Abstract:
The invention relates to a spray gun comprising a gun body ( 1 ), a nozzle arrangement ( 9 ) arranged on said gun body ( 1 ), a compressed air supply channel ( 22, 23 ) which is arranged in the gun body ( 1 ) and which comprises a valve arrangement ( 17 ) for controlling the compressed air supply to the nozzle arrangement ( 9 ), a device ( 31, 33, 37, 42, 40 ) for controlling the compressed air supply, and a pressure measuring device ( 35 ) for recording and displaying the pressure in the compressed air channel ( 22 ). Said invention is characterized in that said pressure measuring device ( 35 ) is secured in a removable manner to the device ( 31, 33, 37, 42, 40 ) for controlling the compressed air supply.

Description:
FIELD OF THE INVENTION 
     The invention concerns a spray gun and a testing air cap for a spray gun. 
     BACKGROUND OF THE INVENTION 
     Such a spray gun is known from EP 1 294 490 B1. With this spray gun with a gun body, a nozzle arrangement on the gun body, a compressed air supply channel arranged in the gun body, with a valve arrangement for the control of the supply of the compressed air for the nozzle arrangement, and a device for regulation of the supply of compressed air, a pressure measuring device for the recording and display of the pressure in the compressed air supply channel is integrated into the device for regulation of the supply of compressed air. The pressure measuring device is thereby accommodated in a housing, wherein the housing is appropriately designed as a turning knob and in this way, the function of an adjustment element is exerted, with which the compressed air supplied to the nozzle arrangement can be regulated. 
     The disadvantage in this arrangement is that for regulation of the supply of compressed air, the pressure measuring device, which has a pressure display, is rotated, wherein the pressure display also assumes various settings, dependent on the setting of the rotating knob, and, under certain circumstances, is upside down in certain settings. In such unfavorable settings, the user can read the pressure display only with difficulty. With the known arrangement, a pressure measuring device, desired as a digital manometer, with a digital display is preferably used. A needed replacement of batteries proves to be cumbersome hereby, since to do this, the device for regulation of the supply of compressed air must first be dismantled from the spray gun and then the pressure measuring device integrated therein. Moreover, with the known arrangement, there is the danger of an unintended adjustment of the rotating knob, wherein, the supply of the compressed air is unintentionally changed. Furthermore, when cleaning the spray gun, the digital manometer can be brought into contact with the cleaning agent and can be soiled or damaged. 
     SUMMARY OF THE INVENTION 
     Proceeding from this, a goal of the invention is to further develop a generic spray gun so that it has a functioning pressure measuring device, which is, if possible, satisfactory at any time. 
     This goal is attained with a spray gun and with a device for incorporation into a compressed air-operated spray gun for regulation of the supply of compressed air, and of a pressure measuring device, as set forth herein. Preferred embodiments of the spray gun, in accordance with the invention as well as other advantageous details and developments of the invention are also set forth herein. 
     With the spray gun, in accordance with the invention, it is possible for the pressure measuring device not to be soiled or damaged during cleaning operations and for a battery replacement during the use of a digital manometer to be carried out simply. With the spray gun, in accordance with the invention, it is ensured that the pressure display of the pressure measuring device is stationary, independent of the setting of regulation of the supply of compressed air, and that it can be read well at any time and that an unintended adjustment of regulation of the supply of compressed air can be avoided. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The invention is explained in more detail, below, with the aid of exemplified embodiments, with reference to the accompanying drawings. The drawings show the following: 
         FIG. 1 : a partially cut side view of a spray gun, in accordance with the invention, with an inserted device for regulation of the supply of compressed air and a pressure measuring device affixed thereon; 
         FIG. 2 : a perspective view of a spray gun, in accordance with the invention, with a drawn-out device for regulation of the supply of compressed air and the pressure measuring device affixed thereon; 
         FIG. 3 : perspective view of the spray gun of  FIG. 2  with an inserted device for regulation of the supply of compressed air and a pressure measuring device removed therefrom; 
         FIG. 4 : side view of a device, in accordance with the invention, for regulation of the supply of compressed air of a spray gun, in accordance with the invention, with a pressure measuring device affixed thereon; 
         FIG. 5 : perspective view of the device for regulation of the supply of compressed air of  FIG. 4 , with a pressure measuring device removed therefrom; 
