JPS6375384A - Feed water supply system provided with constant-pressure valve - Google Patents

Abstract

PURPOSE:To perform a minimum flow recirculation efficiently, by returning part of pumping indirectly to a water receiving tank by way of a suspended pump from an operated pump in two pumps. CONSTITUTION:When a pump 4-1 is operated and another pump 4-2 is suspended, a constant pressure valve 5-1 is locked in closure, and a pressure switch 9 comes into a state of being undisconnected. At this time, a part of pumping is returned to a return pipe 10-1, the suction side of the suspended pump 4-2, a suction pipe 2-2, a water receiving tank 1 in order from the constant pressure valve 5-1. Therefore, overheating in a casing of the operated pump 4-1 is efficiently preventable.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a water supply system using a constant pressure valve, and particularly to a water supply system suitable for preventing overheating when the pump is operated in a closed state for a long period of time.

[Conventional technology]

A conventional water supply system, as described in Japanese Patent Application Laid-Open No. 14027/1984, returns a portion of the water pumped by a constant pressure valve to the suction side of the pump. This is because it is necessary for constant pressure control of the constant pressure valve. However, no consideration was given to preventing overheating inside the pump casing when the valve sliding part inside the constant pressure valve becomes locked in the closed state due to limescale or the like and becomes inoperable.

[Problem that the invention seeks to solve]

As shown in FIG. 3 of the prior art, the return port of the return pipe 20 of the constant pressure valve 14 is on the suction side of the pump, so when the pump is locked in the closed state due to water scale, dirt, etc., the pump cannot be operated in a closed state for a long period of time. However, the problem of overheating inside the pump casing was not considered, and if the inside of the pump casing overheated, the air in the water would accumulate, making it impossible to pump water or, in severe cases, causing the casing to burst. there were. As a countermeasure to this, it is possible to return the return pipe 20 to the water tank, but the recent trend is to assemble the pump, constant pressure valve, valves, pressure tank, pressure switch, and control system on a base into a single unit. Progress is being made to provide it to users as a product. In such a case, returning the return pipe 20 to the water tank requires additional work on the user's side, which is inconvenient. It is also conceivable to return this return pipe to the suction side of the pump, but in this case, it would only circulate and not be very effective. Therefore, an object of the present invention is to configure a water supply system with a plurality of pumps and a plurality of constant pressure valves, and connect the return pipes of these constant pressure valves to the suction side of other pumps instead of returning them to the water receiving tank. During shut-off operation, a portion of the pumped water from this pump is returned to the suction side of another pump via the return pipe of the constant pressure valve on the discharge side of this pump, and is indirectly returned to the water tank to prevent overheating. The purpose is to prevent it.

[Means for solving problems]

Generally speaking, in order to prevent water outages or to take maintenance and inspection into account, water supply equipment is planned to divide the planned maximum amount of water into multiple pumps. Provide a pump. A water supply device is provided in which a small pressure tank and a constant pressure valve (including a pressure reducing valve) are incorporated into these pump equipment to maintain a constant water supply pressure and supply water.

However, these water supply devices are
No. 2 (see Figure 2), when the amount of water used decreases, after the throttle valve 36 closes, the waterway 10
6, the tank 16 is gradually filled with water, and when the pressure here reaches the pump stop pressure, the pump is stopped. However, if the aforementioned waterway 106 becomes clogged with limescale or the like and the throttle valve 36 is locked in the closed state, the pump will be in closed operation for a long period of time. Therefore.

The above object is achieved by connecting the return lines 20 of these constant pressure valves to the suction sides of different pumps.

[Effect]

The throttle valve of the constant pressure valve is locked in the closed state, and the waterway 10
If 6 is clogged, the pump will pump water through orifice 8o.
, lower chamber 84. The return pipe 20, the other pump suction side, the suction pipe, and the water tank are returned in this order to prevent the inside of the pump casing from overheating8 [Example] Hereinafter, an example of the present invention will be described with reference to FIGS. 1 and 2. explain. In the figure, 1 is a water tank, 2-1 and 2-2 are suction pipes, 3-1 to 3-4 are gate valves 24-1, and 4-2 are the first and second pumps, respectively. <5-1.5-2 is a constant pressure valve, 6-1 and 6-2 are check valves, 7 is a water supply pipe, 8 is a pressure tank, and 9 is provided in the water supply pipe 7, and is connected to the pressure in the pressure tank 8. In response, it closes at the lower limit pressure R shown in FIG. 2 and opens at the upper limit pressure P.

