A fuel dispenser is a machine at a filling station that is used to pump gasoline, diesel, ethanol fuel, or other types of fuel into vehicles. Fuel dispensers are also known as bowsers (in Australia)., petrol pumps (in Commonwealth countries), or gas pumps (in North America).
Design
A modern fuel dispenser is logically divided into two main parts: an electronic "head" containing an embedded computer to control the action of the pump, drive the pump's displays, and communicate to an indoor sales system; and secondly, the mechanical section containing an electric pump and valves to physically pump the fuel. In some cases the actual pump may be sealed and immersed inside the fuel tanks on a site, in which case it is known as a submersible pump. A green or yellow handle is used to warn people that the fuel dispensed is diesel.Flow measurement
One of the most important functions for the pump is to accurately measure the amount of fuel pumped. Flow measurement is typically done by a turbine in the fuel flow. In older gas pumps, the turbine is physically coupled to reeled meters (moving wheels with numbers on the side), while newer pumps turn the turbine's movement into electrical pulses using a rotary encoder.Communications components
The technology for communicating with gas pumps from a point of sale or other controller varies widely, involving a variety of hardware (RS-485, RS-422, current loop, and others) and proprietary software protocols. Traditionally these variations gave pump manufacturers a natural tie-in for their own point-of-sale systems, since only they understood the protocols.An effort to standardize this in the 1990s resulted in the International Forecourt Standards Forum, which has had considerable success in Europe, but has less presence elsewhere.
Other components
A modern gas pump will often contain control equipment for the vapor recovery system, which prevents gasoline vapor from escaping to the air.Manufacturers
Fuel dispensers are made by many different companies throughout the world. In earlier decades, it was common for each country to have several competing manufacturers, but consolidation and globalization has occurred in this industry, so that many formerly well-known names such as Satam, Schlumberger and EIN no longer exist as independent companies.
Some of the largest remaining manufacturers are Tokheim, Gilbarco Veeder-Root, Dresser Wayne (of Dresser Industries), and Tatsuno Corporation .
Variations
Modern designs
In modern pumps, the major variations are in the number of hoses or grades they can dispense, the physical shape, and the addition of extra devices such as pay-at-pump devices and attendant "tag" readers.In some countries, pumps are able to mix two grades of fuel together before dispensing; this is referred to blending. Typical usages are to add oil to petrol for two-stroke motorcycles, or to produce an intermediate octane rating from separate high and low octane fuels.
Early designs
Regulations
Since fuel dispensers are the focal point of distributing fuel to the general public, and fuel is a hazardous substance, they are subject to stringent requirements regarding safety, accuracy and security. The exact details differ between countries and can depend to some extent on politics. For example in countries fighting corruption, gas pumps may be more stringently monitored by government officials, in order to detect attempts to defraud customers.Typically, individual pumps must be certified for operation after installation by a government weights and measures inspector, who tests that the pump displays the same amount that it dispenses.
References
External links
Hosed at the Pumps: an Ottawa Citizen investigation in to Canadian fuel pump accuracy, with a searchable database on inspection records. By journalists Glen McGregor, Jessey Bird, Doug Schmidt, and Barb Pacholik.
This article is licensed under the GNU Free Documentation License.
Last updated on Tuesday July 15, 2008 at 23:47:48 PDT (GMT -0700)
View this article at Wikipedia.org - Edit this article at Wikipedia.org - Donate to the Wikimedia Foundation
Copyright © 2008, Dictionary.com, LLC. All rights reserved.