US3303771A

US3303771A - Ventilated ceiling construction

Info

Publication number: US3303771A
Application number: US431831A
Authority: US
Inventors: Nesher Alexander; John K Henderson; Robert J Sigel
Original assignee: ROBERT J SIGEL Inc
Current assignee: ROBERT J SIGEL Inc
Priority date: 1965-02-11
Filing date: 1965-02-11
Publication date: 1967-02-14
Anticipated expiration: 1984-02-14

Description

Mb: 1%? A. NESHER ETAL VENTILATED CEILING CONSTRUCTION 4 Sheets-Sheet 1 Filed Feb. 11, 1965 Feb. M, 1%? A. NESHER ETAL.

VENTILATED CEILING CONSTRUCTION V 4 Sheets-Sheet 2 Filed Feb. 11, I965 1 I n" Fw M1, W? men-am izA'AL VENTILATED CEILING CONSTRUCTION Sheets-Sheet 5 Filed Feb. ll, 1965 wll I United States Patent 3,303,771 VENTILATED CEILING CONSTRUCTION Alexander Nesher, Rosemont, John K. Henderson, Villauova, and Robert J. Sigel, Narberth, Pa., assignors to Robert J. Sigel, Inc., Nat-berth, Pa., a corporation of Pennsylvania Filed Feb. 11, 1965, Ser. No. 431,831 Claims. (Cl. 9840) This invention relates .generally to ceiling constructions and particularly to an improved false sealing construction for a room.

Manufacturing facilities providing the environmental control necessary for the manufacture of todays sophisticated components and systems are known as clean rooms. A clean room is a space in which airborne contamination, and if needed, temperature and humidity are controlled to a far higher degree than conventional air conditioned areas. One approach to the design and operation of a clean room utilizes highly filtered and conditioned air brought into the room through a filter bank covering an entire wall or ceiling of the room, and exhausted through a similar entire surface. The air is moved through the room in a laminar flow fashion, thus making only a single pass through any given area of the room. This laminar flow air movement quickly carries any released contamination brought into the room on personnel and equipment, and airborne contamination generated by operations in the room, out of the room. Contamination generated in localized areas of the room is isolated from other areas by the striations of the luminar air flow. Emphasis is placed on performing critical work in the undisturbed flow of clean air from the incoming air surface. Personnel restrictions, equipment, and operational limitations are minimized.

When a room is provided with a false ceiling, it is quite common to utilize the plenum chamber formed between the false ceiling and the true ceiling as a supply duct for ventilating air, which flows from the plenum chamber downwardly to the room through perforations provided in the false ceiling. But the flow of ventilating air through a ceiling that is merely perforated is non-uniform and turbulent. A laminar air flow room requires a uniform flow of filtered air uniformly distributed throughout the room so that turbulence is reduced to a minimum. The requirements for a laminar air flow room are set forth in Federal Standard No. 29, Clean Room and Work Station Requirements, Controlled Environment. Until the appearance of Federal Standard No. 29, ventilated ceilings were designed only for ordinary air conditioning or ventilating installations, and therefore ventilating rates only ranged up to 5 c.f.m. of air per square foot of ceiling area. A laminar air flow room requires a much higher rate. Accordingly, an important object of the present invention is to provide a false ceiling construction having a maze of nozzles distributed over the entire ceiling area for shower-like delivery of ventilating air at an increased rate from a plenum chamber to the room below in a uniform non-turbulent distribution pattern.

Another object of the invention is to provide such a ceiling construction which directs the air flow in a downward vertical pattern only at a ventilating rate in the order of 150 c.f.m. of air per square foot of ceiling area.

Another object of the invention is to provide such a ceiling construction which gives almost prefect uniformity of air distribution when air is introduced at only one end of comparatively large rooms.

Another object is to provide such a ceiling construc tion comprising an open framework and a system of air diffuser panels carried thereby.

Another object is to provide such a ceiling construc- "ice tion wherein each panel is a one-piece sheet-like member of thermoplastic material formed integrally with panel stiffening corrugations.

