JP2002295705A - Motor-operated valve for preventing water hummer, and its controlling method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a water hummer in relation to a motor-operated valve used for a fire extinguishing facility and its controlling method. SOLUTION: The motor-operated ball valve 2 has a secondary side having a nozzle 5 disposed in an empty water feed pipe, and controlled by a control means 8. The control means 8 initially partially opens the valve to provide a flow speed for preventing the water hummer, and fully opens the motor- operated ball valve 2 after running water reaches the nozzle 5. The other control means 8 initially fully opens the motor-operated valve ball 2 to make water flow for a certain time, and partially opens the motor-operated ball valve 2 slightly before the water reaches the nozzle 5, thereby preventing the water hummer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor-operated valve used in fire extinguishing equipment and the like and a control method thereof.
More specifically, the present invention relates to a motor-operated valve capable of preventing generation of a water hammer and a control method thereof.

[0002]

2. Description of the Related Art In a flood gun of a fire extinguishing system, when a pump starts and a motor-operated valve is opened at the time of fire, fire extinguishing water of a primary side pipe flows into a secondary side pipe (empty pipe) which is not filled with water and a nozzle. Inject from The water pressure in the secondary pipe is detected by a pressure switch, and the control means operates in accordance with the output signal of the pressure switch to control the opening of the electric valve to regulate the pressure to a predetermined pressure.

[0003]

In the conventional example, since the secondary side pipe is an empty pipe, a predetermined pressure is not reached immediately after the valve is opened, and the pressure switch does not turn on. Then, the motor-operated valve is fully opened in an attempt to increase the secondary pressure, so that an excessive flow of fire-extinguishing water flows through the secondary pipe, resulting in a fluid having a large mass. When the flow rate of this fluid is reduced in a flowing water regulating portion such as a nozzle, the fluid collides with the regulating portion and suddenly decelerates to generate an impact pressure wave. This shock pressure wave propagates in the pipe, causing a so-called water hammer phenomenon, which may impair the function of a flood gun or a valve, or may hinder fire extinguishing work.

[0004] In view of the above circumstances, an object of the present invention is to prevent the occurrence of water hammer.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a motor-operated valve provided on a water supply pipe having an empty pipe on the secondary side having a flowing water regulating portion and having an opening controlled by a control means. A water hammer prevention circuit that adjusts the opening degree of the valve so that the flow velocity immediately before the flowing water regulating section becomes the water hammer avoidance flow velocity when the valve is initially opened.

[0006] The present invention is a method of controlling a motor-operated valve provided on a water supply pipe having an empty pipe on the secondary side having a flowing water regulating portion, and the opening of which is controlled by control means; The opening degree of the valve is adjusted so that the flow velocity immediately before the flowing water regulating section at the time of the initial valve opening becomes the water hammer avoiding flow velocity.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to prevent water hammer, for example, as shown in Japanese Patent Application Laid-Open No. 5-253314, improvement of a valve mechanism (mechanical improvement) has been attempted.
The present invention solves this problem by controlling the opening of the motor-operated valve without making any mechanical improvement. That is, a water hammer prevention circuit is provided in the control means of the electric valve, and the opening degree of the valve is adjusted so that the water hammer avoiding flow rate is obtained at the time of initial opening.
Here, the “opening degree” refers to a ratio of an effective falling cross-sectional area in an intermediate valve opening state to an effective falling cross-sectional area when the valve is fully opened. , And other amounts corresponding to the opening degree, such as the lift height.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS. An electric ball valve 2, which is an example of an electric valve, is provided in the water supply pipe 1, and a water tank 3 is provided in a primary pipe 1 a of the valve 2.
Is provided, and the secondary side pipe 1b
A nozzle 5 is provided at the end of the nozzle. This nozzle 5
Is a flowing water regulation part, which is a resistance of fire extinguishing water flow.

A pressure switch 6 for regulating the secondary pressure to a predetermined pressure is provided in the secondary pipe 1b. This pressure switch 6 is connected to control means 8 for controlling the opening of the electric ball valve 2. Have been. As the pressure switch 6, a two-point contact switch is used.

The control means 8 includes a reference circuit 8a and a water hammer prevention circuit 8b. This prevention circuit 8b
When fire extinguishing water first flows from the primary pipe 1a to the secondary pipe 1b, the electric ball valve 2 is half-opened, and for a predetermined time, for example, the first fire extinguishing water flowing from the primary side to the secondary side. This is a so-called timer circuit which maintains the opening degree until the nozzle reaches the nozzle to maintain the water hammer avoiding flow velocity. Further, the reference circuit 8a adjusts the opening degree of the valve based on the detection result of the pressure switch 6 and adjusts the pressure until the valve closing instruction is received so that the secondary pressure is within a predetermined pressure range. It is.

