WO2012063996A1

WO2012063996A1 - Sump device for improving water quality

Info

Publication number: WO2012063996A1
Application number: PCT/KR2011/001637
Authority: WO
Inventors: Kwi Young Kim
Original assignee: Gk Co., Ltd
Priority date: 2010-11-12
Filing date: 2011-03-09
Publication date: 2012-05-18
Also published as: KR101050386B1

Abstract

A sump apparatus for improving water quality, including a sump discharging water into rivers or drainage ditches, a valve body having a vertical tube divided into an upper buoy-passage space section and a lower communication space section by an inner step having a through opening, and a horizontal tube communicating with the vertical tube, the vertical tube having a first inlet hole through which water in the sump is introduced into the upper buoy-passage space section, a buoy floating in the upper buoy-passage space section in accordance with the water level in the buoy-passage space section, a shutter member in surface contact or separate from the inner step to open and shut the through opening, and a link member connecting the buoy and the shutter member.

Description

SUMP DEVICE FOR IMPROVING WATER QUALITY

The present invention relates, in general, to a sump apparatus for improving water quality and, more particularly, to a sump apparatus that discharges rainwater, underground water, undesirable liquids, or the like into rivers or neighboring drainage ditches, the sump apparatus preventing oil introduced into the sump from being discharged out of the sump, thereby improving water quality of the rivers or the like.

Generally, a sump is a structure that collects rainwater, underground water, undesirable liquids, or the like and discharges them into rivers or neighboring drainage ditches.

A conventional sump includes a main body formed by excavating a ground surface or a paved surface and constructing a walled structure inside the excavation space in order to collect rainwater, underground water, undesirable liquids, or the like (hereinafter referred to holistically as ‘rainwater’), a drain pipe communicating with the main body and connected to rivers or neighboring drainage ditches, and a cover mounted on an upper portion of the main body such that it can support pedestrians and cars that pass over the cover, for filtering out foreign substances contained in the rainwater.

The main body is generally formed into a rainwater storage space by excavating the ground surface and pouring concrete mortar along the insides of the walls of the excavation. Here, the main body made of metal may also be installed on the insides of the walls of the excavation hole.

The drain pipe is arranged such that its bottom is above the level of that of the main body while it communicates with the inside of the main body, so that the rainwater introduced into the main body fills the main body from the bottom thereof and when the level of rainwater is above the level of the bottom of the drain pipe, the drain pipe discharges the rainwater.

The cover is made of metal that has strength enough to support pedestrians or cars passing over the sump, and is mounted on the upper portion of the main body in a shape formed like a mesh type filter so that foreign substances contained in the rainwater can be filtered.

In the meantime, if oil leakage occurs and oils sink into the ground, on a rainy day, the oils may be introduced into the sump together with rainwater.

In the oils, light oil having a lower specific gravity than water floats on the water in the sump and heavy oil having a higher specific gravity greater than that of water sinks to the bottom of the sump, so that in a normal state, the drain pipe often discharges heavy oil together with the rainwater into the rivers or neighboring drainage ditches, and in a heavy rainfall, the light oil overflows the sump together with the rainwater and enters rivers or neighboring drainage ditches, thereby causing environmental contamination.

Accordingly, the present invention has been made keeping in mind the above problems occurring in the related art, and an object is to provide a sump apparatus in which an inlet hole of a valve body is arranged above the bottom of a sump and the water level is automatically controlled depending upon the amount of water inflow in order to prevent oils introduced into the sump from being discharged into rivers or neighboring drainage ditches, thereby preventing environmental contamination from occurring and improving water quality of the rivers or the like.

Another object of the present invention is to provide a sump apparatus which detects the existence of oil and the thickness of oil by emitting radio frequency waves and checking the reception rate of reflected waves, and if the thickness of oil exceeds a reference thickness, informs a monitoring system of this fact so that the oil can be removed, thereby improving the water quality of rivers or the like.

