Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
:~3~3~1L34
SENSING OF THE OPEN AND/OR CLOSED CONDITION OF V~LVES
5 Field of the Inv ntion
This invention relates to sensing of the open and/or
closed condition of valves and relates particularly but not
exclusively to sensing such conditions of fire installation
water~valves.
~ 10 Description of Prior Art
: In my Australian Petty Patent No. 549,439 there is
disclosed sensing means for water supply valves in a fire
alarm installation. The sensing means in such valves operates
to sense when the valve is closed from the open position.
15 Th.is requirem~nt is considered to be essential in fire alarm
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-- 3
installations because if the main water supply valve
is closed, then unless some warning can be given to
alert personnel serious consequences can result if
there is a fire.
s The present invention has been devised to
provide an improved valve where better protection
can be obtained.
Therefore in accordance with a first broad
aspect of the present invention there may be pro-
o vided a valve for controlling the supply of fluids
or other materials, said valve being of the type
which is operable to be in a first state where said
fluids or other materials can flow therethrough and
further operable to be in a second state where said
15 fluids or other materials cannot flow therethrough,
said valve having first magnetic sensing
means for sensing a magnetic material part of the
valve when the valve is in an intended one of its
states and for magnetically biasing said first
magnetic sensing means into a non-alarm state,
and second magnetic sensing means in a
non-alarm state positioned adjacent said first
magnetic sensing means so as to sense said magnetic
material part as said valve is operated to be in a
zs non-intended one of its states, and to then be
biased into an alarm state by said magnetic material
part.
In accordance with a particular embodiment
of the invention there is provided a device for
sensing the open and/or closed position of a valve,
comprising:
(a) a valve for controlling the supply of
fluids or other materials, said valve being of the
type which is operable to be in a first position in
3s which said valve is in one of a fully open and fully
closed position and further operable to be in a
~39~34
- 3a -
second position in which said valve is in another of
said fully open and fully closed position and, said
valve being in an intermediate position when it is
not in either of said first or second position, said
s valve having a magnetic material part;
(b) first magnetic sensing means being in a
first condition in the presence of a magnetic
material and a second condition in the absencè of
such a magnetic mate.rial for sensing said magnetic
10 materi.al part of said valve when said valve is in
said first position, said first magnetic sensing
means being biased into a non-alarm state when said
valve is in said first position, said first magnetic
sensing means being biased into an alarm state when
15 said valve is in a position other than said ~irst
position;
(c) second magnetic sensing means being in a
condition corresponding to said second condition in
the presence of a magnetic material and in a
condition corresponding to said first condi~ion in
the absence of such a magnetic material positioned
immediately adjacent said first magnetic sensing
means, for sensing said magnetic material part when
said valve is in an intermediate position adjacent
: 2s said first position, said second magnetic sensing
means being biased into a non-alarm state when said
valve is in said first position, said second
magnetic sensing means being biased into an alarm
state as said vaIve is operated to be in a position
other than said first position whereby said second
magnetic sensing means can sense the operation of
said valve into said first position independently of
said first magnetic sensing means and whereby said
second magnetic sensing means can sense the presence
35 of a magnetic material, other than said magnetic
~L3~343~
- 3b -
material part, which would interfere with opera~ion
of said first magnetic sensing means.
Most preferably said valve has further
magnetic sensing means, positioned at different
s positions adjacent said magnetic sensing means,
whereby to act with said second magnetic sensing
means to sense if a person places foreign magnetic
material in proximity to said first magnetic sensing
means, in attempt to hold said magneti.c sensing
10 means in a non-alarm condition. In this manner one
or more of the magnetic sensing means will sense the
presence of such foreign magnetic material and, in
use, will provide an alarm signal.
Most preferably each of said magnetic
15 sensing means is a two state device arranged so
that it is biased by said magnetic material to be
in one of its states when the valve is
.~l
~30343~L
in said first state, and so that it can assume its other state
when said valve is operated to move to its second state, -
i.e. said magnetic material does not bias it to said one
state. It is also preferred that said first magnetic sensing
S means is biased to be in one of its states and wherein the
states of the others of said magnetic sensing means are
oppositely arranged - i.e. that said magnetic ma-terial does
not bias them into one of their states until the valve is
closed.
