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Fire-protection System in a Liquid Fuel Floating Roof Tank Design and Construction of a Telemetric Measuring system Using Smart Sensors Sotiris Karatzounis, Maria Charalampidou, Spyridon Mouroutsos Dept. of Electrical and Computer Engineering Democritus University of Thrace Xanthi, Greece,,

Abstract— The purpose of this paper is to contribute to the research on Fire Safety Systems by developing a Telemetric System to be used in a floating-ceiling tank filled with liquid fuels. The Fire Safety System is based on a Wireless Sensor Network (WSN) which measures the temperature of fire using wireless micro-sensors. The System’s Center of Surveillance and Control depicts and processes the data in real time, and identifies temperature anomalies. When an anomaly is detected, the System is able to remotely control a network of alarm and fire extinguisher tools. Specifically, we have created a laboratory model designed to replicate a real world Fire Safety System. The model consists of a scaled floating-ceiling tank where we artificially increase the temperature. The micro sensors measure the temperature and depict the figures by using the application "FirePanel". What is more, through this application, a series of lights, an auto-reply machine and a fire extinguisher are activated whenever this is required. The "FirePanel" software is the system's Fire-Protection-Panel which depicts the temperature data in real time and is able to remotely control the sub-systems of the model. This Fire Detection Telemetric System is created based on the procedures and operations applied in a conventional fire safety system similar to the one observed in a real fuel storage area. Keywords- telemetry - smart sensor – telecontrol - fire protection - real time system - tank.

sensor networks since they can collect measurements from inaccessible areas of interest. In our work the PrismaSence platform has been chosen. The platform was introduced in [11], where it was developed in order to cover the needs of condition monitoring. Prisma Sense, via the use of wireless sensor networks, portable computing devices, RFID and web-based architectures, provides maintenance-related information, in order to greatly facilitate decision maintenance practice and decision making. An extension to the platform is given in [12], where the architecture Collector - Gateway (Network coordinator) Server (computer network) that we also use in our work is presented. In this paper we present an application of this platform which has created in order to achieve fire protection in a floating roof tank. The Fire Safety System is based on a Wireless Sensor Network (WSN) which measures the temperature of fire using wireless micro-sensors. The System’s Center of Surveillance and Control depicts and processes the data in real time, and identifies temperature anomalies. When an anomaly is detected, the System is able to remotely control a network of alarm and fire extinguisher tools. Specifically, we have created a laboratory model designed to replicate a real world Fire Safety System.

I. INTRODUCTION With Telemetric Measuring systems we can acquire measurements at a distance and we can achieve remote control. Thus, these systems can efficiently and automatically monitor conditions and control subsystems in remote locations. Telemetric Measuring systems have been an active field of research for years. Both the academia and the industry have been involved in this research and development of applications and systems, many of which are either already commercially available or are expected to be in the near future. Smart sensors, or intelligent sensors, or smart dust, or, simply, motes, form sensor networks, most commonly using wireless technologies, into Wireless Sensor Networks (WSN). WSNs represent a significant improvement over traditional

II. LIQUID FLOATING ROOF TANKS – CAUSES OF IGNITION A. Tanks categorization depending on their construction   

Atmospheric Tanks (atmospheric pressure, oil, gasoline) Pressure Tanks (Pressure greater than17 kPa, propane, butane) Refrigerated Tanks (Temperatures lower than ambient) [1], [2]

B. Atmospheric Tanks   

Fixed roof tanks Floating roof tanks Open roof tanks [1], [2]

C. Floating roof tanks They are considered very safe, because they prevent the coexistence of air and flammable gases in the site overlying the liquid level (figure 1). They are recommended for storing petroleum fractions and products with ignition point lower than the environment. i.e.  Light petroleum fractions and gasolines  crude oil  Light polar compounds (alcohols, ketones, etc.) Generally, these tanks minimize losses and leaks of volatile products in the environment. (figure 2). [1], [2]

A. Fire prevention  

Staff training. Continuous monitoring of machinery and equipment installations.

B. Fire detection 

The choice of the equipment should be made according to the entire under protection system.

The aim is to reduce the risk of injury to personnel due to fire and the property protection.

C. The main fire suppressants      

Water Foaming materials (foams) Chemical powders Carbon dioxide Various organic chemical compounds (e.g. HALONS) Sand, soil, water vapor, covers etc. [3], [4] IV. TEMPERATURE MEASUREMENT - FIRE DETECTION

Figure 1. Floating roof tank D. Causes of Ignition      

Fires take place almost always on the edge of the tank. They are due to the existence of electrical charge at the roof or to vapor escaping from the tank washer. The hitting of the edge by lightning while the roof is at a high point The roof can be sunk into the tank, resulting in the spread of fire throughout the liquid surface. The extinction of most fires in tanks with floating roof is achieved in a short time after their initiation. The extinguishing can be easily achieved by using foam spraying fire pipes jet installation. [3], [4]

The temperature can be measured by a wide range of sensors. They all measure the temperature exploiting some change in a physical quantity (figure 3).  Thermocouples  Apparatuses of variable thermal resistance (RTDs and thermistors)  Pyrometers  Devices with bimetallic plates  Liquid expansion devices. [5], [6], [7]

Figure 3. Sensor measurement

Figure 2. Floating roof III. FIRE PROTECTION 1. 2. 3.

