Provided is a blower installed at a manhole opening, with which it is possible to facilitate an entry or an exit of a worker or an import or an export of an article. The present invention provides a ventilation system comprising a frame and a single or a plurality of airflow generation means arranged at the frame, a direction of an airflow is adjusted so that the airflow generated from the airflow generation means flows along with a virtual axis penetrating a virtual surface which the frame is regarded as to periphery, and the airflow flows while swallowing up the surrounding air of the virtual axis, and an air volume more than two times of total fluid volume of the airflow is generated.

Embodiments of a valve assembly and a plumbing system incorporating the same are provided herein. In some embodiments, a valve assembly for use with an enclosed environment includes a housing having an interior volume, an inlet disposed at a first end of the housing and fluidly coupled to an environment surrounding the housing, and an outlet disposed at a second end of the housing opposite the first end and fluidly coupled to the enclosed environment; a first valve having a first valve seat and a first sealing member at least partially extending through a first opening in the first valve seat in a closed position; and a second valve disposed beneath the first valve and having a second valve seat and a second sealing member at least partially extending through a second opening in the second valve seat in a closed position.

The present disclosure relates to a method of controlling a ventilatory volume for inhibiting a release of a harmful gas such as an offensive odor or a toxic substance from a closed-type duct. The method of controlling a ventilatory volume is characterized in that (i) the closed-type duct is divided into a single main duct and multiple branch ducts in a planned area and depends on a harmful gas prevention closed-type duct model in which a negative pressure may be formed by a separately provided means for forcedly discharging gas, (ii) in a state in which no forced gas discharge from the closed-type duct is made, the harmful gas is determined as a standard flow velocity by comparing inverse velocity values of natural positive-pressure flow velocities according to a difference in temperature, a difference in concentration, a difference in elevation of the duct, a stack effect, and the like, (iii) the standard flow velocity is assigned in a lump to flow velocities in the single main duct and the multiple branch ducts provided in the closed-type duct, a sum of the flow rate in the main duct and the flow rate in the multiple branch ducts is basically determined as a ventilatory volume by the means for forcedly discharging gas, and particularly, only the flow rates in the branch duct at the junction points are corrected and determined in a lump based on a ratio of a pressure loss in the main duct to a pressure loss in the branch duct. The method of controlling a ventilatory volume may be applied to the closed-type duct having various usages and shapes and may provide a quantitative criterion related to a minimum ventilatory volume required to inhibit a release of a harmful gas, thereby reducing costs, maximizing operational efficiency, and an operational criterion practical to various types of ventilation devices.

The present disclosure relates to a method of controlling a ventilatory volume for inhibiting a release of a harmful gas such as an offensive odor or a toxic substance from a closed-type duct. The method of controlling a ventilatory volume is characterized in that (i) the closed-type duct is divided into a single main duct and multiple branch ducts in a planned area and depends on a harmful gas prevention closed-type duct model in which a negative pressure may be formed by a separately provided means for forcedly discharging gas, (ii) in a state in which no forced gas discharge from the closed-type duct is made, the harmful gas is determined as a standard flow velocity by comparing inverse velocity values of natural positive-pressure flow velocities according to a difference in temperature, a difference in concentration, a difference in elevation of the duct, a stack effect, and the like, (iii) the standard flow velocity is assigned in a lump to flow velocities in the single main duct and the multiple branch ducts provided in the closed-type duct, a sum of the flow rate in the main duct and the flow rate in the multiple branch ducts is basically determined as a ventilatory volume by the means for forcedly discharging gas, and particularly, only the flow rates in the branch duct at the junction points are corrected and determined in a lump based on a ratio of a pressure loss in the main duct to a pressure loss in the branch duct. The method of controlling a ventilatory volume may be applied to the closed-type duct having various usages and shapes and may provide a quantitative criterion related to a minimum ventilatory volume required to inhibit a release of a harmful gas, thereby reducing costs, maximizing operational efficiency, and an operational criterion practical to various types of ventilation devices.

An apparatus to allow or stop an air flow into an enclosed environment or piping system comprises (a) a housing, (b) a first valve seat, (c) a first sealing member, (d) a second valve seat, (e) a second sealing member, (f) at least one locking mechanism configured to limit a movement of the first sealing member and/or the second sealing member; wherein the first sealing member moves away from the first valve seat when the second pressure is greater than the first pressure in a predetermined pressure difference; wherein the second sealing member moves away from the first valve seat when the third pressure is greater than the second pressure in a predetermined pressure difference; wherein the first pressure communicates with a system pressure in the piping system; and wherein the third pressure communicates with an ambient air pressure.

An odor neutralization device for a wastewater lift station wastewater vent. The device is formed from a housing having a vertical standpipe with a first end securable to the receiver vent of a wastewater lift station and a second end extending above an admixture of essential oils and a surfactant. A baffle arrangement increases the velocity of air exiting or entering the wastewater lift station. The accelerated air is directed across the surface of the admixture for altering the characteristics of any odor laden air.

An odor neutralization device for a wastewater lift station wastewater vent. The device is formed from a housing having a vertical standpipe with a first end securable to the receiver vent of a wastewater lift station and a second end extending above an admixture of essential oils and a surfactant. A baffle arrangement increases the velocity of air exiting or entering the wastewater lift station. The accelerated air is directed across the surface of the admixture for altering the characteristics of any odor laden air.

A manhole cover system (10) for sealing manholes to minimize water infiltration includes a manhole cover (12) re-movably inserted into a manhole cover frame (14) having a compressible gasket (28) attached thereto. Manhole cover (12) includes a base (16) and a peripheral rim (18). Peripheral rim (18) includes a cover outer peripheral surface (20) and a horizontal cover seat (22). Manhole cover frame (14) includes a frame cover restraint wall (24) and a frame seat (26). During assembly, peripheral rim (18) is removably seated on frame seat (26) of manhole cover frame (14). Compressible gasket (28) forms a seal within a vertical clearance space (32) between cover outer peripheral surface (20) and frame cover restraint wall (24).

A manhole cover system (10) for sealing manholes to minimize water infiltration includes a manhole cover (12) re-movably inserted into a manhole cover frame (14) having a compressible gasket (28) attached thereto. Manhole cover (12) includes a base (16) and a peripheral rim (18). Peripheral rim (18) includes a cover outer peripheral surface (20) and a horizontal cover seat (22). Manhole cover frame (14) includes a frame cover restraint wall (24) and a frame seat (26). During assembly, peripheral rim (18) is removably seated on frame seat (26) of manhole cover frame (14). Compressible gasket (28) forms a seal within a vertical clearance space (32) between cover outer peripheral surface (20) and frame cover restraint wall (24).

Embodiments of a valve assembly and a plumbing system incorporating the same are provided herein. In some embodiments, a valve assembly for use with an enclosed environment includes a housing having an interior volume, an inlet disposed at a first end of the housing and fluidly coupled to an environment surrounding the housing, and an outlet disposed at a second end of the housing opposite the first end and fluidly coupled to the enclosed environment; a first valve having a first valve seat and a first sealing member at least partially extending through a first opening in the first valve seat in a closed position; and a second valve disposed beneath the first valve and having a second valve seat and a second sealing member at least partially extending through a second opening in the second valve seat in a closed position.