         FIG. 6 : blow-up representation of the device for regulation of the supply of compressed air of  FIG. 4  with a pressure measuring device affixed thereon; 
         FIG. 7 : detailed view of the device for regulation of the supply of compressed air of  FIG. 4 , in cross-section ( FIG. 7   a ) and detailed view of the device for regulation of the supply of compressed air in cross-section, with a pressure measuring device affixed thereon ( FIG. 7   b ); 
         FIG. 8 : perspective view of a digital pressure measuring device; 
         FIG. 9 : perspective view of another digital pressure measuring device; 
         FIG. 10 : perspective view of another spray gun, in accordance with the invention, with an inserted device for regulation of the supply of compressed air; 
         FIG. 11 : the spray gun, in accordance with  FIG. 10 , with a pressure measuring device removed therefrom; 
         FIG. 12 : perspective view of a testing air cap with pressure measuring device, in accordance with the invention; and 
         FIG. 13 , the testing air cap, in accordance with  FIG. 12 , with a pressure measuring device removed therefrom. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The spray gun shown in  FIGS. 1-3  contains a gun body  1  with a grip  2  and an upper part  3 , on which a suspension hook  4  is formed. A passage borehole  5 , which is continuous from front to back and is multiply graduated and in which a nozzle needle  6  is conducted axially, so that it can be displaced, runs through the upper part  3 . In a front area, the passage borehole  5  forms an expanded holder space  7 , into which an inclined inflow borehole  8  opens for the mounting of a paint-holding container, which is not depicted. On the front end of the passage borehole  5 , a nozzle arrangement  9  is mounted, which contains a fixable paint nozzle  10 , by means of a thread, on the upper part  3  of the gun body  1 . The paint nozzle  10  has a nozzle borehole  11 , on its front end, which, together with a tapering front end part of the nozzle needle  6 , which can move axially via an actuation lever  12 , forms a regulatable inflow for the paint, varnish, or the like. The actuation lever  12  is connected with the nozzle needle  6  in such a way that it is pushed backwards against the force of a spring  13 , when the actuation lever  12  is retracted, and opens the nozzle borehole  11  for the release of the paint. The pretension of the compressed spring  13  and the path of the nozzle needle can be adjusted, when the actuation lever is retracted, by means of an adjusting screw  14 , with a corresponding counter nut  15 , located on the back end of the passage borehole  5 . By means of the actuation lever  12 , furthermore, a valve arrangement  17  for the control of the supply of the compressed air to the nozzle arrangement  9  can be actuated via a bar  16 . 
     The valve arrangement  17  contains a closing cone  18 , connected with the rod  16 , and a valve seat  20 , provided in a borehole  19  in the gun body  1 , against which the closing cone  18  is pressed by a spring  21 . When the actuation lever  12  is retracted, the closing cone  18  is lifted above the rod  16  from the valve seat  20 , against the force of the spring  21 , wherein a connection is opened to the nozzle arrangement  9 , between a lower part  22  of a compressed air supply channel for the supply of the compressed air, placed upstream from the valve arrangement  17  and an upper part  23 , placed downstream from the valve arrangement  17 . A compressed air connection  24  for a compressed air conduit, which is connected with the lower part  22  of the compressed air supply channel, is located on the underside of the grip  2 . 
     From the upper part  23  of the compressed air supply channel, the compressed air is conducted to an air conducting system  25  and, from there, to an annular gap  26 , which is formed by the nozzle borehole  11  and the front ends of the paint nozzle  10 . In the area of the nozzle borehole  11 , the compressed air produces a vacuum, through which the paint is suctioned from the paint nozzle borehole and is entrained with the compressed air, forming a round jet. Via so-called horn air boreholes  27  in the projecting horns  28  of an air cap  29 , surrounding the paint nozzle  10 , the compressed air can also exit for the formation of the round jet into a flat jet. The air cap  29  can be affixed, via a union nut  30 , on the upper part  3  of the housing  1 . Control boreholes  27   a  in the air nozzle are thereby used for the formation of the jet. 
     Furthermore, a device for regulation of the supply of compressed air is located in the borehole  19  in the gun body  1 . This device contains a rotatable sleeve  31 , which has a transverse borehole  32  in the area of the discharge of the lower part  22  of the compressed air supply channel into the borehole  19 . The sleeve  31  is connected, in a stationary manner, with a rear holding part  33 , which is arranged, so it can rotate, on the rear end of the borehole  19 . By rotating the holding part  33 , it is thus possible to rotate the sleeve  31  also and thus it is possible to regulate the air passage in the area of the transverse borehole  32 . 
