An eccentric reducer is a
fitting
Fitting can refer to:
** A dress fitting.
*** A fitting model, the model, trying on the clothes.
** Any machine component, piping, or tubing part that can attach or connect two or more prominent parts. For example, see coupling, compression f ...
used in piping systems between two pipes of different diameters. The same fitting can be used in reverse as an eccentric increaser or expander. They are used where the diameter of the pipe on the upstream side of the fitting (i.e. where flow is coming from) is larger than the downstream side, and where there is a danger that vapour may accumulate.
Unlike a
concentric reducer A concentric reducer is used to join pipe sections or tube sections on the same axis.
Reducer. (n.d.). Retrieved June 26, 2016, from http://www.pipingstudy.com/reducer.html The concentric reducer is cone-shaped, and is used when there is a shift in ...
, which resembles a cone, eccentric reducers have an edge that is parallel to the connecting pipe, referred to as the flat side. This parallel edge results in the two pipes having offset center lines. Because eccentric reducers are asymmetrical, they create asymmetrical flow conditions; flow is faster along the angled side, resulting in increased pressure.
Horizontal liquid reducers are always eccentric, with the flat side on the top, which prevents the build up of air bubbles in the system, (unless on control set, same as PV, TV, HV, LV) or in a pipe rack. In a pipe rack, the flat side of an eccentric reducer is on the bottom, so that the position of the bottom of the pipe will be constant, and supported by the rack.
Eccentric reducers are used at the suction side of pumps to ensure air does not accumulate in the pipe. The gradual accumulation of air in a concentric reducer could result in a large bubble that could eventually cause the pump to stall or cause
cavitation
Cavitation is a phenomenon in which the static pressure of a liquid reduces to below the liquid's vapour pressure, leading to the formation of small vapor-filled cavities in the liquid. When subjected to higher pressure, these cavities, cal ...
when drawn into the pump.
Horizontal gas reducers are always eccentric, bottom flat, which allows condensed water or oil to drain at low points.
Reducers in vertical lines are generally concentric unless the layout dictates otherwise.
See also
*
Reducer
A fitting or adapter is used in pipe systems to connect straight sections of pipe or tube, adapt to different sizes or shapes, and for other purposes such as regulating (or measuring) fluid flow. These fittings are used in plumbing to manipulate ...
*
Rotodynamic pump
A rotodynamic pump is a kinetic machine in which energy is continuously imparted to the pumped fluid by means of a rotating impeller, propeller, or rotor, in contrast to a positive displacement pump in which a fluid is moved by trapping a fixed am ...
References
* {{cite web, url=https://www.hydrocarbonprocessing.com/Article/2663961/Eccentric-reducers-and-straight-runs-of-pipe-at-pump-suction.html , title=HP Reliability: Eccentric reducers and straight runs of pipe at pump suction , last=Bloch , first=Heinz P. , work=Hydrocarbon Processing , date=September 2010 , access-date=19 June 2021 , url-access=subscription
Pumps
Piping