JP4598792B2 - Vent pipe structure - Google Patents

Description

  The present invention relates to a vent pipe structure in which a gas phase portion of a tank for storing a volatile liquid such as petroleum is communicated with outside air, and an exhaust valve is installed at the front end portion or in the middle thereof.

  Underground tanks are installed at gas stations and other facilities that handle petroleum such as gasoline and light oil. In this underground tank, since the internal pressure changes due to the entry and exit of petroleum, vaporization, etc., a vent pipe is provided to communicate the gas phase part of the underground tank with the outside air so that the inside pressure and the outside air pressure of the tank match. ing.

  Conventionally, a vent pipe is generally provided as a simple pipe, and a fire net of about 40 mesh is attached to the vent on the outside air side so that a flame does not enter the tank even if a fire occurs outside. However, the inside of the tank and the outside air were always in communication with each other, and in normal times, harmful vapors such as gasoline continued to be released from the tank in a state of flowing down to the outside air.

  In recent years, due to the increasing awareness of environmental problems, the release of harmful vapors has stopped, and the release of harmful vapors during normal times has stopped, and only when the pressure inside the tank exceeds a certain permissible pressure, The exhaust valve to be discharged is now installed at the end of the vent pipe or in the middle. Also, with regard to petroleum stored in tanks, E3 gasoline containing 3% ethanol has begun to be used for testing due to environmental concerns. In particular, since ethanol is a liquid that hates moisture, The installation of an exhaust valve that shuts off the inside air from the tank has been approved by the fire department, and the installation of the exhaust valve is in progress from this point.

  The applicant of the present application also worked on the development of this exhaust valve, and disclosed the structure of an exhaust valve suitable for installation in a vent pipe in Patent Document 1. By installing this exhaust valve, the spillage of harmful vapors such as gasoline is eliminated, environmental problems are improved, and loss (depletion) due to volatilization of gasoline in the tank can be reduced.

  However, the installation of this exhaust valve caused a new problem. In other words, the inside of the vent pipe is always sealed except when the pressure in the tank exceeds a certain allowable pressure and the exhaust valve is activated, and a temperature difference has occurred between the outside air and the vent pipe in winter. In this case, a cooling liquefaction phenomenon of petroleum vapor inside the vent pipe occurs, and a so-called condensation phenomenon occurs in which the liquid adheres to the inner wall of the vent pipe. When this dew condensation occurs, the pressure in the tank rises when unloading, etc., and when the exhaust valve is activated and the vent pipe is opened, the liquid adhering to the inner wall of the vent pipe spouts with the vapor and drops to the ground To do. The liquid dropped on the ground is a dangerous liquid such as gasoline, and there is a risk of causing a major accident such as an explosion or fire if the dropped gasoline is ignited.

This kind of vapor liquefaction phenomenon (condensation phenomenon) inside the vent pipe and the resulting dripping of liquid onto the ground is a new phenomenon caused by the installation of an exhaust valve in the vent pipe. The countermeasures were not considered.
JP 2007-40387 A

  The problem to be solved by the present invention is to provide a means for preventing the occurrence of a cooling liquefaction phenomenon (condensation phenomenon) of steam inside the vent pipe in the vent pipe structure provided with an exhaust valve.

As a ventilation mechanism for taking outside air into the ventilation pipe in the ventilation pipe structure that has a ventilation pipe that communicates the tank that stores volatile liquid and the outside air, and an exhaust valve is installed at the tip of the ventilation pipe or in the middle An exhaust valve opening tool for forcibly opening the exhaust valve is provided, and the operation and non-operation of the exhaust valve opening tool can be set by remote control.

  In this way, the ventilation pipe is provided with a ventilation mechanism, and by operating this ventilation mechanism, outside air is taken into the ventilation pipe and there is no temperature difference between the inside of the ventilation pipe and the outside air. Occurrence of the phenomenon is prevented. During the operation of the ventilation mechanism, the steam in the vent pipe is released to the outside air. However, the ventilation mechanism is activated when the temperature of the outside air is low, such as in winter, so the amount of steam released from the vent pipe Is negligibly small. Further, when there is no fear of a cooling liquefaction phenomenon, such as in summer, the function of the exhaust valve can be exhibited as usual by disabling the ventilation mechanism.

