JPH0639321Y2 - Standard gas injector for diffusion gas detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a calibration gas injector used during calibration work of a diffusion gas detector.

(Prior Art) A so-called diffusion type gas detector in which a combustible gas is introduced into a detection element by natural inflow is usually equipped with a flame arrester to take explosion-proof measures.

In the calibration of such a gas detector, as shown in FIG. 6, the cap member A provided with the gas inlet a and the gas outlet b is attached to the flame arrester C portion of the gas detector main body B. A method of exposing the gas detecting element to the standard gas by pumping the standard gas under pressure with the pump P is adopted.

However, since the pump used for pressure-feeding the standard gas is usually a diaphragm type and a respiratory action due to a pulsating flow is generated, the standard gas to be supplied to the gas detection element by drawing the atmosphere from the gas outlet b. However, there is a problem in that the concentration is reduced by being diluted with the atmosphere, and an error occurs in the calibration result.

(Purpose) The present invention has been made in view of such a problem, and an object thereof is to provide a gas detection element in a state in which the gas concentration of a standard gas source is maintained regardless of the pulsating flow of a pressure source. It is to provide a calibration gas injector capable of supplying a standard gas to the.

(Structure) Therefore, details of the present invention will be described below based on illustrated embodiments.

1 and 2 show an embodiment of the present invention.
In the figure, reference numeral 1 is a bottomed cylindrical cap member that is detachably attached to the outer circumference of the gas detector B, and is connected to a standard gas pressure source by a gas inlet pipe fitting 2 provided at the top. A gas diffusion member 3 having a size that does not close the discharge port 2a is disposed on the discharge port 2a side, and a seal for hermetically engaging the outer periphery of the gas detector B on the inner surface of the lower portion. A member 4 is provided. A pipe joint 2 is provided on the peripheral surface of the cap member 1.
A gas outlet 5 is provided on the opening side (lower side in the figure) of the cap member 1 so that when the inside of the cap member 1 has a negative pressure, the valve body 6a contacts the valve seat 6b. A check valve 6 is provided which is in contact with and closes the flow path. In the figure, reference numeral 6c is
It shows the valve body retainer.

In this embodiment, when the cap member 1 is covered with the gas detector B and the seal member 4 is elastically engaged with the outer circumference of the gas detector B, the cap member 1 is hermetically attached to the gas detector B. .

When the standard gas is pressure-fed by activating a pump (not shown) at the stage where such preparations are completed, the standard gas becomes
Flowing out from the discharge port 2a, colliding with the gas diffusion member 3, once diffused in all directions in the upper space of the cap member 1, then flows toward the gas outlet 5 side, and a gentle flow velocity from around the gas detector B. So flow into this. As a result, the gas detector B receives the action of the standard gas in a state similar to the natural diffusion in the normal use state, and outputs the detection signal controlled only by the standard gas concentration.

On the other hand, since the internal pressure of the cap member 1 rises due to the inflow of the standard gas, the check valve 6 opens the flow path to allow the excess standard gas to escape to the outside to maintain the standard gas in the cap member 1 at the atmospheric pressure. To do.

In such a state, when the pressure of the standard gas supplied to the pipe joint 2 is instantaneously decreased due to the pump pulsating flow, the valve body 6a of the check valve 6 is at atmospheric pressure and the internal pressure of the cap member 1. The gas outlet 5 is instantly closed by receiving the differential pressure of. This prevents the atmospheric air from flowing into the cap member 1 and prevents the internal standard gas from being diluted by the atmospheric air.

Below, the check valve 6 repeatedly opens and closes in accordance with the pressure fluctuation at the gas inlet to keep the pressure inside the cap member 1 constant, and the gas concentration to the gas detector to be calibrated becomes the concentration of the standard gas source. maintain.

FIG. 3 shows an embodiment of the present invention, in which reference numeral 11 is a bottomed cylindrical cap member that can be attached to and detached from the outer circumference of the gas detector B. Cap member 14
Pipe fitting for standard gas inflow that penetrates through and communicates with the outside 12
And a through hole 13 communicating with the inner surface of the second cap member 14 is provided, and a seal member 15 that is airtightly engaged with the outer circumference of the gas detector B is provided on the lower inner circumference surface. . Reference numeral 14 denotes a second cap member having a cylindrical shape with a bottom as described above, which has a constant gap with the outer peripheral surface of the cap member 11 and has a lower end portion which is screwed with the cap member 11 so that the top portion contacts the first cap member. By joining together in an airtight manner, a space 16 is formed with the cap member 11, and a gas discharge port 17 communicating with the outside is provided at a position symmetrical to the through hole 13 with respect to the axis.

In this embodiment, when the cap member 11 is put on the gas detector B and the seal member 15 is elastically engaged with the outer circumference of the gas detector B, the cap member 11 is hermetically attached to the gas detector B. .

