JPS63111462A - Gas mixer - Google Patents

Abstract

PURPOSE:To obtain two kinds of gaseous mixtures which are stable in component concn. by providing pressure decreasing pipes consisting of capillary resistance pipes between secondary pressure reducing valves respectively for gaseous carbon dioxide and air and flow dividers or between the flow dividers and gaseous mixture outlets. CONSTITUTION:The gaseous carbon dioxide from a carbon dioxide supply source 1 is fed through a solenoid valve 2, the pressure reducing valve 3 and the pressure decreasing pipe 4 to the flow dividers 6, 7. The air from a pressurized air source 11 is fed through the solenoid valve 12, the pressure reducing valve 13 and the pressure decreasing pipe 14 to the flow dividers 16, 17. The gas and the air are mixed at confluent points 8, 18 and are outputted as two kinds of the gases having different concns. from the gaseous mixture outlets 9, 19. The pipes 4, 14 are constituted of the capillary resistance pipes. The pressure of a branch point 5 is introduced as a pilot pressure to the pressure reducing valve 13 and the pressure at the branch point 15 changes in proportion to the pressure change at the point 15. Then, the secondary pressures of the valves 3, 13 are stabilized and the mixing concn. is stabilized.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a gas mixing device, and particularly to a gas mixing device suitable for producing a mixed gas of carbon dioxide and air used in a blood gas analyzer. It is.

[Conventional technology]

In a blood gas analyzer, it is necessary to manufacture two or more types of aqueous solutions with known carbon dioxide gas and oxygen partial pressures as calibration standard solutions within the device. This generally involves carbon dioxide gas of known composition filled in a cylinder.

A mixed gas of oxygen and nitrogen is used to saturate the aqueous solution. U.S. Patent No. 3,464,434 (hereinafter simply referred to as a known example) improves this point and discloses a gas mixing device that supplies carbon dioxide gas in a pure gas state from a gas cylinder, and uses air to create a mixed gas for oxygen and nitrogen. The feature of the above-mentioned known example is that it uses a relief type differential pressure pressure control valve, and by releasing the air pressure that has become higher than the pressure of carbon dioxide to the atmosphere through the relief boat, both pressures can be adjusted. are made equal. In other words, air is higher than atmospheric pressure.
, is supplied at a high pressure of about 1 kgf/ci.

[Problem that the invention seeks to solve]

Operating at such a low pressure has the following problems. First, the carbon dioxide gas in the cylinder (about 65% at room temperature)
It is necessary to reduce the pressure (which is liquefied at a pressure of kgf/a#) to about 0.1 kgf/cd using cage pressure with a stability of 1% or less, which cannot be achieved with a commercially available pressure reducing valve, so a special pressure reducing valve is required.・Secondly,
The mixture of low-pressure carbon dioxide gas and air results in a pulsating flow state, and the concentration of, for example, carbon dioxide gas in the mixed gas fluctuates by several percent over a period of several minutes. Thirdly, the external shape is complex, and the assembly of parts requires repeated steps, resulting in high assembly costs.

The purpose of the present invention is to use a general commercially available pressure reducing valve.

An object of the present invention is to provide a gas mixing device capable of obtaining a mixed gas whose component concentration is stable.

[Means for solving problems]

The above purpose is to produce two types of mixed gases with different concentrations of carbon dioxide gas from carbon dioxide gas filled in a cylinder and air in the atmosphere. This is achieved by providing a step-down tube made of a capillary resistance tube between the mixed gas outlet.

[Effect]

In general commercially available pressure reducing valves, when the secondary pressure is made low, the stability of the secondary pressure fluctuates by several percent over a period of several minutes.

Since the set value of the secondary pressure fluctuates when the operation and stop are repeated, the secondary pressure is set high and a pressure reducing valve using a welded metal bellows with a low elastic modulus is used to increase the secondary pressure. The pressure was lowered by a step-down tube consisting of

〔Example〕

The present invention will be explained in detail below using the embodiments shown in FIGS. 1 to 10.

