MXPA97005306A - Restricted filter indicator visi - Google Patents

Abstract

The present invention relates to an indicator for signaling the restricted flow of air through an air filter mounted in a filter assembly, which includes: a housing that includes a central space, a side wall adjacent to the central space, a end wall adjacent to the central space, an end inlet in the end wall, and a side outlet in the side wall; a mounting element for mounting the end inlet of the housing in a mounting opening of the filter assembly, located downstream of the filter, whereby the housing is mounted inside the filter assembly, with the housing exposed to the suction pressure in the filter assembly, which moves air through the filter; the central space of the housing, the trip member including a signal portion extending adjacent the end entrance; a movement element for moving the door member; ring in the housing between a non-signaling position, wherein the signal member does not extend markedly through the end entrance, and a signaling position where the signal portion extends markedly through the entrance at the end, and is easily seen: a release element that responds to the pressure at the lateral outlet, to initially contain the firing member in the non-signaling position, and to prevent movement by the movement element, and to subsequently release the firing member when the suction pressure at the side outlet drops below a predetermined value in relation to an ambient air pressure outside the filt assembly.

Description

VISIBLE RESTRICTED FILTER INDICATOR FIELD OF THE INVENTION The present invention generally relates to an indicator for restricted flow through a filter, and more particularly to a visible indicator for an air filter assembly that gives a signal when the flow through the air filter it is restricted in an undesirable way.

BACKGROUND OF THE INVENTION When using an apparatus with an air filter, for example an air compressor, it is difficult to know when to change the air filter during operation, because the apparatus or the compressor unit has to be deactivated with the object to verify the visuality of the filter. In addition, when the filter is checked visually, it is often difficult to determine the amount of dirt already trapped by the filter, and if it is time to change the filter or the filter cartridge.

SUMMARY OF THE INVENTION In accordance with the present invention, a filter indicator system is provided to indicate when the air flow is restricted through a filter (or filter cartridge). In general, the filter indicator system includes an indicator and a filter that is part of a filter set. The filter assembly includes a mounting wall and an element for positioning the filter in the filter assembly, such that the air is directed into an inlet portion (upstream) of the filter assembly on one side of the filter (or filter wall) by a suction pressure through the filter, to an intake portion (downstream) of the filter assembly on the other side of the filter (or filter wall). The filter assembly also includes a mounting opening in the mounting wall, which is downstream of the filter for mounting the indicator. The indicator to give the signal of the restricted flow of air through the air filter includes a housing. The housing includes a central space, a side wall adjacent to the central space, an end wall adjacent to the central space, an end entrance in the end wall, and a lateral outlet in the side wall. A mounting element is provided for mounting the housing end entry to the mounting opening in the mounting wall located downstream of the filter, whereby the housing is mounted inside the filter assembly, with the housing exposed to the suction pressure in the filter assembly, which moves the air through the filter. A trigger member is located in the central space of the housing, and includes a signal portion extending adjacent to the end entrance. Then a movement element is used to move the firing member in the housing between a non-signaling position, where the signal member does not extend markedly through the end entrance, and a signaling position where the signal portion extends markedly through the end entrance, and is easily seen above the mounting wall. A release element responsive to the pressure at the lateral outlet is associated with the firing member to initially contain the firing member in the non-signaling position, and to prevent movement by the movement element, and to release subsequent to the firing member when the suction pressure at the side outlet drops below a predetermined value relative to an ambient air pressure outside the filter assembly, which is also present in the central space of the housing. According to a preferred embodiment, the release element includes: (a) a tolerance between the signal portion and the end entry, whereby the central space of the housing is subjected to ambient air pressure; (b) a seal element that fluidly restricts a flow of air from the central space of the housing to the lateral outlet, such that the seal element is subjected to the ambient air pressure on one side thereof, and to the suction pressure on the other side thereof, - and (c) a forcing element for forcing the seal element against the movement, the forcing element allowing a release movement of the seal element when the suction pressure falls below the previously determined value, and a reset movement of the seal element when the suction pressure rises above the predetermined value. In addition, the lateral outlet of the housing includes a side tube extending away from the side wall of the housing, and fluidly connecting the central space of the housing with the suction pressure in the filter assembly. Then the trigger member includes a trap portion, and the seal member is a plug member, such as a ball located in a cylindrical bore of the side tube adjacent to the trapping portion of the trigger member, when the trigger member it is in the non-signaling position, in such a way that the plug member is forced to engage with the trapping portion by the forcing element, to prevent movement of the housing to the signaling position. In the preferred embodiment, the forcing element includes a spring, a lid member, a small opening in the lid member, and a releasable attachment element for attaching the lid member to a free end of the side tube, such that The spring and ball are held in the cylindrical hole of the side tube by the end cap, but can be inserted and removed from the side tube by removing the end cap from the free end. In addition, the mounting element includes: (a) a mounting collar erect from the end wall that surrounds the end entry, and extends through the mounting opening in the wall of the filter assembly; (b) a lock collar that fits inside the mounting collar, and that has a central opening through which the signaling portion extends, and an outer flange extending away from the signaling portion, and rests against the mounting wall; and (c) a connecting element for attaching the lock collar to the end wall of the housing, such that the mounting wall is trapped between the outer flange of the lock collar and the end wall of the housing. Preferably, the housing is cylindrical, and the central space is defined by a cylindrical wall. The trigger member then includes a main body that is cylindrical and is closely adjacent to the cylindrical wall of the housing, such that the main body is mounted coaxially for a guided movement in the central space. The trigger member also includes a catch portion on the main body that engages with the release element. In addition, the signaling portion is cylindrical, coaxial with the main body, and extends from one end of the main body. More preferably, the housing includes an end opposite the end wall, and an end opening opposite the end. The movement element then includes a spring, a seal member, and a releasable seal element for attaching the cover member to the opposite end opening of the housing, opposite the end wall, to seal the opposite end opening. . With this construction, the spring is held in the housing with the spring compressed against the firing member by the end cap, but the spring and firing member can be inserted and removed from the housing by removing the end cap from the opposite end of the accommodation. It is an advantage of the present invention that an indicator is provided that is done in an inexpensive manner and is simple to install. It is also an advantage of the present invention that the disclosed indicator is economical to produce, and is easily seen to determine when a filter in use has a restricted air flow therethrough, up to the point where it was replaced. filter. It is a further advantage of the present invention that the indicator can be reset and used in association with a new filter once the capped filter has been replaced. It is still another advantage of the present invention that the indicator is made primarily of simple and inexpensive plastic and / or metal parts, and that it can be used in any orientation. Other features and advantages of the present invention are stated in, or are apparent from, the detailed descriptions of the presently preferred embodiments of the invention, which are found hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevation view in cross section of a filter system including an indicator in accordance with the present invention. Figure 2 is an elevation view in cross section of the indicator illustrated in Figure 1, in a non-signaling position. Figure 3 is an elevation view in cross section of the indicator illustrated in Figure 1, in a signaling position. Figure 4 is a part separated view of the indicator illustrated in Figures 2 and 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings, in which like numerals represent like elements throughout all views, in Figure 1 the filter indicator system 10 is illustrated for use with an air compressor (not shown). The filter indicator system 10 is used to indicate when the air flow has been restricted through a filter assembly 11, which includes a cylindrical filter 12, above a certain amount, typically because the air filter 12 is capped. with dirt or similar. As shown, the filter 12 is suitably placed in the filter assembly 11 by a suitable element, such as a threadably coupled holding plate 13, such that the filter assembly 11 is divided by the cylindrical filter 12 into a portion inlet or upstream 20 outside the filter 12, and an intake portion or downstream 22 entered from the filter 12, according to the air flow (schematically illustrated by the arrows). This air flow is caused by the compressor or the like, to which the filter assembly 11 is threadably attached, by mounting the tube 16 extending from the holding plate 13, as is well known in the art. As the air is directed through the filter 12, it will be appreciated that there is a suction pressure in the intake portion 22, and that this suction pressure is increased (the actual low pressure) when the filter 12 becomes clogged, and decreases the air flow through the filter 12. It will also be appreciated that, outside the filter assembly 11, there is an ambient air pressure. Provided in any suitable place in a mounting wall 14 of the filter assembly 11, which is a mounting opening 24. Mounted in the mounting opening 24 by a mounting element 18, there is an indicator 26 which is illustrated in detail in FIGS. Figures 2 to 4. It will be appreciated that the filter assembly 11, and consequently, the indicator 26, can be oriented in any direction besides that illustrated, and the position of the mounting opening 24 by the mounting wall 14 is selected for convenience. The indicator 26 includes a hollow plastic housing 28 which is preferably cylindrical. A central space 30 is provided in the housing 28, which is defined by an internal cylindrical wall 32. The housing 28 also includes an end wall 34 adjacent the central space 30, with an end entry 36 therein, as well as an end 38 also adjacent to central space 30 and opposite end wall 34, with an opposite end opening 40 therein. Extending between the end wall 34 and the opposite end 38, there is a side wall 42 adjacent the central space 30, with a side outlet 44 therein. Preferably, the side outlet 44 is formed by a side tube 46 extending away from the side wall 42. The side tube 46 includes a free end 48 and a cylindrical hole 50 therein, which connects to the intake portion 22. with the central space 30. As noted above, the housing 28 is mounted on the mounting wall 14 of the filter assembly 11 by a mounting element 18. The mounting element 18 includes a mounting collar 52 erect from the wall end 34. The mounting collar 52 surrounds and extends the end entrance 36 up through the mounting wall 14., as shown in Figures 2 and 3. Located above and on the mounting collar 52, there is a plastic lock collar 54. As shown, the lock collar 54 includes an outer flange 56 extending along of the mounting wall 14, such that the mounting wall 14 is trapped between the outer flange 56 and the end wall 34. The lock collar 54 also includes a central opening 58 which is defined by a portion of the divided leg 60. A connecting element 62 links the locking collar 54 with the end wall 34, with the mounting wall 14 trapped therebetween. The connecting element 62 conveniently is a trapping lip 64 formed on the outside of the leg portion 60, the leg portion 60 reaching a point, and dividing to facilitate insertion of the secure collar 54 at the inlet end 36. of the end wall 34. Obviously, other suitable joining elements are possible as is well known in this field, such as a threaded coupling or opposing teeth which would provide the ability to trap different sizes of mounting wall 14. Also possible are still possible. other joining elements, including other twisted coupling mechanisms, other instantaneous insurance mechanisms, screws, or the like. Provided in the central space 30 of the housing 28, there is a plastic firing member 66. The firing member 66 includes a main cylindrical body 68 that is sized to fit closely adjacent to, but separate from, the cylindrical wall 32 of the housing 28. , so that the firing member 66 is mounted in this manner for a coaxial movement guided in the cylindrical central space 30 of the housing 28. Provided in the main body 68, there is a catching portion 70, which is conveniently formed as a semicircular groove.

Extending away from one end of the main body 66, and upwardly through the end entry 36, there is a cylindrical signaling portion 72. It will be appreciated that the signaling portion 72 also extends through the central opening 58 of the collar 54, with a small tolerance therebetween, such that the central space 30 of the housing 28 is substantially at ambient atmospheric pressure outside the filter assembly 11. In order to move the firing member from a position which is not signaling, as illustrated in Figure 2, to a signaling position as illustrated in Figure 3, a movement element 74 is provided. It will be appreciated that, in the non-signaling position, the end free of the signaling portion 72 is substantially flush with the external surface of the external flange 56 of the lock collar 54; while, in the signaling position of Figure 3, the free end of the signaling portion 72 extends substantially above the lock collar 54. If desired, the signaling portion 72 is appropriately colored or marked to do more. easy to see or notice when the signaling portion 72 is in the signaling position. The movement element 74 includes a spring 76 which is compressed between the end 38 of the housing 28 and the main body 68 of the firing member 66. Conveniently, the firing member 66 and the spring 76 are loaded into the housing 28. through the opening of the opposite end 40 provided at the end 38. To accomplish this, the movement member 74 includes a plastic seal member 78 that sealingly closes the opposite end opening 40 to maintain the ambient pressure in the central space 30. The seal member 78 is releasably stopped in place in the opening of the opposite end 40 by a suitable releasable seal element 80. Conveniently, the releasable seal member 80 is similar to the attachment element 60. , and includes a split catch lip 81 that elastically stops seal member 78 on end 38 as shown. Obviously, other releasable seal elements are also possible, as is well known to ordinary experts in the field. The indicator 26 also includes a release element that responds to the pressure 82 located in the side outlet 44. The release element 82 is used to initially stop the firing member 66 in the non-signaling position, and thus preventing movement of the firing member 66 by means of the movement element 74. In other words, the release element 82 stops the firing member 66 against the force of movement exerted by the compressed spring 76. Then, when the suction pressure in the intake portion 22 falls below a predetermined value, for example, up to a value where the increase in suction pressure corresponds to a pressure drop through the filter 12 of 5 percent, the release element 82 releasing the firing member 66, such that the movement member 74, by the action of the spring 76, moves the firing member 66 from the non-firing position. signaling to the signaling position. In this preferred embodiment, the release element 82 includes a seal member or a pressure responsive member 84. The seal member 84 is preferably a cap member, such as a round steel ball 86 that is located in the hole 50 of the side tube 46. The ball 86 is dimensioned to fit movably in the hole 50, but to substantially fill the hole 50. The ball 50 is also sized to fit in the catching portion 70 of the firing member 66, when trigger member 66 is in the non-signaling position. With the 86 ball in place, it will be appreciated that the ball 86 is subject to the ambient air pressure on the side facing the central space 30 of the housing 28, and to the suction pressure of the intake portion 22 on the other side. Normally, the ball 86 is held in place in the trapping portion 70 of the firing member 66 by the resilient force of a force member 88. In the position engaged with the trapping portion 70, it will be appreciated that the ball 86 prevents the trigger member moves from the non-signaling position to the signaling position. The clamping force of the forcing element 88 is sufficient to stop the ball 86 in its position, despite the designated pressure difference between the ambient air pressure in the central space 30 and the suction pressure in the intake portion 22. However, when the filter 12 becomes sufficiently clogged, and the suction pressure is increased in the intake portion 22 (low), the biasing element 88 is designed to release the increased pressure differential through the ball 86, due to the increased suction pressure, and consequently, to allow a release movement of the ball 86 from the trapping portion 70. It will also be appreciated that after the filter 12 is replaced, the trapping member 88 also provides a force to move the ball 86 back to engage with the catching portion 70 when the signal portion 72 is pushed back into the housing 28 to reset the in The biasing element 88 preferably includes a spring 90 and a plastic cap member 92 with a small opening 94 therein. The small opening 94 in the cover member 92 ensures that the suction pressure present in the intake portion 22, is also present on the associated side of the ball 86. Conveniently, the cover member 92 stops on the free end 48 of the side tube 46 by a releasable attachment element 96. The releasable attachment member 96 is formed by opposing arms 98 that trap an outer lip 100 of the free end 48 as shown. In use, the filter indicator system 10 requires that first the mounting opening 24 (by design or with a drill or the like) be provided in the wall 14, in a position that is easily seen, and that is accessible from the inside and from outside the filter assembly 11. Once the mounting opening 24 is present, an indicator 26 is assembled otherwise, except for the lock collar 54; the mounting collar 52 of the housing 28 is passed from the inside of the filter assembly 11 through the mounting opening 24 in the mounting wall 14. While the indicator 26 is thus stopped in place, the collar is inserted. secure 54 through the mounting wall 14 from outside the filter assembly 11 around the signaling portion 72 of the trigger member 66, and inside the mounting collar 52, until the catch lip 64 of the lock collar 54 fit under the mounting collar 52. It will be appreciated that, since both the mounting collar 52 and the lock collar 54 are formed of a suitable elastic plastic material, the tolerance between the lock collar 54 and the signaling portion 72 allows the insertion of the lock collar 54 into the mounting collar 52, and the catch lip lock 64 after insertion. Once the trapping lip 64 is trapped under the mounting collar 52, the mounting wall 14 is comfortably caught between the outer flange 56 of the lock collar 54 and the end wall 34 of the housing 28; in this way the indicator 26 is mounted securely inside the filter assembly 11. Obviously, to have different thicknesses of the mounting wall 14, both the lock collar 54 and the mounting collar 52 would have different heights. It is also possible to disassemble the indicator 26, either by breaking the lock collar 54 from outside the filter assembly 11, or by squeezing the trap lip 64 (after removing the trigger member 68 as discussed subsequently) from inside the assembly. filter 11. In operation, whenever a suction pressure is present in the intake portion 22 of the filter assembly 11, the suction pressure on the associated side of the ball 86 in the side tube 46 is also present, under of the opening 94 in the cover member 92. Since the ball 86 substantially fills the hole 50, in this way the ball 86 essentially seals the hole 50, such that the other side of the ball 86 is subject to pressure of ambient air from outside the filter assembly 11, which is transmitted to the central space 30 by means of the tolerance between the signaling portion 72 and the central opening 58 in the lock collar 54. Actually, it is will leak around the ball 86 when the ball 86 is mounted to allow axial movement in the hole 50, but this leak would be smaller and would be easily compensated (as noted subsequently). With the ambient air pressure on one side, and the suction pressure on the other side, the ball 86 is forced towards the suction pressure by differential pressure through the ball 86. The spring 90 of the side tube 46 serves to counteract this pressure differential, provided that the suction pressure is above a predetermined value (or a previously determined value that has been compensated by the expected leak around the ball 86). The previously determined value is selected as some value that is reached when the filter 12 becomes sufficiently covered, and a replacement or cleaning is desirable.

When the predetermined value of the suction pressure is reached or exceeded, the counteracting force offered by the spring 90 is insufficient to counteract the force of movement of the pressure differential through the ball 86. Accordingly, the ball 86 is moves away from the catching portion 70 of the firing member 66, such that the firing member 66 no longer stops at the non-signaling position. Therefore, under the action of the spring 76, the firing member 66 moves toward the end wall 34, and the signaling portion 72 extends substantially beyond the end entry 36 and the lock collar 54, so as to easily viewed and serve as an indication that it is time to change the filter 12. After the indicator 26 has signaled that the filter 12 should be replaced by extending the signaling portion 72 above the end entry 36, and that the filter 12 has been replaced, it will be appreciated that the indicator 26 is easily reset to perform the same function again. This is done by simply manually pushing down on the extended signaling portion 72. Initially, this causes the ball 86, which is forced into engagement with the surface of the adjacent portion of the main body 68, but which is still trapped in the body. hole 50 through this coupling, is pushed back into the hole 50 as the ball 86 travels along this surface. Accordingly, by pushing down until the free end of the signaling portion 72 is flush with the outer flange 56 of the lock collar 54, the main body 68 of the trigger member 66 is returned to the position where the ball 86 is forced inward from the trap portion 70 by the spring 90. Since the suction pressure in the intake portion 22 is now above the previously determined value (because the new filter will not exit causing a suction pressure. below the previously determined value, or the suction pressure is not being exerted while the filter assembly 11 of the compressor is removed, and the filter 12) is replaced, in this way the ball 86 stops the firing member 66 in the position which is not signaling once the signaling portion 72 is manually released. Either they are mounted in the filter assembly 11 or not, the different parts of the indicator 26 can be Move and maintain / clean or replace as required. Preferably, this is done by first removing the cover member 92 by suitably pulling on the cover member 92 to allow access to the hole 50. Once the cover member 92 is removed, both the spring 90 and the ball can be removed. 86. With the cover member 92 removed, the spring force 90 of the ball is removed 86, so that the firing member 66 can also be removed. Firing member 66 is removed by first pulling seal member 78 'from end 38 of housing 28. This gives access to central space 30, and easy removal of spring 76 and firing member 66.

The rearming preferably occurs in the reverse order. Although the present invention has been described with respect to the exemplary embodiments thereof, it will be understood by ordinary experts in the field, who can use variations and modifications within the scope and spirit of the invention.

Claims (17)

NOVELTY OF THE INVENTION Having described the above invention, it is considered as a novelty, and therefore, the content of the following is claimed as property: CLAIMS

1. An indicator for signaling the restricted flow of air through an air filter mounted in a filter assembly, which includes: a housing including a central space, a side wall adjacent to the central space, an end wall adjacent to the space central, an end entrance in the end wall, and a lateral exit in the side wall; a mounting element for mounting the housing end entry in a mounting opening of the filter assembly, located downstream of the filter, whereby the housing is mounted inside the filter assembly, with the housing exposed to the pressure of the filter assembly. suction in the filter assembly, which moves the air through the filter; a firing member located in the central space of the housing, the firing member including a signal portion extending adjacent the end entrance; a movement element for moving the firing member in the housing between a non-signaling position, wherein the signal member does not extend markedly through the end entrance, and a signaling position wherein the portion of signal extends remarkably through the end entrance, and is easily seen; a releasing element that responds to the pressure at the lateral outlet, to initially contain the firing member in the non-signaling position, and to prevent movement by the movement element, and to subsequently release the firing member when the suction pressure at the side outlet drops below a previously determined value in relation to an ambient air pressure outside the filter assembly.

2. An indicator of compliance with claim 1, characterized in that the release element includes: (a) a tolerance between the signal portion and the end entry, whereby the central space of the housing is subjected to the Ambient air pressure outside the filter assembly; (b) a seal member that fluidly restricts a flow of air from the central space of the housing to the lateral outlet, such that the seal element is subjected to the ambient air pressure on one side thereof, and to the pressure of suction on the other side of it; and (c) a forcing element for forcing the seal member against movement, the forcing element allowing a release movement of the seal element when the suction pressure falls below the previously determined value, and a reset movement of the seal element. when the suction pressure rises above the previously determined value.

3. An indicator of compliance with claim 2: wherein: the lateral outlet of the housing includes a lateral tube extending away from the side wall of the housing, and fluidly connecting the central space of the housing with the pressure of suction in the filter assembly; wherein the firing member includes a trapping portion, and wherein the seal member is a plug member located in the side tube adjacent to the trapping portion of the firing member, when the firing member is in the position that it is not signaling, and wherein the plug member is forced to engage with the trap portion by the forcing element, to prevent movement of the housing to the signaling position.

4. An indicator of compliance with claim 3, wherein the cap member is a round ball, and wherein the side tube includes a cylindrical hole where the ball is mounted for movement.

5. An indicator of compliance with the claims of claim 4, characterized in that the forcing element includes a spring, a lid member, a small opening in the lid member, and a releasable attachment element for attaching the lid member to a free end of the side tube, such that the spring and the ball are held in the cylindrical hole of the side tube by the end cap, but can be inserted and removed from the side tube by removing the end cap from the free end.

6. An indicator of compliance with claim 1, characterized in that: the mounting element includes: (a) a mounting collar erect from the end wall that surrounds the end entrance, and extends through the mounting opening in the mounting wall of the filter assembly, - (b) a locking collar that fits inside the mounting collar, this secure collar including a central opening through which the signaling portion extends , and an outer flange extending away from the signaling portion, and resting against the mounting wall; and (c) a connecting element for attaching the lock collar to the end wall of the housing, such that the mounting wall is trapped between the outer flange of the lock collar and the end wall of the housing.

7. An indicator of compliance with claim 1 in claim 1: wherein the housing is cylindrical and the central space is defined by a cylindrical wall; wherein the trigger member includes a main body that is cylindrical and is closely adjacent to the cylindrical wall of the housing, such that the main body is mounted coaxially for a guided movement in the central space, and a trapping portion in the main body that engages with the release element; and wherein the signaling portion is cylindrical, coaxial with the main body, and extends from one end of the main body.

8. An indicator of compliance with claim 1: wherein the housing includes an end opposite the end wall, and an end opening opposite the end, - and including a spring, a seal member , and a releasable seal element for attaching the cap member to the opposite end opening of the housing, opposite the end wall, to seal the opposite end opening, and in such a manner that the spring is held in the housing with the spring compressed against the firing member by the end cap, but the spring and the firing member can be inserted and removed from the housing by removing the end cap from the opposite end of the housing.

9. An indicator of compliance with claim 6, wherein the housing is cylindrical and the central space is defined by a cylindrical wall, wherein the trigger member includes a main body that is cylindrical and is closely adjacent to the cylinder. the cylindrical wall of the housing, such that the main body is mounted coaxially for a guided movement in the central space, and a catch portion in the main body that engages the release element; and wherein the signaling portion is cylindrical, coaxial with the main body, and extends from one end of the main body.

10. An indicator of compliance with claim 9, wherein the housing includes an end opposite the end wall, and an end opening opposite the end; and wherein it includes a spring, a seal member, and a releasable seal element for attaching the cap member to the opposite end opening of the housing, opposite the end wall, to seal the opposite end opening, and such that the spring is held in the housing with the spring compressed against the firing member by the end cap, but the spring and firing member can be inserted and removed from the housing by removing the end cap from the opposite end of the housing. accommodation.

11. An indicator of compliance with claim 5, characterized in that the mounting element includes: (a) a mounting collar erect from the end wall that surrounds the end entrance, and extends through the Mounting opening in the mounting wall of the filter assembly; (b) a locking collar that fits inside the mounting collar, this secure collar including a central opening through which the signaling portion extends, and an outer flange extending away from the signaling portion, and that rests against the mounting wall, - and (c) a joining element for attaching the lock collar to the end wall of the housing, such that the mounting wall is trapped between the outer flange of the lock collar and the end wall of the housing.

