Bellows Pump Compressors – For Constant Flow and Greater Control!
A modern bellows pump compressors is a precise, high powered pump system used in a variety of medical and scientific laboratory applications. Very different from it’s origins in iron smelting and welding around 5,000 BC. Understandably, many people might still think of a blacksmith who traditionally operated a bellows by hand to deliver a constant supply of oxygen to maintain the furnace fire.
The principle of “a constant flow” with “greater control” remain key factors in the use of a bellows pump, especially if there is requirement to accurately pump fluid containing “fragile” solids. A bellows pump is categorised as a type of Positive Displacement Pump (PDP).
Generates the same flow whatever the discharge pressure
A Positive Displacement Pump is “a chamber that can be expanded or contracted by an external force”, and generates the same flow at a set speed whatever the discharge pressure. Displacement of fluid can take place by a variety of methods including, by plunger, piston or diaphragm, and some pumps will have the expanding cavity at the suction side and/or a decreasing cavity at the discharge side.
Where a sump pump operates by the use of a rotating impeller within a centrifugal system, inside a positive displacement pump, liquid is pressurised and drawn through a chamber that contracts to force a moderate amount of liquid out of the pump at the required pressure along the system. The much lower fluid velocity plus the controlled rate of flow and pressure is particularly critical in medical applications and laboratory analysis.
Medical and laboratory applications
A titanium bellows is often used to directly dispense medicine or to reduce the blood temperature during surgery. Other typical medical uses include, artificial dialysis, blood screening, urine testing, endoscope and biochemical analysis.
Within a laboratory setting, a bellows system is commonly used in electromagnetic analysis, mass spectrometry, heat analysis and liquid chromatography. Further applications are found in environmental control systems for the analysis of ground water, gas and total organic carbon (TOC).
Use in extreme test environments
The enduring image of a bellows is, of course, two large rigid boards connected to a flexible leather bag, which is expanded and contracted by moving the handles attached to the boards in and out. This is far removed from modern polymer materials and, increasingly, metals including, AM-350 stainless steel, beryllium copper or extremely corrosion-resistant materials such as Inconel 625.
Today, bellow compressor pumps are constructed from unique welded metal technology that also enables their use in extreme test environments where zero leakage or contamination is essential. Levels of performance can be achieved which is not always possible with conventional vacuum pumps and compressors.