A Polish manufacturer developed a system to protect liquid petroleum gas (LPG) from being illegally unloaded during transportation, where in most cases, the theft was committed by the driver of the vehicle. The manufacturer's requirements included safe transport and a monitoring device that could also register events en route.
Based on simple physics, when LPG is removed from the tank, the temperature of the tank will drop rapidly, and will remain low until unloading is stopped. This basic principle allows the detection of any unauthorised removal of LPG.
For safety reasons, the intelligent data loggers had to operate without interfering with the tank structure and pump system and they had to be protected against illegal access so no one could falsify data. Anti-sabotage switches were built into the module and sensor housings and could operate on both an independent power source or on batteries. Finally, the device had to be compatible with external analysis systems such as the customer's laptop computer or any other portable computer system.
The system mainly consists of three ADAM-4000 modules enclosed in a special case and a battery unit for mounting on the vehicle. The most important and only active element in the system is the ADAM-4500 with some ROM and RAM capabilities (for data collection), a simple CPU unit and a battery supplied realtime clock. The ADAM-4500 has built-in COM1 and COM2 communication ports.
The first facilitates an RS232 connector and links the system with external PCs, whereas the latter functions as a main data gateway for other ADAM modules.
The ADAM 4500 runs on specially-designed software to enable intelligent monitoring of temperature values and switching states. It is able to log relevant data onto the virtual hard disk in an Events log file with time and stamp.
The second module is the ADAM-4050 which features seven digital input channels and eight digital output channels. The input channels are connected to anti-sabotage switches integrated with thermocouples and cover the data logging. The output channels are alarm indicators including four LEDs and one high volume siren. One digital input channel is reserved for the start button which is used when the LPG tanks have been filled.
The last module is the ADAM-4018 for analog data inputs. These input channels are connected to four thermocouples, one for each tank.
Every 15 seconds the system checks all four thermocouples and compares the temperature with the last measured values. If an irregularity is detected, the system reports this in the Events log file with date, time, present and last value. The system also checks all anti-sabotage switches and reports abnormalities in the Events log file. If the system detects any alarm, the ADAM-4050 gives the appropriate digital signal to the LEDs and switches on the siren.
After the truck has reached its destination, the customer connects his portable PC system to the COM1 port of the ADAM-4500 to stop the monitoring process and retrieves all relevant data.
By using the basic rules of physics, a more effective and safe delivery of LPG has been implemented. The system was easily installed, providing versatility in design, with low application and labour costs.
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