If, for practical reasons, an industrial Washer Extractor Machine (WEM) is not fully loaded, regulations still demand that the full amount of detergent and water be used for the load. This leads to unnecessarily high resource and energy consumption.

In co-operation with the laundry company Ahrens Textilservice, Ott Wäschereitechnik has developed an innovative control solution based on Eaton technology, that will save both money and resources. Simultaneously, the solution enables the co-ordinated drainage of a number of washing machines connected to a shared drain pipe.

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 200 kg of laundry is operated with just 100 kg, 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 solution 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. 

“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,” explained Frank Dräger, Project Manager at Ott.

In principle, Ott uses this control solution 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 solution, just like any other customer.

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