Another object is to provide such a ceiling construction wherein for a given pressure in the plenum chamber and a given flow of ventilating air, the size and number of nozzles per unit of ceiling area are predetermined.

Other objects of the invention will become apparent when the following description is read with reference to the accompanying drawings, in which:

FIGURE 1 is a diagrammatic perspective view of a clean room, part of the true ceiling being broken away to show a false ceiling construction in accordance with the invention;

FIGURE 2 is an enlarged vertical section on line IIII in FIGURE 1;

FIGURE 3 is a section on line IIIIII in FIGURE 2;

FIGURE 4 is a section on line IVIV in FIGURE 3;

FIGURE 5 is a perspective view looking at the top of an air diffuser panel;

FIGURE 6 is a perspective View looking at the bottom of a diffuser panel;

FIGURE 7 is an enlarged perspective view of one corner of a dilfuser panel, as viewed from the top;

FIGURE 8 is an enlarged perspective view of one corner of a diffuser panel, as viewed from the bottom; and

FIGURE 9 is a diagram showing a family of performance curves.

The following description is directed to the specific form of the invention illustrated in the drawings and is not intended to be addressed to the scope of the invention itself, which may be practiced in a variety of forms.

Referring particularly to FIGURE 1, four upright walls, designated 10, rest upon a true floor 12 and support a true ceiling 14 from which is suspended a false ceiling 16 disposed over a room 18. Between the false ceiling 16 and the true ceiling I4 is a plenum chamber 20 into which air may be conducted through a duct 22. Air entering the plenum chamber 20 through the duct 22 passes through the false ceiling 16 into the room 1% below and out of the room through an open grille type floor 24, raised above the true floor 12 to form a plenum 25. The air flows out of the plenum 25 through the duct 27. The direction of air flow is shown by arrows.

The false ceiling 16 comprises an open framework, generally designated 26, which framework includes a pair of rolled angle members 28 and a pair of rolled angle members 36 secured to the walls 1%, as by nails 32. Bridging the members 28 are a set of laterally spaced T-bar members 34, and bridging the members 30 and the T-bars 34 are short T-bar members 36. The

members

28, 30, 34 and 36 are secured together to afford a rigid open framework which is suspended from the true ceiling 14 by means of suitable hangers 38. The openings in the framework are designated 40 in FIGURES 2, 3 and 4.

Referring particularly to FIGURES 2 to 8, a diffuser panel 42 constructed in accordance with the invention is a thin, sheet-like rectangular member made of thermoplastic material, which may be opaque, translucent or transparent. Preferably, the panel is made of a polyvinyl. The panel is provided with a peripherally extending flange, generally designated 44, having a planar outer rim area 46 and an inner area 48 inclined relative to the plane of the rim area. The area of the panel bounded by the flange 44 is provided with raised areas, generally designated 50, whereby to form a series of corrugations 52 including a number of ridges 54 separated by furrows 56. The bottom of each furrow is a panel area 57 coplanar with the rim area 46. Inclined panel areas, designated 60, join the furrows and the ridges. The furrows 56 terminate at each end in an upright panel area 62. Depending from each raised area 50 are a number of nozzles 64, each in the form of the frustum of a cone disposed with its base uppermost and its smaller end lowermost. The nozzles are hollow, of course, and they extend downwardly to a level below the plane of the rim area.

The air diffuser panel is thermoformed, that is, it is molded by placing a sheet of thermoplastic material, in the order of i040 of an inch thick, over a suitably heated die member and drawing the sheet to the die member by vacuum. After the sheet is thus molded to the shape of the die, it is removed from the die and the lower ends of the nozzles are opened up.

In the erection of the false ceiling 16, the open frame- Work 26 is arranged preferably with the T-

bars

34 and 36 on twenty-four inch centers thereby to accommodate diffuser panels approximately twenty-four inches square. The framework 26 may be suspended from the true ceiling 14 by hangers 38 or supported in any other suitable manner. Thereupon, a diffuser panel 42 is placed over each opening 40. The rim area 46 seats on the horizontally extending legs of

angles

28 or 30 or the horizontally extending legs of the T-

bars

34 or 36, as shown.

The size and number of nozzles per square foot of ceiling area are determined -by reference to the performance curves shown in FIGURE 9. For example, for a static pressure of 0.20 inch of water gauge and an air flow of 140 cubic feet per minute per square foot of ceiling area, thirty-six /s-inch-diameter nozzles per square foot of ceiling area are .required. The air is supplied through ducts 22 to the plenum chamber 20, from whence it is discharged into the room 18 below through the maze of nozzles 64 for shower-like delivery in a uniform distribution pattern with a minimum of turbulence.

A ceiling constructed in accordance with the invention provides an almost perfect uniformity of air distribution when air is introduced at only one end of the room, in rooms up to about 100 feet in length. Heretofore, when a ceiling was constructed of high efiiciency particulate air filter units, in accordance with Federal Standard 209, the length of air travel from any one source was limited to approximately 20 feet from the source.

What is claimed is:

1. In a clean room, the combination comprising upper and lower ceilings forming an air supply upper plenum chamber, said lower ceiling including an open framework,

and a plurality of air difiuser panels carried by said framework and covering the openings therein, each of said panels having a planar peripherally extending rim, sections of the panel area within said rim raised above the plane of the rim thereby to provide panel stiffening corrugations, and nozzles depending from said raised sections of the panel area, said panels conjointly affording a maze of nozzles distributed over substantially the entire ceiling area, upper and lower floors forming an air discharge lower plenum chamber, said upper floor being of open grille type form, means for supplying comparatively large quantities of ventilating air at substantial overpressure to said upper plenum chamber for showerlike delivery thereof through said maze of nozzles to the room below in a uniform distribution pattern, the air being discharged from said room through said upper floor and lower plenum chamber.

2. The combination according to claim 1 wherein the nozzles are axially tapered and of a length to extend below the plane of the rim.

3. The combination according to claim 1 wherein each air diffuser panel consists of a single sheet of thermoplastic material.

4. The combination according to claim 1 wherein the nozzles of each panel are uniformly distributed thereover.

5. The combination according to claim 1 wherein the size and number of nozzles per unit of ceiling area are predetermined for a given pressure in the upper plenum chamber and flow of ventilating air through the nozzles in accordance with the diagram shown in FIGURE 9.

References Cited by the Examiner UNITED STATES PATENTS 2,291,220 7/ 1942 Germonprez 98--400 2,807,993 10/ 1957 Ericson 9840 2,912,918 11/1959 Mead 98-40 2,962,875 12/1960 Barroero 62-419'X 3,117,427 1/ 1964 Gessel 62-419 X 3,252,400 5/1966 Madl 9840 MEYER PERLIN, Primary Examiner.

ROBERT A. OLEARY, Examiner.

W. E. WAYNER, Assistant Examiner.

Claims

1. IN A CLEAN ROOM, THE COMBINATION COMPRISING UPPER AND LOWER CEILINGS FORMING AN AIR SUPPLY UPPER PLENUM CHAMBER, SAID LOWER CEILING INCLUDING AN OPEN FRAMEWORK, AND A PLURALITY OF AIR DIFFUSER PANELS CARRIED BY SAID FRAMEWORK AND COVERING THE OPENINGS THEREIN, EACH OF SAID PANELS HAVING A PLANAR PERIPHERALLY EXTENDING RIM, SECTIONS OF THE PANEL AREA WITHIN SAID RIM RAISED ABOVE THE PLANE OF THE RIM THEREBY TO PROVIDE PANEL STIFFENING CORRUGATIONS, AND NOZZLES DEPENDING FROM SAID RAISED SECTIONS OF THE PANEL AREA, SAID PANELS CONJOINTLY AFFORDING A MAZE OF NOZZLES DISTRIBUTED OVER SUBSTANTIALLY THE ENTIRE CEILING AREA, UPPER AND LOWER FLOORS FORMING AND AIR