     The device for the regulation of the compressed air supply also comprises a housing connecting piece  42  and an affixing plate  40 , formed on it as one piece. The holding part  33  is shoved into the hollow-cylindrical connecting piece  42 , in a manner so it can be turned. The connecting piece  42  is affixed on the spray gun body  1 , via an affixing screw  51  ( FIGS. 2 and 3 ), which meshes into a borehole  50  on the connecting piece  42  ( FIG. 4 ). The connecting piece  42  and the holding plate  40 , formed thereon, can therefore not be turned, vis-a-vis the spray gun body  1 . A pressure measuring device  35  is affixed on the affixing plate  40  in such a way that it can be removed. 
     The device for regulation of the supply of compressed air, with the pressure measuring device  35 , is shown, in  FIG. 4 , in a side view and, in  FIG. 6 , in a blowup representation, in detail. From the blowup representation of  FIG. 6 , one can see the structure of the device for regulation of the supply of compressed air and the pressure measuring device  35 , affixed thereon, in detail. As shown in  FIGS. 4 and 6 , the device for regulation of the supply of compressed air comprises the hollow-cylindrical connecting piece  42 , on which the affixing plate  40  is formed, as one piece. The connecting piece  42  and the affixing plate  40  are preferably made of metal. The affixing plate  40  and/or the connecting piece  42  can also be made of plastic, combinations of metal/plastic, or other suitable materials. A longitudinal hole  45  is introduced in the hollow cylindrical connecting piece  42 , on the outer circumference of the connecting piece  42 , which extends over an angular area of approximately 90° C. The angular area should be maintained more or else. With an angle of approximately 60°, namely, a sufficient rotational movement would not be possible at all; with an angle of approximately 180°, the rotational movement would be undesirably large. A central passage borehole  43  is introduced in the affixing plate  40 . The front part of the holding part  33 , depicted dark in  FIG. 6 , is shoved in the hollow-cylindrical connecting piece  42 , so that it can turn. The holding part  33  is connected with the sleeve  31 , in a stationary manner, via a form-locking connection, for example, a square (hexagonal) and fixed on the holder part  33  by means of an affixing screw  52  and is sealed off with a sealing element, designed here as a sealing ring  46 . A sealing element could also be injected or affixed in some other manner. A regulating lever  37  is shoved over the outer circumference of the hollow-cylindrical connecting piece  42  and placed so that it cannot rotate, relative to the connecting piece  42 . The regulating lever  37  has an annular base  37   a  with two vanes  37   b ,  37   c , formed on it, as one piece, and is connected with the holding part  33  by means of a connecting bolt  47 , which meshes through the longitudinal hole  45 . The regulating lever  37  can be turned, relative to the connecting piece  42 , in an angular area specified by the longitudinal hole  45 . Upon rotating the regulating lever  37 , the holding part  33 , articulated on it, with the bolt  47 , and the sleeve  31 , connected with it in a stationary manner, turn. In this way, the compressed air supplied to the compressed air supply channel  23 , from the compressed air channel  22 , can be regulated upon rotating the regulating lever  37 . The end areas of the two vanes  37   b ,  37   c  of the regulating lever overlap the outer circumference of the affixing plate  40  and on the outer circumference of the affixing plate, markings on which the position of the regulating lever can be read off are preferably placed. 
     To record the pressure of the compressed air supplied to the compressed air supply channel  23 , the compressed air measuring device  35  is provided, which is affixed, in a removable manner, on the device to regulate the supply of the compressed air. The structure of the pressure measuring device  35  and the mode of fastening on the device for regulation of the supply of compressed are likewise visible from the blowup representation of  FIG. 6 . The pressure measuring device  35  comprises a housing lower part  35   a , a pressure measuring unit  35   b  with a pressure recorder  38 , and a housing lid  35   d . In the embodiment shown in the drawings, the pressure measuring device  35  is designed as a digital manometer with an electronic digital display  39 . Instead of a digital manometer, however, a manometer with an analog pressure display (pointer indicator) can also be used. In the digital manometer represented here graphically, a removable battery  35   c  is provided for the energy supply. In order to be able to replace the battery  35   c , the housing lid  35   d  can be removed from the housing lower part  35   a.    
