Patent Publication Number: US-6712586-B2

Title: Gas suction pump device, gas feed adapter and gas alarm unit

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a gas suction pump device, a gas feed adapter and a gas alarm unit. 
     2. Description of the Background Art 
     There are generally frequent occasions when it may be possible in, for example, underground job sites or gateways, or other places where persons enter, or working regions that air in an environmental atmosphere is in a dangerous state, or will become a dangerous state, such as occasions when harmful gases such as carbon monoxide and hydrogen sulfide gases may possibly be contained in air in such an environment, or when the oxygen gas concentration in air may possibly be lowered. 
     When the air in the environmental atmosphere has become a dangerous state to persons due to high concentration of the dangerous gases contained or low oxygen gas concentration, it is necessary to sense the fact. 
     From such a demand, there have been proposed various types of portable gas alarm devices to date. As such portable gas alarm devices, for example, those having a structure that a sucking means such as a pump is installed in a gas alarm device body, and air in the objective space is forcedly sucked by this sucking means to perform the concentration measurement of a gas to be detected, and those of the so-called “diffusion type” that air in the objective space is introduced by natural diffusion are known. 
     However, such a portable gas alarm device cannot be used in a place where no person can enter because the portable gas alarm device basically requires that a person should enter the place to perform the concentration measurement of dangerous gases in order to confirm the safety of air in an environmental atmosphere. 
     Therefore a method is used in which a sucking device such as a pump is connected to the portable gas alarm device so as to suck air in the objective space to perform the concentration measurement of the dangerous gases up to the gas alarm device body by the sucking device. 
     Since the conventional sucking devices are generally large in size and heavy, however, they involve problems that they are considerably unhandy to carry and make a great obstacle to practice the intended work or the like. 
     In addition at the actual situation, such a sucking device is unsuitable for use as a sucking means that is connected to the portable gas alarm device, because it requires much time or labor in maintenance work such as filter exchange or pump exchange. 
     SUMMARY OF THE INVENTION 
     The present invention has been made on the basis of the foregoing circumstances. 
     It is the first object of the present invention to provide a gas suction pump device which is easy to be fabricated as a small-sized one handy to carry and high in convenience for use. 
     The second object of the present invention is to provide a gas feed adapter by which air from such a gas suction pump device can be surely fed to a gas detecting part of a portable gas alarm device. 
     The third object of the present invention is to provide a portable gas alarm unit which makes good use of such a gas suction pump device and is high in convenience for use. 
     The first object of the present invention can be achieved by any one of the following constitutions [1] to [8]. 
     [1] A gas suction pump device suitable for being connected by a connecting tube to a portable gas alarm device for use, which comprises: 
     a casing having a substantially rectangular frame-like sectional shape composed of 2 side walls opposite to each other, and upper and lower walls which connect the side walls to each other, and formed slenderly in a gas flowing direction and into a size holdable by grasping with a hand; 
     a control circuit board provided in the casing so as to extend in a longitudinal direction along the upper wall; 
     a pump unit arranged in a region on the side of one side wall under the control circuit board, in which one end and the other end of a gas flow path defined by the pump unit and extending in the longitudinal direction of the casing communicate with a gas inlet port opened forward of the casing and a gas outlet port opened backward of the casing, respectively; and 
     a battery fitting chamber provided in a region on the side of the other side wall. 
     [2] The gas suction pump device according to the constitution [1], wherein the pump unit is composed of a pump and a pump driving motor provided integrally with the pump, and wherein 
     the pump is located in the vicinity of one side wall in the casing, and the pump driving motor is arranged in a state located in the vicinity of the other side wall. 
     [3] The gas suction pump device according to the constitution [2], wherein the pump making up the pump unit has a gas discharge quantity of 0.2 to 0.5 L/min. 
     [4] The gas suction pump device according to any one of the constitutions [1] to [3], wherein a driving power source is a battery. 
     [5] The gas suction pump device according to any one of the constitutions [1] to [4], wherein a recessed part for receiving an end part of the connecting tube is formed in the casing, and a connecting terminal to which the connecting tube is connected is provided at the gas outlet port in the recessed part in a state projected backward from the rear wall thereof. 
     [6] The gas suction pump device according to any one of the constitutions [1] to [5], wherein a branched gas flow path opened upward is defined in a gas flow path forming member connecting the pump unit to the gas outlet port, and a pressure sensor is connected to the branched gas flow path in a state arranged on the control circuit board side of the gas flow path forming member. 
     [7] The gas suction pump device according to any one of the constitutions [1] to [6], wherein the casing is formed by joining a front case with a rear case detachably to each other, and an anti-detaching metal band for preventing both front case and rear case from detaching from each other is fitted on the joined area between the front case and the rear case. 
     [8] The gas suction pump device according to the constitution [7], wherein the anti-detaching preventing metal band is fitted in a state that both ends thereof overlap each other and fixed to the casing by a screw at a position where both ends overlap each other. 
     The second object of the present invention can be achieved by the following constitution [9]. 
     [9] A gas feed adapter for connecting the gas suction pump device according to any one of the constitutions [1] to [8] through a connecting tube to a portable gas alarm device equipped with a plurality of gas sensors which detect gases of different kinds from one another, which comprises: 
     a casing having an engaging part and detachably engaged with a gas alarm device body, wherein a gas feed port common to the respective gas sensors in the gas alarm device body is defined in one outer end wall of the casing, a connecting terminal to which the connecting tube is connected is also fitted so as to project outward, and a gas outlet for opening the internal space in the casing to the air is defined in the other outer end wall, and wherein 
     a main gas inlet passage extending zigzag from one to the other in the casing is formed in the casing, and a plurality of branched gas inlet passages independent of one another for introducing air in the objective space to perform the measurement of gases into the respective gas sensors in the gas alarm device body are formed in the main gas inlet passage. 
     The third object of the present invention can be achieved by any one of the following constitutions [10] to [14]. 
     [10] A gas alarm unit comprising the gas suction pump device according to any one of above the constructions [1] to [8], a connecting tube connected to the gas suction pump device at an end thereof and a portable gas alarm device connected to the other end of the connecting tube through the gas feed adapter according to the construction [9], into which air in the objective space to perform the measurement of gases is introduced from the gas suction pump device. 
     [11] The gas alarm unit according to the construction [10], wherein the portable gas alarm device comprises a substantially box-like casing composed of a case body provided with a fitting member fixing part in which a fitting member for fitting on a person&#39;s body to carry the alarm device is installed and having an opening at a lower part, and a lid for closing the opening in the case body, and a gas detecting part is formed at one side surface of the casing in such a manner that a plurality of the gas sensors are arranged side by side in a plane direction of said one side surface. 
