Title of Invention	AN AUTOMATIC DYNAMIC PRESSURE NEUTRALISATION DEVICE USEFUL FOR CONTROL OF FIRE IN UNDERGROUND COAL MINES
Abstract	An automatic dynamic pressure neutralization device useful for control of fire in underground coal mines, which comprises differential pressure sensor for measuring the difference from two air pressure sources, characterized in that the said differential pressure sensor consisting of a thin metallic diaphragm (21) with two metallic needles (22) & (23) on its either sides, supported at the middle of a rectangular chamber (24) and insulated from it by rubber (25) or other non conducting gasket, the said chamber has two ports (26) on either side of the diaphragm for connection to pressure sources whose pressure difference is to be measured, the said metallic needles (22) & (23) are connected to resistors (27) and a source of electric potential (28) , the output of the said resistors (27) is connected to ADC (analog digital converter) port of a microprocessor (20), I/O (input/output) port of the said microprocessor is connected parallel to two stepper motors (18 & 19) for controlling valves fitted in air intake pipes

Title of Invention

AN AUTOMATIC DYNAMIC PRESSURE NEUTRALISATION DEVICE USEFUL FOR CONTROL OF FIRE IN UNDERGROUND COAL MINES

Abstract

An automatic dynamic pressure neutralization device useful for control of fire in underground coal mines, which comprises differential pressure sensor for measuring the difference from two air pressure sources, characterized in that the said differential pressure sensor consisting of a thin metallic diaphragm (21) with two metallic needles (22) & (23) on its either sides, supported at the middle of a rectangular chamber (24) and insulated from it by rubber (25) or other non conducting gasket, the said chamber has two ports (26) on either side of the diaphragm for connection to pressure sources whose pressure difference is to be measured, the said metallic needles (22) & (23) are connected to resistors (27) and a source of electric potential (28) , the output of the said resistors (27) is connected to ADC (analog digital converter) port of a microprocessor (20), I/O (input/output) port of the said microprocessor is connected parallel to two stepper motors (18 & 19) for controlling valves fitted in air intake pipes

