Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Title: MINE FIRE AND EMERGENCY WARNING STENCH INJECTOR
[001] This mine fire and emergency device relates generally to the
monitoring and control of underground mine warning systems.
BACKGROUND AND SUMMARY
[002] In mine workings underground; situations arise which warrant
the immediate notification and attention of workers underground.
Typical of warning situations would be: fire in any area
underground; dangerous blasting conditions, rock shifts and bursts,
cave-ins and even power failures.
[003] To do this an ethyl mercaptan (rotten egg) smell is injected
into mine ventilation air and compressor systems. This smell is
purposely objectionable and attention getting.
[004] Accordingly it is an object of the present invention to
provide a new and improved device which will provide users a
failsafe manner of injection even with power failures; as a manual
back-up override is provided.
[005] Another object of the present invention is to provide a
device that can be fired immediately and simultaneously from a
central station, even if injection points (i.e the remote-stations)
are kilometres apart.
[006] Another object of the present invention is to provide a
device that has no small orifices, screens or restrictions to plug.
[007] Another object of the present invention is to provide a
device that injects stench at a metered rate (and thus meets
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governmental standards) under various air flows in both ventilation
and compressed air applications.
[008] Another object of the present invention is to provide a
device that has continuous feedback to the central-station giving
the status of the remote-stations under normal as well as firing
conditions.
[009] Another object of the present invention is to provide a
complete operational system with as few moving parts as possible to
provide minimal maintenance.
[0010] Another object of the present invention is to be able to
reload the system easily and quickly; so the device is ready to fire
again should the need arise.
[0011] Another object of the present invention is the ability of
the apparatus to house and fire a single or a multitude of stench
cylinders (reservoirs) (for applications having large air volumes).
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0012] By way of further explanation, exemplary apparatuses will
now be described with reference to the accompanying drawings, in
which:
Fig 1 is a pictorial view of a central-station, showing some of the
components thereat.
Fig 2 is a similar view of one of plural remote-stations.
Fig 3 shows a circuit diagram as it relates to the central-station.
Fig 4 shows the circuit diagram as it relates to tow of the remote-
stations.
[0013] The apparatus 20 shown in the accompanying drawings and
II~
~III
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described below is an example. It should be noted that the scope of
the patent protection sought is defined by the accompanying claims,
and not necessarily by specific features of exemplary embodiments.
[0014] When an emergency situation arises, a call is placed to a
constantly-manned emergency number located at a central-station 23.
This may be a control room, shift office, security gate or hoist
operator station. At these sites there may be a computer console or
a small control panel. An individual at the central-station will
activate the stench warning system. When workers smell the injected
stench, they depart immediately to a refuge station. At this refuge
station all individuals are accounted for and the entrance door is
sealed until notification that the emergency situation is passed and
under control.
[0015] At the central-station 23, indicators 25 indicate stench
injector pressures (in the remote-stations 27) at all times. Two
alarm indicators are also present. These are: a "stench system
charged" alarm 29 (which goes off when the stench pressure in the
stench reservoir or cylinder 30 (at each remote station 27) drops
below the pressure required for full evacuation of the cylinder into
the compressed air line or ventilation air conduit 32; and a "stench
system discharged" alarm 34, which comes on when the full contents
of the stench cylinder 30 (at each remote-station) have been
discharged into the compressor or ventilation conduits 32.
[0016] Another indicating light at the central-station 23 is a
"power on" light 36 which will go out upon a loss of power supply in
the remote-stations 27. If that happens, an. operator at that
remote-station opens the injector enclosure, and opens a manual-
bypass valve 38, to inject the stench into the conduit 32.
[0017] A multitude of the remote-stations 27 can be fired
simultaneously by the operation of a single activation switch 40 at
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the central-station 23. 24VDC switching and indication over
telephone lines allows for control of many remote-stations 27, which
may be kilometres apart and away from the central-station 23. By
this method, central control of all release areas can be provided.
The lines for carrying the activation-signals are connected between
the terminals AS on each remote-station and on the central-station.
[0018] The remote-station 27 is designed as follows (referring
to Figs 2,4). Single or multiple stench reservoirs in the form of
cylinders 30 (held by clamping brackets) feed through stainless
steel, PTFE-lined, hose to a manifold 41. The manifold 41 also
holds the pressure transmitter 43 which sends the pressure signal to
the central-station 23. The pressure-signal is sent to the central-
station along lines connected between the terminals PS-1, PS-a, etc
on the remote-stations, and the corresponding terminals on the
central-station. Also at the remote-station in Fig 2 is a local
pressure gauge 45, the manual-bypass valve 38, a vent-to-atmosphere
valve 47 (used when replacing cylinders), and connections to a
metering valve 49.
[0019] The metering valve 49 at each remote-station includes an
electric actuated ball-valve operated by a repeat cycle timer 50,
which has individual "open" and "closed" time settings. This is the
only moving portion of the complete system. As the ball-valve opens
it reveals a large opening (preventing plug-ups), then closes again.
This sequence is repeated over and over until all stench has been
discharged.
