Operating Principle
This configuration consists of a bare shaft pump assembly, fully mounted with a flexible coupling on a standardized baseplate in accordance with DIN 24259. Thanks to the back pull-out design, the complete rotating assembly can be removed without disconnecting the pipework or motor. This allows the pump to be opened quickly and easily for cleaning, inspection or maintenance. Pump alignment remains unaffected, eliminating unnecessary work and reducing maintenance costs.
Applications: Suitable for all transfer and circulation applications involving corrosive and even highly viscous liquids while maintaining maximum efficiency. This pump series is equipped with the latest semi-open impeller featuring pressure compensation. The impeller is mounted on the shaft independently of the direction of rotation. From model 80-250-3D onwards, a closed impeller is supplied as standard for higher hydraulic efficiency.
Mechanical Shaft Seal
Without question, the most critical component of a centrifugal pump is the rotating mechanical shaft seal. For this reason, ARBO devotes special attention to the development of this component. ARBO manufactures a single, medium-flushed mechanical shaft seal in which only high-grade engineering plastics and silicon carbide components are exposed to the pumped liquid. The spring element that provides the sealing force is located outside the wetted area and is fully encapsulated in plastic or manufactured from Hastelloy C for maximum durability. The stationary seal ring is flexibly mounted to compensate for possible pressure fluctuations. As an option, the pump can be equipped with an electronic seal failure detector. Depending on the pump type, a wide range of seal configurations is available for system pressures from 1.5 to 10 bar. The ARBO TGSI single mechanical seal is also available in a double-acting version with a barrier fluid system at an attractive additional cost. In addition to our own premium seal design, standardized mechanical seals can also be installed without significant modifications to the pump construction.
Double Mechanical Seal 2BL
Typical applications for a double mechanical seal include media that:
- Contain more than 10 wt.% solids.
- May crystallize during operation or standstill.
- Contain very fine particles (< 10 microns) that may damage the seal faces.
Clean water can normally be used as the flush liquid, or an external seal flush system can be supplied to provide one or more pumps with flushing liquid in a closed-loop circuit while minimizing water consumption.
Another option is the use of a thermosiphon system (see Pump Monitoring).
Liquid Seal Monitors
To accurately adjust and monitor the flush liquid pressure and flow rate, we recommend installing Liquid Seal Monitors. These units can be mounted directly on the pump assembly to ensure the correct flushing liquid flow and pressure are maintained at all times.
Thermosiphon
A thermosiphon is a passive heat transfer system based on natural convection, allowing a liquid to circulate without the use of a pump. The circulation may take place in an open loop, where the liquid flows from a reservoir through a connecting pipe to a distribution point, or in a closed vertical loop returning to the original reservoir. The purpose is to simplify the circulation of the seal liquid while avoiding the cost and complexity of an auxiliary pump and minimizing cooling liquid consumption. ARBO offers a range of thermosiphon systems, from simple atmospheric systems using water or a water/glycol mixture to pressurized systems equipped with optional hand pumps, pressure gauges and other accessories.
Materials: The standard material is PPH, making the pump suitable for most applications. For highly abrasive liquids with a high solids content, impellers and pump casing components are available on request in high molecular weight polyethylene (HMPE). For highly corrosive liquid mixtures at elevated temperatures, pumps manufactured entirely from PVDF or pure PTFE are available.