     [12] The gas alarm unit according to the construction [11], wherein a power unit composed of a circuit board flat in shape, on which a secondary battery as a driving power source, a charging terminal for charging the secondary battery and a current limiting resistance are mounted, and an insulating cover provided so as to cover the secondary battery and the current limiting resistance on the circuit board is provided in the casing in such a manner that the circuit board extends in parallel with the lid in the casing, and wherein 
     an alarm annunciating mechanism that raises an alarm when the concentration of a gas detected by the gas sensor exceeds a reference value preset about the gas, and a display mechanism for displaying the concentration of the gas detected by the gas sensor are arranged so as to stand in a plane direction of the circuit board in a state that the alarm annunciating mechanism is located over the secondary battery in the power unit. 
     [13] The gas alarm unit according to the construction [11] or [12], wherein a plurality of the gas sensors are fixed and held by a gas sensor fixing frame member, in which gas inlet ports for the respective gas sensors have been formed in a state independent of one another, in the gas detecting part. 
     [14] The gas alarm unit according to any one of the constructions [11] to [13], wherein 4 gas sensors are arranged in the gas detecting part, and the objective gases to be detected by the gas sensors are gases of oxygen, hydrogen sulfide, carbon monoxide and hydrocarbon. 
     According to the gas suction pump device of the above-described construction, the casing is in the form holdable by grasping by a hand, and the constituent members of the pump device are rationally arranged in a state that a dead space in the casing becomes as small as possible, whereby the gas suction pump device itself can be provided as a small-sized and light-weight one while retaining basically necessary functions. Accordingly, the gas suction pump devices are excellent in portability, and so actually high in convenience can be achieved. 
     According to the gas feed adapter of the above-described constitution, a state substantially equal to natural diffusion can be realized as the main gas inlet passage for feeding air in the objective space to perform gas measurement to a gas alarm device is opened to the atmosphere or air though the air is forcedly introduced by a gas suction pump device. In addition, the main gas inlet passage is formed so as to extend zigzag, and the branched gas inlet passages are formed corresponding to the respective gas sensors, whereby air introduced by the gas suction pump device can be surely fed to the respective gas sensors. 
     According to the portable gas alarm units of the above-described constructions, the portable gas alarm device is fitted to the body of a person and carried together with the body by the person because the pump device making up the gas alarm unit has high convenience while retaining the necessary functions, and moreover the pump device can be held for use by grasping it by a hand, whereby the gas alarm unit has extremely high convenience for use as a portable gas alarm unit. Accordingly, concentration measurement of dangerous gases can be performed even in a place where no person can enter, and high safety can be achieved. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above and other objects, features and advantages of the present invention will become apparent from the following description and the appended claims, taken in conjunction with the accompanying drawings, in which: 
     FIG. 1 illustrates an example of the construction of a gas alarm unit according to the present invention; 
     FIG. 2 is a cross-sectional view schematically illustrating the construction of an exemplary gas suction pump device according to the present invention; 
     FIG. 3 is an exploded perspective view of the gas suction pump device shown in FIG. 2; 
     FIG. 4 is a front elevation schematically illustrating the construction of a front case in the gas suction pump device shown in FIG. 2; 
     FIG. 5 is a longitudinal cross-sectional view taken along line A—A in FIG. 4; 
     FIG. 6 is a front elevation schematically illustrating the construction of a rear case in the gas suction pump device shown in FIG. 2; 
     FIG. 7 is a longitudinal cross-sectional view taken along line B—B in FIG. 6; 
     FIG. 8 is a side elevation schematically illustrating the construction of a pump unit in the gas suction pump device shown in FIG. 2; 
     FIG. 9 is a top plan view of the pump unit shown in FIG. 8; 
     FIG. 10 is a top plan view schematically illustrating the construction of a manifold in the gas suction pump device shown in FIG. 2; 
     FIG. 11 is a transverse cross-sectional view of the manifold shown in FIG. 10; 
     FIG. 12 is a longitudinal cross-sectional view taken along line C—C in FIG. 10; 
     FIG. 13 is a longitudinal cross-sectional view schematically illustrating the construction of an exemplary gas alarm device to which the gas suction pump device according to the present invention is connected viewed from a direction indicated by an arrow A in FIG. 1; 
     FIG. 14 is a transverse cross-sectional view schematically illustrating the construction of a gas detecting part formed at one side surface of the gas alarm device; 
     FIG. 15 is a perspective view schematically illustrating the construction of an exemplary gas feed adapter installed in a gas alarm device body; and 
     FIG. 16 is a front elevation of a sealing member used in the gas feed adapter. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention will hereinafter be described by reference to the drawings. 
     FIG. 1 illustrates an example of the construction of a gas alarm unit according to the present invention. This gas alarm unit is constructed by a gas suction pump device  10 , a connecting tube  95 , a gas feed adapter  130  and a portable gas alarm device  100  in which the gas feed adapter  130  is installed. 
     A gas feed-side socket  95 A, which forms a gas feed-side coupler by being connected to a gas feed-side plug  49  as a connecting terminal provided in the gas suction pump device  10 , is provided at an end of the connecting tube  95 , and a gas inlet-side socket  95 B, which forms a gas inlet-side coupler by being connected to a gas inlet-side plug  134  provided in the gas feed adapter  130 , is provided at the other end of the tube  95 . 
     The length of the connecting tube  95  can be suitably selected within the limit of, for example, 10 m. In an example illustrated, an extensible spiral tube, which is in a state spirally wound in a natural state, is used. This connecting tube  95  has, for example, an extended length of 1 m and an inner diameter of 2.5 mm. 
     &lt;Gas Suction Pump Device&gt; 
     FIG. 2 is a cross-sectional view schematically illustrating the construction of an exemplary gas suction pump device according to the present invention, FIG. 3 is an exploded perspective view of the gas suction pump device shown in FIG. 2, FIG. 4 is a front elevation schematically illustrating the construction of a front case in the gas suction pump device shown in FIG. 2, FIG. 5 is a longitudinal cross-sectional view taken along line A—A in FIG. 4, FIG. 6 is a front elevation schematically illustrating the construction of a rear case of the gas suction pump device shown in FIG. 2, and FIG. 7 is a longitudinal cross-sectional view taken along line B—B in FIG.  6 . In this specification, the left and right direction, upward and downward direction and a direction perpendicular to the drawing in FIG. 2 will hereinafter be referred to as “forward and backward direction”, “upward and downward direction” and “width direction”, respectively. 
     This gas suction pump device (hereinafter referred to as “pump device” simply)  10  is equipped with a casing  11  formed by joining a front case  20  with a rear case  40  detachably to each other. 
     The casing  11  has a substantially rectangular frame-like sectional shape composed of 2 side walls opposite to each other, and upper and lower walls which connect the side walls to each other, and is formed slenderly in the forward and backward direction and into a size holdable by grasping with a hand. 
     The front case  20  is formed of, for example, a resin and has a substantially box-like shape extending in the forward and backward direction as a whole, and tongue-shaped parts  22 ,  22  for fitting, which are respectively extending from rear end edges of the side walls  21 A,  21 B opposite to each other, are formed at the side walls. 
     In the tongue-shaped parts  22 ,  22 , fitting grooves  22 A extending the upward and downward direction are formed at the outer surfaces thereof, and circular through-holes  22 B are formed at rear end parts thereof. 
     A recessed part  23  is formed along the whole periphery of an inner wall surface in the rear end part of the front case  20 , and needle-like projection parts  24  extending rearward are formed at the recessed part  23 . 
     The needle-like projection parts  24  each has a tapered part  24 A that a rear end inclines so as to narrow toward the rear and are formed by, for example, two in a state spaced with each other on each of 4 wall surfaces. The needle-like projection parts  24  thereby function as guide members for a fitting member  41  of the rear case  40 , which will be described subsequently, upon fitting of the rear case  40 , and so attachment and detachment between the front case  20  and the rear case  40  can be easily performed. 
     A tongue-like projection part  25  for prevention of misfitting for fitting the rear case  40  in a correct state is formed on an upper wall surface of the recessed part  23 . Fitting between the front case  20  and the rear case  40  is achieved by inserting the rear case  40  in a state that the prescribed face in the fitting part  41  has been turned up. 
     The rear case  40  is composed of, for example, the same resin as that forming the front case  20  and has a substantially box-like shape extending in the forward and backward direction as a whole, and a recessed part  46  for receiving an end part of a connecting tube  95  to be connected to the portable gas alarm device  100  is formed at a rear part of in one side surface (side surface on facing side of the width direction in FIG.  2 ). 
     The fitting part  41  having a shape corresponding to the recessed part  23  of the front case  20  is formed at the front side part of the rear case  40 . A groove  41 A, in which the tongue-like projection part  25  in the front case  20  will be inserted upon fitting, is formed at a front end edge of the upper surface of the fitting part  41 , and an annular groove  41 B, in which a sealing member  42  such as, for example, an O-ring is fitted, is formed over the whole peripheral surface at a rear end edge thereof. 
     Recessed parts  44 ,  44  each having a shape corresponding to the tongue-shaped parts  22 ,  22  of the front case  20  are formed in outer surfaces of side walls  43 A,  43 B of the rear case  40 . These are fitted with each other, whereby the front case  20  and the rear case  40  are integrally joined to form the casing  11 . 
     At the joined area between the front case  20  and the rear case  40 , a groove  45  for arrangement of a metal band is formed so as to extend over the whole outer peripheral surface continuously with the grooves  22 A,  22 A in the tongue-shaped parts  22 ,  22 , and an anti-detaching metal band  12  is fitted in the groove  45  in a state that both ends thereof overlap each other and integrally fixed to a lower wall  43 C of the rear case  40  by a screw  13  at a position where the both ends overlap each other, whereby detaching of the front case  20  from the rear case  40  can be surely prevented even when the pump device  10  has been dropped by way of example. 
     The anti-detaching metal band  12  is used in a size that the surface of the casing  11 , which tends to carry static electricity because it is formed of the resin, is divided into 2 parts of the front case  20  and the rear case  40  in such a manner that the surface areas of the respective parts are 100 cm 2  or smaller, whereby the pump device  10  itself can be so constructed that it does not become a source of catch fire, namely, it satisfies the standard of so-called explosion-proof specification (intrinsically safe explosion proofness). 
     In the casing  11 , a gas inlet part  26  having a gas inlet port  26 A opened forward of the casing is formed at a position shifted towards the side of one side wall  21 A of the front case  20 , and a gas discharge part  47  having a gas outlet port  47 A opened backward of the casing is formed at a position opposite to the gas inlet part  26  in the longitudinal direction, where the recessed part  46  of the rear case  40  has been formed. 
     The gas discharge part  47  has a small-diameter cylindrical part  48  formed so as to extend forward in parallel with the lower wall  43 C, and the small-diameter cylindrical part  48  is formed at a position somewhat lower than the level of the gas inlet port  26 A. 
     In the recessed part  46  in the casing  11 , a gas feed-side plug  49  as a connecting terminal is arranged in a state projecting backward from the rear wall  43 D thereof by being fitted into the gas outlet port  47 A. FIG. 7 illustrates a state that gas feed-side plug  49  is removed. 
     The gas feed-side plug  49  has a gas discharge port smaller than the opening diameter of the gas outlet port  47 A and having a structure that the opening diameter thereof is preset to a size that a gas exhaust pressure, by which a pressure sensor  84  connected to a manifold  75  which will be described subsequently is actuated, is achieved, namely, so as to have a so-called capillary structure. The gas exhaust pressure from a pump unit  60  which will be described subsequently can be thereby raised to such an intensity, for example 0.4 kPa, that can be detected by the pressure sensor  84 . 
     In the casing  11 , a circuit board-holding mechanism  30  is provided at a position above the gas inlet port  26 A on the front wall  21 C of the front case  20 , and a circuit board-holding mechanism  55  is provided at a position above the gas outlet port  47 A on the inner surface of the rear wall  43 D of the rear case  40 . The circuit board-holding mechanism  30  in the front case  20  and the circuit board-holding mechanism  55  in the rear case  40  are in a state they are located at the same level as each other in the upward and downward direction. 
     The circuit board-holding mechanism  30  in the front case  20  is formed by arranging 2 holding parts  32 , each of which is composed of a pair of pin members provided so as to oppose in the upward and downward direction and has a groove  31  extending in the width direction between the pin members, in a state spaced with each other in the width direction. 
     The circuit board-holding mechanism  55  in the front case  40  is also fundamentally constructed in the same manner as the circuit board-holding mechanism  30  in the front case  20  by arranging 2 holding parts  56 , each of which is composed of a pair of pin members arranged in the upward and downward direction, in a state spaced with each other in the width direction. 
     A flat plate-like control circuit board  15  is caught to be held by the holding parts  32  in the front case  20  and the holding parts  56  in the rear case  40 , thereby being arranged so as to extend in the longitudinal direction (forward and backward direction) in parallel with the upper wall of the casing  11 . 
     On the control circuit board  15 , as illustrated in FIG. 3, 2 light sources  16 A,  16 B each composed of a light emitting diode are mounted at positions in the vicinity of one side edge at the front end edge portion on the upper surface side thereof so as to stand side by side in the forward and backward direction. One light source  16 A located on the front edge side and the other source  16 B are constructed so as to function as a lamp for indicating a power source and as a lamp for indicating an alarm of lower flow rate, respectively. 
     Contactor members  17 A,  17 B for switch are mounted so as to stand alongside of the light sources  16 A,  16 B with a space in the width direction of the control circuit board  15 . 