Full Text	This invention relates to a device useful as an automatic dynamic pressure neutralisation device for control of fire in underground coal mines. The present invention particularly relates to pressure differential device for automatic control of dynamic pressure balancing. Dynamic pressure balancing technique, all over the world has proved to be an effective tool to control fire in underground coal mines. In this technique balancing of pressure is achieved by judicious adjustment of air flow rate, first through the different branches of the ventilation network around the affected zone and secondly, the remaining pressure is balanced by adjustment of air flow rates through pipes and pressure chambers specially designed for this purpose. Air flow rates through pipes in the pressure chamber are presently adjusted manually which is a tedious process and needs skilled personnel. This calls for a device which can automatically adjust the air flow rate through the pipes and thus pressure balancing is achieved. To the best of our knowledge the existence of a device for automatic control of dynamic balancing of pressure to control fire in underground coal mines is not known. However, presently the following procedures are being adopted for implementation of dynamic balancing of pressure technique to combat fire in underground coal mines. Firstly a pressure chamber is made outbye of the isolation stopping sealing the fire affected zone by building a thin brick stopping provided with a small door at about 2 m from the isolation stopping. Two pipes are laid connecting the pressure chamber to main intake as well as return airways. Air sampling pipe through the isolation stopping is used to measure the pressure differential across the isolation stopping by a manometer. Difference in pressure across the stopping, if any, is balanced by adjusting air flow rates through these pipes. It has been observed that for control of fire, balancing has to be maintained round the clock for number of days, extending to over a year in some cases. Obviously maintenance of perfect balancing calls for expert attention over a long period which is one of the main constraints of the system. To overcome these problems and to make maintenance of perfect balancing over a long period an easy task, a device for automatic balancing of pressure is an urgent necessity. The main object of the present invention is to provide a device useful as an automatic dynamic pressure neutralisation system for control of fire in underground coal mines to replace the presently practised manually adjusted pressure balancing system. The device of the present invention is capable of pressure balancing by automatic adjustment of air flowing to pressure chambers by controlling through a microprocessor the valves in the pipes feeding the pressure chamber. The microprocessor is actuated by signals received from a differential pressure sensor connected to a sampling pipe laid across a fire stopping. Thus, automatic control of dynamic balancing of pressure is achieved which helps in controlling fire in underground coal mines in quickest possible time. An embodiment of the device of the present invention is shown in the drawings accompanying this specification In Figs. 1,2, 3, 4, 5(A), & 5(B) of the drawings accompanying this specification details of the device of the present invention is shown. Figure 1 depicts general arrangement of the device fitted in a fire zone of a coal mine worked by bord & pillar method. Figure 2 shows the sectional elevation of the device. Figure 3 shows sectional side view at AA of pipe (7) along with valve (16) and stepper motor (18). Figure 4 shows sectional plan at BB Figure 5 (A) shows sectional view of the valve in open condition and Figure 5(B) shows sectional view of the valve in close condition. The device is placed in a pressure chamber (1) formed in a gallery (2) in between two coal pillars (3) by building a thin brick stopping (4) a small distance away from isolation stopping (5) which isolates the rest of the mine from the fire affected area (6). Two pipes (7) & (8) are provided in the pressure chamber (1). The pipe (7) extends from the pressure chamber (1) along the main intake (9) of the mine. The second pipe (8) extends from the pressure chamber to the main return (10) of the mine through the ventilation stopping (11). The thin brick stopping (4) is also provided with a small airtight door (12). The isolation stopping (5) is provided with a small sampling pipe (13) for drawing air samples and for connection with inlet port (26) of differential pressure sensor by means of polythene or rubber tube (15 ). Ventilation pressure in the mine between the main intake and return galleries (9) & (10) drives a small quantity of air into the pressure chamber (1) through the pipes (7) & (8). Pressure in the pressure chamber (1) is balanced with respect to fire area (6) by adjustment of air flow through the pipes (7) & (8) by regulating the valves (16) & (17) respectively using stepper motors (18) & (19) which are controlled by microprocessor (20) according to pressure imbalance signal received from output of differential pressure sensor (14) & (31). The details of the device of the present invention which is shown in fig. 2, fig. 3, fig. 4, fig. 5 (A) & fig. 5 (B) essentially consists of three parts: a) differential pressure sensor b) a microprocessor (20), programmed to receive, interpret the signals from differential pressure sensor and the n activates a flow control system c) air flow control system comprising two pipes (7) & (8) with stepper motor (18) & (19) controlled valves (16) & (17) which are guided by signals from the microprocessor (20). Accordingly the present invention provides an automatic dynamic pressure neutralization device useful for control of fire in underground coal mines, which comprises differential pressure sensor for measuring the difference from two air pressure sources, characterized in that the said differential pressure sensor consisting of a thin metallic diaphragm (21) with two metallic needles (22) & (23) on its either sides, supported at the middle of a rectangular chamber (24) and insulated from it by rubber (25) or other non conducting gasket, the said chamber has two ports (26) on either side of the diaphragm for connection to pressure sources whose pressure difference is to be measured, the said metallic needles (22) & (23) are connected to resistors (27) and a source of electric potential (28) , the output of the said resistors (27) is connected to ADC (analog digital converter) port of a microprocessor (20) , I/O (input/output) port of the said microprocessor is connected parallel to two stepper motors (18 & 19) for controlling valves fitted in air intake pipes. The differential pressure sensor basically is a thin metallic diaphragm (21) with two metallic needles (22) & (23) on its either sides, supporte3d at the middle of a rectangular chamber (24) but insulated from it by rubber (25) or other non conducting gasket. The chamber has two ports (26) on either side of the diaphragm for connection to pressure sources whose pressure difference is to be measured. The metallic needles (22) & (23) like the diaphragm are insulated from the chamber by rubber (25). The needles and the diaphragm are connected to resistors (27) and a source of electrical potential (28). A small pressure differential applied through the ports (26) across the diaphragm (21) makes it deform and touches the needle (22) thus completing an electric circuit through which a small current flows and a small potential difference develops across one of the resistors (27) connected in the circuit. When the applied pressure ceases, the diaphragm (21) returns to its original position and the electric circuit is broken. When the