JPH01111700A - Piping structure of tank lorry - Google Patents

Abstract

PURPOSE: To surely prevent the back flow of the liquid as the dangerous mate rial in a quantity increase piping by arranging to communicate with a main piping and a discharge piping by the quantity increase piping, and comprising a gate valve, and a check valve located at the upstream side of the gate valve. CONSTITUTION: In the case of the gravity discharging without using a pump 4, a switch valve 5 of a branch piping 6 is opened for the gravity discharging, and a gate valve 8 of a quantity increase piping 9 is opened to perform the unloading of the liquid as the dangerous material loaded in a tank chamber 1, by the discharging. That is, the liquid is sent from the tank chamber 1 to the main piping 3, and then sent to the discharge pipings 7, 7' by the gravity through the branch piping 6 and its switch valve 5 on one side, and through the quantity increase piping 9 and its check valve 15 and gate valve 8 on the other side to be discharged from the discharge valves 14, 14' and unloaded. As the quantity increase piping 9 comprises the check valve 15, the back flow of the liquid can be surely prevented even when the gate valve 8 is left opened after the unloading. That is, the flowing of the liquid from the pump 4 to the main piping 3 by the back flow from the discharge piping 7 to the quantity increase piping 9 can be surely prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a piping structure for a tank lorry in which the inside of a tank is divided into tank chambers. That is, the present invention relates to a piping structure in a tank lorry that loads and transports dangerous liquids such as gasoline, diesel oil, and kerosene into each tank chamber in the tank and unloads them from a discharge piping.

``Conventional technology'' Conventionally, the piping structure of this type of tank truck was as follows.

That is, to explain with partial reference to the plan view of FIG. 1, this piping structure includes a main pipe 3 communicating with each tank chamber l via a bottom valve 2, a pump 4, and a switching valve 5. It had a discharge pipe 7 that communicated with the main pipe 3 via a branch pipe 6, and a volume increase pipe 9 that communicated the main pipe 3 and the discharge pipe 7 and was provided with a gate valve 8.

In addition, in the case of gravity discharge without using the pump 4, this increase piping 9 is connected from the tank chamber 1 to the bottom valve 2. The main pipe 3° switching valve 59 is provided to increase the amount of dangerous liquid that is normally discharged from the discharge pipe 7 via the branch pipe 6 and is small. That is, the switching valve 5 has a small opening area due to its structure, and has a large resistance to the flow of liquid, which reduces the flow rate. was provided to increase and replenish the amount of liquid discharged.

"Problems to be Solved by the Invention" By the way, the following problems have been pointed out in such conventional piping structures.

As described above, in the case of gravity discharge, the gate valve 8 of the volume increase pipe 9 is opened to discharge the dangerous liquid. If you forget to close this gate valve 8 after the fact and leave it open and pump discharge is performed by the pump 4, the following will occur.

That is, in this case, the liquid from the pump 4 enters the volume increase pipe 9 via the discharge pipe 7, passes through the gate valve 8 which remains open, flows backward through the volume increase pipe 9, and reaches the main pipe 3.

First, the liquid enters the branch pipe 6 again from the main pipe 3 and reaches the pump 4. In this way, the liquid circulates within the piping structure, making it difficult to discharge it to the outside and unload it, which has been a problem.

Secondly, as the temperature of the liquid increases as it circulates within the piping structure, strong concerns have been raised about the safety of the liquid, which is a dangerous substance.

Thirdly, if the bottom valves 2 of each tank chamber 1 are opened at the same time in the above-mentioned state, the liquid that flows backwards through the volume increase pipe 9 and reaches the main pipe 3 will be raised to a high pressure by the pump 4. As a result, the flow backs up from the bottom valve 2 to the tank chamber 1.It has also been pointed out that an accident could occur in which dangerous liquid spills out from the manhole, etc. at the top of the tank chamber 1.

In the case of pump discharge, such problems have been pointed out.

In the conventional example, such a point was pointed out.

In view of these circumstances, the present invention has been made to solve the problems of the conventional example described above, and by providing a check valve in the volume increase pipe, it is possible to avoid forgetting to close the gate valve after gravity discharge. The purpose of the present invention is to propose a piping structure for a tank truck that will reliably prevent dangerous liquid from flowing back through the volume increase piping.

