API 676 – Positive Displacement Pumps – Rotary, 3rd Edition, Nov. 2009, is a standard put forth by the American Petroleum Institute. It covers the minimum requirements for rotary positive displacement pumps for use in the Oil & Gas, Petrochemical, and Chemical industries. It provides a purchase specification to facilitate the manufacture and purchase of rotary positive displacement pumps.
Triple screw pumps are self-priming rotating positive displacement pumps suited to handle different oil types and other liquids with a minimum lubricating quality.
The design simplicity makes these screw pumps intrinsically reliable and efficient. Only three moving parts – a driving spindle and two idler spindles – rotate inside a casing with close tolerances, so forming sealed chambers and provoking the axial displacement of the fluid. The idler spindles rotate without contact with the driving spindle because of the fluid itself. The accurate hydraulic balance and the special profile of the screw thread guarantee a continuous flow with minimum pulsations and turbulence, resulting in extremely low noise levels even at high rotational speed.
Till now triple screw pumps on the market are adapted in such a way that they complied with this standard as much as possible. Often these pumps are based on a standard execution and therefor do not represent an optimum in features and cost.
Leistritz decided to make a fresh start on the digital drawing board to find the optimum solution and have been able to come with a new concept.
The new L3MA pump has no separate steel casing with an internal liner for the screw spindles to run in. Due to the uses of a new spindle material it’s possible to have the spindles run directly in a steel casing and avoids an expensive construction with a coating in a separate liner.
Only 3 static seals, executed as O-ring seals instead of flat gaskets, are used. This eliminates the risk of leakage due to insufficient compressed flat gaskets.
A single acting mechanical seal has been chosen as shaft seal which proved it selves in thousands of applications. As an option a cartridge seal is available as well.
Suction and discharge flanges are according ANSI B 16.5 class 300 lbs.
Full assemblies with motor and baseplate and spacer coupling available.
The L3MA series of pumps is available in different frame sizes with multiple, but defined pitch angles offering a wide flow and pressure range.
In separate frame
Leistritz Pumpen GmbH, with their headquarters in Nuremberg, Germany, focuses since 1924 solely on the design, production, marketing and sales of screw pumps and screw pump systems.
Since April 2014 their Benelux sales office supports the local market and is offering a direct contact.