The opening degree of the valve and the time for maintaining the opening degree are as follows:
It is selected as appropriate in consideration of the water hammer avoidance flow velocity,
The opening and the time may be fixed, but may be arbitrarily set on site.

Next, the operation of this embodiment will be described.
When a fire signal is transmitted from a fire detector to a fire receiver (not shown) due to the occurrence of a fire, a fire start signal is sent from the fire receiver to a pump control panel (not shown) from the fire receiver after disaster prevention personnel confirm the fire. The control panel starts the pump 4 and sends a valve opening signal to the control circuit 8 (S1).

Then, the water hammer prevention circuit 8b of the control means 8 makes the electric ball valve 2 half open with a preset opening degree so as to have the water hammer circuit flow rate (S2), and maintains the state for a predetermined time (S2). S3). The fire-extinguishing water in the primary piping 1a flows into the secondary piping 1b and reaches the nozzle 5. Here, the predetermined time refers to a time sufficient to fill the nozzle with water when flowing at the opening degree at that time, and is obtained from the pipe volume by a rough calculation. At this time, since the diameter of the nozzle 5 is significantly smaller than the diameter of the secondary pipe 1b, the flow rate of the fire extinguishing water is rapidly reduced by the nozzle 5,
The fire extinguishing water has a water hammer avoiding flow rate, that is, a flow rate that does not generate a water hammer exceeding the pressure resistance of the facility, so that an excessive water hammer does not occur. The pressure in the secondary pipe 1b is detected by the pressure switch 6, and the detection result is sent to the control means 8. The reference circuit 8a of the control means 8 adjusts the opening degree of the valve based on the detection result to regulate the secondary pressure so as to be in a predetermined pressure range (S4).

When the discharge of water from the nozzle 5 is started, the valve adjusts the opening based on the detection result of the pressure switch 6, the inside of the secondary pipe 1b reaches a predetermined pressure, and the fire extinguishing water can be discharged at the set pressure. It has become. When the disappearance of the fire source is confirmed, the pump control panel is operated to stop the drive of the pump 4 and instruct the control circuit 8 to close the valve. Based on this instruction,
The reference circuit 8a of the control means 8 closes the electric ball valve 2.

A second embodiment of the present invention will be described with reference to FIGS. This embodiment and the first embodiment (FIGS. 1 and 2)
They differ in the following points. (1) The secondary pipe 1b is long, for example, 20 m,
In addition, there is a bent portion 15 on the way. The fire extinguishing water flowing through the horizontal portion 15a collides with the vertical portion 15b of the bent portion 15, and the flow direction is forcibly changed. The bent part 15 constitutes a flowing water regulating part like the nozzle 5.

(2) In the first stage of valve opening (S11),
The water hammer prevention circuit fully opens the valve 2 (S1
2) The state is maintained for a predetermined time, for example, a time until the fire extinguishing water flowing from the primary pipe 1a to the secondary pipe 1b reaches the water hammer prevention point S on the upstream side of the bent portion 15 ( S13) Then, the valve 2 is squeezed at such a speed that water hammer does not occur, and is half-opened to reduce the flow rate (S13).
14) The water hammer avoidance flow rate is set. Therefore, the fire extinguishing water flowing from the primary side to the secondary side rapidly flows to the vicinity of the water hammer prevention point S, so that the secondary pipe 1b can be quickly filled with water. When the water flows from the downstream side to the downstream side, the water supply from the primary side is restricted, so that the water flows through the bent portion 15 at a water hammer avoiding flow velocity. Therefore, excessive water hammer does not occur in the bent portion 15.

(3) When the inside of the secondary pipe 1b is filled with water and the predetermined time has elapsed (S15), the control is performed by a reference circuit for regulating the secondary pressure until a valve closing instruction is received. (S16).

In the step (S14), the electric ball valve 2 is half-opened. However, the degree of opening may be gradually reduced, or the degree of opening may be reduced stepwise at regular intervals. Alternatively, the predetermined time of the full opening in the step (S13) may be set to zero, and the opening degree may be reduced to a predetermined opening degree, for example, 30% by the bent portion 15. The arrival time of the flowing water to the bent portion 15 or the water hammer prevention point S may be calculated or may be obtained by actual measurement in a test facility in advance.