FIG. 1 is a flow path diagram showing an embodiment of the gas mixing device of the present invention. In Fig. 1, 1 is a carbon dioxide gas supply source whose pressure is lowered to a gauge pressure of 2±0.2 kgf/- by a primary pressure reducing valve from a carbon dioxide gas cylinder, 2 is a solenoid valve for opening and closing the flow path, and 3 is a 2 gas supply source whose details will be described later. The next pressure reducing valve, 4 is a step down pipe consisting of a capillary resistance tube, 5
is a branch point, and 6°7 is a flow divider 1. For example, at the confluence point 8, carbon dioxide gas is flowed at a flow rate of 1 mQ/win through the flow divider 6. At the confluence point 18, carbon dioxide gas is supplied at a flow rate of 2 mΩ/win through the flow divider 7. +oin
It is set to flow at a flow rate of . 11 is 0.5±0
, an air pressure source regulated to 1 kgf/ci, 12 a solenoid valve for opening and closing the flow, 13 a secondary pressure reducing valve whose details will be described later, 14 a step-down pipe made of a capillary resistance tube, 15 a branch point,
16 and 17 are flow dividers, for example, flow divider 1 is installed at 1 confluence point 8.
6, air is flowed at a flow rate of 17.11 mQ/lll1n, and air is flowed at a flow rate of 16.05 m1 at the confluence point 18 through a flow divider 17.
It is set to flow at a flow rate of 2/win. 9 is an outlet for mixed gas No. 1, and 19 is an outlet for mixed gas No. 2. 10 is a pilot pressure conduit that transmits the pressure at branch point 5 to pressure reducing valve 13, and controls the opening amount of pressure reducing valve 13 so that the pressure at branch point 15 changes in proportion to the change in pressure at branch point 5. It's like this. 20 is a pressure switch which emits an electric signal when the air pressure drops below 0.4 kgf/ffl.

FIG. 2 is a flow rate diagram showing another embodiment of the present invention, which differs from FIG. Step-down tube 24
．． There is a certain point in providing 25.

FIG. 3 is a configuration diagram showing one embodiment of the secondary pressure reducing valve 3 of FIG. 1. 31 is the valve seat, and 32 is the primary pressure input.

33 is a primary pressure outlet, 34 is a movable valve, and the center portion of the upper base of a metal welded bellows 36 is fixed via a shaft 35 fixed to the movable valve 34. The other end of the bellows 36 is fixed to the valve seat 31. A bonnet 3 has a spring 37 disposed above the bellows 36 and has one end fixed to the valve seat 31.
The valve is compressed by an adjusting screw 38 screwed into a screw hole provided at the top of the valve 9, and by adjusting the gap between the valve seat 31 and the movable valve 34, the secondary pressure is kept constant with respect to the primary pressure. There is.

FIG. 4 is a block diagram showing an embodiment of the secondary pressure reducing valve 13 shown in FIG. The parts that differ from Fig. 3 are the spring 37 in Fig. 3;
Instead of the adjusting screw 38, a pilot boat 40 is provided on the bonnet 39, and depending on the range of the primary pressure 22 secondary pressure, the spring 41 is placed between the valve seat 31 and the upper bottom of the bellows 36.
The point is that it is arranged around 35.

FIG. 5 is a block diagram showing another embodiment of the secondary pressure reducing valve 13 shown in FIG. A relief boat 4 is attached to the upper bottom of the bellows 36.
When the relative relationship with -4+11135 breaks down, that is, when the secondary pressure instantly increases,
Air is discharged from the relief boat 42 to the outside through a hole 44 in a link 43 and an exhaust port 45 in a bonnet 39.

46 is another bellows, which is connected to bellows 3 by link 43.
It is fixed to the upper base of 6 and moves up and down at the same time. Pilot pressure from the pilot boat 40 is transmitted to the bellows 36 via the link 43.

FIG. 6 is an assembly diagram showing an embodiment of the gas mixing device of the present invention, in which (a) is a plan view and (b) is a side view. 50 is a base body, and the base body 50 is equipped with a secondary pressure reducing valve 3°13, a VI & pressure pipe 4,
14, Flow divider 6, 7, 16° 17, Mixed gas outlet 9, 1
9. Pressure switch 20 is assembled. Entrances and exits to these parts, branching points 5 and 15, and merging points 8 and 1B are drilled, and unnecessary portions of these machined holes are sealed with blind plugs 51.