pressure is applied in the reverse direction the diaphragm (21) deforms in the opposite direction and establishes contact with the second needle (23) which energises the electric circuit connected with it,- The signals from the pressure sensor i.e. the voltage drops at the two resistors (27) are fed to the ADC port of the microprocessor (20) and these two signals become the input of the two channels (14) & (31) of the ADC port which the processor scans continuously. The first channel (14) is connected to the output resulting from the interconnection of left side needle (22) and diaphragm (21) while the second channel (31) is connected to the output resulting from the right side needle (23) and the diaphragm (21). The connection is such that the voltage fed to the two channels (14) & (31) are zero [the diaphragm (21) at centre] or one channel gets positive voltage while the other is zero. Flow control system comprises two conduit pipes (7) & (8) provided with air flow control valves (16) & (17) operated by stepper motors (18) & (19). The stepper motors (18) & (19) are driven by the signals coming from parallel I/O port of the processor (20). Two stepper motors (18) & (19) are connected to the two different ports of the 8255 I/O parallel port. Separate windings of the stepper motor is driven by individual bits of the 8255 I/O port through optocoupler and a power transistor driver. One of the pipes (7) is connected to intake (9) and the other (8) is connected to main return (10) of the mine. Air from main intake (9) flows through the conduit pipe (7) laid along the intake (9), enters the pressure chamber (1) and flows out to main return (10) through the conduit pipe (8) laid from the pressure chamber (1) to the return (10). When both the valves (16) & (17) are in open position air flow through the pipes (7) & (8) is maximum. If one of the valves (16), (17) is closed and the other opened, there is no flow of air. In such situation the pressure in the pressure chamber (,1) attains the pressure prevailing at the free end of the pipe whose control valve is in open position. On the other hand if the open valve is now closed and the closed one opened, again there will be no air flow in the pipes (7) & (8) and through the pressure chamber (1). The pressure in the chamber (1) will then be same as the pressure at the free end of the pipe with the open valve. For any intermediate positions of the valves pressure in the chamber (1) can be adjusted to any value in between these two extremes. The stepper motor (18) controls the movement of the valve (16) connected with intake pipe (7) while the stepper motor (19) controls the movement of the valve (17) connected with return pipe (8). Working principle: The microprocessor (20) continuously scans its two ADC inputs (14) & (31) and compares which channel is positive. When the pressure inside the fire affected zone (6) is positive with respect to pressure chamber (1), metallic diaphragm (21) would make contact with left side needle (22) causing flow of current through the left side resistance (27) resulting in voltage drop across it. Hence the first channel (14) of the ADC of the processor would get positive input while the second channel (31) would be zero. On the contrary, when the pressure inside the fire affected area (6) is negative with respect to pressure chamber (1), metallic diaphragm (21) would make contact with right side needle (23) causing flow of current through the right side resistance (27) resulting in voltage drop across it. Hence, under this circumstances the second channel (31) of the ADC of the processor (20) would be positive while the first channel (14) would be zero. The main programme initialises the I/O 8255 ports, sets up a processor internal register as a counter to count certain prefixed number to give appropriate rotation of the valve and calls for a subroutine which outputs fixed bit patterns that are stored in predesigned memory location. This particular bit pattern enables to rotate the stepper motor for the number of prefixed steps as stored in the processor register. At the start of the programme the processor (20) scans the two ADC input channels (14) & (31). If it finds that both of the input channels (14) & (31) have zero input voltage, the processor (20) does not effect any change in the output bit patterns of the 8255 I/O ports, i. e. the control valves (16) & (17) remain in the same position. When the processor (20) finds that the input at first channel (14) is positive, it activates output control signal (29) controlling the stepper motor (18) and rotates the stepper motor (18) a fixed number of steps in clockwise direction. After a certain delay again the processor compares the first (14) and second channel (31) of ADC input. If still the first channel (14) is positive the processor (20) activates the control signal (29) corresponding to stepper motor (18) for further movement of the valve (16). This process would continue for a certain prefixed number of times of driving the stepper motor (18) and after every driving the processor (20) would check whether the pressure balancing is achieved by comparing the ADC inputs. If it fails to achieve balance conditions and still the first channel (14) of ADC is positive while second channel (31)is zero, the processor (20) would drive the stepper motor (19) in the reverse direction through control signal (30). Similarly, if the diaphragm (21) makes contact with right side needle (23) the second channel (31) of the ADC is positive and first channel (14) is zero, the processor rotates the stepper motor (19) in clock wise direction through control signal (30) for a prefixed number of drives, simultaneously comparing the ADC inputs after each drive so as to attain pressure balancing. If after the prefixed number of drives of the stepper motor (19) does not impart pressure balancing, the processor (20) drives the stepper motor (18) in reverse direction. Thus by controlling the appropriate valve, the processor regulates the pressure inside the chamber (1) and maintains pressure; balancing without intervention of expert personnel. The main advantages of the device of the present invention are: 1. Automatic pressure balancing technique would make pressure balancing an easy task to control fire in mines in quickest possible time without intervention of expert personnel for a long period. 2. The device is simple, uncomplicated and cost effective. 3. The device can be used in mines for prevention of heating. 4. The invention is suitable for use in underground coal mines. We Claim: 1. An automatic dynamic pressure neutralization device useful for control of fire in underground coal mines, which comprises differential pressure sensor for measuring the difference from two air pressure sources, characterized in that the said differential pressure sensor consisting of a thin metallic diaphragm (21) with two metallic needles (22) & (23) on its either sides, supported at the middle of a rectangular chamber (24) and insulated from it by rubber (25) or other non conducting gasket, the said chamber has two ports (26) on either side of the diaphragm for connection to pressure sources whose pressure difference is to be measured, the said metallic needles (22) & (23) are connected to resistors (27) and a source of electric potential (28) , the output of the said resistors (27) is connected to ADC (analog digital converter) port of a microprocessor (20) , I/O (input/output) port of the said microprocessor is connected parallel to two stepper motors (18 & 19) for controlling valves fitted in air intake pipes. 2. An automatic dynamic pressure neutralization device useful for control of fire in underground coal mines, substantially as herein described with reference to the drawings accompanying the specification.

