Fuel & Fuel Oil Link to homepage.

Introduction

Though handling fuel oils are not necessarily "challenging," the reliable handling of fuel oils is critical for heating and transportation systems.  Rotary pumps are an excellent means of loading/unloading, transfer, and circulating fuel oil. As the following table shows, application details vary widely.

Capacities: .23 to 230+ M3/H 1 to 1,000+ GPM
Pressures: 1.75 to 175 BAR 25 to 250 PSI
Viscosities: 6.6 to 1,650 cSt 30 to 7,500 SSU
Temperatures: Outdoor ambient to 120C Outdoor ambient to 250F

Pump configurations will also vary from application to application. For example, pump options may include relief valves, mechanical seals, steel-fitted construction, carbon bushings, and jacketing to name a few. Drives may vary as well, from direct drives to gear reducers or V-belts.

Typical dual-pump set up for transferring No. 2 fuel oil.

Slower speeds, lower pressures, and materials designed for the anticipated temperature will pay off in longer trouble-free service, even if oil properties vary from those originally anticipated. Simple do's and don'ts of oil fuel pumping include:

Do's and Don'ts

Don'ts

Installing a vacuum gauge and a pressure gauge on or near the pump will also help lengthen service life. Gauges provide a window into what is happening inside the pumping system. Properly interpreted readings can give clues to the nature of many problems. Long-term readings will show gradual changes taking place within the system.

Typical large capacity No. 6 fuel oil unloading installation.

Given the availability of certain fuels at any particular time, many fuel oil systems now accommodate No. 2 through No. 6 fuel oils. Each fuel oil differs slightly in properties and these differences place unique demands on the system.

Viscosity

Temperature

Lift

Lift is the vertical distance from liquid level to pump port.

Strainer

A strainer prevent solids from entering the pump.

Pump

Overpressure Protection

Any PD pump should have overpressure protection. That is, there should be some provision in the system or drive to protect the pump and piping from excessive pressures in case of unintentional closing of the discharge line.

Some manufacturers include relief valves as standard equipment on heavy duty pumps. Moreover, a second pressure relief valve is mounted in the line set at a lower pressure than the one on the pump. This keeps the pump-mounted valve from bypassing except in extreme emergencies. Continual bypassing of the pump-mounted valve can cause heat buildup, vapor bubbles, and a potentially dangerous situation.

Mount inline pressure relief valves near the pump. Significant pressure drops may result if the valves are far away from the pump. Also bear in mind that a small return line from the valve may have a significant pressure drop which adds to the differential pressure across the valve.

Suction Line Size & Suction Check Valve Location

If the pump is below the storage tank, suction line size on either a No. 2 or No. 6 fuel oil system is not a problem as long as calculations indicate the vacuum condition at the pump will not exceed 15" Hg. Even with a "flooded" suction (a liquid above the level of the pump) it is possible to pull a vacuum at the pump if the pipe friction losses exceed the suction head pressure.

With the pump above suction lift, the liquid level in an underground storage tank, the suction line size for handling No. 2 fuel oil should at least equal the port size of the pump. Lift and line loss calculations will indicate if the next size larger is necessary.

 



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