Q & A > Question Details
Why is the range of electrical conductivity (unit:pico siemens/m) given as 50-450 for processing
jet-A1(kerosene fuels)?
what happen if range exceeds (i.e >520picosiemen/m) due to more chemical dosing during plant maloperations?
what does effects does it have on mechanical parts of aviation fuel?
19/11/2013 A: Naveed Ahmed, Attock Refinery Ltd., naveedahmed@arl.com.pk
Just to add, the high conductivity may upset the capacitance type fuel-gauges in aircraft.
07/07/2010 A: Lewis Buckle, Sub-Contractor to Airbus Operations Ltd, lewis.buckle@airbus.com
The velocity of the aviation fuel through a given pipe will impart an electrical charge. Dependent on the conductivity of that fuel, and the velocity, the charge will dissipate, increase, or of course there's the elusive point at which it will remain static, during transit. There are various national standards indicating 7 metres/second as being a safe limit to the fuel velocity, but some suggest that doped fuel exceeding 50 pS/m removes the risk. Through an air drop, the recommended maximum velocity is reduced to circa 1 metre/second. As the fuel is usually ejected, and is propelled by gravity, this can be difficult to achieve. In this instance the primary dissipatitive route is through the fuel itself, back to source, so a higher doping value would be recommended.
Exceeding the higher limit? I'm not sure, but thoughts of oversaturation and potential dissolution come to mind. Collected puddles of doping solution could bring potential problems to engine efficiency, particularly during take-off...
01/06/2010 A: Lindsay McRae, Pall Corporation, Lindsay_McRae@pall.com
High electrical conductivity can also be indicator of water/caustic carryover from caustic treater or water/salt breakthrough from the salt drier on jet rundown.
Besides possibly going off-spec for haze, jetfuel conductivity can be adversely effected also. Can result in corrosion in the unit itself , pipes and tanks and off spec jetfuel. TSS Spec for export quality is 1 mg/L solids. Sometimes final product filter ( 2 or 10 um absolute rated filter) is required to ensure specifications are routinely met for TSS.
A high efficiency Liquid-Liquid coalescer may be required to remove haze. Water/caustic carryover can be very stable emulsion with a low IFT (Interfacial Tension) and problematic as it increases salt consumption and may result in salty water breakthrough and foul clay tower requiring clay replacement.
15/05/2010 A: keith bowers, B and B Consulting, kebowers47@gmail.com
Jet fuel (kerosene, Jet a, 41-43 water white...) usually has a vapor pressure at normal ambient temperatures that results in explosive concentrations in a closed container--such as storage tanks, aircraft fuel tanks, 5 gal. cans.
This product is also very pure, often highly refined, and has the potential to accumulate a very high static electrical charge which can lead to spark discharge and ignition of the explosive vapors.
Note gasolines have vapor concentrations too rich to ignite, and diesel fuels are too lean, but kerosene is often not merely ignitable, but explosive.
Thus the interest in the electrical conductivity of jet fuel. Airlines and regulations require that the fuel be made safer by addition of anti-static agents to reduce the sparking potential.
Like many (most) specifications for petroleum products, electrical conductivity limits were determined by observations and measurements of many sample fuels of differing heritages under different storage and handling conditions. The acceptable range of conductivity was then established to help ensure safe storage characteristics while in fuel tanks and tank farms. Electrical conductivity too low means the fuel can hold a lot of static electrical charge. Too high a conductivity might indicate poor quality fuel due to conductive contaminants (rust, water, organic acids, copper, etc.) and thus raises those concerns. High electrical conductivity DOES NOT NECESSARILY mean the fuel is bad, but DOES indicate it is not of normally observed (known good) composition and thus should not be used in aircraft where it may cause engine damage (and potential loss of life and aircraft).