Full Text

This invention relates to a device useful as an automatic dynamic pressure neutralisation device for control of fire in underground coal mines. The present invention particularly relates to pressure differential device for automatic control of dynamic pressure balancing.
Dynamic pressure balancing technique, all over the world has proved to be an effective tool to control fire in underground coal mines. In this technique balancing of pressure is achieved by judicious adjustment of air flow rate, first through the different branches of the ventilation network around the affected zone and secondly, the remaining pressure is balanced by adjustment of air flow rates through pipes and pressure chambers specially designed for this purpose. Air flow rates through pipes in the pressure chamber are presently adjusted manually which is a tedious process and needs skilled personnel. This calls for a device which can automatically adjust the air flow rate through the pipes and thus pressure balancing is achieved.
To the best of our knowledge the existence of a device for automatic control of dynamic balancing of pressure to control fire in underground coal mines is not known. However, presently the following procedures are being adopted for implementation of dynamic balancing of pressure technique to combat fire in underground coal mines. Firstly a pressure chamber is made outbye of the isolation stopping sealing the fire affected zone by building a thin brick stopping provided with a small door at about 2 m from the isolation stopping. Two pipes are laid connecting the pressure chamber to main intake as well as return airways. Air sampling pipe through the isolation stopping is used to measure the pressure differential across the isolation stopping by a manometer.

Difference in pressure across the stopping, if any, is balanced by adjusting air flow rates
through these pipes. It has been observed that for control of fire, balancing has to be
maintained round the clock for number of days, extending to over a year in some cases.
Obviously maintenance of perfect balancing calls for expert attention over a long period
which is one of the main constraints of the system. To overcome these problems and to
make maintenance of perfect balancing over a long period an easy task, a device for
automatic balancing of pressure is an urgent necessity.
The main object of the present invention is to provide a device useful as an automatic
dynamic pressure neutralisation system for control of fire in underground coal mines to
replace the presently practised manually adjusted pressure balancing system.
The device of the present invention is capable of pressure balancing by automatic
adjustment of air flowing to pressure chambers by controlling through a microprocessor
the valves in the pipes feeding the pressure chamber. The microprocessor is actuated by
signals received from a differential pressure sensor connected to a sampling pipe laid
across a fire stopping. Thus, automatic control of dynamic balancing of pressure is
achieved which helps in controlling fire in underground coal mines in quickest possible
time.
An embodiment of the device of the present invention is shown in the drawings
accompanying this specification
In Figs. 1,2, 3, 4, 5(A), & 5(B) of the drawings accompanying this specification details of
the device of the present invention is shown.