     On the other hand, on the lower surface side of the control circuit board  15 , a manifold  75 , which will be described subsequently, is fixed at a substantially central position in the forward and backward direction by a plurality of screws  18  inserted from the upper surface side of the control circuit board  15 , and a pressure sensor  84  connected to the manifold  75  is mounted at a position in front of the fixed position of the manifold  75  in the vicinity of one side edge. 
     On the control circuit board  15 , a connector  74 B for connection of the pump unit is mounted so as to stand alongside of the pressure sensor  84  in the width direction, and a minus-side contactor member  19 A is mounted at a position in the vicinity of the other side edge at the rear end edge portion of the control circuit board  15 . 
     On the control circuit board  15 , an electronic circuit having a function of controlling operations of the respective parts in the pump device  10  as above is provided, and the operations of the pump unit  60 , which will be described subsequently, the pressure sensor  84 , the lamp  16 A for indicating a power source, the lamp  16 B for indicating an alarm of lower in flow rate, etc. are controlled by this control circuit board  15 . 
     In the casing  11 , a battery fitting chamber  50 , in which an AA size dry battery as a driving power source for the pump device  10  is placed, is formed in a region on the side of the other side wall under the control circuit board  15  in such a manner that it extends in the forward and backward direction, and its rear end portion projects rearward from the rear end edge of the rear case  40 . At the projected end portion  50 A of the battery fitting chamber  50 , a cap  51  provided with a metal sleeve is detachably fitted on a connecting projection part  50 B formed on the outer peripheral surface thereof, whereby the battery can be exchanged. 
     In the battery fitting chamber  50 , a blade-like support member  52  extending forward from the front surface thereof in parallel with the lower wall  43 C is integrally provided. A claw member  52 A for interlocking with the manifold  75  is formed at the tip part of this blade-like support member  52 . 
     A guide groove  53  extending in the forward and backward direction is formed in the upper part of the battery fitting chamber  50 , whereby the control circuit board  15  is inserted by guiding the minus-side contactor member  19 A mounted on the surface thereof to a prescribed position along the guide groove  53  and arranged in the casing  11  in a state connected to the metal sleeve of the cap  51 . 
     In the casing  11 , the pump unit  60  is arranged in a region on the side of one side wall under the control circuit board  15  in a state that a gas suction pipe  65  forming one end of a gas flow path defined by the pump unit  60  has been connected to the gas inlet port  26 A in the front case  20 , and a gas discharge pipe  66  forming the other end of the gas flow path has been connected to the gas outlet port  47 A in the rear case  40  through the manifold  75  which is a gas flow path forming member in such a manner that the gas flow path extends in the longitudinal direction of the casing  11 . 
     &lt;Pump Unit&gt; 
     FIG. 8 is a side elevation schematically illustrating the construction of a pump unit in the gas suction pump device shown in FIG. 2, and FIG. 9 is a top plan view of the pump unit shown in FIG.  8 . 
     The pump unit  60  is constructed by a pump  61  of the so-called diaphragm system and a pump driving motor  70  provided integrally with the pump. In FIG. 9, reference numeral  68  indicates a support member for supporting the driving motor  70 . 
     The pump  61  has a pump room  62  having a substantially box-like shape as a whole, and this pump room  62  is equipped with a first pump room  62 A and a second pump room  62 B partitioned by a partition wall  62 C so as to stand side by side in the width direction. 
     In the first pump room  62 A, a diaphragm  63  is airtightly provided in a state extending in parallel with the partition wall  62 C and covering an internal space in the first pump room  62 A. A drive shaft  63 A extending in the width direction is connected to the diaphragm  63 , and a sleeve member  63 B is integrally provided at the tip of the drive shaft  63 A. 
     In the second pump room  62 B, the gas suction pipe  65  and the gas discharge pipe  66  are provided at diagonal positions in compartment walls  64 A,  64 B opposite to each other so as to extend in the forward and backward direction. 
     Two communication holes  67 A,  67 B for communicating the internal space of the first pump room  62 A and the internal space of the second pump room  62 B with each other are formed in the partition wall  62 C partitioning the first pump room  62 A and the second pump room  62 B. The opening diameter of the communication hole  67 A formed on the side (upper side) of the gas suction pipe  65  is greater than that of the communication hole  67 B formed on the side (lower side) of the gas discharge pipe  66 , whereby the pump is so constructed that air is passed through from the side of the gas suction pipe  65  to the side of the gas discharge pipe  66  in the second pump room  62 B by reciprocating operation in width direction of the diaphram  63 . 
     The pump driving motor  70  is supported in such a manner that a rotating shaft  71  thereof extends in a direction perpendicular to the direction in which the drive shaft  63 A of the pump  61  extends i.e. forward and backward direction. The drive shaft  63 A of the pump  61  is connected to the rotating shaft  71  through a cam mechanism  72 . 
     More specifically, a shaft member  73  eccentrically fixed to the rotating shaft  71  of the pump driving motor  70  is fitted in and held by the sleeve member  63 B, thereby forming the cam mechanism  72  which is a power transmission device of the pump driving motor  70  for the pump  61 . A connector  74 A illustrated in FIG. 3 is connected to the connector  74 B for connection of the pump unit mounted on the control circuit board  15 . 
     The pump device  10  according to the present invention preferably has a performance that a gas can be fed to the portable gas alarm body  100  at a flow rate of 0.2 to 0.5 L/min, for example. As the pump  61  making up the pump unit  60 , a pump having a performance that a gas discharge quantity of the pump device  10  is 0.4 to 0.45 L/min, for example, is used. 
     The pump  61  preferably has an ultimate vacuum of 0.6 to 0.75 Pa (80 to 100 mmHg). 
     &lt;Manifold&gt; 
     FIG. 10 is a top plan view schematically illustrating the construction of the manifold in the gas suction pump device shown in FIG. 2, FIG. 11 is a transverse cross-sectional view of the manifold shown in FIG. 10, and FIG. 12 is a longitudinal cross-sectional view taken along line C—C in FIG.  10 . 
     The manifold  75  which is a gas flow path forming member connecting the pump unit  60  to the gas outlet port  47 A is formed by a cylindrical part  76  forming a gas flow path  78  extending in the forward and backward direction and a plate part  77  formed so as to extend from the side surface of the cylindrical part  76  to a direction (width direction) perpendicular to the direction of the gas flow path, and screw-fixing parts  79  extending upward are provided. 
     A front opening  78 A in the gas flow path  78  of the cylindrical part  76  is connected to the gas discharge pipe  66  of the pump unit  60  and a rear opening  78 B in the gas flow path  78  is connected to the small-diameter cylindrical part  48  in the gas discharge part  47 , as illustrated in FIG. 2 in a state that the screw-fixing parts  79  have been fixed to the surface of the control circuit board  15  by screws  18 . 
