JPS5839885A - Gate valve for pipeline - Google Patents

Abstract

PURPOSE:To obtain a gate valve for a pipeline free from the phenomenon of water hammer by providing a valve plate with a main bore of small flow-passage resistance and a sub-bore of large flow-passage resistance. CONSTITUTION:A main bore 2 of the equal diameter with a flow passage 5 and a sub-bore 3 of a smaller diameter than the above are bored on a valve plate 1, which can be vertically slided in a body 4. The illustration shows the valve plate 1 on the way of sliding from an opening position to a closing position; the main bore 2 to meet with the flow passage 5 at the opening position is brought down to be disconnected, while the sub-bore 3 is connected to the flow passage 5. Since some flow is kept in the flow passage 5 through the sub-bore, a valve can be prevented from the phenomenon of water hammer caused by its sudden closing.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gate valve for controlling the flow rate of a liquid delivery pipeline, and particularly to a gate pulp useful for preventing water leakage.

The water hammer P8 in the pipeline is A...The propagation velocity of the fluid pressure in the pipe determined by the type of fluid flowing and the pipe material of the flow path (if the fluid is water, it is approximately 100 ゛
/see )L...Length of flow path piping Ts...Required time to open and close the control gate valve (SeC
) vO...Fluid flow velocity before gate valve closure (m/
5ec), it is generally expressed by the calculation formula <1) or (2) below.

(Re Ps -Vo X A/ 98 (Kg f
/cell ) (2) Ps = LXV
o /98 (Ts - L/A) (Kff/c + C) The calculation formula (1) is applied when T8≦2x and A, and the calculation formula (2) is applied when Ts)2X and A. Applies to.

The above formula (1) is when the closing speed of the gate pulp is large,
In other words, when the gate pulp is closed quickly, the equation (2) corresponds to when the closing speed of the gate pulp is small, that is, when the gate pulp is closed slowly.Therefore, from equation (2), water pressure P8 can be calculated. It can be seen that in order to reduce the number of strokes, it is necessary to increase the number of days, that is, to close the gate valve more slowly. In flow rate control with such a small pulp stroke, even if T8 in equation (2) is simply increased,
Water hammer P8 cannot be effectively suppressed.

The purpose of this invention is to avoid the above-mentioned conventional drawbacks, and the purpose of this invention is to provide a gate pulp valve plate with a control gate hole, that is, a main bore, and an appropriate number of auxiliary holes, that is, subbores adjacent to the main bore (of course). The main bore should be of sufficient size, and the resistance of the pipeline should be extremely small, and the sub-bore should be a small hole that can be used in the middle of the stroke of the valve plate until the main bore fully closes the flow path. The sub-bore passes through the flow path and occupies a part of the flow path in a positional relationship with respect to the main bore.

An embodiment of the present invention will be described below with reference to the drawings. 1st
Figures 3 to 3 show three stages from the fully open state to the fully closed state of the gate pulp. (IJ is a valve plate and has a main bore (2) and two sub-bores (3) of different diameters adjacent to each other as shown in the figure.The podium (4) has a flow path (5) (Fig. 2,
3) is open, but in FIG. 1, the gate pulp is fully open, so the flow path (5) overlaps the main bore (2). In FIG. 2, the plate (1) has moved downward and the main bore (2) is completely out of the flow path (5), but the sub-bore (3) is aligned with the flow path (5).

In Figure 3, the own plate (1) is further lowered and the subbore (
3) is also completely out of the flow path (5).

At the intermediate opening stage in Fig. 2, the subbore (3) is connected to the flow path (
5) is partially opened, so water hammer is prevented at this stage. After passing through this intermediate stage, the boat board (
By shifting 1) to the fully closed state shown in FIG. 3, the flow rate of the pipeline can be controlled while preventing water leakage.

Water hammer can be prevented by calculating the water weight by equation (2) and determining the total cross-sectional area, number, and positional relationship of the sub-bore (3) with respect to the main bore on one plate.

As shown in Figure 4, the ball (6) is placed in the subbore (3').
A check valve consisting of a thorn (7) can also be provided. In the figure, (1') indicates the valve plate, and (2') indicates the main bore. When the upstream hydraulic pressure exceeds a predetermined value during flow rate control, this check valve opens and the subbore (3') is opened to prevent water hammer.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the fully open state of the gate pulp of the present invention, Fig. 2 is a diagram showing the intermediate opening state, Fig. 3 is a diagram showing the fully closed state, and Fig. 4 is a diagram showing another example. It is a diagram. 1... Valve plate 2... Main bore 3...
・Subbore 4...Body 5...Flow path Patent applicant Shimadzu Corporation Representative Patent attorney Gomi Kyu 2vJ1 Figure 9PS4 Figure

Claims (1)

[Claims] In a gate valve that has a valve plate that reciprocates between a position where the flow path of the pipeline is fully opened and a position where it is fully closed, the valve plate has a valve plate that operates as the flow path of the pipeline and has relatively low flow path resistance. A gate valve for a pipeline, comprising a main bore and an appropriate number of sub-bores which are kept at a certain distance from the main bore, have a relatively greater flow resistance than the main bore, and have a smaller opening cross-sectional area than the main bore.