Pumps for
Airbus’s Flying Lavatories

With pump maintenance problems mounting in a difficult water filtering operation for airplane lavatories, aerospace giant, Airbus, turned to ITT Industries Lowara division for a pump solution that includes an “intelligent” frequency converter.

The first toilets in airplanes were simple buckets. Information on early flushing systems is not available, however aircraft cabin were not pressurized and it was easy to open doors and windows.
Today, and happily for people living close to airports or under flight paths, there is no more falling manure thanks to modern plumbing installed on commercial aircraft.

Pump Maintenance Plaguing Aircraft Lavatories
Lavatories with vacuum flush systems are standard on all new aircraft. These toilets, designed on a modular concept, can nearly be installed anywhere in the aircraft’s cabin. Centralized waste tank and water supply are connected to the toilets with small tubes instead of usual large plumbing pipes. Fast and powerful pumps suck from below the bowls to discharge the sludge into the waste tank.
These lavatories on many of the Airbus aircraft had a problem that had been affecting the filtering unit of the chemical toilets. In particular, the Airbus “Maintenance and Infrastructures” staff had discovered that there were faults in the water filtering pro-cess, supported by a Uranus 55 pump, which led to the need for frequent and very costly maintenance. To be more specific, the filter tended to clog up and lead to pump cavitation, resulting in irritating noise both in the hydraulic circuit and in the motor. Furthermore, the increased wear of the mechanical seal and anomalous overheating of the motor caused pump breakdown and the toilet ceased working. The solution came when Airbus engineers met the local Lowara ITT Industries representative in Nantes.

Optimizing operation
An inspection carried out by Lowara technicians on the filtering unit pinpointed the technical aspects of the problem and identified Hydrovar as the device capable of improving and optimizing the operation of the filtering unit. Specifically designed for the hydraulic sector, Hydrovar is a frequency converter fitted with a microprocessor for managing pump performance automatically on the basis of the conditions and requirements of the unit.
This frequency convertor is the world’s first pump mounted microprocessor based pumping system controller. The Hydrovar does much more than just change motor speed. It has been designed to manage pump performance to match a wide range of system conditions, allowing energy savings of up to 70%. Due to the unique design, the convertor can be mounted or retrofitted to any standard I.E.C. motor.

Less control systems
Because of its advanced pump control features, the frequency convertor eliminates the need for complex control panels, system control valves and large pressure accumulators. Hydrovar also provides value in improving pump life cycle cost as it protects against conditions such as dry running, over/under voltage, motor over temperature, inverter over temperature, pump running beyond minimum pressure setting, pump overload and sensor failure.
Easy to install on any standard motor, the frequency convertor provides a plug and play solution that makes it possible to transform any pump into an “intelligent pump”. Because of these features, it was found suitable for inclusion in the retrofit project for the mo-dernization and reconfiguration of the hydraulic systems in Airbus planes.

Filter cleaning
The faults in the filtering process were eliminated with the installation of the device. The pump, regulated at a constant flow setting, now performs in accordance with the filter specifications.
Furthermore, installing a frequency convertor also solved the problem of cavitation which occurred during the filter cleaning stage and which led to the displacement of the pump’s operating point to the right of the pump curve. Finally, the reconfiguration of the system eliminated the motor overheating and mechanical problems, guaranteeing flawless operation of the pump and power board.
The Airbus staff confirmed that the operation was found to be advantageous not only from the technical point of view but also from an economic one because the company has recovered its investment in just a few months. This emerges from the comparison between the costs of installing the frequency convertor and the costs for frequent maintenance and for fast wear of the pump due to filtering unit malfunctions. <<