The Linear-motor-driven Free Piston System (Pat.) has an internal piston inside the cylinder which is driven by an electro-magnet and spring system controlled by the mains alternating current. The Pump is quiet and vibration free, and offers the advantages of easy maintenance and a long operating life. The net result is there are no diaphragms to burst, therefore, no sudden failures occur due to rubber fatigue or over pressue, Wear of the piston is usually gradual over a period of years. Warranty is 2 years