[0002] Conventional methods of vertically transporting sewage (e. g., waste from toilets, bath tubs, sinks and the like) are disclosed and often prescribed by local or national plumbing and drainage codes for sanitary plumbing--for example, Australian National Plumbing and Drainage Code AS/NZS 35002. 2: 1996. While these methods are generally satisfactory for single-story (single-storey) constructions, they are less than completely satisfactory when applied to multi-story buildings (that is, buildings having more than one floor or story) of a residential or commercial nature connected to a main ground or underground sewer line.

[0003] More particularly, it has been found that such methods do not provide sufficient ventilation to the sewage network of such multi-story buildings.

Thus, separate and independent ventilation may be required in a single multi- story building in order to provide sufficient ventilation to the sewage network, thereby substantially increasing the construction and maintenance costs associated with the sanitary plumbing and thus the building. Absent such separate and independent ventilation systems, the sewage being discharged into the vertical sanitary stacks of a multi-story building tends to exhaust foul and odifcrous fumes and vapors from the top of each stack. This unsatisfactory and possibly unlawful resell may necessitate the cosdy and unsightly remedy of connecting the tops of each of the various stacks in a building to one or more exhaust pipes which re- direct the foul and odiferous fumes and vapors to a location remote from the building prior to their discharge into the atmosphere.

[00041 Accordingly, it is an object : of the present invention to provide a forced ventilation system which, in a preferred. embodiment precludes the exhausting of foul and odiferous fumes and vapors from the tops of the generally t vertical sanitary stacks in a multi-story building.

[oO Another object : is t ; o provide such a system which, in a preferred embodiment, does not require separate and independent ventilation systems for each stack or means for directing the gaseous exhaust from the tops of the stacks to a remote location.

[0006] It is another object of the present invention to provide such a system- which, in a preferred embodiment, is simple and economical to construct, operate and maintain.

[00071 it is a further object to provide a method for operating such a system.

SUMMARY OF THE INVENTION [0008] The present invention is directed to a system for forcibly ventilating generally vertical sanitary stacks in a multi-story building connected to a main sewer line. The system comprises at least one generally vertical sanitary stack in gaseous communication adjacent the top thereof with atmosphere and adjacent the bottom thereof with a ventilating pipe. In turn, the ventilating pipe is in gaseous communication with each stack (below the lowermost sanitary inlet to each stack) for receiving the gaseous content, either directly or indirectly, from adjacent the bottom of each stack. At least one stack fan (or blower) is in gaseous communication with each stack adjacent the top thereof for forcibly and continuously blowing air down each stack to the ventilating pipe. A pipe fan (or blower) is in gaseous communication with the ventilating pipe for forcibly and continuously exhausting off the gaseous content of the ventilating pipe to atmosphere at a location remote from the stacks.

[0009] Tn a preferred embodiment, each stack has a respective one of the stack fans, with each stack fan being disposed adjacent the top of a respective stack. A plurality of the stacks are in gaseous communication with the single ventilating pipe, and the single ventilating pipe is dimensioned to receive the aggregate gaseous content being received from each of the plurality of stacks. The ventilating pipe is generally horizontal along a major portion of its length, with the pipe fan being disposed adjacent the exhaust end of the ventilating pipe. The ventilating pipe is also preferably in gaseous communication with a main sewage line.

[00101 Preferably each stack fan provides for its respective stack a positive air pressure downwardly at least sufficient to overcome the frictional loss of the air being blown downwardly through and in contact with the interior of the respective stack under a maximum frictional loss condition (that is, a condition in which there is no liquid or solid waste traveling downwardly in contact with the interior of the respective stack to minimize the frictional loss of the air being blown downwardly). The positive air pressttre downwardly is neutralized-'by the maximum frictional loss under a no waste load condition--at a neutral point adjacent the bottom of the respective stack. The pipe fan provides a negative air pressure within the ventilating pipe at least sufficient to overcome the frictional loss of the air passing through and in contact with the interior of the ventilating pipe under a maximum frictional loss condition.

[0011] The present invention further encompasses a method for forcibly l ventilating generally vertical sanitary stacks in a multi-story building connected to a main sewage line. The method comprises the step of providing at least one generally vertical sanitary stack in gaseous communication adjacent the bottom thereof with a ventilating pipe, and a ventilating pipe in gaseous communication with each stack (below the lowermost sanitary inlet to the stack) for receiving the gaseous content from adjacent the bottom of each stack. A stack fan is provided for each stack, and a pipe fan is provided for the ventilating pipe. In operation of the system, each stack fan forcibly and continuously blows air down its respective stack and into the ventilating pipe, and the pipe fan forcibly and continuously exhausts the gaseous content of the ventilating pipe to atmosphere at a location remote from the stacks.

BRIEF DESCRIPTION OF THE DRAWING [00121 The above and related objects, features and advantages of the present invention will be more fully understood by reference to the following detailed description of the presently preferred, albeit illustrative, embodiments of the present invention when taken in conjunction with the accompanying drawing wherein [0013] FIG. 1 is a fragmentary schematic of a multi-story building illustrating a sanitary piping plan according to the present invention; and [00141 FIG. 2 is an isometric view of a roof-top stack fan suitable for use therein.

10015] For clarity and pedagogic purposes, the various conduits (e. g., stacks, the ventilating pipe, and the like) for transporting gases, liquids or slurried solids are represented by only a single line in the schematic.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0016] Referring now to the drawing, and in particular to FIG. 1 thereof, therein illustrated schematically is a portion of a sanitary piping plan of a multi- story residential or hotel building generally designated by the reference letter B.

The building B has at least one generally vertical sanitary stack, generally designated by the reference numeral 10, for the transport of liquid, slurried and gaseous waste. Each of the three stacks 10 acts as a vertical sewer line. A stack fan or blower 11 is disposed at the top of each stack 10 preferably at or slightly above roof level of the building B. Each stack fan 11 is in gaseous communication with the interior of its respective stack 10 adjacent the top thereof for forcibly and continuously blowing atmospheric air down its respective stack and directly or indirectly into a ventilating pipe 16.

[00171 To this end, each stack 10 is illustrated as being in gaseous communication adjacent : the top thereof with atmosphere (that is, the ambient atmosphere about the roof top) and adjacent the bottom thereof immediately with a generally horizontal sewage drainage network including branch lines 13 and 14 (illustrated as extending generally horizontally in the schematic). It will be appreciated that the branch lines 13, 14 are disposed and connected to the stacks 10 below the lowermost sanitary inlet to each respective stack 10 so that the branch lines 13,14 receive all of the gaseous, liquid and slurried solid waste developed in the sanitary system of the building B. The branch lines 13,14 in turn direct the liquid and slurried solid waste into the main sewage line 15 (illustrated as extending vertically downwardly in the schematic).

[0018] The ventilating pipe 16 (illustrated in dash line for contrast with the branch lines) is in gaseous communication with each stack 10 (via the branch lines 13, 14 when present) for receiving the gaseous content from adjacent the bottom of each stack 10. The ventilating pipe 16 is sized to accommodate the aggregate air flow of each of the individual stacks 10 feeding into the ventilating pipe 16 via the branch lines 13,14 (when present). While the ventilating pipe 16 is preferably generally horizontal for a major portion of its length, adjacent the exhaust end thereof it typically turns into a generally vertically upright orientation leading to atmosphere (as illustrated in the schematic). Preferably the ventilating pipe 16 is also in gaseous communication with the main sewer line 15 for receiving any gaseous content therefrom. Accordingly, it may be said that the ventilating pipe 16 is in gaseous communication indirectly with each stack 11, and preferably directly with the main sewer line 15 as well, although the latter is not essential.

[00191 A pipe fan or blower 17 is in gaseous communication with the exhaust or discharge end of the ventilating pipe 16 for forcibly and continuously exhausting off the gaseous content of the ventilating pipe 16 to atmosphere at a location remote from the stacks 10 and otherwise lawful and proper for the anticipated gaseous content being exhausted. The size and capacity of the pipe fan 17 need only be sufficient to provide a negative air pressure within the ventilating pipe 16 sufficient to overcome the frictional loss of the air passing through and in'contact with the interior surface of the ventilating pipe 16 under a maximum frictional loss condition.

[CtOkO] In operation, the forced ventilation system of the present invention employs a stack fan 11 for directing air, fumes and vapors down a generally vertical sanitary stack 10 to a position below a lowermost sanitary inlet to the stack 10. Such gaseous content is directed by branch lines 13, 14 into a ventilating pipe 16 for transporting such gaseous content to an atmospheric discharge location under the influence of pipe fan 17, preferably disposed adjacent the exhaust or discharge end of the ventilating pipe 16. By providing a forcible and continuous air stream vertically down the stacks 10 at a predetermined flow rate, pressure and velocity, having due regard to the length, diameter and design sewage loads to be carried by the stack, the present invention avoids exhausting foul and odiferous fumes and vapors from the tops of the stacks 10 by redirecting them to the ventilating pipe 16, and hence (via pipe fan 17) to atmosphere at a location remote from the stacks 10. The liquid and slurried solid sewage also travels down the stacks 10, through the branch lines 13, 14 (when present), and hence into the main sewage line 3 ; 5.

279411. 1 [0021] Referring now to FIG. 2 m particular, the stack fan or blower 11 contains an in-line fan 21 communicating with atmosphere via a vent cowl 23 over the stack top portion 22. The in-line fan 21 is preferably electrically driven.