In an aspect, the present invention provides a sump apparatus for improving water quality, including:

a sump discharging water, including rainwater, underground water, undesirable liquids, or the like, into rivers or neighboring drainage ditches;

a valve body having a vertical tube divided into an upper buoy-passage space section and a lower communication space section by an inner step provided in the middle of the vertical tube, the inner step having a through opening, and a horizontal tube communicating with the vertical tube and connected with an external drain pipe, the vertical tube having an inlet hole through which water in the sump is introduced into the upper buoy-passage space section;

a buoy floating in the upper buoy-passage space section in accordance with the level of water introduced into the buoy-passage space section;

a shutter member in surface contact or separated from the inner step by means of floating of the buoy, so as to open and shut the through opening; and

a link member connecting the buoy and the shutter member, separated from each other by a certain distance.

According to the present invention, the sump apparatus prevents oils introduced into the sump from being discharged into rivers or neighboring drainage ditches, and if the thickness of oils is detected as being above the reference thickness, the monitoring system is informed of that situation so that the oils can be removed, thereby preventing environmental contamination from occurring and improving the water quality of rivers or the like.

FIG. 1 is a constructional diagram showing a sump apparatus according to a first embodiment of the present invention;

FIG. 2 is a view showing the operation of the sump apparatus of FIG. 1;

FIG. 3 is a constructional diagram showing a sump apparatus according to a second embodiment of the present invention;

FIG. 4 is a view showing the operation of the sump apparatus of FIG. 3;

FIG. 5 is a block diagram showing an oil gauge of the sump apparatus of FIG. 3;

FIG. 6 is a plan view showing another example of a shutter member shown in FIG. 3;

FIG. 7 is a constructional diagram showing a sump apparatus according to a third embodiment of the present invention; and

FIG. 8 is a view showing the operation of the sump apparatus of FIG. 7.

< Major Reference Numerals of the Drawings>

1: Sump 10, 110: Valve Body

20: Valve Cylinder 30: Seat

140: Gasket 50, 50’, 150: Buoy

60, 160: Link Member 70, 70’, 170: Shutter Member

90: Oil Gauge

Hereinafter, the construction and operation of embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a constructional diagram showing a sump apparatus according to a first embodiment of the present invention, and FIG. 2 is a view showing the operation of the sump apparatus of FIG. 1.

As shown in the drawings, the sump apparatus of the first embodiment includes a valve body 10, a valve cylinder 20, a seat 30, a gasket 40, a buoy 50, a link member 60, and a shutter member 70.

The valve body 10, which is installed in a sump 1 such that it protrudes out of the sump, has a vertical tube 11 and a horizontal tube 12 that communicate with each other. The vertical tube 11 is provided in the middle portion with an inner step 13 having a through opening 14 that perforates in a vertical direction, so that an upper buoy-passage space section 15 and a lower communication space section 16 are defined by the inner step 13.

The inner step 13 protrudes from an inner wall of the vertical tube.

The valve body 10 above the inner step 13 has an inlet hole 17 through which water is introduced into the inside of the valve body, i.e. the buoy-passage space section 15. Also, the inside of the valve body below the inner step 13, i.e. the communication space section 16, communicates with the horizontal tube 12.

The horizontal tube 12 is connected with an external drain pipe 3 through a side wall 2 of the sump 1.

The valve cylinder 20 has a lower open end and is inserted into the buoy-passage space section 15 of the valve body 10 such that it comes into close contact with the inner wall of the buoy-passage space section 15, and also has an inlet hole 21 that is located to correspond to the inlet hole 17 so that they communicate with each other, so that water can be introduced into the valve cylinder through the inlet hole 21.

The seat 30 sits on the upper portion of the inner step 13, the through opening 14 of which was blocked by the shutter member 70, in order to prevent water from leaking through a gap between the shutter member 70 and the inner step 13, and at this time, for further improving the sealing effect, the gasket 40 is mounted on the seat 30.

Here, in order to prevent the seat 30 and the gasket 40 from being pushed away out of the

inlet holes

17 and 21, the inner step 13 is preferably positioned below the

inlet holes

17 and 21.

