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Back pressure (or backpressure) is the term for a resistance to the desired flow of fluid through pipes. Obstructions or tight bends create backpressure via friction loss and pressure drop.
In distributed systems in particular
A common example of backpressure is that caused by the exhaust system (consisting of the exhaust manifold,
event-driven architecture
Event-driven architecture (EDA) is a software architecture paradigm concerning the production and detection of Event (computing), events. Event-driven architectures are Continuous design, evolutionary in nature and provide a high degree of fault to ...
, back pressure is a technique to regulate flow of data, ensuring that components
Component may refer to:
In engineering, science, and technology Generic systems
*System components, an entity with discrete structure, such as an assembly or software module, within a system considered at a particular level of analysis
* Lumped e ...
do not become overwhelmed.
Explanation
A common example of backpressure is that caused by the exhaust system (consisting of the exhaust manifold, catalytic converter
A catalytic converter part is an vehicle emissions control, exhaust emission control device which converts toxic gases and pollutants in exhaust gas from an internal combustion engine into less-toxic pollutants by catalysis, catalyzing a redox ...
, muffler and connecting pipes
Pipe(s), PIPE(S) or piping may refer to:
Objects
* Pipe (fluid conveyance), a hollow cylinder following certain dimension rules
** Piping, the use of pipes in industry
* Smoking pipe
** Tobacco pipe
* Half-pipe and quarter pipe, semi-circu ...
) of an automotive four-stroke engine
A four-stroke (also four-cycle) engine is an internal combustion (IC) engine in which the piston completes four separate strokes while turning the crankshaft. A stroke refers to the full travel of the piston along the cylinder, in either directi ...
, which has a negative effect on engine efficiency, resulting in a decrease of power output that must be compensated by increasing fuel consumption.
In a piston-ported two-stroke engine
A two-stroke (or two-stroke cycle) engine is a type of internal combustion engine that completes a Thermodynamic power cycle, power cycle with two strokes of the piston, one up and one down, in one revolution of the crankshaft in contrast to a f ...
, however, the situation is more complicated, due to the need to prevent unburned fuel/air mixture from passing right through the cylinders into the exhaust. During the exhaust phase of the cycle, backpressure is even more undesirable than in a four-stroke engine, as there is less time available for exhaust and the lack of pumping action from the piston to force the exhaust out of the cylinder. However, since the exhaust port necessarily remains open for a time after scavenging is completed, unburned mixture can follow the exhaust out of the cylinder, wasting fuel and increasing pollution. This can only be prevented if the pressure at the exhaust port is greater than that in the cylinder. Since the timing of this process is determined mainly by exhaust system geometry, which is extremely difficult to make variable, correct timing and therefore optimum engine efficiency can typically only be achieved over a small part of the engine's range of operating speed.
Liquid chromatography
Back pressure is the term used for the hydraulic pressure required to create a flow through a chromatography column inhigh-performance liquid chromatography
High-performance liquid chromatography (HPLC), formerly referred to as high-pressure liquid chromatography, is a technique in analytical chemistry used to separate, identify, and quantify specific components in mixtures. The mixtures can origin ...
, the term deriving from the fact that it is generated by the resistance of the column, and exerts its influence backwards on the pump that must supply the flow. Back-pressure is a useful diagnostic feature of problems with the chromatography column. Rapid chromatography is favoured by columns packed with very small particles, which create high back-pressures. Column designers use "kinetic plots" to show the performance of a column at a constant back-pressure, usually selected as the maximum that a system's pump can reliably produce.
See also
* Exhaust pulse pressure charging * Expansion chamber * Scalar quantityReferences
{{DEFAULTSORT:BackPressure Engine technology Pressure Piping Two-stroke engine technology