The pressure reducing valve 3.13 is connected to the base body 5 by a stopper 54 and a screw 55.
The primary pressure side of the pressure reducing valve 3 is airtightly connected to the solenoid valve 2 with an adapter. The solenoid valve 2 is connected to the adapter 58 with a screw 59, the adapter 58 is connected to the holding plate 56 with a screw 60, and the holding plate 56 is connected to the base 50 and the stopper 5 with a screw 57.
4 is the installation. The same applies to the pressure reducing valve 13.

7 to 9 are enlarged detailed cross-sectional views showing one embodiment of the connecting portion of the flow path in FIG. 6. FIG. Figure 7 shows 1 of pressure reducing valve 3.
This is the connection on the next pressure side. Adapter 58 has union 1'
is screwed in, and is held airtight by a gasket 62. On the other hand.

The two-way solenoid valve 2 is also mounted pressure-tight with screws 59 using 61 as a gasket. The flow path from union 1' is 2
It reaches the pressure reducing valve 3 via the solenoid valve 2.

The primary side of the pressure reducing valve 3 is hermetically sealed by an O-ring 73 held by a guide 72 via a filter 71 made of sintered metal. FIG. 8 shows the secondary side of the pressure reducing valve 3 and the base body 50.
This is the connection part. O-ring 75 held by guide 74
6 shows the connection of the inlet of the flow divider (capillary resistance tube) 7 to the base body 50. A filter 76 made of sintered gold (t7) is attached to the base body 5o with an O ring 81. The flow divider 7 is airtightly fixed to the screw 77 with a 0 ring 80. The outlet of the 0 flow divider 7 is airtightly fixed to the screw 77 with the 0 ring presser 79 and the screw 78, but the outlet is not shown.
○ ring 80, 0 ring presser 79 directly on the base body 50. It is airtightly fixed with a screw 78. As can be seen from the above description, the chips from the screw part are sealed with an O-ring or the like so that they do not fall off and get mixed into the clear flow path. Union 1', 1
1', mixed gas outlet 9, 19 (both using unions), etc. are screwed directly into the flow path, but after screwing these in, blow away the chips with a high-pressure air flow, Attach to other parts. In this way, the final assembly is held airtight by an O-ring held on a guide etc.
It is fixed with a book screw 55 and four screws 57.

FIG. 10 is an explanatory diagram of the shape of the confluence point 8. For example, when the flow rate is large, a stable flow can be obtained by disposing the air fitA linearly in the mixed flow M and intersecting the carbon dioxide gas flow C at right angles from the middle, as shown in FIG. 2(b). When the flow rate is low, either (a) or (c) produces a very stable flow. However, in either case, it is better that the change in flow velocity is not large.

Now, the resistances of the shunts 6, 7, 16.17 are respectively Re.
e R7+ R1111R17, and set these values to the following values.

Ra=116X10'''kH-win/am'R?
= 58 X 10-8kg-w1n/cs'R+e=
6.7X10''''kg-n+in/am'R17=
7, 3 x 10-3kg-I! Similarly to Iin/am', the resistances of step-down tubes 4, 14, and 24.25 are R4w.
Rza and R21Rzs, and set their values to the following values.