The buoy 50 floats along the inside of the valve cylinder 20 in accordance with the level of water introduced into the buoy-passage space section 15. The buoy is connected with the shutter member 70 located below it and separated from it by a certain distance by means of the link member 60, so that as the buoy 50 floats up and down, the shutter member 70 also moves up and down.

Here, the link member 60 is connected with the buoy 50 above it by means of a coupler 61. Further, the link member is connected with the shutter member below it by means of fastener means, which includes an external screw portion on a lower circumference of the link member and nuts 62, in such a manner that the shutter member 70 is inserted through the lower circumference of the link member 60 and then nuts 62 are fastened to the link member through the link member at the upper and lower portions of the shutter member 70, thereby fixing the shutter member 70 to the lower portion of the link member 60.

The coupling of the shutter member 70 to the lower portion of the link member 60 by means of screw-coupling using upper and lower nuts 62 allows the distance between the buoy 50 and the shutter member 70 to be adjusted and therefore the water level that allows the through opening 14 to be opened can also be regulated.

That is, as the distance between the buoy 50 and the shutter member 70 becomes shorter, the water level allowing the through opening to be opened is lower, and vice versa.

When the buoy 50 comes down as the water level in the sump 1 falls, the shutter member 70 also goes down together with the buoy 50 and comes into surface-contact with the seat 30 to thereby seal the through opening 14 of the inner step 13 so as to prevent water in the sump from being discharged out of the sump. Further, when the buoy 50 goes up as the water level in the sump 1 rises, the shutter member 70 also goes up together with the buoy 50 and separates from the seat 30 to thereby open the through opening 14 of the inner step 13 so as to allow water in the sump 1 to be discharged out of the sump 1.

The shutter member 70 may have a lateral width slightly larger than an inner diameter of the valve cylinder 20 such that water cannot leak through a gap between the shutter member 70 and the valve cylinder 20 while the shutter member 70 moves up and down in the valve cylinder 20. Further, the shutter member 70 may preferably be made of a resilient rubber material.

The upper and lower ends of the vertical tube 11 are blocked by covers 80 to prevent water from being introduced into the upper and lower ends, and an outer end of the horizontal tube 12 is coupled with an external drain pipe 3 by a flange 82.

The operation of the sump apparatus having the above-mentioned construction will now be described. When the water level falls below a certain level as shown in FIG. 1, the buoy 50 comes down in the valve cylinder 20, so that the shutter member 70, connected with the buoy 50 by means of the link member 60, also moves down in the valve cylinder 20 and stops at the seat 30 on the inner step 13.

Then, the through opening 14 is blocked by the shutter member 70, and the shutter member 70 comes into surface-contact with the gasket 40 to prevent water from leaking therebetween, so that water or oil (including light oil 4 and heavy oil 5) is no longer discharged into the neighboring drain pipe 3 by the valve body 10.

Here, since the highest height H of the

inlet holes

17 and 21 is lower than the water level when the through opening is blocked, light oil floating on the water is essentially prevented from being introduced into the buoy-passage space section 15 via the

inlet holes

17 and 21.

Further, when water such as rainwater is introduced into the sump 1 from the exterior and the water level rises as shown in FIG. 2, the buoy 50 also goes up in the valve cylinder 20, so that the shutter member 70, connected with the buoy 50 by means of the link member 60, also moves up and separates from the seat 30 in the valve cylinder 20.

Then, the through-opening 14 of the inner step 13 becomes open so that water in the sump 1 is discharged into the neighboring drain pipe 3 through the valve body 10.

Here, since the lowest height h of the

inlet holes

17 and 21 is higher than the bottom of the sump 1, heavy oil 5 sunk on that bottom is not discharged into the neighboring drain pipe 3 through the valve body 10.

FIG. 3 is a constructional diagram showing a sump apparatus according to a second embodiment of the present invention, and FIG. 4 is a view showing the operation of the sump apparatus of FIG. 3.