     In the two other development forms shown graphically in  FIGS. 8 and 9 , a compartment  100  is located in the housing part  35 , in which the battery  35   c  is kept and accordingly can be pushed in and out without any problem and therefore can be replaced, without the digital manometer having to be taken apart. Appropriately, the compartment  100  is essentially shaped in the form of a block and has a positioned cylindrical blind hole  101 , whose size is coordinated with the size of the battery  35   c , designed here as a round cell battery, in such a way that its surface closes planarly with the surface  102  of the compartment  100 . The compartment  100  is placed in an opening  103  provided in the housing  35  so that it can be moved and is sealed hermetically tight, relative to the housing  35 , by means of (nondepicted) sealing elements. If the compartment is made of plastic, the sealing effect can preferably be produced by sealing lips formed on the plastic compartment. However, it can also be brought about by O-rings or the like. In the embodiment according to  FIG. 8 , the compartment  100  is thereby located right below the digital display  39  in the housing lid  35   d  and thus, in the front, on the pressure measuring device  35 , whereas with the embodiment according to  FIG. 9 , it is provided in a lateral area of the housing lower part  35   a . Since this housing lower part  35   a  is rounded off, the front area  104  of the compartment is also rounded off here. In both embodiments, the length of the compartment  100  is selected in such a way that the front area  104  of the compartment  100  projects slightly over the surface of the housing lid  35   d  or the housing lower part  35   a , so that the compartment  100  can be gripped well for the battery replacement. However, it would also be possible to provide a hook-like or knob-like projection on the front area  104  of the compartment  100  as a handle. Other developments of the compartment  100 , for example, in the frame or the like, are conceivable. 
     In another embodiment, which is not depicted, the compartment  100  is supported on its rear area, opposite the front area  104 , by one or more springs on the housing  35 . Positionings for the compartment  100 , for example, latching elements, are provided on the compartment  100  and/or on the housing opening  103 . In this way, an automatic opening and perhaps, closing of the compartment  100  can be implementing after exerting slight manual pressure on the front area  104  of the compartment  100 . 
     Affixing elements  49  are provided on the rear side of the housing lower part  35   a . These affixing elements  49  are designed in such a way that they work together with complementary affixing elements  41  on the affixing plate  40 , if the pressure measuring device  35  is affixed on the device for regulation of the supply of compressed air. In the embodiment example shown here graphically, the affixing elements  49  and  41  are complementary elements of a dovetail joint. To affix the pressure measuring device  35  on the device for regulation of the supply of compressed air, the affixing elements  49 , located on the rear side of the housing lower part  35   a , are shoved into the complementary affixing element  41  of the dovetail joint, as they are alluded to, in  FIG. 3 , with the double arrow. In order to prevent an unintended loosening of the dovetail joint, a latching connection is also provided, which is implemented by a latching groove  53  in the affixing plate  40  and a latching lug  54 , complementary to it, on the rear side of the housing lower part  35   a  ( FIGS. 4 ,  5 , and  7 ). In order to guarantee a correct positioning of the pressure measuring device  35  on the affixing plate  40 , a projection  55  is also provided on the rear side of the housing lower part  35   a ; it works together with a complementarily shaped recess  56  of the affixing plate  40  ( FIG. 5 ). The recess  56  makes possible, with a removed pressure measuring device, the complete unscrewing of the adjusting screw  14  and the dismantling of the nozzle needle  6 , without dismantling the affixing plate  40 . Furthermore, it makes possible a particularly simple positioning of the display. The detachment, in accordance with the invention, is therefore very effective and, nevertheless, can be simply managed. 
     The pressure measuring device  35  could, however, be affixed by means of a clamping, screwing, bayonet-type, or latching connecting, by means of a magnetic connection, in another way, on the device  31 ,  33 ,  37 ,  42 ,  40  for regulation of the supply of compressed air. 
     In other nondepicted embodiments, the pressure measuring device  35  could be affixed, in a nondetachable manner, by the device  31 ,  33 ,  37 ,  42 ,  40  for regulation of the supply of compressed air. Such embodiments can, for example, be produced by the cementing or welding of the pressure measuring device  35  on the device  31 ,  33 ,  37 ,  42 ,  40 . 
     In another embodiment which is also not depicted, the affixing plate  40  and the housing  35   a  are made as one piece. 
     An air channel  36 ,  43 , which produces a connection from the compressed air supply channel to the pressure measuring device  35 , is provided in the device for regulation of the supply of compressed air for the transfer of the pressure of the compressed air from the compressed air supply channel  23  to the pressure measuring device  35 . The air channel comprises a capillary  36 , running in the holding part  33 , in its longitudinal direction, which discharges into the passage borehole  43  in the affixing plate  40 . The holding part  33  is sealed off by means of an O-ring  33   a , with respect to the hollow-cylindrical connection  42 . An air entry opening  57  is provided on the rear side of the housing lower part  35   a  of the pressure measuring device  35  ( FIG. 7 ). If the pressure measuring device is affixed on the device for regulation of the supply of compressed air, the air entry opening  57  is connected with the compressed air supply channel  22 ,  23  via the passage borehole  43  and the capillary  36 , and the pressure of the compressed air supply channel occurs on the pressure measuring device  35 . 
     The pressure-transferring connection between the pressure measuring device  35  and the device for regulation of the supply of compressed air is shown, in detail, in the section drawings of  FIGS. 7   a  and  7   b . In  FIG. 7   a , the rear area of the device for regulation of the supply of compressed air with the connecting piece  42  and the affixing plate  40 , located thereon, and the capillary  36 , running through the holding part  33 , is shown.  FIG. 7   a  shows the device for regulation of the supply of compressed air with a removed pressure measuring device. In this state, the passage borehole  43  in the affixing plate  40  is closed by a valve  44 . By means of the valve  44 , with the removed pressure measuring device  35 , the cleaning agent or varnish can be reliably prevented from penetrating, in an uncontrolled manner, into the capillary  36  and clogging it. Also, the exiting of compressed air and the penetration of liquid is prevented by the valve  44 . 
     With the embodiment example shown here graphically, the valve  44  is formed by a ball valve with a closure ball  44   a  and a spring  44   b  ( FIG. 6 ), wherein the spring  44   b  presses the closure ball  44   a  into the passage borehole  43 , if the pressure measuring device  35  is not affixed on the affixing plate  40 . In this position, a part of the closure ball  44   a  protrudes over the surface of the affixing plate  40 , as shown in  FIG. 7   a . If the pressure measuring device  35  on the affixing plate  40  is affixed, the rear side of the housing lower part  35   a  of the pressure measuring device  35  pushes the closure ball  44   a  against the force of the spring  44   b  from the passage borehole  43  back in the direction of the capillary  36 . In this way, the air channel  36 ,  43  is automatically opened. To produce the connection between the air channel  36 ,  43  and the air entry opening  57  on the pressure measuring device  35 , the air entry opening  57  is slightly moved, radially, toward the capillary  36 . By means of the radial movement, the air entry opening  57  on the pressure measuring device  35  is not closed by the closure ball  44   a  and the pressure prevailing in the compressed air supply channel  23  occurs on the pressure measuring device  35 . This effect could also be attained by a different valve, for example, a cone valve or a plate valve. A pressure recording space  34  is provided in the pressure measuring device  35 ; it is connected with the air entry opening  57 . Also, a pressure recorder  38 , for example, in the form of a piezo-resistant pressure recorder, is located in the pressure measuring device  35 ; by means of it, the occurring pressure is recorded in the pressure recording space  34  and is indicated by a digital or analog display device  39 . In order to guarantee a close connection between the air entry opening  57  on the pressure measuring device  35  and the passage borehole  43  in the affixing plate  40 , a sealing element  48 , in the form of an O-ring or an injecting plastic sealing element around the air entry opening  57 , is located on the reverse of the housing lower part  35   a . This sealing element  48  is pressed by the dovetail joint of the affixing elements  41 ,  49  between the reverse of the housing lower part  35   a  and the front side of the affixing plate  40 , so that the pressure in the transition range between the passage borehole  43  in the affixing plate  40  and the air entry opening  57  cannot escape. 
