Pumping station for the pressurization of antifire plants, civil plants and the like

Abstract

 The pumping station comprises at least a pump for delivery of water to the users and means for the control of the pressure and/or the flowrate to said users; the delivery manifold (9) and the intake manifold (1) of said station are connected to each other and, on the fitting (17) a valve (19) is inserted able to put into communication the delivery manifold (9) with the intake manifold (1) when the delivery pressure value exceeds a predetermined threshold; a flowmeter (11) on the delivery side controls the processed flowrate and activates and deactivates the pumps according the the flowrate required by the users.

Description

[0001] The invention refers to a pumping station for water pressurization in antifire plants, civil plants and the like, of the type comprising at least a pump for delivery of water to the users and means for the control of pressure and/or flowrate to said users.

[0002] In the hydraulic plants which comprise a pumping station for water pressurization, significant variations in the users' demand, and thus in the flowrate, are likely to occur. For instance, in the civil plants for the distribution of water to the waterworks of an apartment building or similar, the flowrate that the pumping station has to cope with varies significantly in the course of the day according to the number of users who avail themselves of the plant at the same time. The delivery pressure of the pumping station must, however, remain as constant as possible. Since the characteristic curves of the pumps usually employed for these plants have a head pattern heavily dependent on the delivered flow, with significant reductions of the head as the flowrate increases, provision must be made for flowrate and/or pressure control means. Currently, the control is obtained by providing for a certain number of pumps in parallel, which are connected and disconnected according to the required flowarate, and also by acting on the number of revolutions of the pump: when the flowrate tends to drop because of an increase of the flowrate demand, the number of revolutions of the pump(s) is increased, thereby maintaining the head variation within acceptable limits. Currently, in order to adjust the delivery pressure and make it less variable with the varying flowrate, pumps are used having particularly flat characteristic curves which are, however, rather expensive. The adjustment of the number of revolutions of the pumps is complex and requires particularly costly regulation systems. Moreover, the adjustment obtained is usually of fairly coarse, stepwise type and is not able to provide constant pressure and/or flowrate.

[0003] It is an object of the present invention to provide a pumping station of the above mentioned type that does not exhibit these drawbacks and which, in particular, is able to stabilize the pressure and/or flowrate of the pumping station by particularly reliable and economical means.

[0004] These and other objects, which will result evident to those skilled in the art from a reading of the following description, are achieved by a pumping station characterized in that the delivery manifold and the intake manifold of said station are connected to each other; a valve inserted on the connection being able to put the delivery manifold and the intake manifold into communication with one another when the value of at least a parameter of the delivery flow exceeds a predetermined threshold; and in that a flowmeter, located on the intake side, controls the processed flowrate.

[0005] When the value of the control parameter exceeds the predetermined threshold, the valve opens partially or totally in an automatic way to reset the normal operation conditions. Practically, the controlled parameter may be the pressure in the delivery manifold; in this case, the flowmeter, which senses the processed flowrate, connects or disconnects the pumps according to the variations in the flowrate demand, whilst a pressure increase in the delivery line is suppressed by the valve which directly or indirectly by-passes a portion of processed flow (for example, by the interposition of a storage and collection tank) towards the intake. The opening of the valve is gradual and controlled to keep the pressure value substantially constant.

[0006] Advantageously, the valve may have an adjustable intervention rate.

[0007] In a feasible embodiment, the valve comprises a main valve with a spring-loaded obturator member which defines a chamber connected to the delivery manifold and to the intake manifold, a pilot valve being interposed on the intake manifold connection line which opens and closes according to the value of the pressure inside the delivery manifold. In practice, on the connection line between the delivery manifold and said chamber, an adjustable pressure reducer may be inserted to adjust the intervention rate of the valve. The same delivery pressure control function may be obtained by valves of other type.

[0008] The invention further refers to a method for controlling the pressure and/or the flowrate of a pumping station for water pressurization in antifire plants, civil plants or the like, characterized by putting into communication the delivery manifold and the intake manifold of the pumping station when the value of a parameter for controlling the delivery flow exceeds a predetermined threshold, so as to by-pass a portion of the flow from the delivery manifold to the intake manifold. In practice, the control parameter may be the pressure in the delivery manifold.

[0009] The invention will better understood by following the description and the attached drawing, which shows a practical, non limitative exemple of the same invention. In the drawing:

Fig. 1 shows a scheme of a pumping station according to the invention; and

Fig. 2 shows a scheme of a possible valve that can be employed for controlling the pressure and the flowrate.

[0010] According to what is illustrated in the attached drawing, the station according to the invention comprises an intake manifold 1 connected to the intake side of a pilot pump 3 and of two capacity pumps 5 and 7. It is evident that the number of pumps may vary according to the requirements and to the size of the plant to be served. The pumps 3, 5 and 7 lead into a delivery manifold 9 on which a flowmeter 11 is fitted. Also connected to the delivery manifold 9 are two plenum chambers 13 and 15 for pressure stabilization. The flowmeter 11 checks the flowrate to the users and governs the connection and disconnection of the capacity pumps 5 and 7 to meet the demand.