A third embodiment of the present invention will be described. In this embodiment, at the time of test water discharge after construction, water is discharged at a predetermined opening degree,
The time from the opening of the valve to the start of water discharge is measured, and the time is used as the predetermined time and applied to the first and second embodiments. In this embodiment, since the actual time is used, it is possible to simply and appropriately prevent the water hammer. The control means 8 may be provided with an input device (not shown) that can arbitrarily set the opening degree of the valve 2 and the predetermined time to prevent water hammer.

A fourth embodiment of the present invention will be described. In this embodiment, the electric valve has a structure that can be operated manually, and a storage circuit for storing the manual operation is provided. At the time of test water discharge after construction, a skilled worker operates the valve with a pressure gauge or sound or vibration of the secondary piping as a clue so that water hammer does not occur and water can be discharged early. (Time function of degree) is stored in the storage circuit, and the valve opening operation is performed by the control of the storage circuit.

In this embodiment, the same operation as that of the skilled operator is performed via the memory circuit, so that the water hammer can be properly prevented, and water can be discharged at an early stage.
Its settings are simple.

A fifth embodiment of the present invention will be described. The movement of the motor-operated valve (time function of the opening) is programmed in advance from the design drawing of the construction piping. For example, when the valve is fully opened when the valve is opened, the primary pressure H1 and the secondary pressure H2 of the electric valve are constantly measured, and the differential pressure H = H1−H2 (H is a time function H (t)
) And the time function X (t)% of the opening X, the valve opening area S
Then, the flow rate Q is calculated by the following equation (a). Note that C
(X) is a flow coefficient of the motor-operated valve 2 and is a function of the opening degree X (t).

Equation (a) Q = C (X) · X (t) · S · √ (2g · H (t)) This is integrated over time t to obtain a water supply amount V through the valve 2,
When the water supply amount V approaches the secondary-side piping volume or the piping volume up to the flowing water regulating portion of the second embodiment, the opening degree is reduced to a predetermined degree, for example, 30%, at such a speed that water hammer does not occur. To Then, the predetermined opening degree is set when reaching the flowing water regulating portion such as the bent portion of the pipe.

After the start of nozzle water discharge, the opening is gradually increased to fully open. The start of nozzle water discharge may be known by providing a pressure switch on the nozzle, or by calculating the water supply amount V
May be determined as having passed. In addition,
The program may be simpler. For example, the equation (a) may be calculated as Q = C (X) · S · ・ (2g · H (t)) by replacing all variables with appropriate estimated values. In this case, the opening is set to 100%, and C is a flow coefficient of the opening.

The present invention is not limited to the above embodiment. For example, an electric globe valve, an electric gate valve, an electric butterfly valve or the like can be used as the electric valve instead of the electric ball valve. It is.

[0026]

According to the present invention, the water hammer can be easily prevented without changing the valve structure of the motor-operated valve.

[Brief description of the drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention.

FIG. 2 is a flowchart of the first embodiment of the present invention.

FIG. 3 is a diagram showing a second embodiment of the present invention.

FIG. 4 is a flowchart of a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Water supply pipe 2 Electric ball valve 5 Nozzle 8 Control means 8b Water hammer prevention circuit

Claims (4)

[Claims] 1. A motor-operated valve which is provided in a water supply pipe having an empty pipe on a secondary side having a flowing water regulating section and whose opening degree is controlled by a controlling means; A water hammer prevention circuit, which is provided with a water hammer prevention circuit that opens at a preset valve opening so that the flow velocity immediately before the section becomes the water hammer avoidance flow velocity. 2. The water hammer prevention motor-operated valve according to claim 1, wherein the water hammer prevention circuit first opens the valve halfway to a water hammer avoidance flow rate, and fully opens after passing through the flowing water regulating portion. 3. The water-hammer prevention electric valve according to claim 1, wherein the water-hammer prevention circuit opens the valve fully at first, and opens the valve half-way at the next stage to obtain the water-hammer avoidance flow rate. . 4. A method for controlling a motor-operated valve which is provided on a water supply pipe having an empty pipe on the secondary side having a flowing water regulating section and whose opening degree is controlled by a control means; A method for controlling an electric motor for preventing water hammer, characterized in that the opening degree of the valve is adjusted so that the flow velocity immediately before the flowing water regulating part at the time of valve opening is the water hammer avoiding flow velocity.