Planetary gearboxes for driving peristaltic pumps for driving peristaltic pumps

In the water industry peristaltic pumps are preferable for many applications. However, there are specific requirements in finding a suitable gearbox. Vibration, unbalanced loading and the need for high reduction ratios means that traditional transmissions are often too large, inefficient or prone to damage to function on larger pumps. A solution comes from planetary gear boxes which are low maintenance, compact gearboxes capable of incredibly high reduction ratios. The principle of the peristaltic pump is based upon alternating compression and relaxation of the inner hose via two shoes positioned 180° apart on a rotor. As the rotor turns, the tube under compression closes thus forcing the fluid through the tube. Additionally, upon restitution of the hose, a vacuum develops which draws the fluid along the hose with no possibilityof cross contamination.

Thesepumps are capable of pumping liquid with up to 80% solid content. The pumpedliquid is totally contained within the hose so does not come into contact with anymoving parts ensuring sterilization of the fluid, or indeed the pump. A gearboxwith high torque and an ability to cope with out of balance radial loads is required to ensure the consistent operation of such pumps, especially those of the size usedin the water industry.

In today's climate, energy efficiency is also of utmost importance; especially when running a pump continuously. The planetary gearboxes tackle this problemproviding 98% energy efficiency per stage. As there are three planetary gears inside a toothed outer ring the load is spread among many contact points, this leads to less point pressure and less internal friction and more efficiency. Other high reduction transmissions may have as low as 50% efficiency meaning a significant saving can be made. This efficiency means that a smaller motor is required which results in lower running costs for the pump overall.

In larger pumps and other water treatment processes it is necessary to move large rotors at low speeds. It is therefore essential that a high torque is achieved. Brevini's planetary range provides torque from between 1.6 kNM to 800 kNM. The planetary gears create more contact points which means that the system is capable of maintaining the power without slipping. While this kind of torque is possible with other gear systems, they will be up to twice the size and require a far larger motor to run them. The torque distribution of these systems means that they are more resistant to shock loading and provide rigidity.

Many gear systems are unreliable when used in a system with requirements similar to that of peristaltic pumps. Yorkshire Water's Rawcliffe Sewage Treatment Works has the ability to process water at a flow rate of 23,600m3/day. However, until they installed planetary gearboxes this maximum rate was impossible due to constant breakages. Brevini's gearboxes have been successfully integrated into many water plants as, with features such as twin taper roller bearings and extremely high torque rates, they are capable of surviving in conditions where other transmissions fail.

Many users of large peristaltic pumps find that conventional gearboxes are far too cumbersome to be used effectively. These large gears require massive support structures to house them. Planetary gearboxes as made by Brevini can be up to half the size and 60% lighter than conventional 'worm and wheel' gears. This smaller size means that a smaller support structure can be used which is ultimately easier to handle.

The planetary design offers flexibility for solutions to any non-standard application. For example Brevini was the only company able to design a solution for Thames Water that complied with their 'no engineering' rule when an old gearbox broke, saving both down time and money. This flexibility is a great advantage for peristaltic pump users as each pump needs specific requirements, for example the planetary system is able to run clockwise and anti-clockwise and any standard motor can be direct mounted.

Peristaltic pumps continue to be preferable to water authorities. The introduction of a planetary gearbox system such as the range offered by Brevini ensures that these pumps will run more efficiently with less maintenance. Brevini have the widest range of planetary gearbox solutions in the world. The products are widely available and provide compact, solutions that offer savings in running costs.