The stack top portion 22 preferably includes roof level flashing 24 about the in- line fan 21 and terminates at or adjacent the vent cowl 23. Of course, the stack top portion 22 containing the in-line fan 21 need not be integral below the roof level with the respective stack 10 and may'simply constitute an extension thereof adapted to receive an in-line fan 21 and vent cowl 23.

[0022] To summarize, the system of the present invention provides a suitably sized and powered electric stack fan 11 adjacent the top of each generally vertical sanitary stack 10, typically at roof level. These fans 11 provide a forcible and continuous air stream vertically down each stack 10 at a predetermined flow, pressure and velocity, based upon the length, diameter and sewage loads entering each stack. At the base or bottom of these stacks 10, a generally horizontal drainage network 13, 14 collects and transports the sewage and air streams to a single main sewer connection discharge point leading to a main sewer line 15 or a conduit leading thereto. Thus, the liquid and slurried solid sewage is ultimately discharged into the main sewer line 15 via the generally vertical stacks 10 and the generally horizontal drainage network including branch lines 13,14.

C0023] A ventilating pipe 16 communicates with the generally horizontal drainage network (including branch lines 13-and optionally the main sewer line 15 as well--adjacent the horizontal drainage network exhaust (that is, the sewer connection discharge point) to receive the gaseous content thereof. The pipe 16 preferably extends generally horizontally for the majority of its length, prior to turning vertically upward to a suitable location for discharge of its gaseous content to atmosphere. An electric pipe fan 17 at or adjacent the exhaust end of the ventilation pipe 16 is sized and powered to accommodate the aggregate total gaseous content of-, ! l the individual stacks and discharge the same to atmosphere at a lawful and proper point of discharge.

[0024] The introduction of electric fans (including the stack fans 11 and the pipe fan 17) directly into the drainage piping network allows for mechanical control of the performance of the water/air relationship within both the vertical and horizontal drainage pipe network. Such mechanical control obviates the conventional need for a separate and independent ventilation piping throughout the building B while maximizing the water/air performance within the pipe network. The result is a high performance and cost-effective sanitary plumbing system for multi-story buildings.

[0025] The system described hereinabove is easily operated by causing each stack fan 11 to forcibly and continuous blow air from atmosphere down its respective stack 10 and directly or indirectly into the ventilating pipe 16, and by causing the pipe fan 17 to forcibly and continuously exhaust the gaseous content of the ventilating pipe 16 to atmosphere at a location remote from the stacks 10.

[00267 It will be appreciated that not every stack fan 11 need be the same, and the specific stack fan 11 for a given stack 10 may be selected (i. e., sized and powered) according to the total sanitary load connected to such stack7 its dimensions, etc. The object of the stack fan 11 is to create a positive air pressure within the stack driving the air flow and the gaseous content of the waste towards the bottom of the stack 10.

[00271 Selection of a proper stack fan 11 is based on the situation where there is no liquid or solid waste falling into the stack 10. This results in the air stream created by the stack fan experiencing its maximum frictional loss due to contact of the air stream with the interior surface of the stack. It may be t determined by calculating the total length of the stack multiplied by the frictional loss per meter. The neutral point, where the frictional loss of the air stream will just overcome the air pressure provided by the fan, is designed to be at the base of each stack. After the neutral point, the low level extraction-type pipe fan 17 suffices to evacuate the gaseous content from the base of each stack under negative pressure and draw the gaseous content thereof for exhaustion to atmosphere. Thus a combination of positive pressure stack fans 11 and a negative pressure extraction-type pipe fan 17 provides a forcible and continuous air stream which is constant when a no tiquid/no solid flow situation occurs.

L0028] Interestingly, when a given stack is experiencing its maximum design load of liquid and solid waste, the water/air relationship is in equilibrium, with both the water and the air traveling downwardly at equal velocities so that the air (traveling in a core surrounded by the water) does not experience any frictional loss from contact with the interior surface of the stack. Low liquid and solid waste flow rates in a stack result in the air flow undergoing a frictional loss intermediate the maximum design flow loss and the no design flow loss. It is well within the competence of one skilled in the engineering arts to determine an appropriate size and power level for each stack fan so that it provides a forcible, continuous and constant downward air stream with a velocity and direction equal to that of the hypothetical"sheet water curtain" (determined by the terminal velocity of waste water based upon the maximum fixture unit loadings discharging into the stack).

[0029] To summarize, the present invention provides a force ventilation system which precludes the exhausting of foul and odiferous fumes and vapors from the lops of the generally vertical sanitary stacks in a multi-story building, yet does not require separate and independent ventilation systems for each stack or means for directing the gaseous exhaust from the tops of the stacks to a remote location. The system is simple and economical to construct, operate and maintain.

[0030] Now that the preferred embodiments of the present invention have been shown and described in detail, various modifications and improvements thereon will become readily apparent to those skilled in the art. Accordingly, the spirit and scope of the present invention is to be construed broadly and limited only by the appended claims, and not be the foregoing specification.