7 replies to this topic

[vinod]

Sir

I have a jet fuel storage tank....................it has a floating type suction in the outlet line ,which going to the suction of a pump......why a floating type is given?

Vinod

[Art Montemayor]

Vinod:

If you are a practicing engineer and have, from time-to-time, had to be transported by helicopter to an off-shore platform or a remote jungle processing unit (as I have) then this topic should be of much importance to you. The helicopter you fly should be using JP-type of fuel and it should be kept in mind that passenger lives depend on the quality of such fuel. An off-spec fuel can cause an engine failure in flight and the consequences are often fatal. That is why JP fuels are held to a rigid standard and experienced and qualified pilots often personally test the quality of the fuel that is pumped into their aircraft. Water and other contaminants accumulated in storage tanks can cause an engine failure if they are allowed to be pumped into the aircraft.

Water is denser than Jet A, and will collect on the bottom of a tank. Jet A storage tanks must be “sumped” on a regular basis to check for water contamination. It is possible for water particles to become suspended in Jet A, which can be found by performing a “Clear and Bright” test. A hazy appearance can indicate water contamination beyond the acceptable limit of 30ppm (parts per million).

To avoid the pumping of any water (or other contaminant) floating suction units are available in various configurations suitable for a wide range of tank types, sizes and products.

The floating suction unit is designed to keep the product inlet at a set position below the surface of the product to stop unwanted particles on the surface from being drawn-off.

Floating suctions are able to siphon a product from just under the product surface, regardless of the surface level. This design avoids sucking up particles or sediment deposited at the bottom of the reservoir.

The floating suction design is usually equipped with swivel joints and a float. It adjusts itself automatically to the level of the product, thus guaranteeing uncontaminated transfer. A low stop prevents the floater from dropping to the lower, water deposit area.

I don't know who designed and fabricated your floating suction unit, but if I were you, I would be very interested in keeping it operating 100% efficient, 100% of the time.

[vinod]

Dear Art


Its an amazing answer.Thanks a lot.

Regards

Vinod

[djack77494]

Just goes to illustrate an amazing principle that all people practicing design should keep in mind. Whenever something looks strange, there is probably a reason. Tend not to change it unless you understand that reason. If you don't understand an existing design, you should come to master it before instituting changes to it. Some might give it a cute label like, "First do no harm". Happy designing.

[Qalander (Chem)]

Dear vinod,

Although this might be surprising or even shocking that the floating suction system if not equipped with some sreen or mesh can suck floating impurities/contaminants especially if Jet fuel storage tank roof, breather/vent system is not maintained good and Bird's nest etc. foreign materials find their way in &onto surface of tank material.

Another thing on watch-out list may be a 'lid closed sample bottle' if dropped by sampling personnel accidentally.

Such things get into floating suction un-noticed and may be cause of unexpected problems (Although remote possibilities).
Hope this helps
Qalander

[extradoctor]

Dear Art

In some depot facilities, jet fuels are stored in the internal floating roofs. Is it possible to use this floating suction devices in this tanks? Does we have any limitation due to internal moving deck?

Regards

[herrani]

Hi there

We have installed floating outlets in two internal floating roof tanks in our refinery, to be used for oil skimming in water tanks, and we have not had any problems with that. I believe that the floating roof tanks usually have a mechanical stop, so that the roof can never go the whole way to the bottom of the tank when it is completely empty. you should just ensure that there is enough space in there for your floating outlet device.

[kkala]

A floating suction takes liquid nearly from upper ceiling of liquid, not from bottom. There must be some reason for it.
Probably the intent is to avoid settled water, that could appear even if the jet fuel enters the tank fully dry - you do not know what could happen after a rain. Water is not permitted at all in aviation fuels, since it could plug fuel injection due to freeze in high altitudes. Generally water is not desirable in all fuels, though acceptable limits vary from one sort of fuel to another.