Blast cap

Abstract

The invention provides a blast cap which comprises an outer ventiduct, a flow deflector and an inner ventiduct, wherein the outer ventiduct is arranged on the outer side above a blast cap connecting pipe in a covering manner; an upward exhaust passage is formed in the outer ventiduct; the flow deflector is supported on the outer ventiduct, is positioned in the exhaust passage and is arranged on one side above a top smoke vent of the blast cap connecting pipe; the inner ventiduct extends upwards along the upper end face of the flow deflector to form a side wall capable of receiving wind or rainwater floating to the inner wall of the outer ventiduct to generate bounce, and a drainage section capable of penetrating up and down to exhaust is formed between the side wall and the inner wall of the outer ventiduct; exhaust gas discharged out of the top smoke vent of the blast cap connecting pipe bends after passing through the flow deflector, penetrates through the drainage section, and thenis discharged out of the top outlet of the outer ventiduct. The blast cap can prevent wind or rainwater from floating and flowing backward, also can prevent wind or rainwater from bouncing and flowingbackward and thoroughly solves the flowing-backward problem of the blast cap.

Description

technical field [0001] The invention relates to the technical field of building exhaust ducts, in particular to an anti-backflow hood, in particular to a hood capable of preventing rebounding wind or rainwater from falling into the exhaust duct after impact due to high wind or rainwater kinetic energy . Background technique [0002] At present, the air caps installed at the roof air outlet of the residential exhaust system can be divided into the following three categories: the first type of air cap is to install a flat or umbrella-shaped top cover directly above the air outlet, and the smoke flows from the top. The underside of the cover plate discharges to the perimeter. The disadvantage of this type of hood is that the structure is too simple. When encountering slanting wind and rain, wind and rain can easily flow back into the exhaust duct, which not only hinders the normal discharge of smoke in the exhaust duct, but also rainwater will flow into the room along the exha...

AI Technical Summary

Problems solved by technology

The disadvantage of this type of hood is that the structure is too simple. When encountering oblique wind and horizontal rain, wind and rain can easily flow back into the exhaust duct, which not only hinders the normal discharge of smoke in the exhaust duct, but also rainwater will flow into the room along the exhaust duct.

The second type of wind cap is an improvement on the first type of wind cap. It installs rain-proof shutters at the exhaust port under the top cover, which improves the rain-proof performance of the wind cap to a certain extent, but reduces the exhaust port significantly. The effective ventilation area reduces the airflow velocity at the exhaust port and significantly increases the exhaust air resistance of the hood, resulting in poor exhaust

If the gap between the windshield side plate and the cover plate of the hood is too small, the exhaust air resistance will be large, resulting in difficulty in exhausting smoke; if the gap between the windshield side plate and the cover plate of the hood is too large, the In windy and rainy weather, it is inevitable that wind and rain will pour into the exhaust duct

[0003] Aiming at the defects in the above-mentioned prior art, the applicant made several tests and proposed an improvement (application number 201821919248.8), by setting a top cover and a windproof and rainproof outer cover that cooperate with each other to avoid wind and rain pouring into the exhaust duct, in most cases However, in practice, it is found that when used in areas where storms often occur, there will still be wind or rainwater pouring into the exhaust duct. The applicant has repeatedly observed and tested on-site , it is found that the wind or rainwater poured into the exhaust duct is rebound wind or rainwater. When the wind or rainwater has a large kinetic energy, a small part of the wind or rainwater rebounds after impact, changing the original trajectory and rebounding and sputtering Intake and exhaust

[0004] At present, in the field of exhaust ducts, there is no solution to the problem of rebounding wind or rainwater, and even the phenomenon that wind or rainwater can rebound and cause backflow has not been found.

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