As shown in the drawings, the sump apparatus of the second embodiment includes a valve body 10, a valve cylinder 20, a seat 30, a gasket 40, a buoy 50, a link member 60, a shutter member 70’, and an oil gauge 90.

The valve body 10, which is installed in a sump 1 such that it protrudes out of the sump, has a vertical tube 11 and a horizontal tube 12 communicating with each other. The vertical tube 11 is provided in the middle portion with an inner step 13 having a through opening 14 that perforates in a vertical direction, so that an upper buoy-passage space section 15 and a lower communication space section 16 are defined by the inner step 13.

The inner step 13 protrudes from an inner wall of the vertical tube.

The horizontal tube 12 is connected with an external drain pipe 3 through a sidewall 2 of the sump 1.

The valve cylinder 20 has a lower open end and is inserted into the buoy-passage space section 15 of the valve body 10 such that it comes into close contact with the inner wall of the buoy-passage space section 15, and also has an inlet hole 21 that is located corresponding to the inlet hole 17 so that they communicate with each other, so that water can be introduced into the valve cylinder through the inlet hole 21.

The seat 30 sits on the upper portion of the inner step 13, the through opening 14 of which was blocked by the shutter member 70’, in order to prevent water from leaking through a gap between the shutter member 70’ and the inner step 13, and at this time, for further improving the sealing effect, the gasket 40 is mounted on the seat 30.

Here, in order to prevent the seat 30 and the gasket 40 from being pushed away out of the inlet holes 17 and 21, the inner step 13 is preferably positioned below the inlet holes 17 and 21.

The buoy 50 floats along the inside of the valve cylinder 20 in accordance with the level of water introduced into the buoy-passage space section 15. The buoy is connected with the shutter member 70’ located below it and separated from it by a certain distance by means of the link member 60, so that as the buoy 50 floats up and down, the shutter member 70’ also moves up and down.

Here, the link member 60 is connected with the buoy 50 above it by means of a coupler 61. Further, the link member is connected with the shutter member below it by means of fastener means, which includes an external screw portion on a lower circumference of the link member and nuts 62, in such a manner that the shutter member 70’ is inserted through the lower circumference of the link member 60 and then nuts 62 are fastened to the link member through the link member at the upper and lower portions of the shutter member 70’, thereby fixing the shutter member 70’ to the lower portion of the link member 60.

With coupling of the shutter member 70’ to the lower portion of the link member 60 by means of screw-coupling using upper and lower nuts 62, a distance between the buoy 50 and the shutter member 70’ can be adjusted and therefore the water level that allows the through opening 14 to be opened can also be regulated.

That is, as the distance between the buoy 50 and the shutter member 70’ becomes shorter, the water level allowing the through opening to be opened becomes lower, and vice versa.

When the buoy 50 comes down as the water level in the sump 1 falls, the shutter member 70’ also goes down together with the buoy 50 and comes into close contact with the seat 30 to thereby seal the through opening 14 of the inner step 13 so as to prevent water in the sump from being discharged out of the sump. Further, when the buoy 50 goes up as the water level in the sump 1 rises, the shutter member 70’ also goes up together with the buoy 50 and separates from the seat 30 to thereby open the through opening 14 of the inner step 13 so as to allow water in the sump 1 to be discharged out of the sump 1.

The shutter member 70’ may have a lateral width slightly larger than an inner diameter of the valve cylinder 20 such that water cannot leak through a gap between the shutter member 70’ and the valve cylinder 20 while the shutter member 70’ moves up and down in the valve cylinder 20. Further, the shutter member 70’ may preferably be made of a resilient rubber material.

Further, in order to reduce a pressure difference between water pressure above the shutter member 70’ and atmospheric pressure below the shutter member 70’ to facilitate opening the through opening 14, a plurality of pin holes 71 is formed in the shutter ember 70’.

Here, the number and diameter of the pin holes may diversely vary according to the water pressure or capacity of the sump.

Water sinks into a gap between the shutter member 70’ and the gasket 40 through the pin holes 71, which opens the through opening 14 by the action of water pressure.

Further, the shutter member 70’ or the buoy 50 may have various shapes such as a rectangular section, as shown in FIG. 6, as well as a circular section, according to its capacity, and pin holes 71 may also be formed in the rectangular shutter member, for example.

Compared to the first embodiment, the second embodiment further includes the oil gauge 90 to detect the existence of oil and the thickness of oil, which as shown in FIG. 5, includes a battery 91, a micom 92, an antenna 93, and an A/D converter 94.

Here, the oil gauge 90 will be described for an exemplary oil gauge, which is built in another buoy 50’ so that it detects the existence and the thickness of oil floating on water while moving up and down in accordance with the water level.

The battery 91 supplies electric power to the micom 92, which generates radiates high frequency waves (microwaves) around the surroundings, and detects the existence and the thickness of oil floating on the water by means of checking the reception rate of the microwaves that are reflected and returned to the micom via the antenna 93.

For example, if there is no oil floating on water, the reception rate of reflected microwaves via the antenna 93 is nearly 100%, and if there is oil floating on water, the reception rate of reflected microwaves via the antenna 93 decreases in proportion to the thickness of oil.

Finally, the microwaves received via the antenna 93 are converted into an electric current by the A/D converter 94, so that the micom 92 detects the thickness of oil floating on the water using current intensity. Here, a higher current intensity means that the oil is thicker.

If the oil thickness exceeds a reference thickness, the micom 92 informs a remotely installed monitoring system of this fact (i.e., that the thickness exceeds the reference thickness) so that a user of the monitoring system can remove the oil.

The operation of the sump apparatus having the above-mentioned construction will now be described. When the water level is lowered below a certain level as shown in FIG. 3, the buoy 50 comes down in the valve cylinder 20, so that the shutter member 70’, connected with the buoy 50 by means of the link member 60, also moves down in the valve cylinder 20 and stops at the seat 30 on the inner step 13.

Then, the through opening 14 is blocked by the shutter member 70’, and the pressure difference is reduced by the pin holes 71 formed in the shutter member 70’ while allowing only an extremely smaller amount of water to be introduced between the shutter member and the seat 30 through the pin holes 71, and the highest height H of the inlet holes 17 and 21 is lower than the water level when the through opening is blocked, so that light oil floating on the water is essentially prevented from being introduced into the buoy-passage space section 15 via the inlet holes 17 and 21.

Further, when water such as rainwater is introduced into the sump 1 from the exterior and the water level rises as shown in FIG. 4, the buoy 50 also goes up in the valve cylinder 20, so that the shutter member 70’, connected with the buoy 50 by means of the link member 60, also moves up and separates from the seat 30 in the valve cylinder 20.

Here, since the lowest height h of the inlet holes 17 and 21 is higher than the bottom of the sump 1, heavy oil 5 sunk on that bottom is not discharged into the neighboring drain pipe 3 through the valve body 10.

In the meantime, the micom 92 of the oil gauge 90 built in the buoy 50’ detects the existence and thickness of oil floating on water using the reception rate of microwaves that are emitted from and return to the antenna 93.

When the operation of the sump apparatus shown in FIGS. 3 and 4 is repeated, oil is not discharged and accumulates on the water surface; if the oil thickness exceeds the reference thickness, the micom 92 informs an external monitoring system of the fact that a great amount of oil has been introduced into the sump 1.

FIG. 7 is a constructional diagram showing a sump apparatus according to a third embodiment of the present invention, and FIG. 8 is a view showing the operation of the sump apparatus of FIG. 7.

As shown in the drawings, the sump apparatus of the third embodiment includes a valve body 110, a gasket 140, a buoy 150, a link member 160, and a shutter member 170.

The rectangular valve body 10, which is installed in a sump 1 such that it protrudes out of the sump, has a vertical tube 111 and a horizontal tube 112 communicating with each other. The vertical tube 111 is provided in the middle portion with an inner step 113 having a through opening 114 that perforates in a vertical direction, so that an upper buoy-passage space section 115 and a lower communication space section 116 are defined by the inner step 113.

