Fossil fuels still provide the basic fuels that enable modern societies to function, and their use will likely continue for the foreseeable future. Also known as furnace fuel for its historic use in heating applications, fuel oil, like any other fossil fuel, requires a means to transport it, regardless of whether it’s used for heating or fuel. Oil pumps designed to convey fuel oil from storage to where it’s used must be designed to deal with its various properties.
Fuel oil pumps are also known by other names like fuel transfer pumps or just transfer pumps. Although designed to transport fuel oil, pumps of this type can also handle other liquid fuels, even those not derived from petroleum or other fossil fuels. There are numerous types of oil fuel pumping systems. Because of their diversity, it’s important for those who work with or depend upon them to understand generally how they operate.
Guidance for Fuel Oil Pump Operations
Fuel oil is a derivative of crude oil processing, used for power plant steam boilers, ships, industrial facilities, home heating, and various other applications. It consists of long-chain hydrocarbons that often include alkanes, aromatics, and cycloalkanes. Fuels like gasoline, kerosene, naphtha, and propane have smaller particles with lower boiling points, which are removed earlier in petroleum processing. Fuel oil is heavier and less volatile; like diesel fuel and oil used for lubrication, it’s distilled from crude more slowly.
Fuel oils used for commercial purposes are normally blended with other derivatives from petroleum processing to produce a product with the desired flash point and viscosity. Flashpoints for kerosene, for example, tend to be higher than the typically standard 42°C (108°F) flashpoint for fuel oil. Pumps built to transport this liquid fuel to generate heat, electricity, or both must follow certain guidelines to ensure they operate optimally.
Types of Fuel Oil
Before looking at what a fuel oil pump set entails, let’s look at the different types of fuel oils these pumping systems can carry.
Although there are subcategories for each, the five main categories for fuel oils are:
- Number 1 fuel oil: Known as number 1 diesel, jet fuel, and kerosene, it’s used in higher performance and clean diesel engines, as well as a cooking fuel for pot-type burners.
- Number 2 fuel oil: Used for domestic and some commercial heating, it’s similar in many respects to number 2 diesel.
- Number 4 fuel oil: A commercial heating oil type known as Bunker A, it’s used for burner installations that aren’t furnished with preheaters.
- Number 5 fuel oil: An industrial heating oil that requires preheating to between 171°F to 219°F (77°C to 104°C), it’s sometimes referred to as Bunker B; for some applications, it’s necessary when number 5 fuel oil is pumped to add number 2 fuel oil to change the fuel’s viscosity not to require preheating.
- Number 6 fuel oil: Also referred to as Bunker C or PS-400, this highly viscous fuel oil requires preheating between 219°F to 261°F (104°C to 127°C); it sometimes includes trace contaminants like mineral oil and water.
Rarely used since the mid-20th century, the grading category for number 3 fuel oil has merged with the number 2 fuel oil classification. Number 3 fuel oil was a category of distilled petroleum for burners needing fuel with lower viscosity.
What Makes Up a Fuel Oil Pump Set?
Fuel oil pump sets will normally include:
- Positive displacement pumps
- Duplex strainers
- Interconnecting threaded piping
- Main base frame with drain connections
- Control panel normally mounted on the main base frame
Many fuel oil pump sets will come assembled, tested, and wired. Depending on the manufacturer, some systems are even capable of customization to meet the specifications of a specific application.
Recommendations for Optimizing Fuel Oil Pump Sets
The various guidelines for fuel oil pump sets vary according to their configurations and application. Some fuel oil pumps might include carbon bushings, jacketing, mechanical seals, relief valves, steel construction, and other components. The motors driving the pumps may differ as well. These may vary depending on materials, pressures, and speeds for the estimated temperatures under which it will operate. To ensure oil fuel pumping systems work as expected, operators need to know some basics about what to do with them and what not to do.
What to do with fuel oil pumps include:
- Allowing for plenty of space in which to work around the pumping system.
- Ensuring the supply tank is located as near as possible to the pump.
- Installing a strainer in the fuel oil pump’s suction line.
- Keep manufacturer’s maintenance instructions for the fuel oil pumping system as a reference.
- Protecting from too much pressure from the pump’s discharge side.
- Putting in place preventive maintenance measures like end clearance adjustments, inspection of internal components, and maintaining proper lubrication.
- Rigorously checking alignment once piping and fuel oil pump are installed.
- Utilizing suction piping that’s straight, short, and of a larger diameter.