Figure 1 depicts general arrangement of the device fitted in a fire zone of a coal mine
worked by bord & pillar method.
Figure 2 shows the sectional elevation of the device.
Figure 3 shows sectional side view at AA of pipe (7) along with valve (16) and stepper
motor (18).
Figure 4 shows sectional plan at BB
Figure 5 (A) shows sectional view of the valve in open condition and
Figure 5(B) shows sectional view of the valve in close condition.
The device is placed in a pressure chamber (1) formed in a gallery (2) in between two
coal pillars (3) by building a thin brick stopping (4) a small distance away from isolation
stopping (5) which isolates the rest of the mine from the fire affected area (6). Two pipes
(7) & (8) are provided in the pressure chamber (1). The pipe (7) extends from the
pressure chamber (1) along the main intake (9) of the mine. The second pipe (8) extends
from the pressure chamber to the main return (10) of the mine through the ventilation
stopping (11). The thin brick stopping (4) is also provided with a small airtight door (12).
The isolation stopping (5) is provided with a small sampling pipe (13) for drawing air
samples and for connection with inlet port (26) of differential pressure sensor by means
of polythene or rubber tube (15 ). Ventilation pressure in the mine between the main
intake and return galleries (9) & (10) drives a small quantity of air into the pressure
chamber (1) through the pipes (7) & (8). Pressure in the pressure chamber (1) is balanced
with respect to fire area (6) by adjustment of air flow through the pipes (7) & (8) by
regulating the valves (16) & (17) respectively using stepper motors (18) & (19) which are
controlled by microprocessor (20) according to pressure imbalance signal received from output of differential pressure sensor (14) & (31).
The details of the device of the present invention which is shown in fig. 2, fig. 3, fig. 4, fig. 5 (A) & fig. 5 (B) essentially consists of three parts:
a) differential pressure sensor
b) a microprocessor (20), programmed to receive, interpret the signals from
differential pressure sensor and the n activates a flow control system
c) air flow control system comprising two pipes (7) & (8) with stepper motor (18) &
(19) controlled valves (16) & (17) which are guided by signals from the
microprocessor (20).
Accordingly the present invention provides an automatic dynamic pressure neutralization device useful for control of fire in underground coal mines, which comprises differential pressure sensor for measuring the difference from two air pressure sources, characterized in that the said differential pressure sensor consisting of a thin metallic diaphragm (21) with two metallic needles (22) & (23) on its either sides, supported at the middle of a rectangular chamber (24) and insulated from it by rubber (25) or other non conducting gasket, the said chamber has two ports (26) on either side of the diaphragm for connection to pressure sources whose pressure difference is to be measured, the said metallic needles (22) & (23) are connected to resistors (27) and a source of electric potential (28) , the output of the said resistors (27) is connected to ADC (analog digital converter) port of a microprocessor (20) , I/O (input/output) port of the said microprocessor is connected parallel to two stepper motors (18 & 19) for controlling valves fitted in air intake pipes.
The differential pressure sensor basically is a thin metallic diaphragm (21) with two metallic needles (22) & (23) on its either sides, supporte3d at the middle of a rectangular chamber (24) but insulated from it by rubber (25) or other non conducting gasket. The chamber has two ports (26) on either side of the diaphragm for connection to pressure sources whose pressure difference is to be measured. The metallic needles (22) & (23) like the diaphragm are insulated from the chamber by rubber (25). The needles and the diaphragm are connected to resistors (27) and a source of electrical potential (28). A small pressure differential applied through the ports (26) across the diaphragm (21) makes it deform and touches the needle (22) thus completing an electric circuit through which a small current flows and a small potential difference develops across one of the resistors (27) connected in the circuit. When the applied pressure ceases, the diaphragm (21) returns to its original position and the electric circuit is broken. When the pressure is applied in the reverse direction the diaphragm (21) deforms in the opposite direction and establishes contact with the second needle (23) which energises the electric circuit connected with it,-
The signals from the pressure sensor i.e. the voltage drops at the two resistors (27) are fed to the ADC port of the microprocessor (20) and these two signals become the input of the two channels (14) & (31) of the ADC port which the processor scans continuously. The first channel (14) is connected to the output resulting from the interconnection of left side needle (22) and diaphragm (21) while the second channel (31) is connected to the output resulting from the right side needle (23) and the diaphragm (21). The connection is such that the voltage fed to the two channels (14) & (31) are zero [the diaphragm (21) at centre] or one channel gets positive voltage while the other is zero. Flow control system comprises two conduit pipes (7) & (8) provided with air flow control valves (16) & (17) operated by stepper motors (18) & (19). The stepper motors (18) & (19) are driven by the signals coming from parallel I/O port of the processor (20). Two stepper motors (18) & (19) are connected to the two different ports of the 8255 I/O parallel port. Separate windings of the stepper motor is driven by individual bits of the 8255 I/O port through optocoupler and a power transistor driver. One of the pipes (7) is connected to intake (9) and the other (8) is connected to main return (10) of the mine. Air