The inner step 113 consists of right-angled stopper plates shaped like ‘┏’ and ‘┛’, which are fixed at different heights on opposite inner wall portions of the vertical tube 111.

The valve body 110 above the inner step 113 has an inlet hole 117 through which water is introduced into the inside of the valve body, i.e. the buoy-passage space section 115. Also, the inside of the valve body below the inner step 113, i.e. the communication space section 116, communicates with the horizontal tube 112.

The horizontal tube 112 is connected with an external drain pipe 3 through a sidewall 2 of the sump 1.

When the shutter member 170 blocks the through opening 114 of the inner step 113, in order to prevent water from leaking through a gap between the shutter member 170 and the inner step 113, the gasket 140 is mounted on the inner step 113 contacting the shutter member 170.

The buoy 150 floats along the inside of the vertical tube 111 in accordance with the level of water introduced into the buoy-passage space section 115. The buoy is connected with one end of the shutter member 170 located below it and is separated by a certain distance therefrom by means of the link member 160, so that as the buoy 150 floats up and down, the shutter member 170 rotates clockwise or counterclockwise.

The shutter member 170 has, at the middle portion, a rotation axis 171 which is coupled to the inner wall of the vertical tube 111, so that the shutter member 170 can rotate about the rotation axis 171.

When the buoy 150 comes down as the water level in the sump 1 falls, the shutter member 170 rotates counterclockwise so that one end thereof comes into surface contact with the gasket 140, provided on the inner step 113, and the other end thereof comes into surface contact with the gasket 140, provided below the inner step 113 to thereby seal the through opening 114 of the inner step 113, thereby preventing water in the sump from being discharged out of the sump.

On the contrary, when the buoy 150 goes up as the water level in the sump 1 rises, the shutter member 170 rotates clockwise about the rotation axis 171 and separates from the gasket 140 to thereby open the through opening 114 of the inner step 113, thereby allowing water in the sump 1 to be discharged out of the sump 1.

The upper and lower ends of the vertical tube 111 are blocked by covers 180 to prevent water from being introduced into the upper and lower ends, and an outer end of the horizontal tube 112 is coupled with an external drain pipe 3 by a flange 182.

The operation of the sump apparatus having the above-mentioned construction will now be described. When the water level is lowered below a certain level as shown in FIG. 7, the buoy 150 comes down in the buoy-passage space section 115, so that the shutter member 170, one end of which is connected with the buoy 150 by means of the link member 160, rotates counterclockwise about the rotation axis 171 and stops at the inner step 113.

Here, one end of the shutter member 170 comes into surface contact with the gasket 140, provided on the inner step 113, and the other end thereof comes into surface contact with the gasket 140, provided below the inner step 113 to thereby seal the through opening 114 of the inner step 113, thereby preventing water in the sump from being discharged out of the sump.

That is, the shutter member 170 blocks the through opening 114, and the shutter member 170 comes into surface contact with the inner step 113 by the gasket 140 to prevent water leakage therebetween, so that water or oil (including light oil 4 and heavy oil 5) is no longer discharged into the neighboring drain pipe 3 from the valve body 110.

Here, since the highest height H of the inlet holes 117 is lower than the water level when the through opening is blocked, light oil floating on the water is essentially prevented from being introduced into the buoy-passage space section 115 via the inlet holes 117.

Further, when water such as rainwater is introduced into the sump 1 from the exterior and the water level rises as shown in FIG. 8, the buoy 150 also goes up in the buoy-passage space section 115, so that the shutter member 170, connected at one end with the buoy 150 by means of the link member 160, rotates clockwise and separates from the inner step 113.

Then, the through-opening 114 of the inner step 113 becomes open so that water in the sump 1 is discharged into the neighboring drain pipe 3 through the valve body 110.