When the standard gas is pressure-fed to the standard gas inlet 12 by operating a pump (not shown) at the stage of such preparation, the standard gas flows into the first cap member 11 and diffuses into the gas detector B. On the other hand, the surplus portion flows through the through hole 13 into the space 16 formed by the first and second cap members 11 and 14 and flows out from the gas outlet 17 into the atmosphere. When the standard gas is dangerous, connect a gas recovery tool to the gas outlet 17 to recover the standard gas, or fill the space 16 with a gas absorbent such as activated carbon to absorb it. You can do this.

In such a state, when the pressure of the standard gas supplied to the standard gas inlet 12 decreases due to the pump pulsating flow, the pressure in the internal space of the cap member 11 correspondingly decreases, and The gas filling the space 16 formed by the second cap member 14 flows into the internal space of the cap member 11 through the through hole 13. Needless to say, since the gas filling this space is the standard gas discharged from the cap member 11, the backflow does not cause a decrease in the standard gas concentration in the cap member 11, and the gas The concentration of the standard gas supplied to the detector B will be maintained constant regardless of the pulsating flow of the pump.

According to this embodiment, it is possible to improve reliability by eliminating the need for a valve element that is a movable portion.

FIG. 4 shows a third embodiment of the present invention,
Folds 11a, 11a, 11a, ... and 14 that alternately intersect the outer circumference of the first cap 11 and the inner circumference of the second cap 14 in the radial direction.
a, 14a, 14a, ... Are provided so that their tips have a gap between them and the peripheral surface. According to this embodiment, the outlet 17
It is possible to extend the effective flow path length between the through hole 13 and the through hole 13 to reduce the air flow into the first cap member 11 as much as possible.

FIG. 5 shows a fourth embodiment of the present invention, in which reference numeral 21 denotes a cap member which can be attached to and detached from a gas detector,
A seal member 22 that is airtightly engaged with the outer circumference of the gas detector is provided on the inner surface of the lower portion, a gas inlet 23 communicating with the inside of the cap member 21 is provided at the top, and a gas inlet 23 is provided at the outer circumference. A gas outlet 24 is provided on the opening side of the cap member 21, and a pipe 25 having a volume larger than the flow rate change due to the pulsating flow of the pump is connected to the gas outlet 24 so that the cap member 21 communicates with the atmosphere. Has been made.

In this embodiment, when the cap member 21 is attached to the gas detector B and the standard gas is pumped by the pump, the standard gas flows into the cap member 21 and diffuses into the gas detecting element, while the surplus portion is discharged from the outlet 24. Through pipe 25 into the atmosphere. In such a state, when the gas pressure inside the cap member 21 decreases due to the pulsating flow of the pump, the standard gas filling the pipe 21 flows back into the cap member 21. This allows
Regardless of the pressure drop at the standard gas inlet 23, the standard gas in the cap member 21 maintains its concentration at the standard gas source concentration while maintaining the pressure at atmospheric pressure.

In the second to fourth embodiments described above, the calibration accuracy can be further improved by disposing the gas diffusion member on the discharge side of the gas inlet.

Further, in the above-mentioned embodiment, the case where the standard gas is pressure-fed by using the pump has been described as an example, but it is clear that the same effect can be obtained when the gas bag is used.

(Effects) As described above, in the present invention, the cap member having the opening at one end for hermetically and detachably engaging the outer circumference of the gas detector has the gas inlet port on the surface facing the opening. A check valve that has a gas outlet on the side surface near the opening, a gas diffusion member near the gas inlet, and a gas outlet that closes the gas outlet when the cap member has a negative pressure. Since it is provided, the standard gas is supplied into the cap while being diffused at a pressure as close to atmospheric pressure as possible,
The standard gas can be introduced into the gas detector to be inspected by diffusion, and the gas detector can be inspected in a state close to its actual use environment.

[Brief description of drawings]

1 and 2 are a sectional view and a plan view of an apparatus showing one embodiment of the present invention, and FIGS. 3, 4, and 5 are sectional views showing another embodiment of the present invention and a perspective sectional view, respectively. , And 6th
The figure is a perspective view showing a conventional calibration technique. 1 ... Cap member 2 ... Pipe fitting for standard gas inflow 3 ... Gas diffusion member, 4 ... Seal member 5 ... Gas outlet, 6 ... Check valve B ... Gas detector

Claims (1)

[Scope of utility model registration request] 1. A cap member having an opening at one end thereof that is airtightly and removably engaged with the outer periphery of a gas detector, a gas inlet is provided on a surface facing the opening, and a side surface near the opening is provided. A gas outlet is provided, and a gas diffusion member is provided in the vicinity of the gas inlet, and a check valve is provided at the gas outlet to close the gas outlet when the pressure inside the cap member becomes negative. Standard gas injector for diffusion type gas detector.