Fire Prevention Fire discovery - Fire detection Fire fighting

A. Thermocouples The operation of thermocouples is based on the phenomenon of thermoelectricity, or otherwise the Seebeck effect. Specifically, when two different metals are joined at one point, then at this point a voltage is developed. Between the free ends of connected metal wires develops a voltage E. This voltage, however, depends on the temperature. So if the two metal wires are joined at two points situated at a different temperature, two thermoelectric tensions of different value will appear. The difference between the two values is proportional to the temperature difference between the two points. Types of thermocouples:  Iron - Constantan or Type J  Nickel / Chrome - Nickel / Aluminum (chromelalumel) or Type K  Copper – Constantan or Type T [5], [6

B. RTDs The electrical resistance of certain metals varies in a known and predictable manner depending on the rise or fall of temperature. As temperatures rise, the electrical resistance of metals increases, whereas with the fall in temperature electrical resistance decreases. The RTDs use this feature as a basis for measuring the temperature. [5], [6 C. Thermistor They are based on the resistance switching capacity in a ceramic semiconductor.  Made of semiconductor materials,  have a large temperature coefficient,  are chemically steady,  not affected by aging of the material, strong magnetic fields, radiation, and  have low mechanical strength.  They have a maximum operating temperature of 150 ° C. Types of thermistors:  NTC (Negative Temperature Coefficient) the resistance decreases when the temperature increases.  PTC (Positive Temperature Coefficient) the resistance increases when the temperature increases. [5], [6]

Figure 4. Comparison of temperature sensors V. TELEMETRY - TELECONTROL

D. Bimetallic plate If two metals have different coefficients of expansion, as the temperature changes, one metal element will expand more than the other, thereby causing the device to bend. It can be used to determine the ambient temperature, provided that the degree of bending can be measured. [6]

A. Telemetry The information obtained from a measurement system, usually must be transferred to another system for further processing. Many times this is done in order to control the measured values or in order to store them (figure 5). [9]

E. Pyrometers They are used for temperatures exceeding 1600o C.  Optical Pyrometers: comparison of colour and brightness of an object with that of the tungsten filament  Radiation Pyrometers: measure the temperature of a body measuring a part of the radiated energy from the warm body. [6], [13]

Figure 5. Diagram of measurements using smart sensors B. Smart sensors These are sensors using locally a microcontroller in order to reach more precise information than that obtained by a common sensor. The smart sensors monitor various natural values and process automatically this information. [7] C. Information transmission system 1) Wired networks  4-20 mA current loop  USB communication standard  I2C communication standard etc. 2) Wireless networks  WiFi  Bluetooth  Zigbee etc.

D. Measurement management system The exploitation of measurements is made by processing the measurement data, on the basis of algorithms and decisionmaking techniques, enabling remote monitoring of an application and thus, composing a telemetry and remote monitoring system. Such systems are generally described by the term SCADA. (Supervisory Control and Data Acquisition). [10] VI. PRESENTATION OF A FIRE PROTECTION SYSTEM A. Measurements collector (figure 6)   

It is called Quax DT (Development Tool) made by Prisma Electronics company. It provides various ports for the connection of external sensor circuits. It allows communication with the Monitoring Centre via the router to which the communication is based on the ZigBee communication protocol.

Figure 6. Collector Quax MS B. Application Sensors (figure 7)  NTC type thermistor & Converter  Diode type temperature sensor A diode can be used as a temperature measurement device, since the voltage drop of the diode in its correct polarization depends on the temperature. So, the diode as a semiconductor shows a similar behavior with the thermistor in the correct polarity.

Figure 8. WSN's gateway. D. The "FirePanel" application Generally, the application program was developed using the Microsoft Visual Studio 2010 and requires for its execution the operating Microsoft Windows 7 and the NetFramework 4 software. 1) The application environment FirePanel. (figure 9) The application window can easily be divided conceptually into two parts. On the left is the table on which are reflected the values of all measured temperatures from all registered sensors in our network, while on the right we see the part of the thermometers, the alarms and the switches that activate the devices. The available measurements that can be read from the "FirePanel" are Temperature measurements (Tmp1, Tmp2) corresponding to the thermistor and the diode thermistor. This section allows the user to visualize the latest temperature measurements that are available from a Collector while at the same time it allows manual control of the emergency devices so that in case of a failure to have an activation of the fire protection system by the user. The remote monitoring part allows the definition of the temperature limits of operation of the Fire Protection System, determining the scope of permissible temperatures resulting from the measurements of one collector at a time. If these limits are exceeded, the respective fire protection systems are activated in order to achieve extinguishing and alarm. In our case this is done using the fire extinguisher, the Auto alarm dialer and the light and horn alarm.

