Horizontal Pumps and Multistage Pumps
When to Choose Horizontal Pumps or Multistage Pumps
There are literally hundreds of situations in which it is necessary to direct the flow of some kind of liquid. Whether it is required to transfer fuel into your car’s fuel tank, to power the decorative fountain in your swimming pool, to provide the supply of borehole water in order to irrigate a field of crops, or to clear slurry from a mining operation, the motive force will have been provided by some form of pumping device. Orientated vertically or in the horizontal plane, configured as either single or multistage units, wherever it is necessary to propel a liquid, gas, or reasonably fluid material along a pipeline, one or more pumps of one type or another are certain to be providing the necessary muscle.
When undertaking any mechanical operation, selecting the most appropriate tool for the task in hand is important and, in the case of a pumping operation, that choice will depend on a number of factors.
One such consideration is space. A vertical installation, for instance, occupies a very small footprint although, for ease of maintenance, it does require fairly substantial headroom. By contrast, where it may be possible to make use of horizontal pumps, even though they tend to require a significantly larger footprint, they are a more versatile option for several reasons.
Firstly, the lower headroom requirement means they are more suitable for indoor applications and also means that installing and maintaining this type of unit is simpler due to the ease with which its internal parts, such as rotors, can be accessed when required. Also, unlike the vertical units that must be directly coupled to an electric motor for their operation, these units offer their users the additional option of powering them by means of a turbine or a diesel engine.
One area in which the vertical installation does excel, however, is in its ability to handle higher operating temperatures and working pressures. The latter is especially important to ensure the available suction is sufficient to prevent the phenomenon known as cavitation in which air bubbles are formed that could damage the impeller and pump housing.
One way to increase pressure in horizontal installations is with multistage pumps that are fitted with additional impellers although the same effect may be achieved by operating several single-stage units in series. Under other circumstances, it may be the flow rate that needs to be increased rather than the pressure. In such cases, the solution is to employ a number of individual units, not in series, but in parallel.
In practice, there are many more aspects of pumping technology that will serve to determine the most suitable type to employ in any given application than the few considerations outlined above. Naturally, a sound understanding of the principles of hydrostatics and the underlying calculations would certainly be a valuable advantage. However, in most cases, the more practical solution when considering the suitability of horizontal and multistage pumps is to seek the advice of an expert. In South Africa, the Pretoria-based Water Pump Group is widely regarded as the experts in sustainable and reliable pumping solutions.