JP2502841Y2 - Micro flow rate detector - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a minute flow rate detection device used for pipe leak detection such as equipment for supplying gas to each home from a collective supply device composed of a plurality of LP gas cylinders Is.

[Conventional technology]

There is known a device in which an orifice is provided in a main pipe forming a gas flow passage and a gas flow rate is detected by a pressure loss generated in this portion.

[Problems to be solved by the device]

In the detection device as described above, when the pipe diameter of the main pipe becomes large, the pressure loss at the minute flow rate becomes small, and the detection accuracy decreases.

In this case, in order to improve the detection accuracy, it is sufficient to reduce the diameter of the orifice, but if this is done, the pressure loss at the time of a large flow rate becomes too large and the gas cannot be supplied at a constant pressure.

An object of this invention is to detect a minute flow rate with high accuracy regardless of the gas flow rate in the main pipeline.

[Means for solving the problem]

In order to solve the above-mentioned problems, the present invention provides a pressure regulator provided in a main pipeline through which a large amount of gas is provided with a small flow-rate bypass pipeline, and the bypass pipeline is provided with an orifice and an outlet from the pressure regulator. A small pressure regulator on the downstream side of the orifice in which the pressure is set a little higher is provided, and a pressure sensor is further provided in the bypass pipe line to output a signal when the differential pressure before and after the orifice becomes close to zero. I did.

[Action]

The present invention is configured as described above, and since the outlet pressure of the small pressure regulator is set to be slightly higher than the outlet pressure of the pressure regulator of the main pipeline, a large amount of gas that flows through the main pipeline is reduced. The part always flows through the bypass line.

Also, even if the gas flow in the main pipeline decreases and the gas stops flowing through the pressure regulator, the small pressure regulator has its outlet pressure set a little higher, so no gas flows in the bypass pipeline. Since the flow path and its bypass line have a small flow rate, the pressure loss at the orifice is large, and the gas flow rate is close to zero and at the same time the pressure loss is close to zero. The presence or absence of is detected.

〔Example〕

In the embodiment shown in FIG. 1, reference numeral 1 is a collective supply device comprising a plurality of LP gas cylinders 2 and an automatic switching regulator _{3 in} which a plurality of pressure regulators R ₁ , R ₂ and R ₃ are combined.

Reference numeral 4 is a main pipeline of the collective supply apparatus 1, and the tip thereof is a pipeline branched into a plurality of pipelines leading to each home (not shown).

In the case of the embodiment shown in FIG. 1, the secondary pressure regulator R ₃ is connected to the main pipeline 4.
Bypass line 5 for bypassing is provided, an orifice 6 and a small pressure regulator 7 are provided in this pipeline 5, and the outlet pressure thereof is set to be slightly higher than the outlet pressure of the pressure regulator R ₃ ,
When the gas flows through the main pipeline 4, the gas always flows through the bypass pipeline 5.

If the inlet pressure of the pressure regulator R ₃ fluctuates, a small pressure regulator 8 is added.

Reference numeral 10 is a detection pipeline connected to the bypass pipeline 5, and this pipeline is
A pressure sensor (11) is connected to (10), and a display section (12) operated by the pressure sensor (11) is provided.

This embodiment is configured as described above, and now, the gas cylinder 2
From the pressure regulators R ₁ and R ₂ to the gas of pressure P ₁ is supplied to the pressure regulator R ₃ and the upstream side of the orifice 6, and the pressure on the downstream side of the orifice 6 is P _2. When a large amount of gas is flowing inside (when normal gas is used), P ₂ becomes equal to the set pressure of the pressure regulator R ₃ . At this time, the outlet pressure of the small pressure regulator 7 is higher than the outlet pressure of the pressure regulator R ₃ , so that the gas always flows in the bypass line 5.

Next, when the gas is no longer used, P ₂ gradually rises,
It becomes higher than the set pressure of the pressure regulator R _3, a pressure regulator R ₃
The gas stops flowing into. On the other hand, since the outlet pressure of the small pressure regulator 7 is set to be slightly higher than the outlet pressure of the pressure regulator R ₃ , gas continues to flow in the small pressure regulator 7 (bypass line 5), and P ₂ is When the pressure becomes higher than the set pressure, the gas does not flow to the small pressure regulator 7, and the gas flow in the bypass pipe 5 stops.

As described above, the gas flow occurs in the bypass pipe line 5 not only when the gas flows in the pressure regulator R ₃ , but also when the gas stops flowing. Therefore, since the bypass pipe line 5 has a small flow rate, its flow appears at least significantly,
The orifice 6 causes a significant pressure loss (P ₁ > P ₂ ).