10-1 and 10-2 are return pipes that return from the constant pressure valve 5-1.5-2 to the suction side of the other pump 4-2.4-1, respectively;
When these pumps are in cut-off operation, they are indirectly returned to the water tank.

Further, 11 is a unit base, and one or more parts are assembled on this base.

FIG. 2 is a diagram showing the operating characteristics of the water supply system of this embodiment, with the pressure H on the vertical axis and the water amount Q on the horizontal axis. Curve A is the Q when the first and second pumps described above are operated individually.
-H performance is the primary side pressure of constant pressure valve 5-1.5-2. Another song, If! B is the water supply pressure on the secondary side of the second constant pressure valve 5-1, 5-2, which has almost constant pressure characteristics due to the action shown in Japanese Patent Application Laid-open No. 14027/1983.

Although this embodiment shows an example in which the first and second pumps are operated alternately, the water supply is sent to the water supply terminal by the operation of either of these pumps. In this case, as shown in Fig. 2, the pressure on the discharge side of this pump changes on the curve MA as the demand water volume fluctuates.

The water supply pressure is operated along curve B as described above. Now, the first pump 4-1 is operating, and the second pump 4-
2 is assumed to be stopped. In this state, even though the amount of water used is small, the constant pressure valve 5-1 locks in the closed state and if the operation continues for a long period without turning off the pressure switch 9, a portion of the pumped water (5 to 101/m i n) is returned in this order from the constant pressure valve 5-1 to the return pipe 10-1, the suction side of the second pump 4-2 that is inactive, the suction pipe 2-2, and the water tank 1, and then returns to the pump 4-1. Prevent overheating inside the casing of 1. The second pump 4-2 operates, and the second pump 4-1
Even when the water is at rest, the water is returned to the water tank 1 from the return pipe 10-2 via the suction side of the rest pump 10-1 to prevent overheating, as described above. The above embodiment is an example of a combination of two pumps, but even when three or more pumps are combined, overheating in the pump casing can be prevented by returning the water to the water tank via the idle pump.

According to this embodiment, there is no need to take measures such as providing a temperature sensor, and it is possible to easily prevent overheating of the pump.

〔Effect of the invention〕

According to the present invention, it is possible to prevent overheating of the pump by indirectly returning a part of the pumped water from the pump in operation to the pump that is inactive, so that it is possible to prevent the pump from overheating. This has the effect of making it possible to assemble the pump and valves into one product, and there is no need to take measures to prevent overheating after installation.

This has the effect of reducing equipment costs and man-hours.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of one embodiment of the present invention, Fig. 2 is an operational characteristic diagram of the water supply device shown in Fig. 1, and Fig. 3 is a system diagram of a conventional water supply device (Japanese Patent Laid-Open No. 54-14027 (excerpt from issue). 1...Water tank, 2-1.2-2...Suction pipe, 3-1 to 3-4...Gate valve, 4-1.4
-2...Pump, 5-1.5-2...
Constant pressure valve, 7... Water supply pipe. 8...Pressure tank, 9...Pressure switch 2]〇-1, 10-2...Return pipe. $ 1 Figure 0M θyu $ 3

Claims (1)

[Claims] 1. Consists of a water tank, multiple pumps, their suction pipes, multiple constant pressure valves provided on the discharge side of these pumps, and a water supply pipe connected to the discharge side and equipped with a pressure switch and a pressure tank. In the water supply system, the suction sides of the plurality of pumps and the return ports of the plurality of constant pressure valves that are not operated at the same time are connected by a plurality of return pipes, and when the pumps are operating, the return pipes are connected. A water supply device equipped with a constant pressure valve, characterized in that part of the pumped water is returned to the water tank via the suction side of a pump that is inactive to prevent overheating.