What not to do with fuel oil pumps include:
- Employing a suction line with a lift that’s too long and too large of a diameter.
- Running the pump above approved pressures, speeds, or temperatures.
Another way to ensure a long service life for fuel oil pump sets is installing pressure and vacuum gauges, either on or near the pump. This allows operators a real-time view of the pump’s performance. While properly interpreting the readings from such gauges can provide insight into any problems, longer-term readings can also show overall pump performance over time.
Types of Fuel Oil Pumps
A fuel oil pump must be capable of propelling liquid fuels from where they’re stored to where they’re needed. Several kinds of industrial pumps are used by the petroleum processing industry for transporting fluids. Understanding how each type functions will enable operators to keep their pumping systems performing optimally.
The basic categories of fuel oil pumps are:
Centrifugal Pumps
The most common type of fuel oil pump used in the petroleum refining industry, centrifugal pumps are named for their use of centrifugal force to rotate the pump’s impeller when it draws fluid into the pump’s intake, forcing the liquid fuel through the discharge section, with control valves that regulate the pump’s flow. While single-stage centrifugal pumps mainly transfer less viscous fluids, which require higher flow rates, they’re generally used within a larger pumping system. For more viscous fuel oil, pumps tend to be water injection pumps for secondary gas and oil recovery, while for crude oil transportation, they’re usually horizontal multistage pumps.
Diaphragm Pumps
Using positive displacement to transfer fluid, diaphragm pumps utilize a diaphragm with a valve to either increase or decrease pressure within a vacuum. This makes them especially suitable for high-volume applications like transferring fuel within a refining facility. Diaphragm pumps also feature fewer moving parts, resulting in less friction when in operation while also being compact in design. However, these pumps do not work well when low-pressure conditions develop within a fuel oil pumping system, slowing the fluid transfer. This can be mitigated with a back-pressure regulator. For this reason, they’re disadvantageous for applications without high-pressure conditions; such is the case for pumping fluids continuously over a long distance.
Gear Pumps
This fuel oil pump utilizes interlocking gears to transport fluid through displacement. Commonly used to transfer industrial fluids, gear pumps operate well with highly viscous fluids, so are often used when transporting certain chemical solutions.
The two primary variants of gear pumps are:
- External gear sets that operate using spur gears externally for pumping lubricating fluids.
- Internal gear sets that utilize timing gears to drive the shaft, which in turn moves the pump’s internal mating gears.
Using either positive or fixed displacement, these pumps transport a certain amount of fluid each time they revolve. As their gears are made with tight tolerances, they’re normally used for cleaner fuel. Oil pump systems like these will also feature a relief valve in the discharge piping to protect the pump from higher pressures.
Metering Pumps
These fuel oil pumps deliver a precise yet adjustable flow rate by moving a specific amount of fuel over a certain period. Often, a metering pump is called such based on the application for which it’s used, with many that can be described as simple reciprocating pumps that feature a diaphragm liquid end or packed plunger pumps. The former type tends to be preferred since it seals the fluid within the diaphragm so that no liquid leaks.
Progressive Cavity Pumps
Also known as an eccentric cavity pump or screw pump, these pumps use positive displacement to transport fuel oil. Pumping systems featuring these fuel oil pumps move fluid each time its rotor turns, pushing it through small sequential cavities with fixed dimensions. Progressive cavity pumps often feature in applications where particularly viscous fluids are being pumped or if blending is undesirable. Progressive cavity pumps maintain a constant flow and speed despite the system’s pressure. However, flow slippage will occur at higher pressures, so a relief valve is essential to prevent too much pressure within the piping.
Reciprocating Plunger Pumps
Universally used as industrial fuel oil pumps within the petroleum processing industry, plunger pumps utilize reciprocating motion by pistons and plungers to create pressure that moves the fluid through an enclosed cylindric chamber and into the system’s piping. These pumps maintain a constant flow rate regardless of the pressure within the system, and like progressive cavity pumps, they require a relief valve to prevent too much pressure within the pump and piping. However, because of their design, plunger pumps need maintenance more frequently than centrifugal pumps. Additionally, they make more noise during operation.
Fuel Oil Pumps & Sets by Hayes Pump
Hayes Pump Inc. designs, engineers, and builds fuel oil pumps that are built to last. Dependable and easy to operate, their robust construction and the highest quality components make our fuel oil pumps second to none. Add to this our commitment to supporting our customers after the sale, and you’ll understand why so many industries use pumps from Hayes. To learn more about our various fuel oil pump sets, contact the experts at Hayes Pump today.