Ra = 3, 5 x 10-”kg-win/ax
BRxa=39X10''kg・sin/cm'R
1a = 6, 7 x 10-8kg-5in/as'
Rza=6.7X10″″8kg-1lin/cffl
δ and the secondary pressure of pressure reducing valves 3 and 13 to 0.200 kgf/
Set to ad. In the flow path diagram of Fig. 1, branch points 5 and 15
In the flow path diagram of FIG. 2, the pressure at the confluence points 8 and 18 is 0.100 kgf/ad. That is, in both the flow path diagrams of FIGS. 1 and 2, the flow divider 6,
7, 16. The differential pressure can only be doubled by doubling the resistance in 17 (in the case of a capillary resistance tube, the length will be doubled), but if a step-down tube is used, it will be 1.5 times more. We set the pressure at the 0 branch points 5 and 15 or the confluence points 8 and 18 to 1/2 of the pressure reducing valve's secondary pressure, which would be sufficient if the pressure was lower than 1/3, but it would be even more effective. be. In addition, when the secondary pressure of the pressure reducing valve increases, the pressure regulation function improves significantly, and even with a commercially available pressure reducing valve, the fluctuation in carbon dioxide concentration is 5.6 ± 0.06% and 11% at the flow rate and pressure of the above numerical values. .2±0.11% can be easily achieved.

〔Effect of the invention〕

As explained above, according to the present invention, even if a shunt with low resistance is used, a step-down pipe is used, so the differential pressure can be increased, and the secondary pressure of the secondary pressure reducing valve can be increased. 0
．． It becomes easy to increase the pressure to 1 kgf/aJ or more, which means that even if a commercially available pressure reducing valve is used as the secondary pressure reducing valve, the stability of the secondary pressure of the pressure reducing valve can be kept below 1%.
n If you want more stability in the carbon dioxide concentration in the associated gas, you can use a pressure reducing valve with a welded metal bellows diaphragm, and now also use pilot pressure control and relief boat control. In order to prevent the contamination of chips due to the screwing of each component, it is attached to the base body using an O-ring and a small number of tightening screws, which has the effect of significantly reducing the number of assembly steps.

[Brief explanation of the drawing]

FIG. 1 is a flow path diagram showing one embodiment of the gas mixing device of the present invention, FIG. 2 is a flow path diagram showing another embodiment of the present invention, and FIG. 3 is a flow path diagram showing the secondary pressure reducing valve 3 of FIG. 1. FIG. 4 is a block diagram showing one embodiment of the secondary pressure reducing valve 13 in FIG. 1, and FIG. 5 is a block diagram showing another embodiment of the secondary pressure reducing valve 13 in FIG. FIG. 6 is an assembly diagram showing an embodiment of the gas mixing device of the present invention. 7, 8, and 9 are enlarged detailed cross-sectional views showing one embodiment of the connection part of the flow path in FIG. 6, and FIG. 7 shows the pressure reducing valve 3.
8 is the secondary side of the pressure reducing valve 3, and FIG. 9 is the base 5.
10 is a cross-sectional view of the connection part of the inlet of the flow divider 7 to the flow divider 7, and FIG. 10 is a shape explanatory diagram of the confluence point 8. 1... Carbon dioxide gas supply source, 3, 13... Secondary pressure reducing valve,
4゜14.24.25...Step-down device (capillary resistance tube), 5
゜15... Branch pipe, 6,7,16.17... Flow divider, 8゜18... Merging point, 9, 19... Mixed gas outlet, 11... Air pressure source, 36.46 ...Bellows, 4
0...Pilot boat, 42...Relief boat, 43...Link, 50...Base.
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Claims (1)

[Claims] 1. In a device that produces two types of mixed gases with different concentrations of carbon dioxide gas from carbon dioxide gas filled in a cylinder and air in the atmosphere, between the respective secondary pressure reducing valves and the flow divider or A gas mixing device characterized in that a step-down tube made of a capillary resistance tube is provided between the flow divider and the mixed gas outlet. 2. A welded metal bellows is used as at least the secondary pressure reducing valve for air among the secondary pressure reducing valve for carbon dioxide gas and the secondary pressure reducing valve for air, and the carbon dioxide pressure after pressure reduction is used as pilot pressure. Gas mixing device of scope 1. 3. The gas mixing device according to claim 1 or 2, wherein the secondary air pressure reducing valve is provided with a relief boat. 4. All parts such as multiple flow paths provided in the base, electromagnetic valves that open and close the carbon dioxide gas flow paths and air flow paths, each of the secondary pressure reducing valves, each of the flow dividers, and the step down pipe, etc. A gas mixing device according to claim 1, 2, or 3, wherein the gas mixing device is provided with: