JPS5829864B2 - Bourdon tube pressure gauge safety device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a technology for improving the safety of, for example, primary side pressure gauges of pressure regulators and other Bourdon tube pressure gauges used for measuring fluid pressure in various fluid pipelines.

For example, when taking out oxygen, etc. from a high-pressure cylinder by dropping it to the desired pressure by 1, the container valve must be opened gradually in accordance with the regulations, but even so, the high-pressure fluid may suddenly flow out due to the large diameter of the valve. However, when the pulp is opened, a large pressure is momentarily applied to the high-pressure side pressure gauge of the pressure regulator, and the Bourdon tube inside the pressure gauge may be damaged.

Moreover, since the valve opening operation for container pulp tends to be quick, the actual risk is even higher, and if the valve is opened rapidly due to such use, it will directly lead to a breakage accident of the Bourdon tube. Easy and extremely dangerous.

Also, for example, backfire may occur during welding work and abnormal pressure is applied to the oxygen or acetylene pipeline, or the downstream pipeline may be blocked due to the pipeline being bent or being trampled by a heavy object. There is also a risk that a similar Bourdon tube breakage accident will occur if the fluid pressure in the pipeline increases abnormally.

For this reason, as illustrated in FIG. 4, consideration was given to buffering the introduction pressure when the container valve is opened by constricting the starting end of the pressure fluid introduction path 06 of the Bourdon tube pressure gauge 05A and screwing a so-called insect 07. However, there is a limit to the cross-sectional area of the constricted part formed in the insect 07 due to the manufacturing process, and in practice, it is only possible to create a through hole with a diameter of 0.1 m. Because of this, its pressure buffering effect is as described below.
This is insignificant compared to the case where the cylinder is not inserted, and it is not only insufficient as a measure to prevent damage to the Bourdon tube, but even if such measures are taken, in the unlikely event that the cylinder falls over or If the Bourdon tube were to be destroyed by colliding with an object, a large amount of gas would not be ejected from the broken point, and this aspect of safety was not taken into account.

The safety device for the Bourdon tube pressure gauge according to the present invention was developed in view of the above-mentioned circumstances. The pressure fluid introduction path 6 to the Bourdon tube is temporarily blocked due to the generation of a pressure difference between When the blockage state is released and a pressure difference occurs due to a pressure drop on the negative side, the pressure fluid introduction path 6
This feature is characterized in that a valve body 7 configured to open the valve is inserted.

Therefore, there is no need to create or process the pressure fluid introduction channel to be extremely narrow, and it is possible to open the pulp, or when abnormal high pressure fluid flows into the pipeline due to some unknown reason while using pressure fluid. The pressure difference between the front and rear of the valve plugs the valve plug and narrows it into a tiny flow path, and the pressure fluid gradually flows into the Fulton tube, exerting a remarkable pressure buffering effect, reducing the instantaneous pressure. This prevents damage to the Bourdon tube due to rising, and even if the Bourdon tube is destroyed due to an external cause such as contact with another object, the valve body will be closed due to the pressure difference, and fluid will not flow from the broken point. It functions as a safety valve that suppresses eruptions, ensuring safety.

In addition, if the pressure in front and behind the valve body is equalized due to fluid inflow through the minute gap in the closed state, the closed state due to the pressure difference will be released and the valve body will return to the open position, or at least the closed state will be released. Since the biasing force holding the tube in its position is released, the pressure fluid inside the Bourdon tube can be quickly released when the pulp is clogged or when the cause of abnormal pressure rise is removed.

EMBODIMENT OF THE INVENTION Hereinafter, an embodiment in which the present invention is applied to a high-pressure side pressure gauge of a pressure regulator for a high-pressure gas container will be described based on the drawings.

Figure 1 shows an example of a pressure regulator, with reference numeral 1 being a handle for mounting on a pressure vessel such as an oxygen cylinder, and reference numeral 2 being a handle for adjusting pressure.
・3 is a handle for opening and closing the pulp container (not shown), 4 is a pressure fluid outlet, 5A is a Bourdon tube pressure gauge communicating with the high pressure side of the pressure regulator, and 5B is a Bourdon tube pressure communicating with the low pressure side. It is a total.

In this embodiment, the above-mentioned pressure gauge 5A is installed in the branch flow path of the pressure regulator main body, which is an example of the branch pipe 9, to generate a pressure difference between the primary side and the secondary side as the pressure of the downstream fluid increases. Pressure fluid is guided to the Bourdon tube by pressing against the end face of the pressure fluid introduction passage 6 to temporarily close this introduction passage 6, and through a minute gap formed between the pressure fluid introduction passage 6 and the end face in this closed state. The safety device is constructed by interposing a valve body 7 configured to release the closed state by eliminating the differential pressure as pressure fluid flows in.