"Means for Solving the Problems" The technical means of the present invention to achieve this objective are as follows.

This piping structure is for a tank truck in which the inside of the tank is divided into tank chambers, and includes the following main piping, discharge piping, and volume increase piping.

That is, the main piping is connected to each tank chamber via a bottom valve.

The discharge piping is via a branch piping equipped with a pump and a switching valve.
It is connected to the main pipe.

The increase pipe communicates the main pipe with the discharge pipe, and includes a gate valve and a check valve disposed upstream of the gate valve.

"Function" Since the piping structure of the tank lorry according to the present invention is comprised of such means, it functions as follows.

First, in the case of gravity discharge without using a pump, the gate valve of the volume increase pipe is opened and the dangerous liquid loaded in the tank chamber is discharged and unloaded.

If you forget to close this gate valve after the fact and leave it open and then the pump discharges,
It becomes as follows.

That is, since the increase pipe is provided with a check valve, backflow of liquid is reliably prevented. Therefore, in the case of pump discharge, liquid from the pump is reliably prevented from flowing backward from the discharge piping through the increase piping and reaching the main piping.

Therefore, the liquid is transferred to the main pipe between the tank chamber and the discharge pipe.

It will flow as expected through branch pipes, pumps, switching valves, etc.

"Example" The present invention will be described in detail below based on the example shown in the drawings.

First, the configuration will be explained in the order of its piping structure and the check valve used therein.

The piping structure is as follows.

FIG. 1 is a plan view showing an embodiment of a piping structure for a tank lorry according to the present invention.

The inside of the tank 11 of the tank lorry 10 is divided into tank chambers 1 by partition walls 12 along the width direction of the tank 11, and a bottom valve 2 is provided at the bottom of each tank chamber 1.

A main pipe 3 is disposed along the longitudinal direction on the outer surface of the bottom of the tank 11, and this main pipe 3 communicates with each tank chamber 1 via each bottom valve 2.

The branch pipe 6 is connected at one end to the main pipe 3, is gradually inclined downward toward the other end to form a flow path, and is bent along the longitudinal direction of the tank 11 from the middle. This branch pipe 6 is provided with a pump 4 and a switching valve 5, and the switching valve 5 is opened and closed and switched between pump discharge and gravity discharge using its operating section 13.

The discharge pipe 7 is arranged along the width direction of the tank 11,
It is connected to the other end of the branch pipe 6 near its center and communicated with the main pipe 3 via the branch pipe 6, and discharge valves 14 are provided at both ends facing both sides of the tank 11.

Further, in the illustrated example, a discharge pipe 7° is provided toward the rear side in order to enable discharge and unloading from both the left and right sides of the tank 11 as well as from the rear side. That is, this discharge pipe 7° is arranged along the longitudinal direction of the tank 11, one end thereof is connected to the above-mentioned discharge pipe 7, and the other end is located facing the rear end of the tank 11, and the discharge pipe 7° is located at the rear end of the tank 11. Valve 1
4° is provided.

The increase piping 9 is connected to the main piping 3 and the discharge piping 7.
It is provided with a gate valve 8 and a check valve 15 disposed upstream of the gate valve 8. The check valve 15 is a check valve that allows liquid to flow only from the main pipe 3 toward the discharge pipe 7 and prevents the liquid from flowing backward.

Note that the bottom valve 2. The gate valve 8 and the like are operated by an operating section such as a lever (not shown).

The piping structure is like this.

Next, the check valve 15 will be explained in detail.

FIG. 2 is a longitudinal sectional view showing this check valve 15.

The check valve 15 used here has an inlet port 16 and a discharge port 1.
7 are eccentric, and the valve seat 18 is inclined with respect to the valve body 19, such that the free end 19.7 of the valve body 19 is eccentric. There is always a gap between the two, and the casing 20 is formed to have the same diameter, so that the bottom surfaces of the casing 20 and the discharge port 17 are flush with each other.

