Most of chemical enterprises cannot run their production processes without health and life endangering hazardous materials. These materials are transported, stored and processed. Experience from all over the world shows that, despite strict regulations and great care related to these activities, it is likely that these materials will contaminate the environment. Therefore the atmosphere needs to be checked for the presence of such materials and measurements of their concentration in the air shall be taken. We usually distinguish at least two levels of their concentration in the atmosphere:

• Increased, meaning that the concentration of the hazardous material in the air is above the standard limit but is of not a risk to people’s health;
• Emergency, meaning that permissible values are exceeded.

An additional two or even more levels can be added depending on the type of the material and internal regulations or applicable standards. It is necessary to adopt measures in terms of notifying the employees or the people living close by the given enterprise.

The solution has been designed as an integrated monitoring, warning and notification system. The system provides direct monitoring of the concentration of the hazardous materials. In order to increase the safety level, monitoring system sensors function independently from the technological control systems and are directly connected to the AMADEO radio unit. We usually distinguish at least two levels of hazardous material concentration. As far as the first level is concerned, the system notifies the operators and, for automated workplaces, the employees on duty who can check the reasons for such a higher level of concentration and can take safety measures without any emergency event announced. Once the second level is exceeded, warning message broadcasting is activated. Based on the type of the material or based on the applicable regulations broadcasting activation can be somewhat postponed thereby giving the operators time to check the concentration level using an alternative method. Such activation can be set for a group of operations or for the company’s entire premises. It can even include broadcasting for the people living close to the given enterprise. The system enables automation of all the processes following the alarm initiation and it consists of the following: 

• Central workplace, which can be automated;
• Radio controlled AMADEO radio units, which can be equipped with additional modules to increase the number of inputs for on a higher number of the sensors;
• Hazardous material detectors;
• Loudspeakers designed for 100 V circuits;
• High-power pressure distribution systems;
• Beacons;

Depending on the extent of the hazards, the acoustic system covers only the threatened workplaces in the company’s premises or it can also provides coverage of the surrounding area in order to warn the people living close to the company in question. Visual alarms are used in noisy operations to increase the efficiency of the warning message broadcasting. The system can be connected to a superior public address system managed by the state or a municipality.

Dispatching centre The main tasks of the dispatching centre are as follows:

• Continuous monitoring of the status/functionality of the entire system;
• Monitoring the concentration of the hazardous materials using the sensors connected to the central units;
• If increased levels of hazardous material exceed the first threshold, operator notification is activated a) locally, b) via phone for automated workplaces;
• If increased levels of hazardous material levels exceed the emergency threshold, the warning message is broadcasted;
• In the case of a more serious emergency situation the notification process is activated, i.e. supervisory employees are called in to the workplace and relevant institutions are informed of such an event;
• It is connected to an external public address system, which is then activated in the case of more extensive environmental contamination;
• Recording communication at the dispatching centre for its analysis;

The system consists of:

• A computer equipped with the VEKTRA software;
• Additional modules for notification and recording;
• The AMADEO central office or a central communication unit;  

Local AMADEO radio units
Individual operations are equipped with AMADEO radio units connected to a superior dispatching workplace. They can also work in the autonomous mode if communication with the superior dispatching workplace is interrupted. Hazardous material detectors are connected to each radio unit. The level of hazardous material is usually measured by two sensors and only then is the data is considered reliable, if both of the sensors show the identical value. 100V line circuits and loudspeakers with 5 - 20W output are used to broadcast acoustic warning messages in the internal premises with standard background noise. Noisy plant shops and external areas require the use of high-power horn loudspeakers with 150-300W output. Beacons are applied to make the warning process in noisy operations more efficient.

Communication network
This type of the solution mainly uses radio communication infrastructure. TCP/IP network communication or any other line-based communication is rarely used due to the high establishment cost of the high-quality underground lines between individual operations and due to the simple susceptibility of aerial lines to failures. Just like the radio units, network communication is backed up for 72 hours of operation during a power outage.

System control
The system can be controlled:

• From a dispatching centre;
• From local control units connected to the radio units; depending on their configuration they can even control other radio units;
• From the mobile phones of the employees on duty;

• If it is suitable or desired to separate the operation and warning monitoring system;
• If there is no operation monitoring system available;
• If maximum activity automation is required or if an automated dispatching workplace is required;
• If a multi-staged reaction to higher concentration levels of hazardous materials is required;