Here, the gas flow continues to occur only in the bypass pipeline 5 when the main pipeline 4 normally leaks. That is, even if the gas is no longer used and a large amount of gas flow in the main pipeline 4 is stopped, if gas leakage occurs, the amount of leakage is usually extremely small compared to the large flow rate in the main pipeline 4, so the main pipeline There is no significant effect on the pressure of the main line 4
The gas pressure P ₂ reaches the set pressure of the pressure regulator R _3, gas flow pressure regulator R ₃ is stopped. For this reason, the gas flow due to the leakage occurs only in the bypass pipe line 5, and since the bypass pipe line 5 has a small flow rate, a remarkable pressure loss is caused by the orifice 6 even with the minute flow.
That is, even a minute flow in the entire main pipeline 4 causes a significant pressure loss (P ₁ > P ₂ ) in the bypass pipeline 5.

Further, leakage of about 3 liters / hour is allowed under the legal regulation of gas, and a flow of such a degree (flow near zero) does not cause a significant pressure difference in the orifice 6. Therefore, when the operating pressure of the pressure sensor 11 keep the P _1, for the detection line pressure acting on the pressure sensor 11 from 10 is lower P ₂ than P ₁ while the gas is flowing, the pressure sensor 11 does not operate But,
When the gas flow in the main pipe line 4 becomes close to zero or stops, the differential pressure before and after the orifice 6 disappears and P ₁ = P ₂ , and the pressure sensor 11 operates and the gas flow on the display unit 12 becomes zero. Near or stopped is displayed. In this way, the pressure sensor 11 reliably detects a minute flow in the main conduit 4 such as a gas leak, indicating that it is near zero or has stopped.

FIG. 4 shows an example in which a lamp 13 is used in the display unit, a pressure switch 14 that closes the circuit at pressure P ₁ is used as a pressure sensor, and the pressure switch 14 is inserted in the power supply circuit 15 of the lamp 13. In this case, the main pipeline 4 When the gas flow inside becomes close to zero or stops, the switch 14 is closed and the lamp 13 is turned on.

FIG. 2 shows an example in which the differential pressure type pressure sensor 17 is used. In this case, the detection pipe lines 18 and 19 branched from the front and rear of the orifice 6 are connected to the sensor 17.

In this case, a differential pressure switch 20 is used as a differential pressure type pressure sensor as shown in FIG. 5, and this switch 20 is inserted into the power supply circuit 15 of the lamp 13 as a display section.

Also in the case of the above embodiment, when the gas is flowing through the main pipeline 4, the differential pressure switch 20 is opened by the differential pressure on both sides of the orifice 6 and the lamp 13 is extinguished, but the gas flow in the main pipeline 4 becomes close to zero. When stopped, the pressures on both sides of the orifice 6 become equal, the differential pressure switch 20 is closed and the lamp 13 is turned on.

Further, as shown in FIG. 3, a bypass conduit 21 for short-circuiting the primary pressure regulators R ₁ and R ₂ may be provided, and the bypass conduit 21 and the main conduit 4 may be connected by the bypass conduit 5. Also in this case, the other circuit configuration is the same as that shown in FIG.

[Effect of device]

This invention is to provide a small flow rate bypass pipe bypassing a pressure regulator provided in a main pipe through which a large amount of gas flows, and a small pressure regulator in which the outlet pressure is set to be slightly higher than the pressure regulator in the bypass pipeline. Since the presence and absence of a pressure loss and a differential pressure between the container and the orifice are detected, the orifice diameter can be reduced regardless of the large diameter of the main pipeline and the large flow rate.

[Brief description of drawings]

1 to 5 are circuit diagrams showing respective embodiments of the minute flow rate detecting device according to the present invention. 1 ... Collective supply device, 2 ... LP gas cylinder, 3 ... Automatic switching regulator, 4 ... Main pipeline, 6 ... Orifice, 7, 8
...... Small pressure regulator, 10 ...... Detection line, 11 ...... Pressure sensor, 12 ...... Display, 17 ...... Differential pressure type pressure sensor, R ₁ , R ₂ ,
R ₃ …… Pressure regulator.

Claims (1)

(57) [Scope of utility model registration request] 1. A pressure regulator provided in a main pipeline through which a large amount of gas is provided with a small flow rate bypass pipeline, and an orifice and an orifice in which an outlet pressure is set to be slightly higher than the orifice in this bypass pipeline. A small flow rate detecting device in which a small pressure regulator on the downstream side is provided, and a pressure sensor is further provided in the bypass conduit to output a signal when the differential pressure before and after the orifice becomes close to zero.