     Sealing members  80 A,  80 A such as, for example, O-rings are respectively interposed between an inner peripheral surface in the front opening portion of the cylindrical part  76  and an outer peripheral surface of the gas discharge pipe  66  of the pump unit  60 , and between an inner peripheral surface in the rear opening portion of the cylindrical part  76  and an outer peripheral surface of the small-diameter cylindrical part  48  in the gas discharge part  47  to be airtightly sealed. Reference character  80 B in FIG. 11 indicates a ring-like holding member for holding the sealing member  80 A. 
     A side hole  81  opened to the rear surface of the plate part  77  is formed in a side surface in the cylindrical part  76  of the manifold  75 . The blade-like support member  52  in the rear case  40  is inserted into this side hole  81 , and the claw member  52 A formed at the tip part of this blade-like support member  52  is interlocked with a front end edge of a compartment wall  81 A for forming the side hole  81 , whereby the manifold  75  is arranged in the casing  11  in a state positioned at a prescribed position. 
     A through-hole  82  communicating with the gas flow path  78  and opened upward is formed in the cylindrical part  76  of the manifold  75 . A pressure sensor  84  is connected to a branched gas flow path  83  defined by this through-hole  82 . More specifically, the pressure sensor  84  is arranged in a space defined between the cylindrical part  76  of the manifold  75  and the control circuit board  15  as illustrated in FIG. 3, to which a gas inlet pipe  84 A of the pressure sensor  84  is connected in a state airtightly sealed by a sealing member  80 C such as, for example, an O-ring interposed between an outer peripheral surface thereof and an inner peripheral surface of the through-hole  82  and held by a ring-like holding member  80 D. 
     A plus-side contactor member  19 B is supported on a rear surface of the plate part  77  of the manifold  75 , and the plus-side contactor member  19 B is inserted into the guide groove  53  in the battery fitting chamber  50  in a state that the manifold  75  has been installed in the rear case  40 , thereby being connected to the battery. 
     In the above, the pump unit  60  is fitted to the manifold  75  in a state that the pump  61  is located in the vicinity of one side wall in the casing  11 , and that the pump driving motor  70  is located in the vicinity of the other side wall, whereby a rear end part of the pump driving motor  70  is received in a space defined by the manifold  75  and the other side wall  21 B in the casing  11 , and so the pump unit  60  is substantially held in a state that it does not project forward from the front end edge of the control circuit board  15 . 
     As illustrated in FIG. 5, a cylindrical filter unit fitting part  27  projecting forward from the front end edge of the front case  20  is formed in the front case  20  in the casing  11  in a state that an internal space thereof communicates with an internal space of the front case  20  through the gas inlet port  26 A. 
     A filter unit  85  for feeding air in the objective space to perform the measurement of gases to the gas alarm device  100  in a state that dust has been removed is fitted in the filter unit fitting part  27  as illustrated in FIG.  2 . 
     More specifically, as illustrated in FIG. 3, the filter unit  85  is composed of a cylindrical filter case  86  and a two-stage cylindrical sealing member  87  in which a rear end part of the filter case  86  is fitted, and a small-diameter cylindrical part  87 A provided so as to project and extend rearward in the sealing member  87  is inserted into the gas inlet port  26 A. 
     The filter case  86  is formed by, for example, a transparent resin, and, for example, a cotton filter material  86 A is filled in the interior of the filter case  86 . The filter case  86  is formed by the transparent resin, whereby the stained condition of the cotton filter material  86 A filled in the interior can be visually observed from the outside to easily sense the time when the cotton filter material  86 A is to be exchanged. 
     For example, a primary filter  88 A composed of Teflon (trademark), a metal mesh  88 B and a secondary filter  88 C composed of Teflon (trademark) are fitted in the sealing member  87  in this order in the gas flowing direction in the forward and backward direction. 
     A connecting member  89  for introduction of a gas is provided at the tip part of the filter case  86 , and a tip nozzle  90  is connected to the connecting member  89  for introduction. 
     The tip nozzle  90  is composed of, for example, a tapered tube or pipe that the outer diameter thereof gradually diminishes toward the tip thereof in the whole. With respect to a gas inlet hole  90 A of the tip nozzle  90 , the inner diameter also gradually diminishes toward the tip. 
     In FIGS. 4 and 5, reference character  26 B indicates a recess in which a cushioning member  26 C for supporting the pump unit  60  is fitted,  27 A a fixing groove for detachably fitting the filter case  86  making up the filter unit  85 ,  35  a window for displaying the power source lamp formed at a position corresponding to the lamp  16 A in the control circuit board  15 ,  36  a window for displaying the alarm lamp of the lower flow rate formed at a position corresponding to the lamp  16 B,  37   a  display panel covering the window for displaying the power source lamp and the window for displaying the alarm lamp of the lower flow rate, and  38  a rotary disc-type switch for connecting the contactor members  17 A,  17 B mounted on the surface of the control circuit board  15  to each other by being rotated. 
     In FIGS. 6 and 7, reference numeral  57  indicates a fitment holding part having a through hole for installing a carrying holder such as, for example, a strap. 
     An example of specific numerical values of the pump device according to the present invention will be described. With respect to the pump unit  60 , the inner diameters of the gas suction pipe  65  and the gas discharge pipe  66  are both 2 mm, the volume of the pump room  62  is about 1.2 cm 3 , the eccentricity of the shaft member  66  to the rotating shaft  71  of the pump driving motor  70  is 0.9 mm, and the electromotive force of the pump driving motor  70  is 3.0 V. With respect to the gas feed-side plug  49 , the opening diameter of the gas outlet port is 0.6 mm. The battery fitting chamber  50  has a cylindrical internal space for receiving a battery, whose inner diameter is 14.5 mm and whose length is 51.6 mm. 
     The operation of the pump device  10  of the above-described constitution will now be described. 
     When the switch  38  is rotated in a state that the battery has been fitted in the battery fitting chamber  50 , the contactor members  17 A,  17 B for switch mounted on the surface of the control circuit board  15  are connected to each other, whereby a current from the battery is fed as an operating current for the respective parts through the control circuit board  15 . Supply voltage is raised to 3.0 V by the control circuit board  15  to actuate the pump driving motor  70  in the pump unit  60 , whereby driving power by the rotating shaft  71  of the pump driving motor  70  is transmitted to the drive shaft  63 A provided at the diaphragm  63  through the cam mechanism  72 , and the drive shaft  63 A is driven in the upward and downward directions reciprocally by a cam action. The diaphragm  63  is thereby operated to suck air in the objective space to perform measurement of gases through the tip nozzle  90 . 
     The air sucked through the tip nozzle  90  is introduced into the pump device  10  from the gas inlet port  26 A through the filter unit  85 , passed through the pump room  62  in the pump unit  60  and the gas flow path  78  in the manifold  75  and discharged in a pressurized state compared with a case where it is opened to the atmospheric air as it is due to the effect of the capillary structure of the gas feed-side plug  49 . 
     On the other hand, an exhaust pressure from the pump unit  60  is measured by the pressure sensor  84  connected to the branched gas flow path  83  in the manifold  75 , thereby detecting pressure drop when the flow rate is lowered because of, for example, suction of water or clogging of the filter. At this time, the lamp  16 B for indicating an alarm of lower in flow rate is lighted, and the operation of the pump unit  60  is forcedly stopped. 
     Right after the power source is turned on, the operation of the pump unit  60  is not forcedly stopped even when the lower gas flow rate is detected, and the pump driving motor  70  is controled to be stopped at the time the prescribed period of time, for example, about 10 seconds have elapsed. Utilizing such operation characteristics, it can be confirmed that the pump device  10  is in a normally operating condition, by closing the gas suction port of the tip nozzle  90  with a finger or the like for a short period of time upon determination of the condition of air in the objective space to perform measurement of gases. 
     According to the above-described pump device  10 , the casing  11  can be held by a hand, and the essential constituent members of the pump device  10  are rationally arranged in a state that a dead space in the casing  11  becomes as small as possible, whereby the pump device  10  itself can be provided as a small-sized and light-weight one while retaining basically necessary functions. 
     Specifically, the pump unit  60  in the pump device  10  is small in size, the driving power source is an AA size battery, and moreover (1) the pump unit  60  is arranged in such a manner that a gas flow path extending in the forward and backward direction is formed in the region on the side of one side wall in the casing  11 , (2) the battery fitting chamber  50  is formed in the region on the side of the other side wall in the casing  11  to receive the battery therein, and (3) the control circuit board  15  is arranged at a position above these parts, whereby the constitutive members of the pump device  10  can be arranged in the casing  11  at a high space utilization factor. The pump device  10  itself can be thereby provided as a small-sized and light-weight one while retaining basically necessary functions. 
     With respect to the dimensions of the respective parts in the pump device  10  according to the present invention, for example, the whole length is about 200 mm including the tip nozzle  90  whose tip opening diameter is 4 mm and whose rear end opening diameter is 6 mm, the maximum dimension in the upward and downward direction is about 30 mm, the maximum dimension in the width direction is about 34 mm, and the weight is about 105 g including the battery. Accordingly, the pump device is excellent in portability, and so actually high convenience can be achieved. 
     The constitutive members of the pump device  10  can be arranged in the casing  11  at a high space utilization factor by satisfying the following constitutions (A) and (B), whereby the pump device  10  can be more miniaturized. 
     (A) The pump  61  making up the pump unit  60  is located on the side of one side wall of the casing  11 , the pump driving motor  70  is located on the side of the other side wall of the casing  11 , as well as a part of the pump driving motor  70  is arranged in a state received in a side space defined by the manifold  75  and the other side wall of the casing  11 . 
     (B) The pressure sensor  84  is arranged on the side of the control circuit board  15 , i.e., by utilizing a space defined between the manifold  75  and the control circuit board  15 . 
     A recessed part  46  for receiving an end part of the connecting tube  95  is formed at a rear end part on the side of one side wall in the casing  11 , and the gas feed-side plug  49  is fitted in the gas outlet port  47 A opened in the recessed part  46 , whereby the length of the gas flow path in the casing  11  can be shortened, the pump device  60  and the manifold  75  forming the gas flow path can be made small compared with a case where no recessed part  46  is formed, and moreover a joined part between the pump device  10  and the connecting tube  95  is formed within the recessed part  46 , whereby the joined part can be protected, and release of the joined state between the pump device  10  and the connecting tube  95  can be prevented with certainty. 
     In the above-described pump device  10 , the anti-detaching metal band  12  is fitted on the joined area between the front case  20  and the rear case  40 , and the anti-detaching metal band  12  is fixed to the casing  11  by the screw  13 , whereby exchange of, for example, the pump  61  and other maintenance works can be carried out by extremely simple work that the screw  13  is removed to remove the anti-detaching metal band  12 , and the joining between the front case  20  and the rear case  40  is released, and high convenience for use is hence achieved. 
     &lt;Portable Gas Alarm Device&gt; 
     FIG. 13 is a longitudinal cross-sectional view schematically illustrating the construction of an exemplary gas alarm device connected to the pump device according to the present invention viewed from a direction indicated by an arrow A in FIG. 1, FIG. 14 is a transverse cross-sectional view schematically illustrating the construction of a gas detecting part formed at one side surface of the portable gas alarm device, and FIG. 15 is a perspective view schematically illustrating the construction of an exemplary gas feed adapter installed in a gas alarm device body. 
     In this specification, the left and right direction, upward and downward direction and a direction perpendicular to the drawing in FIG. 13 are referred to as “forward and backward direction”, “upward and downward direction” and “width direction”, respectively. 
     A gas alarm device body  100 A has a substantially box-like casing  110  formed by a case body  111  having an opening at a lower part and formed of, for example, a polymeric material, and a conductive lid  112  joined and fixed to the opening part in the case body  111  by a plurality of screws (not illustrated) with a sealing member  101  composed of a ring-like packing therebetween. Fitting member fixing parts  113  in which a fitting member (not illustrated) such as, for example, a band for fitting on a person&#39;s body to carry the gas alarm device body  100 A is installed are respectively formed at lower end parts in the front end edge and rear end edge of the casing  110 . 
     As illustrated in FIG. 1, a gas detecting part is formed along one side surface (side surface on an inmost side in FIG. 13) of the casing  110  in such a manner that a plurality of gas sensors, which detect gases of different kinds from each other, are arranged side by side in a plane direction of said one side surface. 
     A charging terminal  107  for charging a secondary battery  147  as a driving power source, which will be described subsequently, and a communication terminal  108  for transmitting a gas concentration data detected by the gas sensors are provided at the other side surface in the casing  110 . 
     In FIG. 1, reference numeral  152  indicates a light emitting part for alarm which raises an alarm by light emission. 
     A power unit  140  composed of a flat plate-like circuit board  145 , on which the charging terminal  107 , the secondary battery  147 , a current limiting resistance  148  and other various necessary functional elements are mounted, and an insulating cover member  142  provided integrally with the circuit board  145  to cover the whole surface of the circuit board  145  is arranged in the casing  110  in such a manner that the circuit board  145  extends in parallel with the conductive lid  112  in the forward and backward direction. Fixing claw parts  141  respectively formed so as to extend downward at the front end part and rear end part of the insulating cover member  142  are engaged with and fixed to recessed parts  114  formed in an inner wall surface of the case body  111 . 
     A panel-like display mechanism  155  composed of a liquid crystal display panel and an alarm buzzer  160  making up an alarm annunciating mechanism are arranged on the upper side of the power unit  140  so as to stand in a plane direction (forward and backward direction) of the circuit board  145 , and the alarm buzzer  160  is contained in a cylindrical buzzer holding part  161  formed in the case body  111  in a state located over the secondary battery  147  in the power unit  140 . 
     A signal processing unit  150  composed of a control circuit board  153 , on which a memory element for saving log data, an external operation switch  151 , a light emitting element for alarm and other various necessary functional elements are mounted, is arranged under the panel-like display mechanism  155 , and the panel-like display mechanism  155  is connected to the control circuit board  153  through a plate-like conductive member  156  composed of anisotropically conductive rubber. 
     A window plate  157  for protection is arranged over the panel-like display mechanism  155 . 
     A light guide plate is provided at a position under the panel-like display mechanism  155 , and a back light composed of a light emitting diode (not illustrated) that the panel-like display mechanism  155  is irradiated with light through the light guide plate is provided. 
     The conductive member  156  exhibits conductivity in the upward and downward direction, and the control circuit board  153  is held fixedly by a holding part  116  formed in the case body  111  in a state that the conductive member  156  has been pressed in the upward and downward direction, whereby the panel-like display mechanism  155  is electrically connected to the control circuit board  153 . 
     As described above, a gas detecting part is formed at one side surface in the gas alarm device body  100 A in such a manner that a plurality of the gas sensors, which detect gases of different kinds from one another, are arranged side by side in a plane direction of said one side surface. 
     As illustrated in FIG. 14, a sensor holding part  115  which holds a plurality of gas sensors on one side surface of the casing  110  is formed in the gas detecting part  121 . Four (4) button type gas sensors  120 A to  120 D, for example, which detect the objective gases to be detected of different kinds from one another, are contained in this sensor holding part  115 , and fixed and held by a gas sensor fixing frame member  126  detachably engaged with the sensor holding part  115  through a sealing member  102 . 
     As the gas sensors  120 A to  120 D, any gas sensor elements may be used according to the kinds of the objective gases to be detected. As examples thereof, may be mentioned a galvani cell type gas sensor element which detects oxygen gas, a potentiostatic electrolysis type gas sensor element which detects carbon monoxide gas, a potentiostatic electrolysis type gas sensor element which detects hydrogen sulfide gas, and a catalytic combustion type gas sensor element which detects hydrocarbon gases. 
     The gas sensor fixing frame member  126  is formed by engaging or interlocking integrally a sensor fixing frame  126 A, a first fixing frame, and a filter fixing frame  126 B, a second fixing frame, with each other, and through-holes  122 A to  122 D are formed corresponding to the respective gas sensors  120 A to  120 D, whereby gas inlet ports  125 A to  125 D as to the respective gas sensors  120 A to  120 D are formed independent of one another. 
     A dust protective filter  127  which removes dust contained in the air being introduced in the gas sensors and is common to the gas sensors  120 A to  120 D is interposed between the sensor fixing frame  126 A and the filter fixing frame  126 B. 
     Since the gas sensors  120 A to  120 D may be affected by interfering gases according to the kinds of the gases to be detected, for example, hydrocarbon gases or carbon monoxide gas, a filter  128  for removing interfering gases is interposed between the sensor fixing frame  126 A and the dust protective filter  127 . 
     The gas sensor fixing frame member  126  engaged with and detachably installed in the casing  110  in the above-described manner is fixed to the casing  110  by screws (not illustrated), whereby the gas sensors  120 A to  120 D can be exchanged by extremely simple work that the screws are removed to remove the gas sensor fixing frame member  126  from the casing  110  when the sensitivity of the gas sensors  120 A to  120 D is lowered due to, for example, long-term service. When the functions of the dust protective filter  127  and the filter  128  for removing interfering gases are lowered, such filters  127 ,  128  can also be exchanged by extremely simple work. 
     A gas feed adapter  130  is detachably installed in the casing  110  of the gas alarm device body  100 A in a state covering the gas detecting part  121  outside the gas sensor fixing frame member  126  in the gas alarm device body  100 A. 
     As illustrated in FIG. 15, the gas feed adapter  130  is equipped with a casing  131  composed of a frame part  131 A in which the gas sensor fixing frame member  126  in the gas alarm device body  100 A should be contained, and a tapered part  131 B formed so as to extend outward in the width direction in continuity with the frame part  131 A. Engaging claws  132 ,  132  detachably engaged with the gas alarm device body  100 A are respectively formed in the front end wall and rear end wall of the frame part  131 A of the casing  131  so as to extend inward in the width direction. The engaging claws  132 ,  132  are engaged with engaging grooves  117 ,  117  formed in the front wall and rear wall of the casing  110  in the gas alarm device body  100 A, whereby attachable and detachable state is retained. 
     A recessed part  133  for arranging a connecting terminal connected to the connecting tube  95 , in which a gas feed port  133 A opened forward has been formed, is formed in the front end part in the tapered part  131 B of the casing  131 . A gas inlet-side plug  134  which is the connecting terminal is installed in the gas feed port  133 A so as to project forward. 
     A gas outlet port  133 B which communicates the internal space in the casing  131  to the air is formed at a diagonal position to the gas feed port  133 A in the rear end part in the tapered part  131 B so as to open backward. 
     On the internal side of the tapered part  131 B of the casing  131 , 4 cylindrical parts  135 A to  135 D extending in the width direction are formed at positions corresponding to the gas sensors  120 A to  120 D of the gas alarm device body  100 A so as to successively stand in the forward and backward direction in an integrally joined state. 
     In the cylindrical parts  135 A to  135 D, communication holes  136  for communicating the internal spaces thereof successively are respectively formed, thereby forming a gas inlet passage extending linearly in the forward and backward direction, and communicating with the gas feed port  133 A and the gas discharge port  133 B. 
     In each of the cylindrical parts  135 A to  135 D, circular recessed portions  137  are respectively formed at the end surfaces on the internal side, whereby sealing member holding parts in which sealing members  103 A to  103 D are respectively received and held are formed. 
     As illustrated in FIG. 16, the sealing member  103 A is formed by a ring-like part  104  and a plate part  105  extending outward in continuity with the outer end surface of the ring-like part  104 , and the sealing member  103 A is held by the sealing member holding part in a state inserted along a groove part  137 A for insertion formed in such a manner that the plate part  105  extends in the width direction at both upper end part and lower end part in the inner peripheral surface of the cylindrical part  135 . 
     In the plate part  105  in the sealing member  103 A, a hole  106  for passing air introduced into the gas feed adapter  130  through in a state received in the sealing member holding part is formed at a position in the vicinity of the ring-like part  104 . 
     The other sealing members  103 B to  103 D are also constructed in the same manner as in the sealing member  103 A. 
     Accordingly, the sealing members  103 A to  103 D are respectively held by the sealing member holding parts in the cylindrical parts  135 A to  135 D, whereby the plate part  105  in each sealing member functions as a so-called baffle that prevents air from being passed through directly from the gas feed port  133 A to the gas discharge port  133 B, and a zigzag main gas inlet passage  138  (indicated by an alternate long and short dash line in FIG. 14) extending in the forward and backward direction as a whole is formed. 
     The internal spaces in the cylindrical parts  135 A to  135 D are respectively airtightly communicated with the gas inlet ports  125 A to  125 D independent of one another in the gas sensor fixing frame member  126  through the sealing members  103 A to  103 D, whereby 4 branched gas inlet passages  139  (indicated by a broken line in FIG. 14) independent of one another for respectively introducing air in the objective space to perform gas measurement in the gas sensors  120 A to  120 D in the gas alarm device body  100 A are formed. 
     The operation of the portable gas alarm device of the above-described constitution will be described. 
     When the portable gas alarm device  100  is operated, the respective gas sensors  120 A to  120 D and the panel-like display mechanism  155  are being operated. In this state, the pump device  10  connected to the potable gas alarm device  100  is driven, whereby air in the objective space to perform gas measurement is fed into the gas feed adapter  130  through the connecting tube  95 , passed through along the zigzag main gas inlet passage  138  in the gas feed adapter  130  while flowing through the respective branched gas inlet passages  139  and then discharged from the gas outlet port  133 B. Accordingly, the air fed into the gas feed adapter  130  by the pump device  10  is introduced into the respective gas sensors  120 A to  120 D making up the gas detecting part  121  in substantially the same state as the state that the air in the objective space to perform gas measurement reaches the gas detecting part  121  by diffusion, whereby the concentrations of the objective gases to be detected are detected. 
     The concentrations of the objective gases to be detected by the gas sensors  120 A to  120 D are sent as current signals or voltage signals to the signal processing unit  150  to be processed. The gas concentrations at each time are stored in a memory device, and the concentration of any gas selected by the external operation switch  151  is displayed by the panel-like display mechanism  155 . The time can be displayed by operating the external operation switch  151  as needed. 
     An alarm actuating signal is generated when the concentration of the objective gas to be detected exceeds the reference value preset as to such a gas, thereby driving an alarm annunciating mechanism to raise an alarm. 
     For example, when the objective gas to be detected is oxygen gas (O 2  gas), the reference value is determined to be 18.0 vol. % by way of example, and an alarm actuating signal is outputted when the concentration becomes a value lower than this reference value. The reference value is determined to be 10% LEL (gas concentration of lower explosion limit) by way of example when the objective gas to be detected is a hydrocarbon gas (HC gas). The reference value is determined to be 25 ppm by way of example when the objective gas to be detected is carbon monoxide gas (CO gas), while the reference value is determined to be 10 ppm by way of example when the objective gas to be detected is hydrogen sulfide gas (H 2 S gas). An alarm actuating signal is generated when the concentration exceeds each reference value. 
     In the illustrated embodiment, the alarm buzzer  160  and a light emitting element for alarm are provided as alarm annunciating mechanisms, and an alarm is raised by buzzer sound and light emission. 
     The alarm annunciating mechanism can be constructed by providing a vibration generator for alarm, which generates low frequency wave of about several tens Hz. In this case, an alarm is raised by buzzer sound by the alarm buzzer  160 , light emission by the light emitting element for alarm and vibration by the vibration generator for alarm. 
     When plural kinds of alarm annunciating mechanisms are provided as described above, it is not necessary to drive all the alarm annunciating mechanisms at the same time, and it is preferable to conduct a cyclic alarm operation that the respective alarm annunciating mechanisms are successively driven only for a predetermined period of time. According to such drive control, the consumption of the battery can be inhibited compared with the case where all or a plural of the alarm annunciating mechanisms are driven at the same time. 
     According to the above-described portable gas alarm device  100 , the gas detecting part  121  is formed at one side surface of the casing  110  making up the gas alarm device body  100 A, and the charging terminal  107  and the communication terminal  108  are provided at the other side surface, whereby calibration operation of the gas sensors  120 A to  120 D can be performed by feeding a standard gas from one side part, and at the same time, the secondary battery  147  as a driving power source can be charged without obstacle to practice the calibration operation of the gas sensors  120 A to  120 D. 
     The portable gas alarm device  100  is basically fitted on a person&#39;s body by the fitting member such as a band and carried together with its body by the person. Accordingly, when the environmental atmosphere of the person becomes a dangerous state due to high concentration of the dangerous gas contained or low oxygen gas concentration, that the condition is annunciated by the display of the panel-like display mechanism  155 , and light emission of the light emission part  152  for alarm, buzzing of the alarm buzzer  160  and operation of the vibration generator for alarm. Accordingly, the person can immediately dispatch, take proper protective means, or take some counter measure such as evacuation from such a site. 
     The above-described portable gas alarm device  100  can detect dangerous gases contained in air in the objective space to perform gas measurement by diffusion as it is. According to the gas alarm unit constructed by fitting such a gas feed adapter  130  and connecting the pump device  100  according to the present invention by the connecting tube  95  as described above, however, the portable gas alarm device  100  is fitted on a person&#39;s body and carried together with its body by the person, and the pump device  10  is used in a state held by a hand, whereby such a gas alarm unit has extremely high convenience for use as a portable gas alarm unit as to dangerous gases in specific spaces. 
     Accordingly, prescribed gas detection can be performed by pointing, for example, the tip nozzle of the pump device  10  to the intended place, so that concentration measurement of dangerous gases can be performed even in a place where no person can enter, and high safety can be kept. 
     According to the above-described gas feed adapter  130 , a state substantially equal to natural diffusion can be realized because the main gas inlet passage  138  for feeding air in the objective space to perform gas measurement to the gas detecting part  121  of the gas alarm device body  100 A is opened to the atmospheric air though the air is forcedly introduced by the pump device  10 . In addition, the main gas inlet passage  138  is formed so as to extend zigzag, and the branched gas inlet passages  139  are formed corresponding to the respective gas sensors  120 A to  120 D, whereby air introduced by pump device  10  can be surely fed to the respective gas sensors  120 A to  120 D. 
     Although the embodiments of the present invention have been described above, various changes and modifications may be added thereto without being limited to the above embodiments. 
     For example, specific constructions of the respective parts in the actual pump device, for example, the gas discharge quantity and other performance of the pump, the internal dimensions of the gas flow path formed in the casing or gas flow rate, the opening diameter of the gas discharge port of the gas feed-side plug and other constitutions can be suitably changed as necessary for the end application intended. 
     A tube having a length of 8 to 10 m, to the tip of which a float has been connected in place of the tip nozzle, can be selectively connected. According to such a construction, when the condition of air in the objective space to perform gas measurement, such as a place where water stays, space within a manhole, for example, is determined, the prescribed determination or measurement can be performed with certainty without sucking water into the pump device by throwing the float in such a place.