US3855910A

US3855910A - Acoustical ventilator

Info

Publication number: US3855910A
Application number: US00287881A
Authority: US
Inventors: B Brinton; L Schorn; H Schorn
Original assignee: Robertson Bauelemente GmbH
Current assignee: Robertson Bauelemente GmbH
Priority date: 1971-11-12
Filing date: 1972-09-11
Publication date: 1974-12-24
Anticipated expiration: 1991-12-24
Also published as: GB1371586A; DE2156189A1; CA968617A; DE2156189C2

Abstract

A ridge ventilator by which exhaust gases, smoke, fumes, dust and heat are discharged from the interior of buildings. The ridge ventilator is uniquely adapted to restrict the acoustical energy which is released from the ventilator without affecting the discharge gases through the ventilator.

Description

United States Patent 1 Brinton et a1.

1451 Dec. 24, 1974- Filed:

ACOUSTICALVVENTILATOR I Inventors: Bernard E. Brinton, Hitdorf,

Germany; Lugwig H. Schorn,

deceased, late of Hitdorf, Germany by Hedwig Schorn, administratrix Robertson Bauelemente G.m.b.H., Monheim-Hitdorf (RI-ILD), Germany Sept; 11, 1972 Appl. No.: 287, 81

Assignee:

Foreign Application Priority Data I Nov. 12, 1971 Germany 2156189 u.s. c1 98/42, 98/66 R, 98/83, 181/50 1m, c1..... F24f 7/02 Field of Search .1 9 /42; 43, 83, 66 R; 1 1/33 0,50

- References Cited UNITED STATES PATENT-S1" .4/1936 Day 181/50 OTHER PUBLICATIONS Hirschman 98/42 Adams... Bohanon...

Cook

Tutt

Robertson Ventilators ,A.1.A. File No. 12-X, Jan. 1956, page Primary Examiner-William F. ODea' Assistant Examiner-W. Tapol'cai, Jr.

Attorney, Agent, or Firm-Harry B. Keck; George 'E. Manias ABSTRACT A ridge ventilator ,by which exhaust gases, smoke, fumes, dust and heat are discharged from the interior of buildings. .The ridge ventilator is uniquely adapted to restrict the acoustical energy which is released from the ventilator without affecting the discharge gases through the ventilator.

4 C1aims, 5 Drawing Figures PATENT El] 0512241974 saw 1 or 3 FIG. I

PRIOR ART PATENTEHBEBZMW 3855.910

' SHEET 2 9f 3 I FIG. 3

1 ACOUSTICAL VENTILATOR consist of an appropriately weather-shielded horizontal, rectangular opening in thereof of a building. While the building may have an essentially flat roof, custom- .arily such ventilators areemployed in ridged or pitchedroofs and the ventilator is provided at the apex of such tional ridge ventilator which is known in the prior art.

FIG. 2 is a cross-sectional illustration similar to FIG. 1 of a ridge ventilator-according to the present invention with certain parts shown in phantomoutline. I FIG. 3 is an exploded view of a typical ridge ventilator according to the present invention illustrating the relation of various components in more detail.

ventilator of FIG. 3.

roofs. Exhaust gases, smoke, fumes, dust and heat are discharged from the interior of buildings through such ridge ventilators most effectively when they are position ed at the apex of the building roof. Theweatherproofing features are designed to preclude entry of atmospheric precipitation without presenting significant obstructions to the free flow of discharging gases. Good aerodynamic design of the shapes of the weatherproofing features will improve the discharging characteristics of such ridge ventilators.

SUMMARY OF THE INVENTION- Recently laws have been promulgated to regulate the amount of acoustical energy which can be released from a building to its surrounding areas. Some acousti- FIG. 4 is a perspective fragmentary illustration of a typical perforated sheet metal FIG. 5 is a fragmentary perspective illustration of a throat of the present acoustical ventilator showing an additional embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Prior Art Referring to FIG. -1, a typical ridge ventilator 10 is mounted on a pitched roof 11 above a roof opening 12 which is generally horizontal and generally rectangular in plan. The roof opening 12 is bordered by curb members including side walls 13 and end walls 14 which define the ventilator throat 15.