  In addition, the part of the ventilation pipe that communicates with the outside air is positioned at a height of 4 m or more according to the law. Therefore, if the ventilation mechanism as in the present invention is operated at the installation position, it becomes a work at a high place and there is a risk. In addition, according to the present invention, since the operation and non-operation of the ventilation mechanism can be set by remote control, there is no need for work at a high place.

  Further, in the present invention, it is preferable that the remote operation of the ventilation mechanism is performed by mechanical means, not by electric means. If electric means are used, sparks may be generated and ignited by steam such as gasoline. On the other hand, according to the mechanical means, the problem of occurrence of sparks is eliminated, and the durability is improved.

  In the present invention, it is preferable that the operation of the ventilation mechanism can be confirmed by the operation unit for remotely operating the ventilation mechanism. Specifically, remote operation of the ventilation mechanism is performed by operating the lever of the operation unit, and the operation and non-operation of the ventilation mechanism can be confirmed by the direction of the lever. As a result, it is possible to check whether the ventilation mechanism is in an operating state or a non-operating state without directly checking the state of the ventilation mechanism at a height of 4 m or more, thereby improving workability and safety. .

The ventilation mechanism is constituted by an exhaust valve opening tool that forcibly opens the exhaust valve, and the operation and non-operation of the exhaust valve opening tool can be set by remote control. With such a configuration, it is not necessary to provide a separate ventilation valve as a ventilation mechanism, and a ventilation effect can be obtained only by adding an exhaust valve opening tool to the exhaust valve portion of the existing vent pipe structure.

  In the present invention, by providing a ventilation mechanism in the vent pipe, it is possible to take outside air into the vent pipe as needed, and therefore, it is possible to prevent the occurrence of a cooling liquefaction phenomenon (condensation phenomenon) of steam inside the vent pipe. Can do. Therefore, the occurrence of a dripping phenomenon in which a dangerous liquid such as gasoline drops from the exhaust valve to the ground is prevented, and the safety in the vicinity of the vent pipe can be maintained. Furthermore, since the operation of the ventilation mechanism is performed by remote operation, the workability is also improved.

Embodiments of the present invention will be described below based on examples and reference examples shown in the drawings.

FIG. 1 shows a first reference example of the vent pipe structure of the present invention.

  The base end of the vent pipe A communicates with a gas phase portion of an underground tank (not shown), and the vent fitting B having the exhaust valve 1 is connected to the tip end of the vent pipe A with an adapter fitting having a bypass pipe 2. It is installed via C.

  The bypass pipe 2 is provided so as to bend downward from the vent pipe A (adapter metal fitting C), and the opening 2a at the tip thereof is disposed downward. And the ventilation valve 3 which opens and closes the opening part 2a of this bypass pipe 2 front-end | tip is installed.

  The ventilation valve 3 opens and closes the opening 2a by rotating with its base end as a rotation axis, and one end of the wire 4 is connected to the tip of the ventilation valve 3 so that it can be opened and closed remotely. The other end of the wire 4 extends to the operation unit 6 near the ground while being guided by a guide member 5 provided in the vent pipe A, and is connected to a lever 6a of the operation unit 6. By operating the lever 6a, the wire 4 The ventilation valve 3 is opened and closed via the.

  That is, as shown in FIG. 1 (b), when the lever 6a of the operation unit 6 is directed to the open position, the tip of the ventilation valve 3 is pulled downward by the wire 4 to open, and the lever 6a of the operation unit 6 is closed. The wire 4 is loosened and the ventilation valve 3 is closed by its restoring force.

  Thus, the ventilation valve 3 can be opened and closed by remote operation by the lever 6a of the operation unit 6 near the ground, and the open / closed state of the ventilation valve 3 can be confirmed by the direction of the lever 6a of the operation unit 6.

