Single Stage In-Line Pumps
In line pumps differ from most other types in that the fluid enters and exits along the same direction. Single stage pumps are those that use only one mechanism, such as an impeller, to drive the fluid, as opposed to other more complicated systems using push-pull pistons, reciprocating screws, etc. A propeller spinning in a length of tube would be a simple example of a basic single stage in line pump.
Probably the most common application of this type of pump is that used in domestic hot-water heating systems, where small in line pumps, usually using an electrical motor powered rotary impeller, are installed, sealed in the closed circuit piping. In this application the advantage of single stage in line water pumps is that the design side steps the main issue with the bigger, two-part pumps: namely keeping a water-tight seal where the drive shaft goes into the pump body.
Where this type of pump is used to move fluids in such closed-circuit systems, there can be considerable energy savings, even in larger scale commercial situations, since the only additional resistance encountered is that of the pipe work. This can be of importance as, from 1 January 2013, new European regulations (641/2009), part of the ecodesign policy of the European Union, come into force for some such applications.
There is a good selection of quality manufacturers of single stage in line pumps to choose from, including such leading brand names as; Grundfos, Lowara, Flygt, KSB, Mono and ABS.