(8) is a filter.

According to the above embodiment, when the pressure regulator is installed with the pointer of the pressure gauge 5A facing upward, by opening the container pulp, as shown in FIGS. 2(a) and 2(b),
The valve body I is pushed up and comes into close contact with the periphery of the starting end of the pressure fluid introduction path 6 and closes the pressure fluid introduction path 6, so that the pressure fluid is prevented from flowing into the Bourdon tube side.

However, in general machining, a minute gap is always formed between the starting end surface of the pressure fluid introduction path 6 and the upper surface of the valve body I, so the pressure fluid flows through this minute gap. It gradually flows in and slowly raises the pointer of the pressure gauge 5A, and when the pressure inside and outside of the valve body 7 is equalized and the pointer of the pressure gauge 5A remains stationary at a predetermined value, it falls due to its own weight as shown in Figure 2. .

When the pulp container is closed after finishing the work, if the pressure gauge has the insect 07 inserted as shown in Figure 3, the flow path is constricted, which prevents the release of the pressure fluid inside the pressure gauge. However, in the case of this embodiment, since the valve body 7 has fallen due to its own weight, when the container pulp is closed, the return of the pressure gauge pointer to the zero point is delayed. , pressure gauge 5A
The pressure fluid inside is quickly discharged to the outside through the filter 8, and the pointer of the pressure gauge 5A instantly returns to the zero point.

Even if the pointer is installed with the pointer facing downward, when the pressure inside and outside of the valve body 7 is equalized, the valve body 7 is pressed against the starting end surface of the pressure fluid introduction path 6 by the pressure fluid. Since the pressure gauge 5A is in a free state, the pointer of the pressure gauge 5A instantly returns to zero due to the above-mentioned blockage of the container pulp.

Incidentally, according to the experimental results, as shown in Fig. 4, the insect 07 is not allowed to enter the pressure fluid introduction path 6 during the time required from the time when the container valve is opened until the pointer of the pressure gauge 5A indicates the pressure value inside the container. The case is 0.29 seconds, and the case when inserting the insect 07 with a figure-7 shaped flow path (A in Figure 4) is 0.305 seconds.
0.347 seconds for Insect 07 with an L-shaped constricted flow path (mouth in Figure 4), and Insect 0 with a straight constricted flow path.
In the case of No. 7 (C in Figure 4), it is 0.29 seconds, and in the case of Insect 07 without a hole that forms a throttle flow path in the surrounding thread groove (2 in Figure 4), it is 0.51 seconds. On the other hand, in the case of the valve body 7 of this embodiment, the time is about 1 to 30 seconds, which shows that the pressure buffering effect is dramatically increased.

This will be explained using the diagram in FIG. 5, taking as an example the case where it is used in a pressure regulator for a high-pressure gas container.

The pressure inside the Bourdon tube (secondary side pressure) increases from zero to 1 (minus side pressure) by opening the container valve.

This required time α) is plotted above the vertical axis.

The opening speed of the container valve is plotted on the right side of the horizontal axis.

This is the valve opening degree (cross-sectional area S
), it becomes ds/at.

And the cross-sectional area of the pressure fluid introduction path to the Bourdon tube is (s)
Then, with (s) as a parameter, the curve l□, 12・
・is determined experimentally.

In this case, (S) is a dog for l than for 12.

On the other hand, if the probability (frequency) of the opening speed (d8/dt) when an operator opens a container valve is plotted below the vertical axis, it can be seen that it becomes a curve O).

Also, if the pressure inside the Bourdon tube increases over a period of time σ), the rate at which the Bourdon tube breaks is plotted on the left side of the horizontal axis.
For new products, the curve becomes b0, and as the number of uses increases, the curve becomes b2. b3 and the curve move to the left.

In this way, for example, if the guarantee condition is a% breakage after 10,000 uses, the breakage rate will be this for a pressure rise time of T=L or less (time for the pointer to reach the primary side pressure value). It turns out that the above is the case.

In actual use of the pressure gauge, there is a time T = U at which if the pressure rise time is longer than this, it will take too much time and is not desirable, so an appropriate pressure rise time ( One naturally sets U<T<L.

On the other hand, from curve 0, we can see that a very common valve opening speed is (S
) and Rinma.

From the above, the safety conditions for obtaining a pressure rise time with almost no damage to the Bourdon tube with a general valve opening operation are as follows: ([1), (L) and (S), fQ), respectively. Since the intersection H, ), (B), (E), Q)) is within the range, the curve 11s 12 ... is S) and (A)
, (C) and the line (Q).

For this purpose, by reducing (s), the curve 11p132・
The conventional way of thinking is to raise the ... upward, but as mentioned at the beginning, this is extremely difficult due to processing limitations.

