Integrated safety concept for water treatment plant

German company Glastechnik Holger Kramp ensures wastewater from grinding, drilling and similar machining functions is cleaned and made available again to the production process in as short a time as possible. The water treatment systems, used predominantly in glass, ceramics and chemical industries, clean wastewater containing various pollutants via several filtration, decantation and release procedures, thereby making an active contribution to environmental protection.

The plants consist of one or more tanks and container systems and operate in close contact with the production facility via incoming and outgoing water pipes and pumps. As water is known to conduct current, the TÃœV certification authority places high demands on safety. In conjunction with Pilz, the company carried out a systematic risk analysis to minimise the risks to man and the environment and prevent damage to the plant. However, it was also important to develop a user- and service-friendly diagnostic concept which, in the case of a fault, would supply quick, specific information on the location and cause, provide advice on how to rectify the fault and thereby reduce downtimes to a minimum. "We set a high environmental standard and we wanted an equivalent solution for safety and diagnostics to go alongside it," stresses company secretary Michael Kramp.

Pilz E-STOP buttons and coded PSENcode safety switches guarantee safety in conjunction with the PNOZmulti and safety PLC. At the customer's request, the multifunctional safety system also undertakes standard control functions. The PNOZmulti monitors emergency stop devices operating locally and across the range of machines, as well as the link between the machines and the water treatment system. A fault around one individual machine doesn't mean the whole plant has to be brought to a standstill. However, if the central water treatment system should fail, this results in a controlled plant-wide shutdown. The safety system also detects potential shorts between contacts, monitors the speed of the pump motors and guarantees that they shut down if a fault occurs.

In complex plants, the integrated diagnostic function is an essential part of the overall concept. Here the company uses Pilz PMImicro diag operator terminals. It has three operator keys, four cursor keys and is intuitive to operate. The transflective display increases the contrast in accordance with the ambient brightness. Even in very bright ambient light, the display is very legible.

All system messages from the PNOZmulti are displayed without any prior configuration. The PMImicro diag and/or the safety system's software tool "” the PNOZmulti Configurator "” provides pre-defined messages for all types of safety devices for plant or machine-specific diagnostics. That saves a lot of time during configuration. The user can customise every message within his application, from the problem description through to the proposed solution. The operator terminal can therefore be adapted flexibly and precisely to suit each respective application.

Intelligent error management on the PMImicro diag means that during operation it can display the most relevant event. In this case, a conscious decision is made to move away from a chronological display so that the operator receives the most important information at first glance.

That way the user is always up to date. If the machine stops, the display indicates the source and cause of the fault using easy-to-understand plain text messages. The diagnostic unit advises the operator on how to get the machine operating again as quickly as possible.

Regardless of the production process in which the water treatment systems are involved, the integrated Pilz diagnostic and safety concept ensures the highest level of safety and guarantees solutions that are user friendly, with simple diagnostics and the greatest possible reliability and flexibility. "Pilz is the right partner for us, because the company is the market leader for innovation and quality in this sector," says Kramp, getting right to the heart of this cooperation.