  FIG. 2 shows an enlarged front end portion of the vent pipe structure shown in FIG. With reference to FIG. 2, the detailed structure of the exhaust valve 1 installed in the vent hole metal fitting B will be described first.

  The exhaust valve 1 normally closes the circular exhaust port 8 provided on the upper portion of the vent fitting body 7 from above, and when the pressure in the tank rises, the pressure rises due to the pressure and opens the exhaust port 8. . Further, an O-ring 9 is provided between the exhaust valve 1 and the exhaust port 8 in order to ensure that the exhaust port 8 is closed by the exhaust valve 1.

  Further, a weight 10 is integrally provided below the exhaust valve 1. The weight 10 extends so as to be positioned below the exhaust port 8. As a result, the position of the center of gravity of the exhaust valve 1 is lower than that of the exhaust port 8, and the balance of the exhaust valve 1 is improved so that the exhaust valve 1 can move smoothly up and down. Further, by adjusting the weight of the weight 10, the exhaust set pressure (pressure when the exhaust valve 1 just rises) can be adjusted.

The weight 10 also serves as the guide portion 11. The guide portions 11 are provided at four locations at equal intervals along the outer periphery of the exhaust valve 1, and each guide portion 11 is provided so as to be inscribed in the inner peripheral edge of the exhaust port 8. As a result, when the exhaust valve 1 moves up and down, it is guided by the guide portion 11, so that the vertical movement of the exhaust valve 1 becomes smoother. In addition, although the guide part 11 was provided in four places in this example , what is necessary is just to provide in the multiple places of at least three or more places. However, it is preferable to provide each guide part at equal intervals in which the weight is balanced.

  2 has an intake valve 12 in addition to the exhaust valve 1 described above. The intake valve 12 normally closes the intake port 13 provided in the exhaust valve 1 from the lower side, and when the pressure in the tank decreases, the intake valve 12 descends due to a pressure difference from the external pressure to open the intake port 13. It is configured. The intake valve 12 is normally biased upward by a coil spring 14 so as to close the intake port 13, and the adjustment of the intake set pressure (pressure when the intake valve 12 is just lowered) is adjusted by the coil spring 14. This is done by adjusting the strength.

  In addition, the vent fitting B is provided with a fire net 15 so that a flame does not enter the tank from the vent fitting B even if an external fire occurs. The fire net 15 is made of a metal net of about 40 mesh, is provided so as to cover the entire upper part of the exhaust port 8 and the exhaust valve 1, and is fixed to the vent hole metal body 7 by a caulking pin 16 and a clasp 17. Yes. In addition, a cap 18 is provided above the fire net 15 to prevent rain and dust, and is fixed to the vent metal fitting body 7 with a tapping screw 19. In this way, in the vent hole fitting B shown in FIG. 2, no housing other than the fire net 15 and the cap 18 is provided above the exhaust port 8 and the exhaust valve 1 (outside air side), and the fire net 15 is exhausted. Since it is provided so as to cover the entire upper part of the port 2 and the exhaust valve 1, a fire net portion serving as a vent can be widened, and a sufficient vent area can be secured.

  In such a configuration, during normal times when the pressure in the tank is substantially equal to the outside air pressure, the exhaust valve 1 and the intake valve 12 close the exhaust port 8 and the intake port 13, respectively, and the tank is shut off from the outside air. The gas inside is not released to the outside air. When the pressure in the tank rises above the set exhaust pressure, the exhaust valve 1 is raised by the pressure and the exhaust port 8 is opened. The gas in the tank is discharged from the exhaust port 8 and passes through the fire net 15 to the outside air side. Released. When the pressure in the tank becomes lower than the exhaust set pressure due to this gas discharge, the exhaust valve 1 descends due to its own weight and closes the exhaust port 8 again. The vertical movement of the exhaust valve 1 is very stable and smooth by providing the weight 10 and the guide portion 11 below the exhaust valve 1 as described above. Therefore, the exhaust valve frequently opens and closes repeatedly. The so-called chattering phenomenon does not occur.

