Designing A Smoke Measurement Instrument: Procedure And Devices

Equations should be on a new line, numbered sequentially on right, with the line right justified. The number should be in brackets, e.g. (1).

Identify symbols when they first appear.

Express numbers clearly – e.g. 6 1023, not 6e23 or 6*10^23.

Use appropriate units on all numerical values.

Express numerical values to the appropriate number of significant figures.

Equations form part of the text; that is, the presence of an equation should appear as if it is part of a sentence, even though it is on a separate line and is numbered. If the equation is at the end of a sentence, it should be followed by a full stop; if it is in the middle of a sentence, then a comma may be required.

In the text, refer to the equation by its number. “As discussed earlier, Equation(1) indicates that …”
Numbered (using roman numerals) in sequence – e.g. “Table II”.

Title at top of table to right of or under table number. Again, the title is actually a caption that describes what the table is displaying.

Results presented with errors (uncertainties) and units.

Literature values (footnoted) may be included for comparison.

Make sure that all captions stay with the appropriate table on the same page.

Refer to all tables appropriately with their numbers in the text; i.e. “Table II shows data on …” not “in the table below”.

Measurement and Instrumentation

Instrumentation is involved the indication, measurement, and recording of quantities. Instrumentation can also be used to refer to taking measurements such as the reading thermometer, using sensors, heating thermostat, and smoke detector. Measurement involves the determination of the quantities of a given variable by the use of an appropriate instrument of measuring. (Abbott, Development and Evaluation of Sensor Concepts for Ageless Aerospace Vehicles: Development of Concepts for an Intelligent Sensing System, 2004) In this project, the main measuring instrument is smoke. Smoke is can be measured by the use of specific measurement instruments and systems that are intended to measure the opacity of the smoke. The measurement instruments are based on laser light source or the white light source. The proportional number of exhaust smoke particles per unit fuel can be calculated as shown in the following equation:

SF =

Where N_CO2 is the amount of plume CO2 in %

N_CO is the amount of plume CO in %

N_HC is the amount of plume HC in %

The procedure of the calibration can be done by the use of neutral filters that are calibrated initially before the experiment. Some of the equipment and devices that are necessary for designing the smoke measurand include input sensor, input measurand, DAQ Card properties, software, actuator element, and circuits. (Abbott, Development and Evaluation of Sensor Concepts for Ageless Aerospace Vehicles: Threats and Measurands, 2014)The different steps and devices that are involved in the designing of the smoke operand are explained below:

Input measurand

The main aim of this project is to design a smoke measurement instrument that can be used for detecting and controlling the amount of smoke in a system such as motor vehicle, houses, factories, and industries. The instrument should be in a position to measure the amount o smoke inside an enclosed system or an open place by detecting the presence of the smoke in the system by the use of the sensor and then measuring the density of the smoke through the use of calibrations on the smoke measurand. The first step in which the smoke is measured involves the use of decomposition apparatus or the fire, chamber of measurement, a hollow pipe through which the smoke will pass through the enclosed area, and a system of measuring the attenuation of light due to the effect of the smoke (Anis Zribi, 2009, p. 187).

The light measurement instrument comprises a source of light, stabilizing pack of power, recording device, and the light receiver. The procedure of the calibration involves the performance of smoke opacity instrument of measurement which is special equipment due to its high sensitivity to the color of the smoke. The procedure of calibration is the use of an optical bench so as to allow the checking of the mechanical alignment on the smoke opacity measuring instrument before the beginning of the process of calibration. The following is the procedure of calibration of the smoke opacity measurement system:

• Checking the mechanical alignment of the system. The intensity of the light is then set to the required value and then the value of transmission adjusted to be approximately 100%. The approved level of light intensity is at 1500cd/m².
• The transmission value of the optics or the extinction coefficient of the opacity of the smoke measurement system is then calibrated against filters of neutral density in the range of the optical density of 0.05 to 2.0. The calculated optical density with the signal of light receiver that has been measured is estimated to be in the range of 5% of the actual value of the filters (Bishop, Electronics - Circuits and Systems, 2011).
• Any device of damping can then be adjusted during the beginning of the calibration process through recording the step response of the filter’s neutral density with a suitable oscilloscope.
• The position of the value of the zero of the coefficient of the coefficient of extinction of the smoke opacity system should be checked on a regular basis after every test of the smoke.
• The measurement equipment should be re-calibrated after the duration of 6 months or after being used for over a year. After calibrating the measurement equipment, frequent servicing and repairing is necessary for proper functioning of the equipment (Bishop, Electronics: Circuits and Systems, 2007).