That is, the check valve 15 has an inlet flange 21 and an outlet flange 22 fixedly installed at both ends of a casing 20 to form a valve box, and the inlet flange 21 has a circular suction port 16 and the outlet A circular discharge port 17 is formed in each side flange portion 22 . The suction port 16 and the discharge port 17 are such that the center of the suction port 16 is the discharge port 1.
It is eccentric so that it is at a higher level than the center of 7.

The valve element 19, which is attached near the upper part of the valve seat 18 so that its base end 19□ is rotatable, faces the suction port 16, and its free end 19. A gap always exists between the valve seat 18 and the lower part of the valve seat 18. That is, the valve seat 18 is slightly inclined clockwise, that is, in the opposite direction to the opening direction of the valve body 19, so that the free end 19+ side has a large gap with respect to the valve body 19 that is suspended as described above. .

The casing 20, which is the main body, has a circular cross section and the same diameter in the flow direction of the liquid, and the casing 20 and the discharge port 1
The area near the bottom of 7 is flush with no steps.

The check valve 15 has this structure.

The piping structure of the tank truck 10 according to the present invention is as described above.

The operation etc. will be explained below.

First, in the case of gravity discharge without using the pump 4, open the switching valve 5 of the branch pipe 6 to switch to gravity discharge, and open the gate valve 8 of the volume increase pipe 9 to discharge the dangerous liquid loaded into the tank chamber 1. Unloading is performed by discharging.

That is, after the liquid passes through the main pipe 3 from the tank chamber 1, it passes through the branch pipe 6 and its switching valve 5 on the one hand, and the increaser pipe 9 and its check valve 15 and gate valve 8 on the other hand, and is discharged by gravity. It reaches the pipe 7 or 7'', is discharged from its discharge valve 14 or 14°, and is unloaded.

If you forget to close the post-sluice valve 8 and leave it open and the pump 4 continues to pump,
It becomes as follows.

That is, even in this case, since the check valve 15 is provided in the volume increase pipe 9, backflow of liquid is reliably prevented. Therefore, the liquid from the pump 4 is reliably prevented from flowing backward from the discharge pipe 7 through the volume increase pipe 9 and reaching the main pipe 3.

The liquid flows from the tank chamber 1 to the branch pipe 6 and its switching valve 5. The discharge pipe 7 or 7 is sent by the pump 4 via the pump 4.
``, and is discharged from the discharge valve 14 or 14' and unloaded.

Therefore, firstly, the subsequent pump discharge can be performed reliably without any problems, secondly, the liquid will not circulate in the piping structure due to backflow and its temperature will rise, and thirdly, the temperature of each tank chamber 1 will not increase. Even when the bottom valve 2 is open, the liquid that flows back flows into the tank chamber 1 from the bottom valve 2 and does not overflow to the outside from the manhole or the like.

The subsequent unloading by pump discharge is thus performed without any problem.

The above is an explanation of the operation of this piping structure.

Note that the operation of the check valve 15 used here will be explained below.

First, a case where a conventional check valve 15' is used will be explained. FIG. 3 is a longitudinal sectional view showing a conventional check valve 15''.

This conventional check valve 15' has an inlet port 16'' and a discharge port 17° formed coaxially, and a valve seat 18° that is normally closed by being in contact with a hanging valve body 19''. in a state. That is, in the illustrated example, the valve seat 18' is inclined slightly counterclockwise from the vertical direction, that is, toward the opening direction of the valve body 19', and the valve body 19' is in contact with it without a gap at all times when no liquid flows therein. . Further, the casing 20'' is curved along the flow direction of the liquid and has a concave portion formed at its bottom, and a step exists at the boundary between the bottom surface of the casing 20'' and the discharge port 17°.

Therefore, when the conventional check valve 15'' shown in FIG.
There is a concern that residual liquid A may occur around 5°. That is, in the final stage of gravity discharge, the flow rate of the liquid decreases due to resistance, but this also weakens the force that opens the valve body 19', and finally the valve body 19' opens even though a small amount of flow still exists. The force disappears, and the valve body 19° moves to the valve seat 1.
8 degrees and the flow path will be closed.