12. An indicator of conformity with claiming in claim 11: wherein the housing is cylindrical and the central space is defined by a cylindrical wall, - wherein the firing member includes a main body that is cylindrical and is closely adjacent to the the cylindrical wall of the housing, in such a way that the main body is mounted coaxially for a guided movement in the central space, and a catch portion in the main body that engages with the release element; and wherein the signaling portion is cylindrical, coaxial with the main body, and extends from one end of the main body.

13. An indicator of compliance with claim 12: wherein the housing includes an end opposite the end wall, and an end opening opposite the end; and wherein it includes a spring, a seal member, and a releasable seal element for attaching the cap member to the opposite end opening of the housing, opposite the end wall, to seal the opposite end opening, and such that the spring is held in the housing with the spring compressed against the firing member by the end cap, but the spring and firing member can be inserted and removed from the housing by removing the end cap from the opposite end of the housing. accommodation.

14. A seventh filter indicator to indicate the restricted air flow, which includes: a filter assembly that includes a mounting wall, a filter, and an element to place the filter in the filter assembly, in such a way that the air is directed into an inlet portion of the filter assembly by a suction pressure, through the filter, to an intake portion of the filter assembly, and a mounting opening in the mounting wall downstream of the filter, - and an indicator to indicate a restricted flow of air through the air filter, which includes: (a) a hollow housing that includes a central space, a side wall, an end wall, an end entrance in the wall of end, and a lateral outlet on the side wall; (b) a mounting element for mounting the end entrance of the housing to the mounting opening in the mounting wall, whereby the housing is mounted inside the filter assembly, with the housing exposed to the suction pressure in the filter assembly, - (c) a firing member located in the central space of the housing, the firing member including a signal portion extending adjacent the end entrance to a position adjacent to the mounting wall, which, the firing member and the central space are subjected to an environmental pressure outside the filter assembly and a trapping portion; (d) a movement element for moving the firing member in the housing between (a) a non-signaling position, wherein the signal member does not extend markedly through the end entrance and the mounting wall , and (b) a signaling position wherein the signal portion extends markedly through the end entry and the mounting wall, and is easily seen outside the filter assembly, - (e) a release element that responds to the pressure at the lateral outlet to initially contain the firing member in the non-signaling position, and to prevent movement by the movement element, and to subsequently release the firing member when the suction pressure in the lateral outlet falls below a previously determined value, including this release element: (a) a member that responds to the pressure located between the firing member and the side outlet that is its subject to the suction pressure on one side through the lateral outlet, and to the ambient pressure in the central space, and (b) a forcing element for forcing the member that responds to the pressure inward of the member trapping portion. trigger, and to release the member that responds to the pressure of the trap portion when the suction pressure falls below a predetermined value relative to an ambient air pressure outside the filter assembly. A filter indicator system according to claim 14, characterized in that the mounting element includes: (a) a mounting collar erect from the end wall that surrounds the end entrance, and extends through the mounting opening in the mounting wall, - (b) a lock collar that fits inside the mounting collar, this lock collar including a central opening through which the cover extends. signaling portion, and an external flange extending away from the signaling portion, and resting against the mounting wall, - and (c) a joining element for attaching the lock collar to the end wall of the housing, in such a way that the mounting wall is trapped between the outer flange of the lock collar and the end wall of the housing. 16. A filter indicator system in accordance with claim 15, wherein the housing includes an end opposite the end wall, and an end opening opposite the end, and wherein it includes a spring, seal member, and a releasable seal member for attaching the cap member to the opposite end opening of the housing, opposite the end wall, to seal the opposite end opening, and in such a manner that the spring is held in place. the housing with the spring compressed against the trigger member by the end cap, but the spring and the trigger member can be inserted and removed from the housing by removing the end cap from the opposite end of the housing. A filter indicator system according to claim 16: wherein: the lateral outlet of the housing includes a side tube extending away from the side wall of the housing, and fluidly connecting the central space of the housing with the suction pressure in the filter assembly, wherein the pressure-responding member is a plug member located in the side tube adjacent to the catching portion of the firing member, when the firing member is in the position which is not signaling, and wherein the plug member is forced to engage the catching portion by the forcing element, to prevent movement of the housing to the signaling position; and wherein the forcing element includes a spring, a lid member, a small opening in the lid member, and a releasable attachment element for attaching the lid member to a free end of the side tube, such that the spring and the cap member are held in the cylindrical hole of the side tube by the end cap, but can be inserted and removed from the side tube by removing the end cap from the free end.