The ventilator cowling consists of curved sheeting 16 and flat end. walls 17. A ridged. cap member 18 has a width greater than the ventilator throatl5- and is discal energy is released through walls and windows of buildings, some through the roofs of buildings and a surprising amount through the open ridge ventilators of buildings. The present invention provides 'a ridge ventilator which is uniquely adapted to restrict the acousti-' cal energy which is released from the ventilator without seriously affecting thedischarge gases through the ventilator. In accordance with the "present invention, the otherwise conventional ridge ventilator is equipped with: v

A. acoustically reflecting curb members at the throat of the ventilator; y I

B. an acoustically absorbant surface disposed beneath the cap of the ridge ventilator in confronting relation with the open throat ofthe ventilator;

C. if desired, supplemental acoustical absorbing panels disposed transversely across the throat of the ventilator;

D. a substantially imperforate connection between the ventilator cowling and. the ventilator curb.

Buildings equipped with the present improved ridge ventilator have significantly lowered acoustical sound release characteristic.

Because of release of acoustical energy from a building accurs through a variety of routes, the present improved acoustical ventilator will not provide noticeable improvement in the performance of a building which is readily sound transmissive through its walls or roofs or windows. However for a building having suitably acoustically non-transmissive walls, windows and roofs,'the improved acoustical ventilator of thisinvention is effective.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a cross-sectional illustration of a convenposed in confronting relation to the ventilator throat 15. The curved sheeting 16 and end walls 17 are supported bysuitablestructural members (usually steel angles or channelslwhich are not shown in FIG. 1. It will beobserved that the bottom ends 19' of the curved sheeting 16 are spaced-apart from the side walls 13 so that any atmospheric precipitation can pass between the bottom ends 19 and the side walls 13 and thence flow downwardly over the pitched roof 11. Frequently air-flow guide vanes 20 are provided between the curved sheeting 16 and the ridged cap member 18 to minimize turbulence within'the ventilator l0 and also to interrupt the straight line flow of atmospheric pre- 'cipitation and thereby prevent ingress through the ventilator throat 15 tothe interior of the building. The ridged cap member 18 and the vanes 20 also are sup ported by means of suitable structural members which do not appear in FIG. l. i

The sheeting 16 may 2,127,099 WHITAKER 1938) or curved (US. Pat.

16 preferably is sheet metal which may be flat, slightly corrugated or embossed.

The Present Invention The improved acoustical ventilator of the present.in-.

vention is illustrated in FIG 2 which is a cross-section illustration similar to FIG. 1 whereincorresponding nu- .merals are employed to'identify corresponding parts. The ventilator of FIG. 2 identified by the numeral 10' 4 is mounted on a pitched roof 11 having a roof opening 12'. The installation includes a generally vertical stack including generally vertical side stack walls l3' and generally vertical end stack walls 14' which define'a ventilator throat 15. Thesuperstructure includes curved sheeting 16', flat end-walls 17', a ridged cap member 18' and. air flow directing vanes 20. The air.

flow directing vanes 20' maybe fixed or, preferably,

panel useful in the ridge be angled (u.s.- Pat. No.

may be pivotally mounted to permit them to serve as dampers as will be illustrated'hereinafter. Alterations to the Ridged Cap Member The ridged cap member 18' is provided with acoustical absorbing surface identified generally by the numeral 21. The usrfac'e 21 extends across its undersurface of the ridged cap memberl8' in direct confrontation with the ventilator throat .15. Preferably the acoustical absorbing surface 21 consists of a perforated rigid plate 22 and a layer 23 of fibrous sound absorbing material. The perforated rigid plate 22 is preferably sheet metal. The sound absorbing layer 23 is preferably mineral wool or glass fibers which will resist elevated temperatures.

Alterations to the Ventilator Stack I The side walls 13' and end wallsl4 have an inner surface of sound reflecting material such as imperforate sheet metal panels in "order to confine the acoustical energy from dissipation outwardly through the walls 13; 14' and further to channelize the acoustical energy into impingement against the sound absorbing surface 21. The structure of the walls 13', 15' will be more fully described in relation to the discussion of FIG. 5.-

The two revisions just described will collectively accomplish the significant reduction in the sound released from the building. In addition to these tworevisions, several further improvements have been incorporated in the ventilator of FIG. 2.

Specifically the bottom ends 19' of thecurved sheeting 16" are contiguous with the outer surface of theside walls 13' so that no gap is presented for the dissipation of acoustical energy. Suitable guttering, discussed supra in relation to FIG. 5, is provided in the region 24 to discharge any accumulations of atmospheric precipitation. e

As a'still further improvemenflone or more panels 25 of acoustically absorbant material may be inserted transversely into the ventilator stack generally parallel to the end walls l4' and normal to the side walls 13. Lightweight metal frames for holding theacoustical panels 25 may be provided to permit removal of the acoustical panel s25 for cleaning and/orv replacement from time to time without requiring dismantling of the ventilator'lO'; The acoustically absorbant panels 25 preferably are formed from fibrous incornbustible materials such a mineral wool or glass wool.