[0011] Advantageously, the flowmeter 11 may be of the type including a rotating device whose rotational velocity is proportional to the flowrate, such as a blade flowmeter or the like. A sensor of electro-magnetic type or other (not shown) senses the rotational speed of the rotating device and transmits such data to an electronic control box 12, from which control signals are generated for the connection and disconnection of the pumps. By this disposition there is obtained an effective and safe control of the pumps.

[0012] The two intake 1 and delivery 9 manifolds are connected one to the other by a fitting 17 made up of two sections 17A and 17B which lead to a valve 19 for pressure control, said valve having the purpose of controlling the pressure and/or the flowrate in the delivery manifold 9. When the pressure in the delivery manifold exceeds a predetermined operating condition value, without the flowrate measured by the flowmeter 11 varying to such an extent as to cause the disconnection of one of the capacity pumps 5, 7, the valve 19 opens, so that a portion of the flow processed by one or more of pumps 3, 5, 7 is by-passed from the delivery manifold to the intake manifold. The opening of valve 19 may be continuously adjusted so as to maintain the pressure in the delivery manifold constant without intervening on the number of revolutions of the pumps and without increasing the number of the latter. Moreover, the pumps may be of a particularly economical type and do not necessitate a flat characteristic curve.

[0013] Fig. 2 shows the scheme of a possible valve that can be used as valve 19 for the control of the pressure. According to what is illustrated in this figure, which shows a device of a type already known for other applications and that may be advantageously employed in a pumping station according to the invention, the outlet valve comprises a main valve 21 with a body in two portions 21A and 21B and respective flanges 23 and 25 for the connection to the sections 17A, 17B, respectively, of the fitting 17. Under normal operating conditions, with the fitting 17 being closed, the two portions 21A, 21B of the main valve 21 are isolated one from the other by a diaphragm 27 urged by a compression spring 29 disposed between the diaphragm and a cap 31. Under these operating conditions through a line 33, on which a filter 35 is located, and a line 27, 39, the pressure present in the delivery manifold plus the force of spring 29 act onto the upper surface of the diaphragm 27. The pressure in the delivery manifold is fed, through a line 40, also to a pilot valve 41 which, when the value of the pressure inside the delivery manifold exceeds a predetermined threshold, opens up thereby putting into communication, via a line 43, the chamber between the diaphragm 27 and the cap 31 with the low-­pressure section 17B of the fitting 27. In this way, the main valve 21 opens thereby letting a portion of the flow processed by the pumps pass, via the fitting 17, from the delivery manifold to the intake manifold. Disposed on the line 37 is a needle valve 45 by which it is possible to adjust the rate of intervention of the valve 19. When the pressure inside the delivery manifold is lowered again below a predetermined threshold value, the pilot valve 41 closes, the chamber between the cap 31 and diaphragm 27 is again pressurized and said diaphragm closes the main valve 21 thus isolating the fitting sections 17A and 17B from one another.

[0014] As stated above, the valve 19 may also be of another type.

Claims

1. A pumping station for water pressurization in antifire plants, civil plants and the like, of the type comprising at least a pump for delivery of water to the users and means for the control of pressure and/or flowrate to said users characterized in that the delivery manifold (9) and the intake manifold (1) of said station are connected to each other, on the fitting (17) a valve (19) being inserted able to put the delivery manifold (9) in communication with the intake manifold (1) when the value of at least a parameter of the delivery flow exceeds a predetermined threshold; and in that a flowmeter (11), located on the delivery, controls the processed flowrate.

2. A pumping station according to claim 2, characterized in that said valve (19) is operated according to the value of the pressure inside the delivery manifold (9), the opening being gradual and controlled to keep the value of the pressure in said delivery manifold substantially constant; and in that the flowmeter (11) controls the connection and disconnection of the pump(s) according to the delivered flow.

3. A pumping station according to claim 1 or 2, characterized in that said valve (19) has an adjustable intervention rate.

4. A pumping station according to one or more of the preceding claims, characterized in that said valve (19) comprises a main valve (21) with a spring loaded obturator member (27) defining a chamber connected to the delivery manifold and to the intake manifold, a pilot valve (41) interposed on the line (43) for the connection with the intake manifold being opened and closed according to the value of pressure inside the delivery manifold.

5. A pumping station according to claim 4, characterized in that a pressure reducer (45) is inserted on the line (33) for the connection between the delivery manifold and said chamber.

6. A pumping station according to one or more of the preceding claims, characterized in that said flowmeter (11) is of the type including a rotary device, whose rotational speed is proportional to the delivered flow; that a sensor, associated to said rotary device, senses the rotational speed and feeds a proportional signal to an electronic control box (12), said control box being capable of processing a signal for the control of the pump according to the input signal.

7. A method for the control of the pressure and/or the flowrate of a pumping station for water pressurization in antifire plants, civil plants or the like, characterized by putting into communication the delivery manifold and the intake manifold of the pumping station when the value of a control parameter of the delivery flow exceeds a predetermined threshold, so as to by-pass a portion of the flow from the delivery manifold to the intake manifold.

8. Method according to claim 7, characterized in that said control parameter is the pressure is the delivery manifold.

Drawing