In this way, as shown in the figure, residual liquid A is generated on the upstream side of the valve body 19'', and residual liquid A is also generated in the recess at the bottom of the casing 20'' on the downstream side of the valve body 19°. Become.

When the conventional check valve 15'' is used, there is a concern that residual liquid A may be generated near the check valve 15'' as described above.

Note that this point is not limited to the conventional swing type check valve 15° shown in Figure 3, but also plunger type and lift type.

Even if butterfly-type check valves were used, there was still a concern that similar residual liquid would occur.

Therefore, as a countermeasure, first use such a conventional check valve 15'', and install the check valve 15'' with the suction port 16'' side facing upward and the discharge port 17° side tilting downward. Conceivable. However, in this case, the mounting space above and below the volume increase pipe 9 becomes large, and the space for the entire piping structure also becomes large, and the position of the tank 11 becomes correspondingly high.

As a result, the vehicle height, that is, the center of gravity, becomes high, and running stability deteriorates, causing safety problems.

Therefore, it is difficult to adopt such measures against residual liquid A.

However, if the check valve 15 shown in FIG. 2 is used here, both the concern about the generation of residual liquid A and the space/vehicle height problems will be resolved.

That is, in this check valve 15, as described above, the valve seat 18 is inclined with respect to the valve body 19, and the free end 19 of the valve body 19.
There is always a gap between them.

Therefore, in the final stage of gravity discharge, even when the amount of liquid decreases and the force to open the valve body 19 weakens and finally disappears, the valve body 19 will not come into contact with the valve seat 18 and close the flow path. . and the free end 19 of the valve body 19. and valve seat 1
8, a small amount of liquid at the final stage also reliably flows from the suction port 16 side to the discharge port 17 side.

Moreover, the suction port 16 and the discharge port 17 are eccentric, the casing 20 is formed to have the same diameter, and the casing 20 and the discharge port 1
7 and the bottom surfaces are flush with each other. Therefore, no liquid remains and accumulates at the bottom of the casing 20.

In addition, this check valve 15 does not need to be installed with an upward and downward slope, and the installation space above and below the increase piping 9 and the entire piping structure does not become large, and problems with vehicle height, center of gravity, or driving stability are avoided. Nor.

As described above, when this check valve 15 is used in the above-mentioned volume increase pipe 9, the concerns about the generation of residual liquid A (see FIG. 3) and the problems of space and vehicle height are both resolved.

"Effects of the Invention" As explained above, the piping structure of the tank lorry according to the present invention is provided with a check valve in the volume expansion piping, so that even if the gate valve is forgotten to close after gravity discharge, the volume expansion piping becomes a hazardous material. The first step is to ensure that the liquid does not flow backwards.
There is no problem when discharging the pump afterwards, secondly, there is no circulation of liquid, and safety concerns due to temperature rise are eliminated, and thirdly, there is no possibility of an accident overflowing the liquid to the outside. , the effects that it brings are significant, such as eliminating the problems that existed in this type of conventional example.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing an embodiment of a piping structure for a tank lorry according to the present invention. FIG. 2 is a longitudinal sectional view showing the check valve. FIG. 3 is a longitudinal sectional view showing a conventional check valve. ■ Tank chamber 2 Bottom valve 3 Main piping 4 Pump 5 Switching valve 6 Branch piping 7 Discharge piping 8 Gate valve 9・Increase piping 15...Check valve z Fig. 3 15'

Claims (2)

[Claims] (1) A piping structure in a tank lorry in which the inside of the tank is divided into tank chambers, with a main piping communicating with each tank chamber via a bottom valve, and a branch piping equipped with a pump and a switching valve, A discharge pipe that communicates with the main pipe, and a volume increase pipe that communicates with the main pipe and the discharge pipe and includes a gate valve and a check valve disposed upstream of the gate valve. The piping structure of a tank truck is characterized by: (2) In the check valve, the suction port and the discharge port are eccentric, the valve seat is inclined with respect to the valve body, and a gap always exists between the valve body and the free end of the valve body, and the casing is the same. The piping structure for a tank lorry according to claim 1, characterized in that the bottom surfaces of the casing and the discharge port are flush with each other.