best option. These containers are designed to fit above the ground, and below the base of the generator set. Sub-base tanks (sometimes called belly tanks) are typically rectangular, are double-walled and are constructed of heavy gauge welded steel. They are fitted with level gauges, emergency pressure release valves, and air vents.

2. Underground Storage Tanks – UST

Larger facilities that require more than 1,000 gallons of fuel may opt for an underground storage tank. These tanks are a bit more costly to install but are protected from the environment, resulting in a longer life. Being that they are constructed from durable fiberglass-reinforced plastic, such tanks are usually ribbed to provide structural strength. There are steel manufactured designs. However, they require an appropriate cathodic protection for both the tanks and any pipes against corrosion. The caveat of underground storage tanks is that leakages and spills are often costly to address.

3. Above-Ground Storage Tanks – AST

While above-ground tanks may be similar in design, there are significant installation differences. The distinctions are based on safety standards. Above-ground tanks pose a fire hazard, therefore must be installed according to state and federal regulations. In many cases, leakage dikes need be built around the containers. The tanks also require protection from harsh environmental conditions.

Fuel Tank Capacity

There are many factors for consideration when determining regular fuel capacity.

  • Emergency Stock: How much fuel do you need that allows for delivery delays and excessive consumption? (typically a 72hr reserve)
  • Lead-Time from Suppliers: What is the time required from your supplier from purchase to delivery?
  • Lead-Time Reserves: How much fuel is minimally necessary to operate during your lead-time?
  • A simple formula helps when figuring your fuel needs: Minimal Storage Capacity = Emergency Stock + Lead-Time Stock. You will determine your fuel tank run-time by calculating consumption off a full tank.
  • Local Run-Time Code Requirements

Your local requirements can vary by state and municipality as well as federally. Therefore specific run-time guidelines differ significantly. This is especially true regarding mission critical facilities. Please check with your local regulations enforcement offices for a clear outline of your requirements. When in question, the local Fire Marshal may have jurisdiction or can be an excellent resource for providing details.

Optional Day-Tank

Sometimes facilities may be experience limits of a sub-base fuel tank. For instance, if there are new regulations or facility expansion. In these examples, an additional day-tank may be the answer. The day tank for a diesel generator has floats inside that keep the fuel level automatically topped off. This is beneficial in that when the generator starts, there is always a fuel supply ready to go.

Diesel Fuel Types

Standard diesel fuel is available in two grades, either Number 1 or Number 2. And, your local climate is an essential factor when determining the type of fuel used for powering a standby generator. In colder regions, Number 1 is a better choice as it is resistant to gelling. Number 2 diesel offers a higher energy output. Therefore it is ideal for warmer territories. Often the fuels are blended which provides the benefits of both fuel characteristics.

Fuel Polishing

After a few months diesel fuel will begin to break down and form solids. Fuel polishing and filtering serve to extend the life of the fuel by fighting micro-organism growth. It also prevents gelling and stabilizes the diesel. Fuel polishing removes water and sediment from the tank and filters contaminants. It also is an earth-friendly method that saves money by avoiding replacing a whole tank of fuel. The fuel is recycled, hence no loss of product or investment.

Fuel Quality Testing

Most issues with fuel quality don’t show up until the generator is running during a power outage. Regularly scheduled fuel quality testing is your best defense and ensures your fuel is always in optimal condition. Monitor your fuel for water and contamination, bottom sediment, or cloud points. Never worry about the reliability of your standby system. Testing also complies with the ASTM standards as required by NFPA 110.

Clean Fuels Associates is the best resource for making sure your facility is prepared for any emergency. Hopefully these facts about diesel storage tanks for backup generators give you a little insight into the importance of regular maintenance. Contact us today for an evaluation today.