US2279961A - Ventilating device and system - Google Patents

Description

April 14, 1942.

c. c. WHI'ITAKER 2,279,961

VENTILATING DEVICE AND SYSTEM Filed No. 12, 1958 2 Sheets-Sheet 1 INVENTOR 2/24/55 fill/Mia 34 BY r i an I If ATTORNEY 1942. c. c. WHITTAKER VENTILATING DFVICE AND SYSTEM April 14 Filed Nov. 12, 1938 2 Sheets-Sheet 2 3% skuks w wm INVENTOR WITNESSES: 0 W

Patented Apr. 14, 19.42

- VENTILATING DEVICE AND SYSTEM Charles C. Whittaker, Pittsburgh, Pa., assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application November 12, 1938, Serial No. 240,207

10 Claims.

My invention relates, generally, to ventilating devices and systems, and, more particularly, to ventilating devices and systems of the explosionproof type.

When control apparatus, and particularly such apparatus which functions to interrupt currentcarrying circuits, is used in the vicinity of mines and in other locations where the surrounding atmosphere may contain an explosive gaseous mixture, it is necessary to enclose such apparatus. It has been found, however, that the mere provision of an enclosure for the apparatus does not provide a satisfactory solution to the problem. When circuit interrupting apparatus is merely provided with a surrounding enclosure for isolating it from the surrounding gaseous atmosphere, severe corrosion and pitting of the metal parts and damage to the insulation of the control apparatus usually results, because of the formation within the enclosure of corrosive acids, due to the disintegration of the air in the enclosure under the action of the arcs occasioned by the interruption of the current-carrying circuits.

Safety provisions require that the enclosure for control apparatus which is to be operated in such gaseous locations shall be sufliciently strong to withstand any internal explosion, without igniting the surrounding gaseous atmosphere.

The provision of gas-tight joints in the control enclosure, so that a neutral atmosphere might be maintained within the enclosure for preventing the formation of corrosive acids, requires accurately machined and gasketed joints, which are an added expense. Likewise, the problem cannot be solved by merely providing for the ventilation of the enclosure in the usual manner. since it is not permissible to exhaust gases from within the control enclosure directly into the surrounding atmosphere on account of the possibility of causing an explosion.

It is, therefore, generally an object of my invention to provide for eifectively and safely ventilating explosion-proof enclosures.

More specifically, it is an object of my invention to provide for the ventilation of an explosion-proof control enclosure, while preventing the propagation of an explosion within the enclosure to the surrounding atmosphere, by suitably restricting the flow of gas from the enclosure and providing for the cooling thereof below the ignition point of the surrounding gaseous mixture before it is exhausted into the atmosphere.

Another object of my invention is to provide a ventilating device for safely effecting the ventilation of explosion-proof enclosures.

A further object of my invention is to provide a simple and effective ventilating device for explosion-proof enclosures which may be readily disassembled for cleaning or inspection and easily reassembled without changing the operating characteristics thereof.

Another object of my invention is to provide a compact and eflicient ventilating device having a restricted passage of predetermined dimensions therethrough for effecting the passage of a ventilating gas and preventing the propagation of an explosion to a surrounding explosive gaseous mixture.

Still another object of my invention is to provide a ventilating unit operated fan or blower utilizing a motor of the usual type for effecting ventilation of an explosion-proof control enclosure without the hazard of an explosion of a surrounding gaseous mixture.

A still further object of my invention is to provide a self-contained explosion-proof ventilating unit for use in ventilating explosion-proof enclosures, which may be located in a surrounding atmosphere comprising an explosive mixture.

Other objects will, in part, be obvious and will in part, appear hereinafter.

According to a preferred embodiment of my invention, a ventilating device for ventilating explosion-proof enclosures may comprise, preferably, a pair of separable members having interfitting parts defining a restricted passage for the flow of a ventilating gas therethrough in such a manner as to permit a non-interrupted flow of the ventilating gas, while presenting sufficient resistance to prevent the propagation of an explosion through the passage. By providing a substantially zig-zag annular passage between the members having a predetermined ratio of length to width, such for example, as 5D to l, which is one ratio found to be satisfactory, so as to present an extensive metallic surface over which the gas must flow, and by maintaining the dimensions of the passage within predetermined limits so that the width thereof, preferably, does not exceed .042 inch, it has been found that the flow of gas therethrough may be suitably restricted, and a stream of heated gas or particles, such as might ignite a surrounding explosive mixture, may be sufiiciently cooled during its passage therethrough to prevent the propagation of an explosion. In this manner, a ventilating device for safely effecting the ventilation of explosion-proof enclosures may be provided,

which may be readily disassembled for inspection or cleaning without the possibility of the loss of, or change in the relation of, parts thereof which might alter the operating characteristics of the device.