Figure 7. Application’s sensors C. Router - gateway (figure 8) It communicates with the collectors via Zigbee and the Monitoring Centre via WiFi. It is composed of:  Microcontroller  Zigbee transceiver  WiFi transceiver

Figure 9. “FirePanel” application

2) The algorithm behind the “FirePanel” application.

the temperature range for which the system operates is a feature not found in other systems. 2) The Collectors with the sensors The collectors with sensors are placed at the edge of the tank to match the real system, since this point is the most dangerous area of a fire outbreak. 3) The electrical installation The electrical installation constitutes the link between the fire protection board (computer, data recovery card) and the fire protection devices. The electrical installation can be divided into the following parts:  Power supply 24V DC  Micro-relay card  Relays  Galvanic connections 4) Controlled fire protection appliances The devices we monitor have been indicatively selected so that to simulate the main fire protection actions for an extended installation. These devices are divided into:  Fire extinction equipment (Fire extinguisher with detonator)  Signaling devices (light and horn alarm, Auto alarm dialer)

E. The laboratory layout The experimental setup (figure 10) was developed to simulate the overall fire protection system in a floating roof tank station, given the limitations of space and the size of an actual installation.

Figure 10. Laboratory layout simulation 1. 2. 3. 4. 5.

The Server The collectors with sensors The electrical installation The controlled fire protection appliances The model of the tank and other equipment

1) The facility manager (server) The computer in conjunction with the application constitute, finally, the fire protection panel system, which is indicated as well by the name of the application "FirePanel". The main advantage compared to a conventional fire protection panel is the continuous temperature indication provided to us by the graphic thermometers. Also, the possibility to change

Figure 11. Real laboratory layout

F. Total sequence of system functions

REFERENCES [1] Storage Tanks and Vessels – Floating Roof Storage Tanks, Online@ (last update june 2012) [2] Τσαχουρίδης.Β, Παρουσίαση «Δεξαμενές Αποθήκευσης», Τμήμα Εκπαίδευσης ΕΛ.ΠΕ [3] NFPA 650, «Standard for Pneumatic Conveying Systems for Handling Combustible Particulate Solids, 1998 Edition» [4] Τεχνικό επιμελητήριο Ελλάδας, τεχνικά χρονικά, «σεμινάριο πυροπροστασίας», Πρακτικά σεμιναρίου [5] Σπυρίδων Γ. Μουρούτσος, «Μετρήσεις Θερμοκρασίας», Ξάνθη 1991 [6] Robert J. Stephenson, Armelle M. Moulin, Mark E. Welland, «Temperature Measurement», 1999 by CRC Press LLC [7] Γαστεράτος, Μουρούτσος, Ανδρεάδης, «Τεχνολογία

μετρήσεων αισθητήρια», 2η έκδοση Απρίλιος 2010, ISBN13: 978-960-387-772-1 [8] I.F. Akyildiz, W. Su, Y. Sankarasubramaniam, E. Cayirci, «Wireless sensor networks: a survey», Computer Networks 38 (2002) 393–422.

VII. CONCLUSION A. Advantages of the System 1) Wireless transmission – Zigbee standard  Enables moving the Fire Protection Panel.  Ease, flexibility and simplicity of installation.  Reliable transmission with uninterrupted function (using batteries).  Wide range coverage (70m)  We achieve high-speed transmissions with a 250 Kbps data rate. 2) Design and operations advantages The "FirePanel" application in relation to a fire protection panel further to the usual operations such as ALARM, provides the following:  Continuous temperature values.  Visualization of measurements in virtual thermometers.  Possibility to determine the system’s operational temperature limits.  Activation of emergency equipment by the user through Manual buttons located in the application environment.

[9] J. A. Stankovic, «Wireless Sensor Networks», Computer V. 41 Is. 10, pp 92 – 95, IEEE Computer Society, Oct. 2008. [10] Technical information bulletin, «Supervisory Control and Data Acquisition (SCADA) Systems», National communications system, 2004. [11] Emmanouilidis, C, Katsikas, S, Giordamlis, C., Wireless Condition Monitoring and Maintenance Management: A Review and a Novel Application Development Platform, Proceedings of the 3rd World Congress on Engineering Asset Management and Intelligent Maintenance Systems Conference. 27-30 Oct. 2008, Beijing, China: 2030-2041. [12] Emmanoulidis C, Katsikas S, Pistofidis S, Giordamlis C, A Wireless Sensing Development Platform for Ubiquitous Condition Monitoring, COMADEM 2009

[13] The Fire Service Technical College, «Automatic Fire Detection Systems», Moreton-In-Marsh, Gloucestershire, u.k, 1998

Fire protection system in a liquid fuel floating roof tank