Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Why ’filling-it-up’ takes more than ’tank capacity’

24.10.2005


You fill up your "empty" fuel tank at the gas station and the pump charges you for more gallons than the tank’s rated capacity. Are you being deliberately overcharged?


Simplified schematic of a vehicle fuel tank (not to scale). Credit: J.Williams/NIST



Unauthorized tampering with pumps does happen, even though state and local weights and measures officials regularly check gasoline pumps to ensure their accuracy. But there are also legitimate reasons for a discrepancy between the amount of fuel metered by a gas pump and an automobile’s rated fuel tank capacity, according to a recent paper from the National Institute of Standards and Technology (NIST).

For example, some manufacturers estimate that actual fuel tank capacity can vary as much as 3 percent from the tank capacity rating because of design characteristics, the manufacturing process, and even the physics associated with the components that monitor emissions and the electronics of the fuel system and fuel indicators.


NIST notes that it is important to consider which parts of a vehicle’s fuel tank are used to determine its capacity rating and what happens to these components when operating and fueling a vehicle. A small area at the bottom of a full tank is considered unusable because the fuel pump cannot reach that level to draw fuel. In addition, the tank’s rated capacity does not include the "vapor head space," the uppermost portion of the tank compartment, nor does it include the volume of the filler pipe where fuel enters the vehicle.

Drivers, however, sometimes fill the tank beyond the pump’s automatic shut-off point, resulting in fuel being drawn into the vehicle’s vapor recovery system or filler pipe. Similarly, if the lanes that surround the service station pumps are not level, fuel can shift into the vapor space allowing more fuel to be delivered into the tank.

NIST cautions against using the "half full" reading on the fuel gauge to determine the exact number of gallons it will take to fill the tank. The fuel gauge is intended as an approximate indication of the fuel level. Manufacturers may set the "full" indicator at a level just below the tank’s actual capacity. Reserve fuel also can be present if the manufacturer designs the fuel gauge to indicate empty at a level above the actual point where the tank runs out of gas.

John Blair | EurekAlert!
Further information:
http://www.nist.gov
http://ts.nist.gov/ts/htdocs/230/235/archive/B-014.pdf

More articles from Power and Electrical Engineering:

nachricht Silicon solar cell of ISFH yields 25% efficiency with passivating POLO contacts
08.12.2016 | Institut für Solarenergieforschung GmbH

nachricht Robot on demand: Mobile machining of aircraft components with high precision
06.12.2016 | Fraunhofer IFAM

All articles from Power and Electrical Engineering >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

Closing the carbon loop

08.12.2016 | Life Sciences

Applicability of dynamic facilitation theory to binary hard disk systems

08.12.2016 | Physics and Astronomy

Scientists track chemical and structural evolution of catalytic nanoparticles in 3-D

08.12.2016 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>