  On the other hand, when the pressure in the tank falls below the intake set pressure, the intake valve 12 descends due to the pressure difference from the outside air pressure to open the intake port 13, and the outside air passes through the fire net 15 and the intake port 13 and enters the tank. Flow into. When the pressure in the tank exceeds the intake set pressure due to the outside air inflow, the intake valve 12 rises due to the urging force of the coil spring 14 and closes the intake port 13 again.

  Thus, even if the pressure in the tank fluctuates, the pressure in the tank returns to a state almost equal to the external air pressure by the operation of the exhaust valve 1 and the intake valve 12.

  Next, the detailed structure of the ventilation valve 3 as a ventilation mechanism installed in the adapter fitting C will be described.

  As shown in FIG. 2, the adapter fitting C is installed in the piping path of the vent pipe A by joining the upper end to the lower end of the vent fitting main body 7 and joining the lower end to the upper end of the vent pipe A. The adapter fitting C is provided with a bypass pipe 2 so as to bend downward from the vent pipe A (adapter fitting C), and the ventilation valve 3 is installed so that the opening 2a at the tip of the bypass pipe 2 can be opened and closed. Yes.

  The ventilation valve 3 is installed below the opening 2a via the pedestal 20, and opens and closes the opening 2a by rotating around the base end as a rotation axis. In addition, a coil spring 21 is attached to the base end portion of the ventilation valve 3, and the ventilation valve 3 is always urged by the coil spring 21 in a direction to close the opening 2 a. Further, a fire net 22 is detachably provided from the outside so as to cover the entire opening 2a above the opening 2a, thereby preventing the intrusion of flame from the opening 2a.

  One end of a wire 4 is connected to the tip of the ventilation valve 3. As described with reference to FIG. 1, the other end of the wire 4 is connected to the lever 6 a of the operation unit 6 in the vicinity of the ground. The operation of the lever 6 a opens and closes the ventilation valve 3 through the wire 4.

  In other words, when the cooling liquefaction phenomenon of the steam in the vent pipe A is likely to occur during winter, the occurrence of the cooling liquefaction phenomenon can be prevented by opening the ventilation valve 3 and taking outside air into the vent pipe A. . On the other hand, when there is no possibility of occurrence of the cooling liquefaction phenomenon, the ventilation valve 3 is closed. If it does so, the function of the exhaust valve 1 and the intake valve 12 mentioned above will be exhibited as usual. The open / closed state of the ventilation valve 3 can be confirmed by the direction of the lever 6a of the operation unit 6 as described above.

FIG. 3 shows a second reference example of the vent pipe structure of the present invention.

The ventilation valve 23 used in this reference example is attached to a pedestal 24 so as to be movable up and down, and the pedestal 24 is mounted in the opening 2 a at the tip of the bypass pipe 2. A plurality of ventilation holes 25 are provided near the center of the base 24, and the ventilation valve 23 is disposed so as to close the ventilation holes 25 from below. A coil spring 26 is mounted between the ventilation valve 23 and the pedestal 24, and the ventilation valve 23 is constantly urged by the coil spring 26 in a direction to close the ventilation port 25.

When the ventilation valve 23 closes the ventilation port 25, the opening 2a at the tip of the bypass pipe 2 is closed. In this reference example , an O-ring 27 is provided between the ventilation valve 23 and the pedestal 24 in order to reliably perform this closing. A receiving tray 28 is provided on the lower surface of the ventilation valve 23, and one end of the wire 4 is connected to the center of the lower surface of the receiving tray 28.

As described with reference to FIG. 1 of the first reference example , the other end of the wire 4 is connected to the lever 6a of the operation unit 6. When the wire 4 is pulled downward by the operation of the lever 6a, FIG. As shown in (b), the ventilation valve 23 moves downward, and the ventilation port 25 and the opening 2a are opened. On the other hand, when the wire 4 is loosened by operating the lever 6a, the ventilation valve 23 is closed by the restoring force of the coil spring 26 as shown in FIG.

