Flexible control system enables savings for washing machines

Ott Wschereitechnik GmbH (Ott) is a supplier to, and service partner of, commercial laundries in Germany, Scandinavia and a number of African countries. It also services many clients in the cruise ship industry. Its comprehensive range of services includes repairs, installations, maintenance and UVV checks (accident prevention regulations). In its workshop, old machines are overhauled, installations are prepared and changes are made to new machines. These include custom-developed systems in the fields of water recycling, and monitoring the control and other systems.

The company is also the official supplier of laundry technology for brands such as Milnor and Lavamac. Milnor's industrial washing machines are characterised by their high robustness and long lifespan. Machines with a service life of 20 years are not uncommon. This means that automation retrofits are normal during the service life of these washing machines, e.g. to enable the water and detergent supply to be load-dependent in older models.

Ott has developed such a system in co-operation with Ahrens Textil-Service GmbH (Ahrens), a professional textile leasing service provider based in Elmshorn. It specialises in workwear hire, door mat hire, linen hire and more. The flexible retrofit system was made possible thanks to control engineering by Eaton.

The cost implications of under loading

Because many industrial washing machines have a service life spanning decades, dry cleaning companies such as Ahrens face the challenge that the washing machine controls of older models do not offer load-dependent quantities of detergent and water. During the daily operation of a laundry business, small loads in the washing machines are inevitable. Washing machines that are not fully loaded have cost implications, because saving energy and the efficient use of resources is more an issue today than ever before. For example, if a Milnor machine designed for 200kg of laundry is operated with just 100kg, the same amount of water and detergent is used for both this load and the full load. This is clearly a waste of water, energy and detergent.

Another challenge posed by Ahrens was that in one area, there were six washing machines that were connected to a common drain pipe, and on occasion they simultaneously drained water. Simultaneous drainage into just one pipeline led not only to an increased electricity requirement, but also to the undesired filling of the washer extractor machines by misdirected or excess wastewater. Earlier attempts made by Ahrens to find a solution failed to produce a suitable integrable control system.

Intelligent retrofitting

The approach developed by Ott is as simple as it is ingenious: during retrofitting, the existing inlet and outlet signals of the Milnor washing machines are directly taken from the easy800 control relay (machine outlets become easy inlets). As a rule, six floating outputs per machine are sufficient. This number can be doubled by using extension modules such as the easy618. The easy control relay receives signals from the control boards of the washing machine, processes them and relays new information as required. The MFD Titan multi-function display serves as an operating and messaging element. Communication between the easy PLC and the MFD takes place via the Ethernet.

Frank Drger, Project Manager at Ott explains: "Because of the simple construction of the automation architecture, this flexible control solution is manufacturer-neutral. It can be implemented in almost all washing machine models, irrespective of whether they are old or new, and regardless of the bus system or communications protocol."

In principle, Ott uses this control system for a range of different applications, two primary cases being integrated control and weight-dependent level control.

For integrated control, the washing machines are networked using an easy control relay. This enables communication between the machines using the "first in, first out' (FIFO) principle. This means that the machines indicate when they want to drain, and the control system queues the commands in the order of receipt, so that only one machine drains at a time. Due to the detergent residue caused by incorrect dosing, additional rinsing is not necessary.

Weight-dependent level control concerns the load-related filling of the water demand. This is determined by means of a flow meter, irrespective of the water type. For this purpose, six different filling levels (three wet and three dry) can be defined. Depending on the model, the operator either enters the weight of the laundry on the MFD, or the MFD indicates it to the operator. In the former case, the load mass must be confirmed before the machine is started. The control system is then able to determine the amount of water required and the appropriate amount of detergent. As such, when the machines are not fully loaded, Ahrens can make significant savings with a retrofitted system, just like any other customer.

Drger says: "An easy control system can be as simple to configure as a circuit diagram, which is very beneficial to me as a trained electrician. In addition, I have rarely experienced such support. In my opinion, the solution provided could not have been implemented in such a way by any other manufacturer. Because of the cost efficiency and flexible retrofitting capability, the easy solution is in high demand. Worldwide, we have already installed around 300 of these control solutions for different applications, and converted about 40 industrial washing machines in this way in laundry services across Germany, Poland, England, Congo and Nigeria and more."

Saving water and detergent

Ott has converted a total of five Milnor machines to the Eaton control system at Ahrens - four at the site in Gorzow, Poland, and one at the head office in Elmshorn. Both Ott and Ahrens are very satisfied with the results.

Peter Scherwath, CEO of Ahrens says: "The conversion paid for itself on the first day. With the four 205kg machines in Poland, which are regularly run in batch mode, we were able to directly save 10-30 per cent of water and detergent in the event of underloading. By saving hot water, we can also reduce energy consumption and save resources. Overall, we now have better control of the whole process, for instance in the matter of detergent concentration. There are many time-bound batch jobs during the daily operation of a laundry service. Often when laundry service providers buy washing machines, they do not know exactly how these will actually be used. Retrofitting using easy control therefore offers a good opportunity to adapt the machines over the years, according to their real usage. We plan to convert three or four more machines here in Elmshorn over the next two years."

To learn more about Eaton control systems, visit www.eaton.eu.