Centrifugal Plastic Pumps
Plastic Pumps, also called Non-Metallic Pumps, are mostely Centrifugal Pumps based on the radial pump technology. In a centrifugal plastic pump all parts in contact with the fluid are from solid plastic. This is what makes plastic centrifugal pumps a perfect match if it comes to corrosive and abrasive fluids. Moreover, centrifugal plastic pumps do comply with common standards and they do meet high demands for safety and reliability that are common in industrial processes.
How a Plastic Centrifugal Pump works
Like in any other centrifugal pump the liquid entering the pump casing is being accelerated by the rotating impeller. At the discharge of a volute casing speed is being converted into pressure. Impeller and volute casing have to match each other to create the best efficient hydraulic unit of the pump. The larger the impeller diameter and speed are, the larger the pressure difference will be and the wider the impeller and volute are the higher the flow of the pump will be.
Most pumps are driven by electric motors. This is not at all different with plastic pumps. The energy a pump requires has a linear increase with pressure and flow. The motor transmits the energy through the pump shaft to the impeller but not all of it is converted into pressure. Energy losses are created by friction on bearings and hydraulic imperfections such as vortexes and backflow. Manufacturers of high quality pumps put considerable efforts into hydraulic R&D in order to minimize these losses. Today those HQ plastic pumps achieve efficiencies up to 80%.
Hermetically sealed plastic pump (series MUNSCH CM).
Wetted parts are from plastic.
Technical Data of Centrifugal Plastic Pumps
Flow rate: up to 3.000 m³/h (13.200 gpm)
Delivery Head: up to 100 m (330 ft)
Operating pressure: up to 16 bar
Operating temperature: up to 180°C (356°F)
Viscosity: up to 300 mm²/s
Heavy Duty: Circulation pumps for sulfuric acid in an exhaust gas scrubber unit of a copper mine – MUNSCH pump series NPC Mammut.
When to think of a Plastic Pump?
In fact the majority of pumps is made of metal. Manufacturers in this segment offer an enormous variety for a reasonable price – as long as one stays within their standardized range of materials. However, selecting the right type of metal for a specific fluid (different from water) is not something you will learn from a YouTube tutorial. Even if only the pH of a liquid drops off occasionally or a small content of chlorides or fluorides can destroy standard metals such as 304, 316L and others.
Metal alloys are specialists – Plastics are all-rounders
In addition, those metal alloys qualified for a specific fluid often do have strict boundaries in terms of concentrations and temperatures. Most plastic materials are much more tolerant. As for PFA one can even say that it is almost universally chemical resistant. In comparison to high alloyed metals plastic pumps do offer significant advantages in availability and price – a major factor for maintenance and plant availability.
There is no reason to accept corrosion and wear as a frequent pump failure
The fact that some plastic materials – above all UHMW-PE – do not only have superior corrosion characteristics but in addition offer an excellent abrasion behavior is often underestimated. The truth is that many centrifugal plastic pumps are currently in operation handling solid loads of up to 20% successfully. These processes are to be found in precious metal refinery or phosphoric acid production where large amounts of gypsum have to be moved.
Plastic pumps for the conveyance of chlorine-containing NaCl sole - MUNSCH NP series.
Applications where Plastic Pumps are unconquerable
- Chlorine production / Chlorine alkali plants
- Metal refinery / metal recovery
- Phosphoric acid production / fertilizer industry
- Surface treatment, pickling, anodization
- Flue gas treatment, exhaust gas scrubbers
- Industrial / pharmaceutical waste water treatment
- Sea water desalination
- Chemical industry: organic and inorganic acids / mixed acids / chlorinated fluids