Here, since the lowest height h of the inlet holes 117 is higher than the bottom of the sump 1, heavy oil 5 sunk on that bottom is not discharged into the neighboring drain pipe 3 through the valve body 110.

The third embodiment is configured so that the buoy 150 is connected with one end of the shutter member 170, which rotates about the central rotation axis 171, so that when the buoy 150 moves up, one end of the shutter member 170 rotates counterclockwise and separates from the inner step 113 so that the through opening 114 can be easily opened even when under water pressure.

The sump apparatus according to the above and other embodiments may be adapted to suit an irrigation canal e.g. for agriculture so as to regulate watering using a floodgate.

Claims

A sump apparatus for improving water quality, comprising:

a sump discharging water, including rainwater, underground water, undesirable liquids, or the like, into rivers or neighboring drainage ditches;

a valve body having a vertical tube divided into an upper buoy-passage space section and a lower communication space section by an inner step provided in the middle of the vertical tube, the inner step having a through opening, and a horizontal tube communicating with the vertical tube and connected with an external drain pipe, the vertical tube having a first inlet hole through which water in the sump is introduced into the upper buoy-passage space section;

a buoy floating in the upper buoy-passage space section in accordance with the level of water introduced into the buoy-passage space section;

a shutter member in surface contact with or separated from the inner step by means of floating of the buoy, so as to open and shut the through opening; and

a link member connecting the buoy and the shutter member, separated from each other by a certain distance..
The sump apparatus according to claim 1, wherein the inner step protrudes from an inner wall of the vertical tube, and the shutter member moves up and down in the buoy-passage space section together with the buoy.
The sump apparatus according to claim 2, wherein a valve cylinder having a lower open end is inserted into the buoy-passage space section such that the valve cylinder comes into close contact with an inner wall of the valve body, the valve cylinder has a second inlet hole that is located to correspond to the first inlet hole so that the first and second inlet holes communicate with each other, to allow the buoy and the shutter member to move up and down in the valve cylinder and allow the water to be introduced into the buoy-passage space section.
The sump apparatus according to claim 2, wherein a seat is provided on the inner step in order to prevent water leaking between the inner step and the shutter member which are in a state of surface contact.
The sump apparatus according to claim 4, further comprising:

a gasket provided on the seat to increase a sealing effect.
The sump apparatus according to claim 2, wherein the link member has, on a lower part, an external screw portion and nuts which are fastened to the external screw portion in such a manner that the shutter member is inserted through the lower part of the link member and the nuts are screwed along the screw portion of the link member at the upper and lower portions of the shutter member, so as to adjust a distance between the buoy and the shutter member.
The sump apparatus according to claim 2, wherein the shutter member is provided with a plurality of pin holes that perforate vertically through the shutter member to reduce a pressure difference between water pressure above the shutter member and atmospheric pressure below the shutter member when the shutter member comes into surface-contact with the inner step.
The sump apparatus according to claim 1, wherein the inner step has right-angled stopper plates, which are fixed at different heights on opposite inner wall portions of the vertical tube, and

wherein the shutter member has, at a middle portion thereof, a rotation axis which is coupled to the vertical tube, so that as the buoy moves up and down, the shutter member rotates about the rotation axis so that one end thereof comes into surface contact with or separates from an upper portion of the inner step and the other end thereof comes into surface contact with or separates from a lower portion of the inner step.
The sump apparatus according to claim 8, wherein a gasket is provided on the upper or lower portion of the inner step contacting the shutter member to prevent water from leaking therebetween.
The sump apparatus according to claim 1, wherein the highest height of the first inlet hole is below the water level when the through opening is blocked, and the lowest height of the first inlet hole is above the bottom of the sump.
The sump apparatus according to claim 1, further comprising:

an oil gauge to detect the existence and thickness of oil floating on water by emitting high frequency waves around the surface of water in the sump and determining the reception rate of returning waves.
The sump apparatus according to claim 11, wherein the oil gauge is built in another buoy provided in the sump to detect the existence and thickness of oil floating on water while moving up and down in accordance with the water level in the sump.