JPS599151Y2 - Dry backfire/backflow prevention device - Google Patents

Description

[Detailed description of the invention] The present invention relates to a dry flashback prevention device that blocks flashback in the combustible gas supply path of gas welding machines, gas cutting machines, gas reaction vessels, and other equipment using combustible gas. The purpose is to reliably block the backflow of impure gas even in a portion of a combustible gas supply path with a large flow rate.

Conventionally, impure gas generated during backfire enters the upstream chamber from the downstream chamber in the flashback prevention device main body through a breathable flame extinguisher, and the backflow pressure in the upstream chamber at that time causes the check valve at the inlet of the upstream chamber to close. It is possible to block it.

However, in this case, the backflow impure gas passes through the check valve before the check valve fully closes, and cannot be shut off.

This is noticeable in the high-pressure, large-flow combustible gas supply path that is close to the combustible gas source (cylinder or gas generator), and has the disadvantage of backflowing back into the impure gas cylinder, reducing the purity of the gas inside the cylinder. be.

Further, when used for gas welding, etc., oxygen may flow back due to the pressure difference, and there is a risk of explosion of the flammable gas source.

In order to reliably block the backflow, the present invention uses backflow pressure in this chamber to operate a valve closing device to close the check valve in the upstream chamber when backflow gas enters the downstream chamber. The check valve is stopped before the backflow gas passes from the downstream chamber through the breathable flame extinguisher and the upstream chamber and reaches the check valve.

Embodiments of the present invention will be described below with reference to the drawings.

In the figure, reference numeral 1 denotes a vertical cylindrical flashback prevention device main body, in which an upstream chamber 2 and a downstream chamber 3 are vertically arranged linearly.

The upstream chamber 2 and the downstream chamber 3 communicate with each other via a vertically cylindrical porous breathable flame extinguisher 4 made of sintered metal and placed in the middle thereof.

The flame extinguisher 4 is fixed to the main body 1 via an annular receiving screw 5 and a set screw 7 with a ventilation hole 6.

An inlet hole 9 is formed in the upper lid 8 of the upstream chamber 2, and a check valve 10 is inserted into the upper space within the upstream chamber 2.

The check valve 10 is guided up and down by the inlet hole 9, and when it falls due to its own weight as shown in FIG. 1, the valve hole 11 opens and opens, and when it is pushed up as shown in FIG. 2, the valve hole 11 closes and the rubber valve seal 12 comes into sealing contact with the valve seat 13 and the valve is in a closed state.

A locking ring 28 that can be expanded and contracted is partially protrudingly supported in the middle of the inlet hole 9 via a receiving groove 29, and a locking groove 27 that can be freely engaged and detached from the locking ring 28 is formed around the upper part of the check valve 10. engraved on the surface.

The check valve 10 is pushed up and closed by a valve closing tool 15 via a rod 14.

The valve closing tool 15 is inserted into the downstream chamber 3 so as to be able to rise and fall, and when it falls under its own weight, it rests on the flashback injection port 16, and when it is pushed up, it comes into close contact with the flashback cutoff port 17.

The flashback blocking port 17 is formed on the lower surface of the center hole of the receiving screw 5,
The flashback injection port 16 is an outlet hole 1 formed in the bottom cover 18 of the downstream chamber 3.
9, and exit hole inlets 19a are radially opened in the upper peripheral wall of the exit hole 19.

The rod 14 is integrally extended upward from the valve closing tool 15,
In addition, it is fitted into a long sliding hole 20 formed in the center of the set screw 7 in an airtight manner so as to be slidable up and down.

This airtightness is achieved by the combination of the O-ring 21 and the fact that the fitting gap is very small and the ventilation resistance is very large.

A breakable safety valve 22 is connected to the side wall of the downstream chamber 3,
This is because the seal breaking plate 23 is connected to the valve box 24 and the pusher 25 by the push screw 26.
The support is fixed by the force of.

Next, its effect will be explained.

FIG. 1 shows the forward flow action of combustible gas.

The combustible gas G enters through the inlet hole 9, passes through the check valve hole 11, the upstream chamber 2, the flame extinguisher 4, the flashback cutoff port 17, the downstream chamber 3, and the outlet hole inlet 19a, and exits from the outlet hole 19.