It should be appreciated that the second magnetic
sensing means provides a backup for the first magnetic sensing
means, so that when the valve is moved from its first state to
its second state, then if the first magnetic sensing means
should not change its state under those conditions due to a
lS failure of the first magnetic sensing means, then the second
magnetic sensing means will trip to the other of its states
when said magnetic material moves into proximity of the second
magnetic sensing means. Accordingly, the second magnetic
sensing means provides a backup for the fail safe detection
20 that the valve has moved from its first state towards its
second state. Because the second magnetic sensing means is
positioned adjacent the first magnetic sensing means, it
provides a reliable indication as soon as the valve is moved
from its first state towards its second state.
In accordance with a further aspect of the present
invention there is provided a first magnetic sensing ~leans and
a second magnetic sensing means mounted in a housing adapted
to be fitted to a valve, to sense if said valve has been
operated to move it from an intended on of its states of
30 operation to a non-intended one of its states of operation,
said first magnetic sensing means being held in said
housing so that, in use, it will be biased by a magnetic
material part of said valve to be in a non-alarm state when
said valve is in an intended one of its states,
said second magnetic sensing means being held in
said housing so that, in use, it will be in a non-alarm state
when said valve is in said intended one of its states and so
~IL303~39L
-- 5 --
that it will be biased by said magnetic material
part to be in an alarm state when said valve is
moved to a non-intended one of its states.
In accordance with a particular embodiment
s of this further aspect there is provided a fluid-
controlling valve having a body member, a fluent
material controlling member and an actuating member
means for causing movement of said fluent material
controlling member, including:
a first means, movable through a locus
having a length in response to movement of said
actuating member means, for altering the ambient
magnetic field in a region, having an extent,
proximate thereto, said magnetic means being in a
15 first position when said valve is in one of an open
and closed state and in a second position when said
valve is in another of said open and closed states;
first and second magnetically operable
switch means, each having first and second
20 conduction states, for assuming a first conduction
state in response to-the presence of an ambient
magnetic field and a second conduction state in
response to a magnetic field different from said
ambient magnetic field and wherein said first and
25 second conduction states of said second magnetically
operable switch means being opposite to said first
and second conduction states of said first
magneticall~ operable switch means;
means for positioning said first and
30 second magnetically opera~le switch means proximate
to said locus of said magnetic means, at adjacent
locations which are spaced at a distance less than
the length of said locus and greater than said
extent,
whereby retention of said first
magnetically operable switch means in said second
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- 5a -
conduction state by an additional magnetic means
other than said magnetic means will cause actuation
from said first conduction state to said second
conduction state of said second magnetically
s operable switch means.
In order that the invention can be more
clear].y ascertained preferred embodiments will now
be described with reference to the accompanying
drawings, wherein:
Figure 1 is a side view of a known gate
valve modified in accordance with an embodiment of
the present invention;
Figure 2 is a sectional view taken along
line 2-2 of F.igure 1 showing the detail of a sensor
15 unit;
Figure 3 is an end view of the sensor unit
- shown in Figure 2 with its lid removed;
. Figure 4 is a plan view of a sensor unit
for a different type of valve, modified with
20 preferred sensing means in accordance with the
present invention and having its lid removed;
Figure 5 is a view similar to Figure 4 but
showing the valve and with its operating handle
removed;
2s Figure 6 is an end view of the sensor unit
shown in Figures 4 and 5;
Figure 7 is a perspective view of the
sensor unit shown in Figures 4, 5 and 6;
Figure 8 is a perspective view showing the
30 sensor unit of Figures 4 throu~h 7 but with the top -
removed and the handle of the valve locked in a
valve open position;
Figure 9 is an underneath perspective view
of the lid of the sensor unit shown in Figures 4
35 through 8i
~L3~39L3~7L
- 5b -
Figure 10 is a perspective vlew of the
operating handle of the valve shown in Figures 4
through 9;
Figure 11 shows a side view of the valve
s in the sensor unit shown in Figures 4 throuyh 10 and
fitted with the handle shown in Figure 10;
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-- 6 --
Figures 12 through 14 show respective positions of
the handle for open, partly closed, and fully closed
conditions of the valve; and
Figure 15 is a block circuit diagram of the
S electrical wiring of a typical installation incorporating the
valve with magnetic sensors in accordance with a preferred
aspect of the present invention.
Detailed Description of Preferred Embodiment
Referring now to Figure 1, there is shown a gate
10 valve 1 which has a valve gate 3 therein. The valve gate 3
connects with a threaded valve stem 5 of brass or bronze
which, in turn, is operatively connected with a threaded
handle 7. Rotation of the handle 7 causes the valve stem 5 to
extend or retract to thereby move the gate 3 up or down within
15 guides 9 in the valve body 2 to open and/or close the gate
valve. In this embodiment, there is provided a sensor unit 11
which comprises a number of magnetic sensing means in the form
of reed switches. These have not been shown in Figure 1. The
sensor unit 11 is fitted to the outside of the valve housing
20 i.e. e~ternal of the valve chamber, but at a position where it
can sense movement of the valve stem 5. This in turn, is
sensing if the gate 3 is open and/or closed.
In order to effect the necessary sensing of the
position of the valve stem 5, i.e. if the gate is opened
25 and/or closed, there is provided appropriate magnetic material
12 and 13 fitted within appropriate holes 14 drilled into the
valve stem 5. The sensor unit 11 can, in turn, sense the
position of either appropriate magnetic material 12 or 13 and
thus determine if the valve is open and/or closed. Typically,
30 the appropriate magnetic material 12 and 13 is a permanent
magnet but it may comprise ferromagnetic material such as mild
steel if the reed switches are of the type which can react by
the presence and/or absence of that mild steel. It should be
appreciated that reed switches come in two types, i.e. one
35 that is not magnetized and which requires a magnet to cause it
to operate, and the other type wherein the reeds are
~3~)3~L3~
-- 7
magnetized or at least one of the reeds is magnetized and
wherein a further magnet and/or other appropriate magnetic
material such as mild steel, can influence the magnetic fields
in the reed switch and cause it to operate. All of these
5 types of switches and appropriate magnetic materials are
considered to be within the scope of the present invention.
Other types of magnetic sensing means are also included such`
as Hall effect devices and the like which when connected to
appropriate circuitry can provide a two state output.
Referring now to Figure 2 there is shown a close-up
sectional view of the sensor unit 11 taken along line 2-2 of
Figure 1. The sensor unit 11 comprises a generally
rectangular block of bronze material which has a c~lbic hollow
interior 15. The sensor unit 11 is mounted to the valve 1 by
15 means of right angle brackets 17 which connect with an upper
yoke part of the valve 1. The sensor unit 11 has a lid 19
which closes the interior 15. The lid 19 is made from bronze
material. The end of the sensor unit 11 which is opposite to
the lid 19 is provided with a small curved shaped depression
20 21. This is provided to enabIe the sensor unit 11 to fit in
close proximity to the valve stem 5. The sensor unit 11 has
five holes 23 counterbored therein. The holes 23 terminate
near the forward end 25 of the sensor unit 11 and at positions
where they will be in general proximity to the valve stem 5.
25 The five holes 23 are arranged in a right angle cross
configuration so that three holes 23 are in line and
transverse to the longitudinal axis of the stem 5 and so that
the other two of the holes 23 are in line with the
longitudinal axis of the valve stem 5 and in line with the
30 central hole 23. Reed switches 27, 29, 31, 33 and 35 are
positioned in each of the respective holes 23. The reed
switches are then encapsulated within the holes 23 by a back
fill of epoxy resin 37.
The view shown in Figure 3 depicts the positions
35 where the respective reed switches 27, 29, 31, 33 and 35 are
fitted. Each of those reed switches is of the type which has
a common lead, a normally open lead and a normally closed
~3~3~3~
-- 8 --
lead. Reed switch 35 is wired so that when the magnet
material 13 is directly adjacent the end thereof - i.e. the
valve is open - its normally closed contacts are open. The
others of the reed switches 27, 29, 31 and 33 are wired so
5 that their normally open contacts are in parallel with the
normally closed contacts of the central reed switch 35 iOe.
their states are different to that of reed switch 35. In the
parallel circuit arrangement of all the reed switches 27, 29,
31, 33 and 35 there will be a normally open circuit condition
10 when the valve is in the fully open condition and the magnet
material 13 is adjacent the end of the reed switch 35. If the
valve is closed, i.e. the valve stem 5 is moved downwardly by
rotation of the handle 7, then the magnetic material 13 will
pass the lower reed switch 33 and cause it to trip to the
15 closed condition. Approximately simultaneously, the contacts
of reed switch 35 which were previously open when the valve
was fully open will now close. The operation of one or other
or both of the reed switches 33 and 35 will cause an alarm
signal to be provided to show that the valve has moved from
20 the fully open condition towards the closed condition.
It should be observed that the reed switch 33 in
this case provides a backup for the reed switch 35 to show
that the valve has moved from the fully open position to the
closed position. If for example reed switch 35 fails to close
25 due to a failure, then reed switch 33 will provide the
necessary backup by the closing of its contacts when the
magnetic material 13 is in proximity to the end of the reed
switch 33.
All of the reed switches 27, 29, 31, 33 and 35
30 cooperate together so as to provide protection for the sensor
unit 11 so that if a person should maliciously attempt to fool
the sensor unit 11 by placing some magnetic material, either
ferromagnetic material or some highly magnetic material such
as a permanent magnet, near the sensor unit 11, then one or
35 more of the reed switches 27, 29, 31, 33 and 35 will trip and
cause an alarm signal to be generated even though the valve
has not moved from the open position to the closed position.
~3~3~3~L
g
This, in turn, will cause an alarm signal to be generated.
The magnetic material 12 is positioned on the valve stem 5 a-t
a position where it will coincide with reed switch 29 when the
valve is in the fully closed position. Thus, an output signal
S can be provided from the reed switch 29 if it is wired
separately from the reed switches 27, 31, 33 and 35, and this
can be caused to provide an indication that the valve is in
the fully closed condition.
In order to enhance the tamper proof qualities of
10 the sensor unit 11 a microswitch 39 is mounted within the
interior lS so that an arm 41 thereof engages with the
undersurface of the lid 19. Typically microswitches have
normally open and normally closed contacts. When the lid is
in place, the switch 39 is wired so it will provide an open
15 circuit. If the lid 19 is removed then the switch 39 will
operate to close its contacts and thus provide an alarm
signal. The switch 39 can be wired in parallel with reed
switches 27, 31, 33 and 35.
The exact wiring of the reed switches 27, 29, 31, 33
20 and 35, is a matter of choice depending on the nature of the
control circuit to which they are subsequently connected. For
e~ample, some control circuits work in a normally closed mode
where there is no alarm given and when the switches open an
alarm is provided. Accordingly, the reed switches can be
25 appropriatel~ wired to their respective normally
opened/normally closed contacts to provide for the required
end results. If required individual ones of the reed switches
27, 29, 31, 33 and 35 can be connected to respective circuits
so that identification of which particular reed switch has
30 operated can be given. All of these variations are included
within the scope of the present invention. In addition, the
sensor unit 11 may be fitted into any one of the embodiments
disclosed in the aforementioned Petty Patent No. S49,439 and
still be within the scope of the present invention.
Referring now to Figures 4 through 14 there is shown
a different type of valve with sensor unit 11 attached
thereto. In this embodiment the valve 43 is a globe valve and
~L3~34~
- 10 -
is used to supply individual water supply lines in, for
example, a fire alarm installation to particular ones of fire
sprinklers. Ilitherto, valves of this type are normally locked
in the open position. Such valves have not previously been
5 provided with magnetic sensors which can tell when the valve
is closed.
Referring firstly to Figure 4 -there is shown the
sensor unit 11 with a lid 45 (see Figures 7 and 9) removed
therefrom. The sensor unit 11 comprises a body of bronze
10 material of generally rectangular configuration. The body has
a front end 47 and a rear end 49. The front end 47 has a
cavity Sl therein in which the valve 43 is placed. The cavity
Sl is of generally T shaped section in plan view as shown in
Figure S and it has a passageway 53 extending therefrom and
lS through which a handle 55 o~ the valve 43 can swing. The lid
45 also has a slot 57 therein, through which the handle SS can
swing. The cavity 51 is of sufficierlt dimensions to enable
the valve 43 to neatly fit therein just underneath the lid 45.
Circular openings 59 (not clearly shown) are provided in the
20 sides of the sensor unit 11 and enable threaded pipe couplings
61 to be screwed into the female ends of the valve 43.
Respective lock nuts 63 are provided on each of the pipe
couplings 61 and when screwed up against the sensor unit 11,
positively hold the valve 43 and the pipe couplings 61 locked
25 as an integral assembly with the sensor unit 11. Cavity 51
can be considered as two parts - the first part 65 being the
head of the T, and the second part 67 being the trunk of the
T. The body of the valve is received in the first part 65 and
the spindle 79 (not clearly shown) is received in the second
30 part 67.
Three magnetic sensing means in the form of reed
switches 69, 71 and 73 are fitted within bores 75 which are
disposed in line and directly underneath the path of swinging
of the handle 55. The reed switches are held in position
35 within the bores 75 by means an epoxy backfill (not shown).
By refe~ring to Figures 10 through 14, it can be seen that the
handle 55 is provlded with an elongate slot 77 at its forward
36[)3~3~
end which enables it to key onto the spindle 79 of the moving
part of the valve 43. A suitable locking nut 81 holds the
handle 55 secured to the spindle 79.
The handle 55 has t~o bent lugs ~3 and 35 at the
5 forward end. These lugs are used to cooperate with a stop 87
moulded integral with the external surface of the body of the
valve 43 to provide for positive stopping of the handle 55 at
the fully opened and or fully closed positions. Each of the
lugs 83 and 85 has suitable magnetic material in -the form of
10 respective permanent magnets 89 and 91 fastened thereto on the
ràdially, outermost surfaces thereof.
When the valve is assembled within the sensor unit
11, the magnets 91 and 89 position themselves relative to -the
reed switches 69, 71 and 73 as shown in Figures 12 through 1~.
15 Thus, in the valve fully open position, permanent magnet 91 is
directly above the central reed switch 71, as shown in Figure
12. The other magnet ~9 is situated remotely from the reed
switches 69, 71 and 73 and does not influence operation of any
one of those reed switches. In the position shown in Figure
20 12, reed switch 71 is biased by the magnet 91 to be in a
normally open condition. Reed switches 69 and 73 are
interconnected in parallel with reed switch 71 so that the
normally open contacts are connected with the normally closed
contacts of reed switch 71. Thus, in the position shown in
25 Figure 12 ali the reed switches will have an open circuit in
the valve open position. Magnet 91 will not influence reed
switches 73 or 69 in this position.
As the valve is closed magnet 91 leaves the
proximity of reed switch 71 and approaches the proximity of
30 reed switch 73. Thus, in this condition, reed switch 71 then
automatically closes and provides an alarm that the valve is
being closed. Simultaneously or approximately so, reed switch
73 trips to the closed position because of the proximity of
the magnet 91 thereto, and this also provides for an alarm
35 signal to be given. In this condition, reed switch 73
provides a backup or fail safe procedure for reed switch 71 in
the event that it does not close and provide an alarm signal.
3~3~
- 12 -
When the valve is fully opened as shown in Figure
14, magnet 39 is in close proximity to reed switch 59 and
c~uses reed switch 69 to close, thereby giving an indication
that the valve is fully closed. ~ccordingly, by wiring o
5 reed switches 71 and 73 in parallel but in opposite states, an
appropriate alarm can be given when the valve is moved from
the open position to the closed position. By independently
wiring reed switch 69 to a separate circuit within the fire
installation, a signal can be given that the valve is in the
10 fully closed position. It is observed that each of the reed
switches 69 , 71 and 73 has three leads therefrom, being
respectively, the common lead, the normally open and the
normally closed lead. Certain fire installations have control
circuitry which causes an alarm signal to be given when a
lS circuit is open. Accordingly, appropriate connection of the
states of reed switches 69, 71 and 73 can be made to provide
an alarm in these circumstances.
Referring now to Figures 4 through 8, it can be seen
that there is a further cavity 93 at the front end 47 of the
~0 sensor unit 11. This further cavity 93 is a shallow
depression in the body of the sensor unit 11 and this further
cavity 93 has three reed switches 95, 97 and 99 therein.
These reed switches are arranged in a triangular pattern as
shown. These reed switches are provided in suitable bores 101
25 (see Figure 6) and held in place by a backfill of epoxy resin
(not shown). Reed switch 97 is arranged to cooperate with
appropriate magnetic material comprising a permanent ma~net
103 fitted within a hole lOS provided in an upstanding
platform 107 formed on the undersurface of the lid 45. Thus,
30 when the lid 45 is closed, the platform 107 is received within
the further cavity 93 and the magnet 103 cooperates with the
reed switch 97. In this condition the reed switch 97 is held
so that its contacts are open when the lid is in situ. If the
lid 4S should be removed the reed switch 47 will trip to the
35 closed condition and an alarm can be given. The other reed
switches 9S and 99 are connected in the normally open
condition and in parallel with the wiring of reed switch 97.
~ 3~ 3 ~ 3 ~
Thus, if a person should attempt to ~ool the reed switch 97,
b~ placing a magnet or other appropriate magnetic material in
proximity thereto, in an attempt to open the lid 45 without
causing an alarm to be given, then one or other of the various
5 reed switches 95, 97 and 99 will trip and provide an alarm
signal. It is also possible in this condition that one or
others of the reed switches ~9, 71 and 73 will also trip and
provide an alarm condition. The reed switches 95, 97 and 99
can be connected in parallel with the reed switches 71 and 73
10 if desired.
It should be appreciated here, that a series
connection of the reed switches in any embodiment could also
be provided if required. The exact wiring configuration of
the reed switches is basically immaterial so long as the reed
15 switches 71 and 97 of this embodiment, are connected in one of
their states when the magnets which cooperate therewith are in
proximity and that the other reed switches are connected in
the opposite of their states so that appropriate protection
can be provided. The same is true of reed switches 35 and 27,
20 31 and 33 of the previous embodiment.
The rear end 49 of the sensor unit 11 has a
rectangular shaped recess 109 therein. The leads from each of
the reed switches can be appropriately wired and terminated
therein at a terminal block 111. It should be noted that the
25 recess 109 is closed by a lid 113 and that a microswitch 115
is fitted within the recess 109 so that the arm 117 thereof
engages with the lid 113 and is caused to be biased into one
of its operative states. Upon removal of the lid 113, the arm
117 can swing and cause the microswitch 115 to trip to the
30 other of its states and thereby provide an alarm signal. The
microswitch 115 is appropriately wired into the terminal block
111. Connecting leads 119 pass through a grommet 121 in a
side wall of the recess 109 and connect with the terminal
block 111.
In order that the valve 43 can be locked in the
fully open position, the body of the sensor unit 11 contains a
lug 123 with a hole 125 therethrough. The handle 55, in turn,
~3 C)3~34
has a further hole 127 therein and a suitable padlock 129 can
pass through holes 125 and 127. In order that the sensor unit
11 can be appropriately mounted to a wall or the like,
suitable mounting brackets 131 are provided at the rear end 49
5 (see Figure 7).
It should be appreciated that two types of lid
removal alarm systems have shown in this embodiment. One
alarm system comprises the reed switches 95, 97 and 99 and the
other comprises the microswitch 115. Either form or both is
10 suitable or mixtures thereof as disclosed. Accordin~ly the
embodiment shown is not to be considered as requiring opposite
types of lid removal alarm sensing means.
It should be appreciated that the reed switches 69
and 73 will act to inhibit against persons placing magnetic
15 material against the body of the sensor unit 11 in an attempt
to fool reed switch 71 as either of those reed switches 69 or
73 and/or reed switch 71 can trip by the influence of such
magnetic fields to provide an alarm~
Referring now to Figure 15 there is shown a block
20 circuit of a typical fire alarm installation comprising an
alarm 113 in the form of a bell, a control circuit 135 and
lamp alarm means 137, 139 and 141. The control circuit 135
typically has two sets of common and open and closed
connections. These are designated A and B respectively. Reed
25 switches 69 or 29 are connected to set A whilst the remaining
reed switches and microswitches are connected to set B. In
this condition lamp alarm means 137 can show that the valve or
valves as the case may be, are open. Lamp alarm means 139 can
show that the valves have commenced closing. Simultaneously
30 with illumination of lamp 139 the alarm bell 113 can be
activated. When the valve reaches the fully closed position
lamp alarm means 141 can be activated. The alarm 113 can
continue to be activated in this condition.
Many modifications may be made to the invention as
35 would be apparent to persons skilled in the alarm protection
arts. For example any of the modifications previously
discussed could be incorporated. Further it is envisaged that
~L303~34
-- 15 --
by appropriate wiring to a suitable control circuit 135
displays can be provided as to individual valves in a fire
installation. It should also be appreciated that land lines
or other connections can be made to a local fire authority
5 from the control circuit 135 to give an alarm condition at the
fire authority.
It should also be appreciated that the invention is'
not limited solely to use in the fire protection fields but
that is has application in any situation where valves need to
10 be left either open and/or closed and alarm condition given if
they are changed from that state.
These and other modifications may be made without
departing from the ambit of the invention, the nature of which
is to be determined from the foregoing description.