The presence of acoustical panels 25 reduces the available cross-sectional free area in the ventilator throat for flow of discharging gases. Accordingly when the acoustical panels 25 are employed, the cross sectional area of the ventilator throat 15' must be increased if the exhausting capacity of the ventilator is to be equivalent to that of a similar ventilator without such acoustical absorbing panels 25. The increase in size can be accomplished by increasing the width of the ventilator throat 15' that is, by increasing the size of the end walls 14' or by increasing the length of the ventilator that is, by increasing the length of the side walls 13, curved sheeting l6, ridge cap member 18 and guiding vanes 20'.

As a general matter, it is impractical to increase the length of a ventilator because ventilation effectiveness depends upon locating the ventilator directly above the heat source within a building. Accordingly it is preferred to increase the width of the ventilator. At the outset, i.e., during design and construction, utilization of transverse acoustical panels should be anticipated. Accordinglythe'width of the ventilator throat should be increased about 40 per cent so that the total exhaust cross-sectional area of the throat is about 40 per cent in excess of the anticipated. unobstructed throat requirement. The design of the ventilator is such that the required number of acoustical panels 25 can be introduced at any time after the building is completed to satisfy the acoustical requirements. The per cent increase which is recommended will permit subsequent introduction of a multitude of acoustical panels 25. For

example, panels having a thickness of 100 millimeters can be spaced 150 millimeters apart without interfering with the required exhaust cross-sectional area if the prescribed 40 per cent width increase is provided.

Referring to FIG. 3, a perspective illustration of a fragment of the improved ventilator is illustrated. It will be observed that the ridged cap member 18 has a covering of corrugated sheet metal 26 supported on sloping structural'members 27. The curved sheeting 16 has corrugated sheet metal 28 mounted on suitably curved frame members 29. The guiding-vanes 20' consist of corrugated sheet metal 30 mounted on a suitably pivotal frame 31. It will be observed that the left-hand vane 20 is shown in a-full-open positionwhereas the right-hand vane 20' is shown in a pivoted position wherein it functions to close the exhaust passageway.

Beneath the ridged cap member 18 is a generally horizontal frame member 32 towhich perforated sheet metal channel sections 33 are secured. A fragment of atypical sheet metal channelse'ction 33 is illustrated for clarity in FIG. 4. The section 33 includes a web 34,

upwardlyextending side walls

35, 36, and

terminal flanges

37, 38 both extending in .thesame direction.

The web 34 preferably is perforated with holes which may be uniformly dispersed in a regular patternor' which may be provided in arandom pattern. The perforations in the web 34 may be of identical size, of several sizes, or may be of randomly selectedsizjes.

The total perforated area should beat least 25 per cent of the area of the web 34 so that the webs 34 can be considered to. be sound-transparent.

Typically the sheet'.metal section 33 is fabricated I from light gauge steel, 26 through 14 gauge. The 'web 34 may range in width from about 25 to 100 centimeters. The side ,

walls

35,36 may range fromabout 1 to 10 centimeters. The vertical side wall 36 should be one metal thickness shorter than the vertical side wall 35 in order that the flange 37 of one section can overlap a I corresponding flange 38 of the adjacent and abutting section.

'Reverting to FIG. 3, the assembled channel sections 33 are covered with a layer 39 of sound absorbing materials such as mineral wool or glass fibers. The layer 39' has a thickness from',.2 to 20 centimeters and is coextensive with the assembly of channel sections 33. Preferably a glass fiber veil, essentially sound-transparent,

, is applied on top of the channel sections 33 to serve as a restraining net whichwill prevent the lose mineral wool from falling through the perforations.

Referring to FIGS there is illustrated a fragmentary filled with insulating material 43 to minimize transmis sion of sound energy through the'side walls 13. The insulating material 43 may be mineral wool or glass fi bers.

The inner sheet 42 preferably .is formed from sheet metal which has a different thickness than the sheet metal of the outer sheet 46. The spacing between inner sheet 42 and outer sheet 46 is preferably about 75 millimeters. The insulating material 43 preferably has a density of about 70 kilograms per cubic meter.