On the other hand, in the device to which the present invention is applied, the shape and size of the valve body 7, the area receiving the pressure of the pressure fluid, and the mounting of the pressure gauge (which affects the gap area between the inner wall of the branch pipe and the outer edge of the valve body) are used as parameters to create a curve. l'□, l! /2... is determined experimentally.

In other words, if the valve opening speed is constant, the pressure increase speed can be changed arbitrarily by changing the shape and size of the valve body.

That is, as described above, in the device to which the present invention is applied, after the pressure fluid introduction path 6 is once closed by the valve body 7, the minute gap existing between the starting end surface of the introduction path 6 and the upper surface of the valve body 7 is closed. In addition, the pressure gauge is installed so that the pressure fluid gradually flows in through the valve body 7, and the gap between the inner wall of the branch pipe 9 and the outer edge of the valve body 7 and the area of the lower surface of the valve body I are also determined depending on the closing speed of the valve body 7 and the area of the valve body 7. It is possible to adjust the pressure rise time depending on the shape and size of the valve body T.

As is clear from the figure, in the device according to the invention, curve 11. , l/2... is linear compensation) and (4), (0,
The line 0 easily connects the intersection between (l, 0).

In other words, common valve opening operations are sufficient to maintain safety;
The pressure rise time can be set to an appropriate time (1 to several seconds).

If a dangerous operation such as suddenly opening the valve is performed, the valve body 7 will instantly block the pressure fluid introduction path 6, and the pressure rise time will be extremely short.
0. It corresponds to the part far above the line height of l/2..., and functions as a kind of safety shutoff valve.

In such a case, once the valve is closed and then opened again at an appropriate opening speed, work can be continued without any problem.

Of course, even when abnormal pressure is applied to the pressure gauge of the fluid pipeline, the pressure fluid introduction channel can be instantly blocked and damage to the Bourdon tube can be prevented.

As for the shape of the valve body 7, in addition to the disk shape shown in the figure with a protrusion in the center, various shapes such as a conical shape, a spherical shape, or a simple disk shape (short cylindrical shape) are used. be able to.

In the valve body 7 having these shapes, the central protrusion and the apex of the cone serve as a guide to make the valve body 7 and the introduction path 6 substantially concentric when the pressure fluid introduction path 6 is closed. It fulfills the following.

In order to quickly release the pressure fluid in the Bourdon tube to the outside and return the pointer to zero when the valve is closed, there is a gap between the lower surface of the valve body 7 and the surface of the seat in the branch tube where the pressure gauge is mounted. Various means can be considered, such as providing grooves or protrusions, or interposing a breathable substance such as a filter as shown in the figure.

). The valve body 7 is pressed against the starting end surface of the pressure fluid introduction path 6 and closes the introduction path 6 while the pressure on the negative side is higher than the pressure on the secondary side, that is, while there is a differential pressure. When the pressure reaches an equal pressure state, the pressing force disappears, and the active blocking state is released.

In this case, if the pressure gauge is installed with the pointer facing upward, the valve body 7 will fall under its own weight and open the pressure fluid introduction path wide, as described above, but if the pointer turns sideways,
If the pressure fluid introduction path is lowered, even if the closed state is released, the pressure fluid introduction path will not be opened to a large extent.

Therefore, for example, by interposing a spring between the starting end surface of the pressure fluid introduction path 6 and the upper surface of the valve body 7, it is kept open at all times, and when a differential pressure occurs between the negative side and the secondary side. The valve body 7 may be configured to close the pressure fluid introduction path 6 only in this case.

This spring also serves as the guide.

[Brief explanation of the drawing]

The drawings illustrate an embodiment of the safety device for a Bourdon tube pressure gauge according to the present invention, and FIG. 1 is a plan view of a pressure regulator for a container;
Figures 2A to 2C are longitudinal sectional views of the main parts, Figure 3 is a vertical sectional view showing the conventional example, Figure 4A to 2 are sectional views illustrating the shape of an insect, and Figure 5 is the function of the present invention. This is a diagram showing. 6... Pressure fluid introduction path, 7... Valve body,
9...Bourdon tube pressure installation is a branch pipe.

Claims (1)

[Claims] 1. The Bourdon tube pressure gauge is installed in the branch pipe 9 by temporarily blocking the pressure fluid introduction path 6 to the Bourdon tube due to the generation of a pressure difference between the primary side and the secondary side due to the rise in the pressure of the downstream side fluid. One,
In this blocked state, the differential pressure is eliminated as the pressure fluid flows in through the minute interval, thereby releasing the blocked state, and when a differential pressure occurs due to a pressure drop on the next side, the pressure fluid introduction path 6 is opened. 1. A safety device for a Bourdon tube pressure gauge, characterized in that it is equipped with a valve body I configured to do so.