Thus, also in this reference example , by opening the ventilation valve 23, the outside air can be taken into the ventilation pipe A, and the occurrence of the cooling liquefaction phenomenon can be prevented. Further, in this reference example , since the tray 28 is provided on the lower surface of the ventilation valve 23, even if the cooling liquefaction phenomenon occurs in the bypass pipe 2 and the vapor is liquefied, the liquid is received by the tray 28. Therefore, it is possible to prevent liquid from dripping onto the ground when the ventilation valve 23 is opened.

  FIG. 4 shows an embodiment of the vent tube structure of the present invention. In this embodiment, an exhaust valve opening tool 29 that forcibly opens the exhaust valve 1 is used as a ventilation mechanism.

  The exhaust valve opening tool 29 includes an operation base portion 29a and an arm portion 29b provided integrally therewith, and the arm portion 29b is inserted below the exhaust valve 1 in the vent hole fitting B. The arm portion 29b has a bent tip, and can be rotated around its axis by a rotation operation by the operation base portion 29a. Further, in order to ensure the airtightness of the vent pipe A, a seal member 30 is provided in a portion where the arm portion 29b penetrates the vent hole fitting main body 7.

As shown in FIG. 5, the operation base 29 a is formed in a disk shape, and one end of the wire 4 is connected to each of two places on the circumference. By operating these two wires 4, the operation base 29a is rotated, and accordingly, the arm 29b is rotated around its axis. The other ends of these two wires are connected to the operation unit 6 as described in FIG. 1 of the first reference example , for example , and the wire 4 can be operated by operating the lever of the operation unit 6.

In the above configuration, when the arm part 29b of the exhaust valve opening tool 29 is brought into the posture of FIG. 4A by operating the two wires 4, the arm part 29b does not interfere with the exhaust valve 1 at all. Works as usual. On the other hand, when the arm portion 29b is brought into the posture of FIG. 4B by operating the two wires 4, the distal end portion of the arm portion 29b pushes up the exhaust valve 1, so that the exhaust valve 1 is forcibly opened. Thereby, outside air can be taken in from the exhaust port 8, and the occurrence of the cooling liquefaction phenomenon can be prevented as in the first and second reference examples .

The 1st reference example of the vent pipe structure of this invention is shown. The front-end | tip part of the vent pipe structure shown in FIG. 1 is expanded and shown. The 2nd reference example of the vent pipe structure of the present invention is shown. The Example of the vent pipe structure of this invention is shown. The operation base part of the exhaust valve opening tool used for the vent pipe structure of FIG. 4 is shown.

A Vent pipe B Vent hole fitting C Adapter fitting 1 Exhaust valve 2 Bypass pipe 2a Opening 3 Ventilation valve 4 Wire 5 Guide member 6 Operation part 6a Lever 7 Vent hole fitting body 8 Exhaust port 9 O-ring 10 Weight 11 Guide part 12 Intake Valve 13 Inlet 14 Coil spring 15 Fire net 16 Caulking pin 17 Clasp 18 Cap 19 Tapping screw 20 Base 21 Coil spring 22 Fire net 23 Ventilation valve 24 Base 25 Ventilation port 26 Coil spring 27 O-ring 28 Sauce plate 29 Exhaust valve opening device 29a Operation base 29b Arm 30 Sealing material

Claims (4)

In a vent pipe structure that includes a tank that stores volatile liquid and a vent pipe that communicates with the outside air, and an exhaust valve is installed at the tip or in the middle of the vent pipe,
A vent pipe structure provided with an exhaust valve opening tool for forcibly opening an exhaust valve as a ventilation mechanism for taking outside air into the vent pipe, and enabling and disabling the operation of the exhaust valve opening tool by remote control. The vent pipe structure according to claim 1, wherein the remote operation of the exhaust valve opening tool is performed by mechanical means, not by electric means. The vent pipe structure according to claim 2, wherein the operation of the ventilation mechanism can be confirmed by an operation unit for remotely operating the exhaust valve opening tool . The vent pipe structure according to claim 3, wherein the remote operation of the exhaust valve opening tool is performed by operating the lever of the operation unit, and the operation and non-operation of the ventilation mechanism can be confirmed by the direction of the lever.

Images