The ventilating device may be utilized in several ways. It may be used as outlet and inlet ports for the control box or enclosure and it may be used as a part of a ventilating unit or blower housing which is attached directly to the control enclosure and located remotely therefrom and connected to the inlet port thereof by a suitable pipe or conduit. Thus it may be seen that my invention contemplates a ventilating device, a ventilating unit or blower housing and a complete ventilating system for control enclosures.

For a more complete understanding of the nature and scope of my invention, reference may be had to the following detailed description, taken in connection with the accompanying drawings, in which:

Figure 1 is a sectional view of a preferred form of ventilating device embodying my invention;

Fig. 2 is a partial sectional view of an alternate form of the invention;

Fig. 3 is a sectional view of a ventilating unit embodying a preferred form of the invention; and,

Fig. 4 is a diagrammatic view of a ventilating system embodying the invention.

Referring particularly to Fig. 1, the reference numeral Iii denotes generally a ventilating device constructed in accordance with my invention, and comprising, generally, a body member i2 and a cap member i 4, which may be secured to the body member in any suitable manner so as to cooperate therewith in defining a restricted passage therebetween for the flow of a ventilating gas.

With a View to providing a restricted path of suflicient length through the ventilating device iii and maintaining the dimensions of the path within relatively narrow limits so as to prevent the passage therethrough of heated gas or particles such as might propagate an explosion in a sur- 2:;

rounding gaseous atmosphere, I prefer to provide a substantially zig-zag annular path or passage through the device, so as to provide a ventilating device which is compact, and in which the available space is most efficiently utilized. To this end, the body member l2 may be substantially cup-shaped and provided with a centrally disposed upstanding boss portion It in the bottom thereof, the outer surface E8 of which is sub-.

stantially cylindrical and concentric with the side 1 walls of the body member, and the inner surface of which slopes inwardly forming a tapered orifice I9, terminating in a centrally located nipple 20, through which connection may be made to an enclosure which is to be ventilated.

A separate baiiie member 22 may be provided, comprising, for example, a ring which may be readily machined as a separate element within a limited tolerances and secured within the body member l2 in any suitable manner, being, for example, positioned therein by means of ,a circumferential shoulder 25 which may be. machined in the bottom of the body member, and secured thereto by means of screws 21. The baffle or ring member 22 is preferably pressed into position to insure a tight joint between it and the bottom of the body member l2. Suitable ports 36 may be provided about theperiphery of the body member 12 for connecting the restricted ventilating passage within the ventilating deviceto thesur rounding atmosphere. An annular flange 32 may be provided about the outer edge of the body member I2 for facilitating the locking together of the body member l2 and cap member i i in operating relation, while the inner surface thereof may be suitably machined to provide a circumferential shoulder and a threaded portion 35 for securing the body member and the cap memher in predetermined relation.

In order to provide a suitable zigzag path within the body member of the ventilating device it, the cap member it may comprise substantially a cup-shaped. member having annular flange portion 55 and a tapered central boss portion 37, which is disposed to cooperate with the tapered orifice portion it of the inlet 2?] in the body member 12, so as to provide an inlet passage to the ventilating device of substantially constant cross-section area, for effecting a smooth flow therethrough of ventilating gas. A separate bafile member 33, comprising, preferably, a metallic ring which may be machined as a separate element within close tolerances, may 9e suitably secured to the cap member M, being, for example, positioned by the circumferential shoulder portion 49, and secured to the cap member by means of screws $2. This bafile or ring member 33 is also preferably fitted tightly to the cup member by a press fit. The finished dimensions of the baffle member 38 are such, that when the cap member M is secured to the body member 52, the bafiie member it will preferably interiit with the baiiie member 22 on the body member and the outer wall it of the raised central boss iii of the body member to define a back and forth or substantially zig-zag annular passage of substantially constant cross-section for permitting a restricted flow of gas therethrough without producing undesirable eddy currents therein which may vary the rate of flow.

As shown in the drawings, the cap member E l may be secured to the body member i2 through the engagement of the threaded outer surface of the cap member with the threaded portion 35 of the body in inber. A circumferential shoulder portion may be provided adjacent to the threaded portion M of the cap member, for abutting against the shoulder 34 of the body member to insure accurate positioning of the two members, and the members may be locked together, if desired, by providing associated openings t? and 1B in the flange portions 32 and 36, respectively, of the body member and cap member, for receiving any suitable locking means, such as a bolt, or the band portion of a sealing device (not shown).

By utilizing removable baffle members 22 and 38 in the manner hereinbef described, to cooperate with the cylindrical surface portions of the cap and body members, I have found it possible to provide a compact and efficient ventilating device for safely effecting ventilation of an explosion-proof control enclosure, while preventing the propagation of an explosion therethrough to ignite a surroun ing gaseous atinospliiere. The bafile members and .iimay be readily machined as separate .ienibers to maintain the limited clearances which are necessary for the proper functioning of the ventilating device, and since they are then firmly secured in operating position within the body and cap members, respectively, the cap and body members may be separated for inspection cle ng when necessary, and reassenzibled without the possibility of any change in the operating characteristics of the device, since there are no parts which may be inadvertently lost or misplaced during separation.

In Fig. 2 an alternate form of ventilating device is illustrated, in which the body member 50 comprises a substantially cup-shaped member having a central orifice 52 surrounded by concentric upstanding tapered ring portions 54, 56 and 51, which define concentric V- shaped grooves 58 and 60.

The cap member 62, which may be secured-to the body member 50 in any suitable manner, such as by the engagement of threaded rim portions, as hereinbefore described in connection with Figure 1, may be provided with a centrally disposed tapered boss 64 for directing the flow of gas through the orifice 52, and upstanding concentric tapered ring portions 66 and 68, which are disposed to be positioned in the concentric grooves 58 and 60 of the body member, when the cap member and body member are assembled, to define a substantially zig-zag annular passage between the central orifice 52 of the body member. Suitable ports 10, may be provided about the periphery of the body member 50 for connecting the outer groove 60 thereof to the surrounding atmosphere.

In this manner I provide a ventilating device having a minimum of parts, and which may be easily and inexpensively manufactured. The parts thereof are readily removable for cleaning and inspection, and the passage defined by the removable parts may readily be machined to provide the desired clearances, which may be easily maintained, since there are no loose parts which may be misplaced or lost, and the body member 50 and the cap member 62 may be always reassembled to occupy the same relative positions, thus ensuring the proper functioning of the device. The width of the passage may be suitably adjusted, if desired, by providing a plurality of aligning openings in either the cap or body member, and changing the relative position of the members and then looking them in the desired position. Since the circumferential flange and groove portions of the body and cap member have a tapered section, any change in the relation between these members will result in a change in the width of the passage therebetween.

Referring to Fig. 3, the reference numeral 15 denotes generally a ventilating unit which may be utilized for efiecting ventilation of explosionproof enclosures without hazarding the possibility of igniting a surrounding gaseous atmosphere through the transmission of heated particle or gas thereto from within the enclosure, even if an explosion occurs therein. As illustrated, the ventilating unit 15 may comprise a housing H, which is provided with a centrally disposed threaded inlet 19 at one end, to which a pipe 8!], for connecting the housing to the enclosure which is to be ventilated, may be secured. A suitable annular mounting flange 82 may be provided adjacent to the inlet 19 for providing an alternate means of mounting the ventilating unit when desired. A ventilating device 84, of the type hereinbefore described in detail, may be secured to one end of the housing 11 in any suitable manner, such as by providing the ventilating devlce with an annular mounting flange 85, which may be disposed in engagement with the rim portion 88 of the housing 11 to provide an explosion-proof joint, and secured thereto by means of bolts 89, only one of which is shown.

In order to provide for the necessary rate of flow of ventilating gas through the enclosure to which the ventilating unit 15 is disposed to be connected, a motor 90, of any well-known type, may be mounted within the housing for operating suitable blower means, such as the fan 92, being preferably mounted in the path of the stream of ventilating gas created thereby, so as to effect ventilation of the motor at the same time. As illustrated, a mounting platform 94 may be provided within the housing for supporting the motor, and in order to provide a ventilating unit having a flexibility of application, I prefer to secure the mounting platform 94 to the ventilating device 84, or form it integral with the flange portion 86 thereof, so that the housing ll may be dispensed with, if desired, and the ventilating unit secured directly to the enclosure which is to be ventilated, by means of the mounting flange 86. Electrical connections to the motor may be made in any suitable manner, such as by providing a suitable conduit connection 91, having a compressible insulating bushing 98 therein which may be compressed by tightening a threaded sleeve 99 for providing a sealed entrance for a suitable cable Hill which passes therethrough.

Fig. 4 illustrates generally a ventilating sys tem utilizing ventilating devices and units embodying my invention for effecting ventilation of an explosion-proof enclosure, such a the control box H0, which may contain circuit interrupting and controlling apparatus, which is to be operated in a location having a surrounding atmosphere comprising an explosive mixture of gases.

Ventilating devices I I2 and I [4, preferably of a type hereinbefore described, may be suitably connected to the control enclosure H!) to provide ventilating ports therefor. In order to provide for forcing the necessary amount of ventilating gas through the control box I ill to effect the removal of any harmful gases created therein by the operation of the circuit interrupting devices, a ventilating unit 15, similar to that shown in Fig. 3, may be connected to the ventilating device H4 by means of a suitable pipe or conduit H6. In this manner, a continuous stream of ventilating gas may, for example, be passed through the control box, from the surrounding atmosphere, through the inlet port H8 of the ventilating unit 15, about the motor therein so as to effect ventilation thereof, and then through the pipe H6 and ventilating device H4 into the control box I H], from which it may be exhausted through the ventilating device H2 to the surrounding atmosphere.

It will be apparent that, when the control apparatus is idle, a restricted opening will be continually maintained between the surrounding atmosphere and the interior of the control box I I 0, through the ventilating devices H2 and H4, so that the explosive gases may in time accumulate within the control enclosure. Upon operation of the control apparatus within the enclosure, an explosion Within the enclosure may result. Since the enclosure is purposely made strong enough to withstand such explosion, no harm will result, and since the ventilating devices H2 and H4 provide only a restricted exit passage from the enclosure, and any gases passing therethrough will not only be limited in their rate of flow, but will also be cooled at the same time by passage over the metallic surfaces within the ventilating devices, these gases will be cooled below the ignition point of the surrounding gaseous mixture by the time they have passed through the ventilating devices, thus confining the explosion, to the control enclosure. Likewise, should sparks from the motor 90 ignite explosive gases within the housing 11 of the ventilating unit 15, the ventilating devices 84 and H4 will confine the explosion to the housing ll.

When it is possible to mount the ventilating unit 15 directly on the control enclosure, the ventilating device H4 may be omitted, if a sufliciently large opening is provided between the control box Hi3 and the ventilating unit housing ll. It has been found, however, that when the ventilating unit 15 must be remotely located, because of the limitations in space available adjacent to the control box I I0, it is preferable to interpose the ventilatin device H4 between the control box I It. and the ventilating unit 15 in order to prevent an explosion occurring within the control enclosure from being communicated to the housing H or compressing the gas within the housing, and then igniting it under pressure, which may result in such a forceful explosion within the ventilating unit housing H as to disrupt the housing and thus cause an explosion of the surrounding gaseous atmosphere.

From the above-detailed description and the accompanying drawings, it will be readily understood that I have provided means for safely and efiectively ventilating explosion-proof enclosures such as used in mines and other locations where the surrounding atmosphere comprises an explosive mixture, so that the corrosion of the metallic parts and the destruction of the control equipment contained therein may be prevented, without incurring the hazard of an explosion of a surrounding gaseous mixture. A ventilating device embodying my invention is simple and inexpensive to manufacture, and economical to maintain. Since there is a minimum of parts, the device may be readily cleaned and inspected without the possible loss or misplacement of any parts thereof, and it can be safely reassembled without the danger of some of the parts being inadvertently omitted, misplaced, or lost, thus ensuring that the proper operating characteristics of the device will be retained and the lives and property being protected thereby will not be endangered.

Since certain changes may be made in the above construction, and different embodiments of the invention may be made without departing 1 from the spirit thereof, it is intended that all the matter obtained in the above description, or shown in the accompanying drawings, shall be considered as illustrative, and not in a limiting sense.

I claim as my invention:

1.. A ventilating device comprising, a recessed body member having inlet and outlet ports there in, a cap member secured to the body member to enclose the recess, and a plurality of removable baffle members positioned in the recess in predetermined spaced relation to define a relatively narrow back and forth passage between the inlet and outlet ports, said body and cap members having shoulder portions for positioning alternate baffle members in fixed relation therewith to maintain them in the predetermined spaced relation.

2. A ventilating device for an explosion-proof enclosure comprising, a pair of separable members secured in fixed relation having portions thereof positioned in overlapping relation for defining a single relatively narrow annular passage having a plurality of back and forth turns with a ratio of length to width of approximately 50 to 1 for restricting the flow of heated gases therethrough and cooling them below the ignition point.

3. Ventilating means comprising, a body member having a central opening surrounded by a plurality of concentric upstanding ring portions, a cap member removably secured in fixed relation to the body member having a central boss portion positioned in the central opening to divert a stream of gas flowing therethrough smoothly and provided with a plurality of concentric ring portions thereabouts disposed in interfitting relation with the ring portions of the body member to define a single relatively narrow continuous path of predetermined dimensions between the members for cooling a stream of heated gas flowing therebetween below the ignition point.

4. Ventilating means comprising a body member having a central port and a surrounding concentrically grooved portion, a separate ring member secured in the grooved portion of the member in predetermined relation thereto, a cap member having a central tapered boss cooperative with the breather port to direct a flow of gas therethrough and secured to said body member in predetermined relation, and an additional separate ring member secured to the cap member for cooperating with the body member and the first-mentioned ring member to define an annular passage of predetermined dimensions for restricting the rate of flow of a stream of gas passing therethrough and cooling said gas below the ignition point.

5. An explosion-proof ventilating unit for ventilating explosion-proof control enclosures comprising, an explosion-proof housing having a ventilating port at one end disposed to be connected to the control enclosure to provide a ventilating passage therebetween, a ventilating device having fixed bailie members defining a relatively long gas path of predetermined dimensions providing a ventilating port to prevent the propagation of an explosion from within the housing secured to the housing at the other end, and a motor provided with blower means positioned within the housing between said ventilating ports in substantially spaced relation to the side walls of the housing for providing a flow of gas between said ventilating ports about said motor.

6. A ventilating system for explosion-proof enclosures comprising, an explosion-proof enclosure, a ventilating port therefor including a ventilating device for providing a restricted continuously open ventilating port for the enclosure, and ventilating means including an explosionproof housing having a ventilating device provided with a relatively long and narrow ventilating passage for preventing the propagation of an explosition from within the housing connected to the enclosure, and blower means positioned within the housing for forcing a stream of ventilating gas through the housing and enclosure.

'7. In a ventilating system for explosion-proof control enclosures, in combination, an explosionproof enclosure which is to be ventilated without igniting a surrounding explosive gas, a ventilating device comprising a pair of separable body members having interfitting concentric flange portions secured thereto for defining a single restricted annular passage of predetermined dimensions secured to the enclosure to provide a. ventilating port disposed to cool a stream of gas passing therethrough below the ignition point, and ventilatin means including an explosionproof blower housing and an additional ventilating device for cooling and restricting the flow of gas therethrough disposed to provide a substantially continuous flow of ventilating gas through the control enclosure and prevent the ignition of a surrounding gaseous atmosphere.

8. The combination with an explosion-proof control enclosure of, a ventilating device comprising a pair of associated body members having interfitting concentric flange portion disposed to define a single continuous annular passage of predetermined dimensions connected to the enclosure to provide a continuously open restricted ventilating port for the enclosure, remotely located ventilating means including an explosion-proof housing having a restricted ventilating port connected to the enclosure, and a motor-operated blower positioned Within the housing for providing a ubstantially continuous flow ofgas through the enclosure and preventing the exhausting from the enclosure of gases heated above the ignition point, and an additional ventilating device interposed between the ventilating means and the enclosure for preventing the propagation of an explosion from the enclosure to the ventilating means.

9. A ventilating unit adapted for attachment to and for circulating a gas through an explosion-proof control closure comprising, a substantially cup-shaped explosion-proof housing memher substantially open at one end and having an outlet ventilating port through the other end disposed to provide for connection to the enclosure which is to be ventilated, a motor provided with a blower positioned within the housing for effecting a flow of a ventilating gas through the nousing member, and a cover secured to the housing member having an inlet ventilating port including a ventilating device mounted thereon with relatively fixed portions positioned to define a relatively long and narrow passage through the cover having a minimum clearance no greater than a predetermined maximum fixed value effective to prevent the propagation of an explosion from within the housing member.

10. A ventilating system for an explosionproof control enclosure comprising, a ventilating device connected to the enclosure to provide a ventilating port therefor, a remotely positioned explosion-proof housing having a blower device positioned therein and an additional ventilating device providing a port in the housing, a conduit connecting the housing to the enclosure, and another ventilating device connected between the conduit and the enclosure, said ventilating devices having a plurality of fixed baffle members for defining restricted back and forth passages therethrough sufiiciently long and narrow to permit the flow of a ventilating gas and prevent the propagation of an explosion therethrough from within the enclosure or housing.

CHARLES C. WHIT'I'AKER.

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