     With the spray gun shown in  FIGS. 10 and 11 , the valve arrangement  17  is provided for the control of the supply of the compressed air in the area of the connection  24  for the (nondepicted) pressure air conduit on the gun body  1 . For example, a compressed air hose can be connected to the hollow-cylindrical connecting piece  200 . The valve arrangement  17  has, as usual, a valve body  201  with a regulating knob  202 . A pressure measuring device  35 , which, as the pressure measuring device  35 , shown in  FIGS. 4-7 , is equipped with a digital display  39 , a housing lower part  35   a , a pressure measuring unit  35   b , a battery (not depicted), and a housing lid  35   d ), is placed, in a removable manner, on the valve body  201  of the valve arrangement  17 . For this purpose, a hole, which serves as the measurement opening, is provided in the valve body  201 . An affixing plate  40 , which is designed like the affixing plate  40 , shown in the previous embodiment examples, for example, in  FIG. 4 , and accordingly has a connecting piece with a central passage borehole  43 , is affixed, in a rotating-proof manner, with this passable borehole  43 , aligned with the hole in the valve body  201 . It can be, for example, screwed on, cemented on, or welded on. A valve assembly with the same or similar details as shown in  FIG. 6  (ball valve  44 , and so forth), is likewise provided; the pressure measurement can, accordingly, take place in the manner described previously. The pressure measuring device  35  is pressed on the affixing plate  40 , with the aid of the dovetail joint of the affixing elements  41 ,  49 , between the reverse of the housing lower case  35   a  and the front side of the affixing plate  40 . 
     The invention is not limited to the concretely described and depicted embodiments; other advantageous developments are readily conceivable. 
     In comparison to the arrangement known from the state of the art, the preferred embodiments of the spray gun, in accordance with the invention, are characterized in that the pressure measuring device  35  is affixed, in a removable manner, on the device for regulation of the supply of compressed air. The device for regulation of the supply of compressed air thereby appropriately comprises an affixing plate  40 , which is firmly joined, via a connected piece  42 , located thereon, and securely connected with the gun body, against turning. A manually actuatable regulating lever is provided on the device for regulation of the supply of compressed air, by means of which the compressed air, supplied to the compressed air supply channel, can be adjusted, without having to turn, for the purpose, the pressure measuring device, relative to the gun body. The pressure display  39  of the pressure measuring device can be read off well, for this reason, with each setting of regulation of the supply of compressed air. The pressure measuring device can be easily affixed, in a removable manner, on the device for regulation of the supply of compressed air, by means of affixing elements  41 ,  49 . This makes possible a simple and rapid, manual removal of the pressure measuring device, without the aid of a tool, if it, for example, is a disturbance during varnishing operations in sites which are difficult to access. Due to the simple removal of the pressure measuring device  35 , it is also possible to use the pressure measuring device for several different spray guns, without a complicated dismantling or installing being required in the gun bodies, from other spray guns. Moreover, due to the simple removal possibility of the pressure measuring device from the device for regulation of the supply of compressed air, a simple battery replacement is also made possible with digital pressure measuring devices. 
     For cleaning operations on the spray gun also, the pressure measuring device can be removed simply, so that it is not soiled or damaged. This is particularly advantageous when using automatic pistol cleaning devices. 
     The pressure measuring device  35  with the advantages described above can be used when using a bottom plate which is provided in the area  42  with a thread, etc., instead of a commercial nanometer, for example, with a cleaning or multiple use, etc. 
     Another advantage of the invention is that the spray gun can also be operated with a removed pressure measuring device  35 . 
       FIGS. 12 and 13  show how the pressure measuring devices  35 , in accordance with the invention, can be used, in other ways, on a spray gun. A testing air cap  300  of a commercial model, which is used to test center and horn air, is equipped with pressure measuring devices  35 . Two affixing plates  40  are affixed here, via affixing cones  400 , so they cannot rotate, for example, by screwing in, tightly, in the testing air cap  300 . A valve assembly with details which are the same or similar, as shown in  FIG. 6  (ball valve  44 , etc.), is also provided; the pressure measurement can accordingly also be carried out here as previously described. The affixing plates  40  also have a central passage borehole  43  here. The pressure measuring devices  35  also have a digital display  39 , a housing lower part  35   a , a pressure measuring unit  35   b , a battery (not depicted), and a housing lid  35   d  and are affixed, in a detachable manner, with the aid of the dovetail joint of the affixing elements  41 ,  49 , between the reverse side of the housing lower part  35   a  and the front side of the affixing plate  40 . 
     The pressure measuring device  35 , in accordance with the invention, however, can also be used in ways other than with spray guns—for example, with a filter unit in the varnishing cabinet area, instead of a usual manometer, or for the pressure measurement of tires of motor vehicles or bicycles. Possibilities of use as replacement of common pressure measuring units in other industrial areas (boiler systems) and nonindustrial areas are likewise conceivable.