Measuring Smoke using Specific Measurement Instruments

The smoke sensor is used in the detection of smoke. The sensors are used for commercial applications and also industrial applications. The smoke sensors work either by the process of ionization or by the detection of the optics. (Dargie, 2017, p. 187) Some sensors use both the ionization process and the optical detection making such sensors to have a higher sensitivity to the smoke particles. These detection methods are explained below:

Optical detection method: In this method, the sensor has a source of light the produces a beam of light and also photodiode. When the smoke particles enter into the sensor, the light will scatter the particles of the smoke.

Ionization method: In this method, there are two chambers which consist of two plates. When the voltage is applied to the two plates, there will be ionization and the electrons will be freed by the atoms because the particles of the alpha will be released by the radioisotope. The movement of ions to negative plate and electrons to positive plate results in minute flow of electric current that is continuous. (Donald G. Fink, 2004, p. 214)When the particles of the smoke enter the chamber where the sensor is located, the smoke will combine with the ions and then neutralize it which will result in the drop in the amount of current. The smoke can then be detected by monitoring the behavior of the current. The figure 2 below shows the circuit diagram of the smoke sensor that has been used in this design.                               

Optical smoke sensor reacts with the particles of the smoke which enters the chamber of the detection. The following are some of the technical specifications of the smoke sensor for this design:

• Power between 10.5V to 14V DC
• Start-up time of 60 seconds
• Detection area; maximum distance of 40m²and a height of 7 m
• Operating temperature; 0 to 50 degrees
• Measuring period; 3 seconds to 5 seconds
• Alarm indication; switching relay (Fabien, 2008, p. 296).

The following are some of the advantages of the smoke sensor:

• Can detect low energy smoke fires
• Less prone to false detection as a result of dust and steam
• Suitable for general use
• Faster detection duration as compared to the heat detector
• Does not have radioactive material (Gautschi, 2013, p. 246).

Disadvantages of the smoke sensor

• It is expensive compared to the heat detectors
• Limited due to the environmental conditions
• Limited technology
• Steam interference
• Deception by the dust

Transducer

This is an electronic device which is involved in the conversion of the physical phenomenon into electrical signals that can be measured. In this report, the main focus is to measure the smoke particles by the use of the transducer. The ability of the DAQ system to measure the smoke particles depends on the transducers to convert the physical phenomena such as the smoke signals from the sensors into the signals that can be measured by the DAQ hardware. The sensors are identical with the transducers in the DAQ systems. (W. Göpel, Michigan, p. 248) There are different transducers for measuring specific parameters such as pressure, fluid flow, and temperature. In the design of smoke measurand, the following are some of the transducers that can be used for this design:

Input Measurand

Passive Transducer: They require the external source of power for their operation. The signal modulation is done by the sensor to produce an output signal.

Active Sensors: They produce the electric signals due to detection of the external stimuli in the surrounding without any energy usage.

Actuators:  These are electronic devices that are involved in the movement and controlling of the mechanical systems. This device is a mechanism through with a system of control can act upon the surrounding (Thomas, 2001, p. 269).

DAQ Card Properties

Data acquisition is a process of sampling signals that measure the physical conditions of the world and then converting the results into samples that are numerical values that are digital in nature and can be manipulated by the PC. DAQ is an abbreviation of Data Acquisition Systems, and it involves the conversion of analog waveforms into values that are digital for the purpose of processing. (Paula, 2004, p. 158) The DAQ system is affected by the following system elements the computer, transducer, signal conditioning, DAQ Hardware, and Software. The DAQ has the following components:

• Sensors: This electrical device is involved in the conversion of physical parameters such as the information concerning the level of smoke that is supposed to be detected into electrical signals which are in form of 0s and 1s.
• Signal Conditioning Circuit: This circuit is involved in the conversion signals from smoke sensors into a form which can be converted into values that are digital.
• Analog-to-digital converters: This is an electronic device which is involved in the conversion of signals from smoke sensors into values that are digital (Paula, 2004, p. 214).

The diagram below shows that block diagram of a Digital Data Acquisition System:

The hardware of DAQ is interfaced between the signal of the smoke and the PC. The specification of the analog inputs can give the data to both the accuracy and capabilities of the DAQ product which is in form of smoke for this specific design. The number of channels for the analog inputs is specified for both the differential inputs and single-ended inputs on the board which has both the two types of inputs. The digital representation is not effective for representing the initial analog signal due to the risk of losing the information during the conversion of analog-to-digital signals. When the resolution is increased to 16 bits, the number of codes from the ADC will also increase from 8 to 65, 536 which will enable an accurate representation of the analog signal (Klaassen, 2002, p. 176).

For the design of smoke measurand, the DAQ is in the form of a module which can be connected to the ports of the computer such as the cards that are interfaced to the slots of MCA, PCI, S-100, and AppleBus. The DAQ card contains numerous components such as ADC, DAC, RAM, multiplexers, High-Speed Timers, and TTL-IO. These components can be accessed by the microcontroller through a bus; the microcontroller is used in running the whole program of the measuring smoke by this experiment. A controller is normally used because it is more flexible that logic of hardware and also it is cheaper compared to the CPU (Geoffrey S. Ginsburg, 2008).

The Procedure of Calibration

The controller will be performing the functions such as waiting for the smoke signal to trigger, initializing the ADC, moving the values of the smoke particles measured to the RAM, switching on and off the multiplexer, acquisition of the TTL input and letting the DAC proceed to the voltage ramp.

The drivers are important in ensuring that the DAQ hardware is working with the PC. The DAQ drivers can also perform some functions on the motherboard of the smoke measurand equipment such as writes/reads on the low level registers for the hardware and exposing the API for the purpose of development of applications for the users in the programming environment to enable effective measurement of smoke particles by the smoke measuring system. (Paula, 2004, p. 278) The following are some of the input devices of the DAQ Device Drivers:

• Analog-to-Digital Converter
• 3D Scanner
• Time-to-Digital Converter

The hardware components of the DAQ Device Drivers include the following components:

• Industrial Ethernet
• Computer Automated Measurement, and Control
• Industrial Ethernet
• Industrial USB
• NIM
• PowerLab
• VXI
• VMEbus

The gain, resolution, and range available on the DAQ board are determined by a small change in voltage which can be detected. The change in voltage is represented in 1 LSB of the value that is digital and is normally called the code width. The 16 bits DAQ boards normally use a voltage range of between 0V to 10V or -10V to +10V and gains of 1, 5, 10, 20, 50, or 100. When the voltage range is between 0V to 10V and the gain is 100, the ideal code width can be calculated as   = 1.5µV; this shows that the value of theoretical resolution of 1 bit in the digitized value is 1.5µV (Office, 2006, p. 198).

Software

There is specialized DAQ software which is normally delivered after the installation together will be the hardware of the DAQ. The software tools that are used for building acquisition system of large-scale data include EPICS. There are other environments of programming that are used in building applications of DAQ such as MATLAB, Visual Basic, LabVIEW, C++, and LabChart. The DAQ hardware uses the driver software which is a layer of software that programs the register of the hardware of the DAQ directly. The software is also involved in the managing operation of the hardware and also integration with the resources of the computer. (Norton, 2006, p. 149) The software of the driver is used to hide the complicated and low-level details of the hardware; this will provide the user with an interface that is easy to understand. The following are some of the applications of the software in the smoke measurement equipment:

• Control the algorithms
• Human machine interface
• Data analysis
• Real-time monitoring
• Data logging

Sensor Types for Smoke Detection

The flow chart below shows different stages of how the software is used in the smoke measurand equipment:

When the circuit of the hardware is determined, the software of the system is programmed by the use of the LabVIEW. LabVIEW is a graphical language for programming which is simple and widely used in virtual equipment that has been developed in the current technological period. LabVIEW is a graphical language of programming which uses an icon as a substitute of instead of text so as to create applications. The LabVIEW uses the program of data flow where the flow of data is what determines the execution. The master control module takes charge of the management of the system’s interface. Acquisition module is involved in the measuring and collection of the smoke signals and then displaying the results of the measured values (IEEE Industrial Electronics Society, 2005).

The module of data management performs the functions of playback, generation of report, and storage of data. The diagram below shows the block structure of the software:

The following are codes that are used in designing the software in LabVIEW. The codes are used to convert the analog readings from the smoke measurements and then software will convert the readings into digital forms which can be read by the measurement system (P.T Moseley, 2014, p. 145).

 main() /* Program to read and scale an analog input */

{

int brd, /* Which board to read analog value from */

chan, /* Analog input channel to read value from */

gain, /* Software-programmable gain to use on channel */

reading; /* Binary result of A/D conversion */

Double voltage; /* Voltage value at input channel after scaling */

brd = 1; /* Read from board 1, */

chan = 3; /* channel 3, */

gain = 100; /* with gain of 100 */

AI_Read(brd, chan, gain, &reading); /* Take a reading */

AI_Scale(brd, gain, reading, &voltage); /* Scale to voltage */

printf(“nThe voltage is %lf volts”, voltage);

}

The codes above are supposed to enable software to read the input signals that are in analog state and then convert the signals into digital form than can b interpreted by the Smoke Measurand.

This is an electronic component which is responsible for motion and controlling a system or a mechanism. An actuator requires a source of energy and a control signal. The control signal can be in the form of pneumatic, electric voltage/current, and hydraulic power. The energy supplied can be in the form of hydraulic fluid pressure, pneumatic pressure, and electric currents. When the signal of control is received, the actuator will respond by the conversion of the energy into mechanical motion. An actuator is a mechanism through which a system of control acts upon its surrounding. The system of control can be in the form of electronic system, robot control system, software-based system, mechanical system, and smoke measurand (Regtien, 2012, p. 305).

Technical Specifications of the Smoke Sensor

In this design, the main focus is the control system for the smoke measurand and its actuator. The following are some of the actuators that can be used in designing the smoke measurand:

• Hydraulic actuator: It consists of a fluid motor which uses the power that is hydraulic to enable mechanical operation. The mechanical motion gives the output which can be in the form of oscillatory, linear, or rotator motion.
• Pneumatic actuator: It converts the energy formed by the air compressed at high pressure into rotary or linear movement. This type of actuator is different because of its quick response when starting and stopping
• Electric actuator: This type of actuator is powered by a motor which is involved in the conversion of electrical energy into torque that is mechanical in nature. This is the most recommended actuator for the design of smoke measurand.
• Mechanical actuator: This device work by executing motion through the conversion of one type of motion into another form of energy; such as from rotary motion into linear motion (Klaassen, 2002, p. 189).     

The relay of smoke is usually closed and the power is delivered to the actuator. The combination of smoke and fire dampers with two sensors of temperature which are heat responsive devices enables the device to function effectively. When the temperature rises to 74 degrees, the primary damper spring will close and hence it will not move to the possition of the potentiometer because of lack of power. When the temperature at the damper rises further until 121 degrees is reached, the secondary sensor will open and the springs of damper will then close until it is manually reset (Donald G. Fink, 2004, p. 196).

Through powering wire 1 and wire 2 with 24V, the actuator moves the damper into the possition which is required for the purpose of measurement by the smoke measurand which is pre-calibrated.