[0020] The "open" and "closed" times in the cycling relay 50
are adjusted in a timed sequence to provide proper underground
exposure according to either the compressor or ventilation SCFM
(standard cubic feet per minute) of air flow. The National
Institute for Occupational Safety and Health through the American
Conference of Governmental and Industrial Hygienists have selected a
STEL (Short
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Term Exposure Limit) for stench applications (ethyl mercaptan) to be
2 ppm (parts per million) in the U.S.A. and 1.5 ppm in Canada.
[0021] In an emergency, when it is necessary to inject stench, the
following is performed (assuming the reservoir cylinder 30 at the
remote-station starts off at full pressure, and the "stench-charged"
indicator 29 at the central-station is on). Now, the operator at
the central-station 23 presses the timed latching switch 40 that
signals all the remote-stations 27 to make stench. As the stench-
agent is discharged, the pressure in the stench reservoir 30 will
slowly fall, and after a few moments the "stench-charged" indicator
light 29 will go off. Then, after four to seven minutes from the
start of the injection cycle, the pressure in the stench-reservoir
30 falls so low that the "stench-discharged" light 34 will
illuminate, indicating that all, or nearly all, the stench-agent has
been injected into the ventilation or compressor conduits 32. After
ten minutes, the switch 40 at the central-station 23 unlatches,
thereby signalling the metering-valves 49 in the remote-stations to
stop cycling, and to remain closed.
[0022] The remote-stations will stay in this closed position
indefinitely until they are recharged. To return the system to
"stand by" for recharging, the operator turns the "activate-
stench" switch 40 at the central-station 23 to the "OFF"
position.
[0023] In the central-station 23, as shown in Figs 1,3, the
"power on" light 36 on the panel indicates power is present in
the remote-stations. The central-station includes pressure
indicators 25 (which may be separate indicators, one for each
remote-station, or may be a single indicator instrument which
registers the respective readings from the remote-stations in
sequence). The indicator 25 at the central-station receives
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signals from the pressure transmitters 43 at the remote-stations.
The central-station also has the alarm settings for "stench-
charged" and "stench-discharged" warning lights 29,34, which
again indicate pressure conditions in the stench-reservoirs in
the respective remote-stations 27.
[0024] The "stench system charged" light 29 in the central-
station 23 comes on when the stench-reservoir 30 in the remote-
station 27 has enough pressure to fully inject the contents of
the reservoir or cylinder 30 into the ventilation or compressor
conduit 32. The "stench discharged" light 34 in the central-
station comes on when, after a discharge of stench-agent at the
remote-station, the stench-cylinder 30 has fully discharged into
the ventilation or compressor conduit 32.
[0025] The signalling system between the remote-stations 27 and
the central-station 23 operates on 24DC supply, and a check is
kept at the central-station that power is present at the remote-
stations, as necessary for transmittal of the injector pressure
signal from the remote-station to the central-station, as well
for receipt of the stench activate signal from the central-
station to the remote-stations.
[0026] The timer-delay relay TDE at the central-station switches
off the stench activate signal, and thereby shuts down the
injection system in the remote-stations, ten minutes after its
initiation. By this time all of the stench-agent has been
injected. The shut-down prevents unnecessary cycling of the
metering valve 49.
[0027] The master activation switch 40 at the central-station 23
controls the release of stench agent at the remote stations 27.
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This switch has a lockable hinged cover over it to prevent
accidental firing of the stench system. Placing the switch 40 in
the "ON" position begins the injection cycle. Placing the switch
in the "OFF" position terminates injection immediately.
[0028] The remote-stations, as shown in Fig 2 and Fig 4, serve to
inject stench-agent stored at the remote-stations into either the
compressed air or ventilation conduits 32, as required. (In Fig
4, which shows two of the remote-stations, the component numerals
have been given suffixes, which indicate remote-station number
one and remote-station number two. It will be understood that an
installation in a typical mine might have e.g six remote-
stations.) The remote-stations include the following components
and functions. The activation-relay AR-1 (at remote-station
number one) accepts the activate signal from the central-station,
to start the stench inject cycle at the remote-station. The
cycle timer relay 50 has independently variable "open" and
"closed" time cycles which operate the local metering valve 49
through local "open" and "close" relays. These relays drive the
metering valve "open" and "closed" respectively, and are time
dependent on the local cycle time settings. These relays also
prevent inductive kick-back generated when the metering valve 49
suddenly and continuously reverses directions.
[0029] In the remote-stations, the metering-valve 49 is normally
closed. When the stench inject sequence begins, this valve
cycles continuously from closed to open to closed etc. The
amount of time the valve is open or closed is set to produce the
SCFM (Standard Cubit Feet per Minute) in the airstream that the
stench system is asked to inject into.
[0030] The power-relay PR-1 in the remote-station-1 is energized
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when the remote-station power is "ON". If there is a power
failure at the remote-station, power-relay PR-1 interrupts the
injector pressure transmitter signal going to the panel indicator
25 at the central-station 23. Thus, this indicator will show an
"ERROR" (interpreted to mean "loss of injector power", which is
indicated by lamp 36 at the central-station). The injector
pressure transmitter 43 sends the pressure signal from the
remote-station to the central-station at all times, provided the
power is "ON".
[0031] A 70w heater H is used to heat the remote-station
enclosure when ambient conditions drop below freezing. This
provides protection for the solid state equipment inside the
enclosure. As well, the heater helps maintain pressure in the
stench cylinder in below-freezing conditions.