from main intake (9) flows through the conduit pipe (7) laid along the intake (9), enters the pressure chamber (1) and flows out to main return (10) through the conduit pipe (8) laid from the pressure chamber (1) to the return (10). When both the valves (16) & (17) are in open position air flow through the pipes (7) & (8) is maximum. If one of the valves (16), (17) is closed and the other opened, there is no flow of air. In such situation the pressure in the pressure chamber (,1) attains the pressure prevailing at the free end of the pipe whose control valve is in open position. On the other hand if the open valve is now closed and the closed one opened, again there will be no air flow in the pipes (7) & (8) and through the pressure chamber (1). The pressure in the chamber (1) will then be same as the pressure at the free end of the pipe with the open valve. For any intermediate positions of the valves pressure in the chamber (1) can be adjusted to any value in between these two extremes. The stepper motor (18) controls the movement of the valve (16) connected with intake pipe (7) while the stepper motor (19) controls the movement of the valve (17) connected with return pipe (8). Working principle:
The microprocessor (20) continuously scans its two ADC inputs (14) & (31) and compares which channel is positive. When the pressure inside the fire affected zone (6) is positive with respect to pressure chamber (1), metallic diaphragm (21) would make contact with left side needle (22) causing flow of current through the left side resistance
(27) resulting in voltage drop across it. Hence the first channel (14) of the ADC of the processor would get positive input while the second channel (31) would be zero. On the contrary, when the pressure inside the fire affected area (6) is negative with respect to pressure chamber (1), metallic diaphragm (21) would make contact with right side needle (23) causing flow of current through the right side resistance (27) resulting in voltage drop across it. Hence, under this circumstances the second channel (31) of the ADC of the processor (20) would be positive while the first channel (14) would be zero. The main programme initialises the I/O 8255 ports, sets up a processor internal register as a counter to count certain prefixed number to give appropriate rotation of the valve and calls for a subroutine which outputs fixed bit patterns that are stored in predesigned memory location. This particular bit pattern enables to rotate the stepper motor for the number of prefixed steps as stored in the processor register. At the start of the programme the processor (20) scans the two ADC input channels (14) & (31). If it finds that both of the input channels (14) & (31) have zero input voltage, the processor (20) does not effect any change in the output bit patterns of the 8255 I/O ports, i. e. the control valves (16) & (17) remain in the same position. When the processor (20) finds that the input at first channel (14) is positive, it activates output control signal (29) controlling the stepper motor (18) and rotates the stepper motor (18) a fixed number of steps in clockwise direction. After a certain delay again the processor compares the first (14) and second channel (31) of ADC input. If still the first channel (14) is positive the processor (20) activates the control signal (29) corresponding to stepper motor (18) for further movement of the valve (16). This process would continue for a certain prefixed number of times of driving the stepper motor (18) and after every driving the processor (20) would check whether the pressure balancing is achieved by comparing the ADC inputs. If it fails to achieve balance conditions and still the first channel (14) of ADC is positive while second channel (31)is zero, the processor (20) would drive the stepper motor (19) in the reverse direction through control signal (30). Similarly, if the diaphragm (21) makes contact with right side needle (23) the second channel (31) of the ADC is positive and first channel (14) is zero, the processor rotates the stepper motor (19) in clock wise direction through control signal (30) for a prefixed number of drives, simultaneously comparing the ADC inputs after each drive so as to attain pressure balancing. If after the prefixed number of drives of the stepper motor (19) does not impart pressure balancing, the processor (20) drives the stepper motor (18) in reverse direction. Thus by controlling the appropriate valve, the processor regulates the pressure inside the chamber (1) and maintains pressure; balancing without intervention of expert personnel. The main advantages of the device of the present invention are:
1. Automatic pressure balancing technique would make pressure balancing an easy task
to control fire in mines in quickest possible time without intervention of expert
personnel for a long period.
2. The device is simple, uncomplicated and cost effective.
3. The device can be used in mines for prevention of heating.
4. The invention is suitable for use in underground coal mines.