The height of theside wallsI13 is greater than the height of the acoustical panels 45.

Also seen in FIG. 5 is a frame member 44 extending transversely across the ventilator throat 15 between the side walls 13 for supporting generally rectangular, vertically presented, sound absorbing panels 45. Four such sound absorbing panels 45 are illustrated in partly-cut-away presentation in FIG. 5. Each one is individually mounted in a suitable frame 44 in such manner that the panel 45 can be removed and replaced easily withoutdismantling the ventilator superstructure.

It should be emphasized that the present ventilator improvement is effective regardless of whether the sound absorbing panels 45 are employed. Their'use will provide further acoustical improvement where such refinements are required. The ventilator has a further advantage that its initial erection is achieved by workmen on the roof. No interior construction is required. The

entire ventilator assembly is essentially above the roof level without any intrusions into the building space.

Typical existing regulations establish allowable acoustical levels for various zones in terms of maximum noise. The noise is measured in decibels on the A network, referred to as db(A). The maximum levels are 35 (night) These noise levels do not apply to the noise level at the source but, in general, are the maximum allowable values at a point which is 1 meter in front of the nearest private dwelling. The noise levels are considered as average values over a period of time but some regulations include additional stipulations concerning the type of noise, the frequency, the maximum intensity, et cetera.

Employing the principles set forth in'the present application under actual tests,- sound intensities were measured at 10 meters from the ventilator in two directions. The first direction was 90 from the ventilator axis; the second direction was in line with the ventilator axis. The sound reduction measured at 10 meters(90 from the ventilator axis) was 25 decibels. The sound 1. In a ridge ventilator which surmounts a generally rectangular and horizontal opening in the-roof of a building, a generally vertical stack including generally vertical side stack walls and generally vertical end stack walls which are connected to each other and which form an open box-like enclosure partly above the said opening, said ventilator including side walls extended outwardly and upwardly from said stack generally parallel with the long edge of the opening and having end walls connected to the side walls and extending upwardly. from the narrow, edge of theopening, and having a cap member disposed above the opening between the side walls and extending substantially entirelybetweenthe end walls,,the improvement comprising: an

I acoustic absorption assembly applied to the unde'rsurface of the said cap member in confrontation with said imperforate inner surfaces channelizing acoustical energy received from'the building interior into impingement against said acoustic absorption assembly.

2. The ridge ventilator of claim 1 including at least one frame extending from one stack side wall across the said opening to the other stack side wall, and a sound absorbing panel supported by the said frame.

3. The ridge ventilator of claim 2 wherein the ventilator side walls'are connected to the stack side walls by an imperforate connection thereby to provide a gutter for draining condensation which accumulates between the inner surface of-the ventilator side wall and the v outer surface of the stack side wall.

4. The ridge ventilator of claim 2 wherein thethickness of the exterior sheet is different from that of the imperforate interior sheet.

Claims

1. In a ridge ventilator which surmounts a generally rectangular and horizontal opening in the roof of a building, a generally vertical stack including generally vertical side stack walls and generally vertical end stack walls which are connected to each other and which form an open box-like enclosure partly above the said opening, said ventilator including side walls extended outwardly and upwardly from said stack generally parallel with the long edge of the opening and having end walls connected to the side walls and extending upwardly from the narrow edge of the opening, and having a cap member disposed above the opening between the side walls and extending substantially entirely between the end walls, the improvement comprising: an acoustic absorption assembly applied to the undersurface of the said cap member in confrontation with said opening, said assembly including a plurality of perforate rigid, sheets confronting said opening and a layer of absorbent for acoustical energy supported between the cap member and the sheets; and each of the end and side stack walls comprising an exterior sheet, an imperforate interior sheet, and an insulating material filling the space therebetween, thereby to minimize transmission of sound energy through the end and side stack walls, the imperforate inner sheet of the end and side stack walls providing imperforate inner surfaces having reflecting properties for acoustical energy, the imperforate innEr surfaces channelizing acoustical energy received from the building interior into impingement against said acoustic absorption assembly.

3. The ridge ventilator of claim 2 wherein the ventilator side walls are connected to the stack side walls by an imperforate connection thereby to provide a gutter for draining condensation which accumulates between the inner surface of the ventilator side wall and the outer surface of the stack side wall.

4. The ridge ventilator of claim 2 wherein the thickness of the exterior sheet is different from that of the imperforate interior sheet.