Getting the colors right
Double diaphragm pumps make sure that the paint mixing process e results you want

givLutz oil-free double diaphragm pumps already have a proven track record in providing blockage-free, continuously adjustable service in a number of industrial applications. These pumps are designed to handle aggressive, contaminated and highly flammable media as well as abrasive, high-viscosity fluids. Users in the paint and lacquer industry appreciate these features very much.

Lutz double diaphragm pumps in sizes between 1/2“ and 1“ are used in applications such as paint mixing systems made by a producer of special machines. The system is used in conjunction with weighing and process control equipment to deliver the color components as defined in the recipe with a very high level of reproducibility. The primary task of the positive displacement pumps is to supply 18 different colors to the metering heads in the multi-component system. The paint also has to be kept moving and homogenized in a circular pipeline. Cyclical pumping rinses the pipes, pumps, storage containers and fittings with medium and prevents the formation of undesirable pigment deposits.

Rugged and reliable
The self-priming pumps deliver the paint components through a combination of suction pipes and tubing directly from the storage containers to the supply line. There is no need to prime and bleed the pumps as would be the case with normal pumps. If the system comes to a halt, foot valves in the suction pipe prevent paint backflow. Depending on product characteristics and system dimensions, a system pressure of 6.8 bar is generated on the delivery side. Because the double diaphragm pumps are designed for dry running and automatically stop if valves close during operation, there is no need for a separate pump monitoring function. The pumps can even handle viscous and very abrasive paints, because the necessary performance has been designed in and hard wearing materials are used. Because of the way they work, oscillating positive displacement pumps generate a pulsating flow.
Getting a handle on pulsating flow
These pumps have one characteristic which is normally irrelevant in normal draining and transfer operations, but which is undesirable in a closed process. In this particular application, variations in pressure and flow are not only annoying – they can actually decrease the quality and reproducibility of the paint mixtures. The solution is simple. Pulsation dampeners store and discharge part of the piston volume in rhythm with the pump action. The internal air cushion alternately expands and contracts. When they have the proper dimensions and are mounted on the delivery side, pulsation dampers compensate almost completely for the pressure peaks caused by the oscillating fluid mass forces. The result is a fairly uniform flow.
You need the right “chemistry“
The chemical resistance of parts that come into contact with the medium is also important. Diaphragms, valve balls and valve seats can be made of Geolast, Santopren, FKM or PTFE. PP, PVDF and Nylon are suitable housing materials for water-soluble paints. However, Atex 100a approved pumps with stainless steel, aluminum or Nylon-C (protection type Ex II 2 G c T4) conductive housings are required for flammable paints that contain solvents. Pumps in sizes between 1/4“⁄ and 3“ are available for a number of individual applications in the paint and lacquer industry. A broad range of accessories (flow meters, fittings, pulsation dampeners) gives users everything they require to obtain the system solutions they need for their applications from a single source.