We Claim:
1. An automatic dynamic pressure neutralization device useful for control of fire in
underground coal mines, which comprises differential pressure sensor for
measuring the difference from two air pressure sources, characterized in that the
said differential pressure sensor consisting of a thin metallic diaphragm (21) with
two metallic needles (22) & (23) on its either sides, supported at the middle of a
rectangular chamber (24) and insulated from it by rubber (25) or other non
conducting gasket, the said chamber has two ports (26) on either side of the
diaphragm for connection to pressure sources whose pressure difference is to be
measured, the said metallic needles (22) & (23) are connected to resistors (27)
and a source of electric potential (28) , the output of the said resistors (27) is
connected to ADC (analog digital converter) port of a microprocessor (20) , I/O
(input/output) port of the said microprocessor is connected parallel to two stepper
motors (18 & 19) for controlling valves fitted in air intake pipes.
2. An automatic dynamic pressure neutralization device useful for control of fire in
underground coal mines, substantially as herein described with reference to the
drawings accompanying the specification.

Documents:

3833-del-1998-abstract.pdf

3833-del-1998-claims.pdf

3833-del-1998-correspsondence-others.pdf

3833-del-1998-correspsondence-po.pdf

3833-del-1998-description (complete).pdf

3833-del-1998-drawings.pdf

3833-del-1998-form-1.pdf

3833-del-1998-form-19.pdf

3833-del-1998-form-2.pdf

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Patent Number

215681

Indian Patent Application Number

3833/DEL/1998

PG Journal Number

12/2008

Publication Date

21-Mar-2008

Grant Date

29-Feb-2008

Date of Filing

24-Dec-1998

Name of Patentee

COUNCIL OF SCIENTIFIC AND INDUSTRIAL RESEARCH

Applicant Address

RAFI MARG, NEW DELHI-110001, INDIAN.

Inventors:

#	Inventor's Name	Inventor's Address
1	BIMAL CHNDRA BHOWMICK	CENRAL MINING RESEARCH INSTITUTE, BARWA ROAD, DHANBAD, BIHAR, INDIA
2	NAGESWAR SAHAY	CENRAL MINING RESEARCH INSTITUTE, BARWA ROAD, DHANBAD, BIHAR, INDIA
3	ISHTIAQUE AHMAD	CENRAL MINING RESEARCH INSTITUTE, BARWA ROAD, DHANBAD, BIHAR, INDIA
4	AMAL KUMAR DUTT	CENRAL MINING RESEARCH INSTITUTE, BARWA ROAD, DHANBAD, BIHAR, INDIA
5	LAKSHMI KANTA BANDYOPADHYAY,	CENRAL MINING RESEARCH INSTITUTE, BARWA ROAD, DHANBAD, BIHAR, INDIA
6	SANTOSH KUMAR RAY	CENRAL MINING RESEARCH INSTITUTE, BARWA ROAD, DHANBAD, BIHAR, INDIA
7	RUDRA PRATAP SHINGH	CENRAL MINING RESEARCH INSTITUTE, BARWA ROAD, DHANBAD, BIHAR, INDIA
8	TIBHUWAN NATH SINGH	CENRAL MINING RESEARCH INSTITUTE, BARWA ROAD, DHANBAD, BIHAR, INDIA
9	SRI MOHAN VERMA	CENRAL MINING RESEARCH INSTITUTE, BARWA ROAD, DHANBAD, BIHAR, INDIA

PCT International Classification Number

B21F 5/14

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA