A BREAK PRESSURE TANK

THIS INVENTION relates to a break pressure tank.

A break pressure tank, as herein envisaged, is used in a downstream location with respect to a water reservoir, particularly for reducing and controlling supply pressures of water supplied from the reservoir at locations downstream of the break pressure tank. A break pressure tank is thus operatively located between a water reservoir and water supply points to which water is fed from the reservoir, particularly where the reservoir is disposed at an elevation substantially above the supply points, i.e. an elevation that will induce excessive water pressures at the supply points.

It is known that existing break pressure tanks, used for the above purpose, for various reasons do not operate reliably and can in fact cause water supplies from a reservoir to be interrupted. Also, because these break pressure tanks often are situated in relatively inaccessible locations, rectifying a problem often is difficult and time consuming.

It is thus an object of this invention to provide a break pressure tank in respect of the use of which the problems associated with known break pressure tanks are at least ameliorated.

Although reference is made herein to the location of a break pressure tank between a water reservoir and water supply points where the reservoir is elevated above the supply points, it must be understood that in situations where the elevation of a reservoir above supply points exceeds predetermined levels, two or more break pressure tanks may be located at different elevations between the reservoir and the supply points.

According to the invention there is provided a break pressure tank which includes

a tank structure;

a pipe arrangement defining a flow line leading through the tank structure from an inlet end, connectable to a pipeline from a reservoir and entering the tank structure near the top end thereof, to an outlet end, connectable to a pipeline leading to water supply points and leaving the tank structure near the bottom end thereof, the pipe arrangement including a perforated pipe segment located within the tank structure near the bottom end thereof and upstream of the outlet end thereof;

a control valve, located in line with the flow line defined by the pipe arrangement within the tank structure between the inlet end of the pipe arrangement and the perforated pipe segment, for controlling the flow rate of water through the flow line defined by the pipe arrangement, the control valve including a closure member displaceable between a fully open position, in which free flow through the flow line is permitted, and a closed position, in which the flow line is blocked; and

a float actuated operating mechanism, located in the tank structure, that is operatively linked to the closure member of the control valve for displacing it between its fully open and closed positions, the float actuated operating mechanism having a float that is displaceable, in response to the water level in the tank structure changing during operation of the break pressure tank, between a first position in the tank structure, when the tank structure is substantially empty, which coincides with the closure member of the

control valve being in its fully open position, and a second position in the tank structure, when the tank structure is filled to a predetermined level, which coincides with the closure member of the control valve being in its closed position.

The tank structure of the break pressure tank of the invention particularly is a substantially rectangular structure including a base wall having typical dimensions in the order of 1000mm x 1000mm and having a height in the order of 1200mm. The tank structure preferably includes a lockable lid which controls access into the interior of the tank structure, which may be required from time to time for maintenance or other purposes. The tank structure may be formed of any suitable material and, particularly, is formed of a suitable sheet metal material.

Further according to the invention, the break pressure tank may include a closure valve located in line with the flow line defined by the pipe arrangement operatively upstream of the control valve, the closure valve being operable for permitting either free flow through the flow line or for blocking the flow line. The flow line typically is a lever operated butterfly-type valve. As such, the closure valve can serve to open and block the flow line, particularly to facilitate maintenance to the components and parts of the break pressure tank. Still further, the break pressure tank may include a strainer arrangement located in the flow line defined by the pipe arrangement for trapping debris and like particulate objects and particles carried within water fed to the break pressure tank from a reservoir, the strainer arrangement being located upstream of the closure valve. The strainer arrangement may include an operating lever that is manually operable for cleaning of the strainer arrangement. Different configuration strainer arrangements suitable for the purpose are already well known.

The closure member of the control valve of the break pressure tank of the invention may comprise a plunger-type closure having a plunger rod extending therefrom, the rod being axially displaceable for displacing the plunger-type closure with respect to a seat formation defined therefor within the body of the control valve. The plunger rod of the

plunger-type closure may be operatively connected to a diaphragm displaceably located within a chamber defined within the body of the control valve, an operating fluid being displaceable into the chamber for displacing the diaphragm within the chamber and thereby displacing the plunger-type closure of the control valve.

For the above configuration control valve, the float actuated operating mechanism may include a piston/cylinder arrangement of which the cylinder communicates with the chamber defined by the body of the control valve for displacing a hydraulic liquid between the cylinder and the chamber and thereby providing for required displacement of the closure member of the control valve. The piston/cylinder arrangement may include a piston rod that extends therefrom and that is mechanically linked with the float of the float actuated operating mechanism, the displacement of the piston of the piston/cylinder arrangement being controlled by the displacement of the float which, in turn, is controlled by the level of water within the tank structure.

The float actuated operating mechanism may include a guide structure located in the tank structure for guiding the displacement of the float along a line parallel to the line of displacement of the piston rod of the piston/cylinder arrangement.

The operation of the break pressure tank of the invention as above defined and, particularly, the operation of the float actuated operating mechanism may be such that with a water level within the tank structure beneath a predetermined level, the float of the mechanism will be at its lowest level and the closure member of the control valve will be in its fully open position, with the float of the mechanism at or above a predetermined highest level, the closure member of the control valve will be in its closed position, and with the float of the mechanism located in any intermediate position between the said levels, the closure member of the control valve will be disposed in an intermediate open position determined by the specific intermediate position of the float at any particular time, thereby to control the flow rate of water through the control valve and hence through a pipeline connected to the outlet of the pipe arrangement, through which water

can be displaced to water supply points from a reservoir to which the inlet end of the pipe arrangement is operatively connected.

The operation of the break pressure tank of the invention in the above regard is explained in more detail hereinafter with reference to an example of a break pressure tank, which is illustrated in accompanying diagrammatic drawings. In the drawings:

Figure 1 illustrates in perspective view the internal configuration of a break pressure tank, in accordance with the invention;

Figure 2 shows the break pressure tank of Figure 1 when viewed in the direction of arrow A;

Figure 3 shows the break pressure tank of Figure 1 when viewed in the direction of arrow B;

Figure 4 shows the break pressure tank of Figure 1 when viewed in the direction of arrow C; and

Figure 5 shows the break pressure tank as shown in Figure 2, illustrating particularly the operation of the control valve thereof.

Referring to the drawings, a break pressure tank, in accordance with the invention, is designated generally by the reference numeral 10. The break pressure tank 10 includes a tank structure 12, the tank structure 12 being a rectangular sheet metal structure including a base wall 14, four side walls 16 and a lid 18, the lid being removable from the remainder of the tank structure 12 by the operation of a locking mechanism 20. The dimensions of the base wall 14 typically is in the order of 1000 mm x 1000 mm, whereas the operative height of the side walls 16 is in the order of 1200 mm, although it must be

appreciated that the overall configuration of the tank structure, including its dimensions, are greatly variable.

The break pressure tank 10 includes further a pipe arrangement 22 that defines a flow line through the tank structure 12, the flow line extending from an inlet end 24 into the tank, near the operative top end thereof, and from the tank to an outlet end 26, near the operative bottom end of the tank. The inlet end 24 is connectable to a pipeline leading from a reservoir, whereas the outlet end is connectable to a pipeline leading to water supply points, the break pressure tank, in its operative configuration, being connected between a reservoir and water supply points at an intermediate level between the reservoir and the water supply points. This is explained in more detail hereafter. The pipe arrangement 22 includes a perforated pipe segment 28 located adjacent the base wall 14 of the tank structure 12, the pipe arrangement further having connected in line therewith a control valve 30, a closure valve 32 and a strainer arrangement 34.

The control valve 30 is operable for controlling the flow rate of water through the flow line defined by the pipe arrangement 22, the control valve typically including a closure member 36 that is displaceable between a closed position, in which flow through the flow line defined by the pipe arrangement is blocked, and a fully open position, in which free flow through the flow line is permitted, intermediate positions of the closure member 36 providing for different flow rates through the flow line, as will be explained in more detail hereinafter with reference to Figure 5 of the drawings.

The displacement of the closure member 36 is controlled by the operation of a float actuated operating mechanism, generally designated by the numeral 38, the mechanism

38 including a float 40 that is operatively linked with the closure member 36 of the control valve 30 to provide for the required displacement of the closure member 36, as explained hereafter. The float 40 particularly is connected to a piston rod 42 of a piston displaceable in the cylinder of a piston/cylinder arrangement 44, the displacement of the float in the direction of arrows 46 providing for displacement of the piston within the

cylinder of the piston/cylinder arrangement 44 and, thereby, for the displacement of a hydraulic fluid between the cylinder of the piston/cylinder arrangement 44 and a chamber defined by the body of the control valve 30, within which a diaphragm 48, effectively forming part of the closure member 36, is displaceable. The diaphragm 48 particularly is connected via a plunger rod to a plunger-type closure 50 of the closure member 36, the plunger-type closure 50 being configured to seat on a complementary seat formation defined therefor by the body of the closure valve 30 for blocking the flow line defined by the pipe arrangement and being displaceable from the complementary seat formation to permit flow through the flow line via the control valve 30. The exact operation of the control valve 30 in this regard is described in more detail hereafter. As is illustrated clearly in the drawings, the displacement of the float 40 is guided by a guide structure 52 within which the float is trapped and which permits displacement of the float 40 only in the direction of arrows 46.

The closure valve 32 comprises a lever operated butterfly-type valve that can effectively block the passage of water through the flow line defined by the pipe arrangement, particularly to permit maintenance to the break water tank to be attended to whenever required. The strainer arrangement 34 is configured to trap debris, including solid particles, carried within water from a reservoir to the break water tank, the strainer arrangement also being lever operable to permit the discharge of debris, and other particles trapped thereby, from the pipe arrangement 22 into the tank structure 12. Different strainer arrangements suitable for the purpose are known and the exact mode of operation of the strainer arrangement 34 is thus not described further herein.

As explained above, in the operative configuration of the break water tank 10, it is connected between a water reservoir at an elevated level and water supply points at a lower level, water flow from the reservoir to the water supply points thus being permitted while the closure member 36 of the control valve 30 is in an open position. The operation of the break water tank is described hereafter from a starting situation in which the control valve 30 is open to permit "maximum" flow of water to the water supply points, in

which situation the level of water within the tank structure 12 will be operatively beneath the perforated pipe section 28 and the float 40 will be in its lowest position. The flow rate of water through the pipeline is determined by the rate of water use at the water supply points and with water used being at a maximum demand level, the closure member 36 of the control valve will be in a position referred to as its fully open position.

When water demand decreases, the control member of the control valve will remain in the same position and, as a result, water will fill into the tank structure via the perforated pipe section 28, the water level within the tank structure thus raising, resulting in operative upward displacement of the float 40. This displacement of the float will continue for as long as water demand decreases and when water demand stops completely, the water level within the tank structure 12 will be at a level that provides for the float 40 to be in a position which coincides with the closure member being in a fully closed position. More particularly, as the level of the float rises, hydraulic fluid will be displaced from the piston/cylinder arrangement 44 to the chamber defined by the body of the closure valve 30, this hydraulic fluid acting on the diaphragm 48 to thereby provide for the required displacement of the plunger-type closure 50.

When water use again occurs at the water supply points, water from the water tank 12 will re-enter the pipe arrangement 22 via the perforated segment 28 and as the resulting water level within the tank 10 drops, the downward displacement of the float will result in the plunger-type closure 50 being forced into an open position, particularly by the pressure of water acting thereon. It will be appreciated that the flow rate of water through the pipe arrangement to the water supply points will be such that the water level within the tank structure will continue to drop as water demand increases and particularly until full demand is again reached, in which case the plunger formation 50 will be in its fully open position and the float will be in its lowest position. It will be appreciated in this regard that the two positions of the float and, as such, of the plunger-type closure 50 of the closure member 36 of the control valve 30 as described, are limit positions and for situations in which water demand is at intermediate levels, the water level within the tank

structure will be such that the float is in a position in which the plunger-type closure 50 is maintained in a required open position to accommodate water demand. The operation of the break water tank in this regard is clearly apparent. An overflow 60 is provided to accommodate overfilling of the tank structure, which may occur if the control valve 30 malfunctions. It will also be understood that as the plunger-type closure 50 moves away from its seat formation, it will act on the diaphragm 48, for displacing hydraulic fluid from the chamber in which it is located to the cylinder of the piston/cylinder arrangement 44.

It is submitted that the operation of the break water tank of the invention as described will be extremely reliable, thus requiring minimum maintenance. Any maintenance that may be required can be carried out by simply removing the lid 18 of the tank structure

12, closing the closure valve 32 and hence attending to requirements, including cleaning of the strainer arrangement 34. It is also apparent that any malfunctioning of the break water tank is very unlikely to occur and it is thus submitted that with the use of the break water tank as described, a reliable water supply to water supply points from an elevated reservoir is ensured.