Gerotor Metering Pumps
Typical Bandit metering pumps are of a gerotor configuration. When we developed the first pump, we had an opportunity to copy another brand of pump but decided to develop our own. Copying sometimes promotes continuing flaws. Fortunately we did not copy. We designed a seal package which was significantly more durable than others on the market. At the early stages, we used a high durometer urethane seal. It lasted a significant amount of time without failure. At that time, 8-12 months, and some longer. The market, with other pumps, was only seeing 2 weeks to 6 months seal life. The only thing we did not like was the groove which was left on the pump shaft. After a few years we switched to a different style seal which did not leave marks on the shaft and extended seal life well into 2-3 years depending on the application. We started using the same type seals on other brands of pumps (smaller seals) and had improved success on those pumps as well. Since that point in time, we made changes to the elastomers and gained even longer seal life. It was apparent that the other brands we repaired could use our same “Bandit Configuration Seal Package”. As of 2004, we plugged the seal pockets in the other brands and installed seals in the Bandit format. This move made very significant changes in seal life in the competitor’s pumps we serviced. It is now our standard for repairing other brands of pumps. The current status is that the seals typically outwear the life of the pump.
We build the metering pumps to fit the chemistry and viscosity of the materials to be dispensed. Great attention is paid to the tolerance of the components. One size does not fit all. We allow a higher viscosity material to typically use a wider tolerance pump. The chemicals to be pumped “pad” the moving parts. This lowers the amount of metal to metal wear much like and automobile engine, but still keeps the systems on a consistent tight ratio with little slippage in the pump. All pumps built have a tolerance stamp on the outside of the pump as well as letters which indicate chemical side the pump is designed for. With Urethanes, a 3 step treatment process is required before assembling the isocyanate pump.