FIG. 2 shows the blocking effect of the back flame F.

The backfire flame F is injected from the outlet hole 19, and when it is injected into the downstream chamber 3 from the backfire injection port 16, the backfire flame F instantly launches the valve closing tool 15 like a bullet with the pressure of the jet, and the valve closing tool 15 Backfire shutoff port 1
At the same time, the check valve 10 is closed via the rod 14.
Enter the downstream chamber 3 while pushing up and closing the valve.

If the backfire flame F and the impure gas such as CO2 generated by it are strong, it may pass through the backfire cutoff port 17 from the downstream chamber 3 faster than the valve closing tool 15 can close the backfire cutoff port 17. .

In this case, the backfire flame F is extinguished by the flame extinguisher 4, but the backflow impure gas is subjected to back pressure due to the ventilation resistance of the flame extinguisher 4.
It flows backward through the upper space in the downstream chamber 3, the flame extinguisher 4, and the upstream chamber 2 at a relatively slow speed, and reaches the check valve 10.

In this way, the backflow impure gas flows from the downstream chamber 3 to the check valve 1.
It takes time to reach 0, and during that time the check valve 10
The valve is completely closed, completely blocking any further backfire.

At this time, flashback pressure rises abnormally rapidly within the main body 1, and the sealing plate 23 of the safety valve 22 ruptures, allowing the abnormal pressure to escape from there.

When the check valve 10 is pushed up and closed, the locking groove 27 is locked by the locking ring 28, and the check valve 10 is held in the closed state.

When the check valve 10 is pushed down from the inlet hole 9 with the valve opening rod, it is separated from the locking ring 28 and returned to the open state.

Note that FIG. 3 shows a modification of the above embodiment, in which the check valve 10 is lightly biased to close by a weak spring 30.

The present invention is constructed and operated as described above, and the check valve starts to be closed by the valve closing tool when oxygen or CO2 generated by backfire or other backflow impure gas enters the downstream chamber, and the backflow is stopped. The impure gas flows from the downstream chamber through the flame extinguisher and the upstream chamber at a relatively slow speed while being subjected to ventilation resistance, and the check valve is completely closed before reaching the check valve. Therefore, the backflow can be completely blocked.

In addition, the valve closing device operates in response to backflow pressure and closes the backfire cutoff port, which is located closer to the appliance than the flame extinguisher, so that the Since carbon particles are less likely to adhere to the flame extinguisher and the flame extinguisher has less flow resistance when reused, it can be reused without requiring readjustment work.

As a result, even when used in a combustible gas passage with high pressure and large flow rate near a combustible gas source, backflow can be definitely blocked.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention; FIG. 1 is a longitudinal sectional front view in a combustible gas forward flow state, FIG. 2 is a longitudinal sectional front view in a flashback cutoff state, and FIG. 3 is a longitudinal sectional front view of the main part of another embodiment. It is a diagram. 1...Flashback preventer body, 2...Upstream chamber, 3...Downstream chamber, 4...Flame extinguisher, 10
...Check valve, 14... Rod, 15.
... Valve closing tool, 17 ... Backfire shutoff port.

Claims (2)

[Scope of utility model registration request] 1. An upstream chamber 2 and a downstream chamber 3 are formed in the flashback prevention device main body 1, the upstream chamber 2 and the downstream chamber 3 are communicated via a breathable flame extinguisher 4, and a check valve 10 is attached to the upstream chamber. A valve closing device 15 that closes the check valve 10 in response to backfire pressure is attached to the downstream chamber 3, and a flashback cutoff port 17 formed in the middle of the downstream chamber 3 is closed by the valve closing device 15. A dry backfire/backflow prevention device characterized in that it is configured to close when a fire closing valve is activated. 2. In the dry backfire/backflow prevention device described in Claim 1 of the Utility Model Registration Claim, an upstream chamber 2 and a downstream chamber 3 are arranged in a straight line, and a breathable flame extinguisher 4 is provided in the middle thereof.
A valve closing tool 15 and a check valve 10 are connected by a rod 14 which passes through the flame extinguishing tool 4 in an airtight slidable manner.