Conclusion

The main aim of this project description research is to provide detailed description and explanation about Smoke Measurand which is an electronic device that can be used in detecting and measuring the density of smoke in an enclosed area. The main components of the Smoke Measurand include the input sensor, input measurand, DAQ Card properties, software, and actuator.  This research paper provides a diagrammatic representation of the Smoke Measurand together with the functions of the different components that are combined for effective measurement of smoke particles. The programming language that have been used programming the software for this measurement device is LabVIEW which represents information inform of cords are explained in this paper.

References

Abbott, D. (2004). Development and Evaluation of Sensor Concepts for Ageless Aerospace Vehicles: Development of Concepts for an Intelligent Sensing System. China: National Aeronautics and Space Administration (NASA).

Abbott, D. (2014). Development and Evaluation of Sensor Concepts for Ageless Aerospace Vehicles: Threats and Measurands. California: National Aeronautics and Space Administration (NASA).

Anis Zribi, J. F. (2009). Functional Thin Films and Nanostructures for Sensors: Synthesis, Physics and Applications. England: Springer Science & Business Media, 2009.

Bishop, O. (2011). Electronics - Circuits and Systems. China: Routledge, 2011.

Bishop, O. (2007). Electronics: Circuits and Systems. Michigan: Routledge, 2007.

Dargie, W. (2017). Principles and Applications of Ubiquitous Sensing. New York: John Wiley & Sons, 2017.

Donald G. Fink, H. W. (2004). Standard Handbook for Electrical Engineers. France: McGraw-Hill.

Fabien, B. (2008). Analytical System Dynamics: Modeling and Simulation. Michigan: Springer Science & Business Media, 2008.

Gautschi, G. (2013). Piezoelectric Sensorics: Force Strain Pressure Acceleration and Acoustic Emission Sensors Materials and Amplifiers. London: Springer Science & Business Media, 2013.

Geoffrey S. Ginsburg, H. F. (2008). Genomic and Personalized Medicine, Volumes 1-2. Michigan: Academic Press, 2008.

Wayne Beaty, D. F. (2012). Standard Handbook for Electrical Engineers Sixteenth Edition.New York: McGraw Hill Professional, 2012.

Harry Elliot Thomas, C. A. (2002). Handbook of Electronic Instruments and Measurement Techniques. London: Prentice-Hall.

IEEE Industrial Electronics Society, K. J. (2005). Proceedings IECON '85: 1985 International Conference on Industrial Electronics, Control, and Instrumentation, Hyatt Regency Hotel, San Francisco, California, November 18-22, 1985 : industrial applications of mini, micro & personal computers. Japan: Institute of Electrical and Electronics Engineers.

Kalantar-zadeh, K. (2014). Sensors: An Introductory Course. California: Springer Science & Business Media, 2013.

Klaassen, K. B. (2002). Electronic Measurement and Instrumentation. New York: Cambridge University Press.

Norton, H. N. (2006). Sensor and analyzer handbook. France: Prentice-Hall.

Office, U. S. (2006). Official Gazette of the United States Patent Office: Patents, Volume 912, Issues 4-5. New York: The Office.

P.T Moseley, J. C. (2014). Sensor Materials. Paris: CRC Press.

Paula, R. P. (2004). Fiber Optic and Laser Sensors, Volume 12. London: SPIE--the International Society for Optical Engineering.

Regtien, P. P. (2012). Sensors for Mechatronics. Michigan: Elsevier, 2012.

Richard S. Figliola, D. B. (2015). Theory and Design for Mechanical Measurements. Michigan: John Wiley & Sons, 2015.

Silva, C. W. (2007). Sensors and Actuators: Control System Instrumentation. London: CRC Press, 2007.

Thomas, H. E. (2001). Handbook of transistors, semiconductors, instruments, and microelectronics. Paris: Prentice-Hall.

Göpel, H. M. (Michigan). Sensors: a comprehensive survey. Micro- and nanosensor technology/trends in sensor markets.2003: the University of Michigan.