|Publication number||US3677300 A|
|Publication date||Jul 18, 1972|
|Filing date||Jul 8, 1970|
|Priority date||Jan 15, 1970|
|Also published as||CA926266A, CA926266A1, DE2035121A1, DE2035121B2, DE2035121C3|
|Publication number||US 3677300 A, US 3677300A, US-A-3677300, US3677300 A, US3677300A|
|Inventors||King Colin F|
|Original Assignee||Dunlop Holdings Ltd|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (7), Referenced by (48), Classifications (14)|
|External Links: USPTO, USPTO Assignment, Espacenet|
United States Patent King [451 July 18,1972
 Assigne'e: Dunlop Holdings Limited, London, En-
gland  Filed: July 8, 1970  Appl.No.: 53,162
 I Foreign Application Priority Data Jan. 15, 1970 Great Britain ..2,001/70  U.S.Cl ..l38/42, 137/6253, 138/40, 138/44 51 Int. Cl, ....Fl5d 1/02  Field of Search 138/42, 43, 44, 40, 41; Y l37/112,517, 625.3
 References Cited UNITED STATES PATENTS 3,042,079 7/1962 Swift ..138/42 Behlen ..138/42 X 1,947,586 2/1934 Fletcher 138/42 2,304,689 12/1942 Hemson 1 38/42 2,090,719. .8/1937 Alt ...l38/44 X 2,815,889 12/1957 Stetz..... ...l38/42 X 2,327,195 8/1943 Koslry ..138/43 Primary Examiner-Herbert F. Ross Attorney-Stevens, Davis, Miller & Mosher ABSTRACT A pressure reducing device comprises an inlet for high pressure gas, an outlet for low pressure gas and -a path therebetween for flow of gas from inlet to outlet. The path includes at least one porous baffle having a relatively coarse pore inner portion disposed in an inner zone of said path and a relatively fine pore outer portion in an outer zone of said path. Porous materials that may be used include layers of gauze, expanded metal, sintered metal, ceramic foams and plastics foams such as rigiditied foams.
16 Claims, 3 Drawing Figures PATENTEDJUL18|972 3677300 SHEET 1 BF 2 FICLI PATENTEU JUL! 8 I972 SHEET 2 OF 2 This invention relates to pressure reducing devices.
It is frequently necessary to reduce a high pressure stream of gas to a low pressure stream. Such a requirement often occurs in high pressure distribution of gases where the pressure is required to be reduced before transmission to the point of use. Conventionally, the reduction in pressure is achieved by passing the high pressure gas through a duct having a relatively large cross-sectional area. This procedure tends to create a high level of noise which can present a serious problem, for example where large quantities of gas are depressurized in urban areas.
According to the present invention a pressure reducing device comprises an inlet for high pressure gas, an outlet for low pressure gas and a path therebetween for flow of gas from inlet to outlet. The path includes at least one porous baffle having a relatively coarse pore inner portion disposed in an inner zone of said path and a relatively fine pore outer portion in an outer zone of said path.
The inner and outer portions of the baffle according to this invention may be integral or independent. When independent the portions may be in contact with one another or spaced apart.
In general, the arrangment of the porous baffles should be such as to permit expansion of the gas while reducing to a minimum the turbulence produced by the expansion.
In a preferred embodiment of the invention the outer portion may be formed by a female cone of porous material having an axial bore. In an alternative embodiment the outer portion may be formed by a series of co-axial annular discs of a porous material, whose internal diameters increase from inlet to outlet. These discs may or may not be contiguous. Advantageously, the inner portion is conical or part-spherical.
The outer portion may be uniform throughout or it may have one or more cavities therein. These cavities may be enclosed at least in part by porous material. Thus, for example the pressure reducing device may comprise an outer portion formed from a female cone of porous material, wherein, the body of the female cone is hollow, thereby forming a cavity which is totally enclosed by porous material.
Porous materials that may be used in the present invention include: layers of gauze, expanded metal, sintered metal,
ceremic foams and plastics foams such as rigidified foams.
The baffles according to this invention may be housed in a tube of suitable material positioned between the high pressure inlet and the low pressure outlet, in which case the baffles are sealed in the tube to prevent gas from by-passing them. Alternatively, the baffles may be coated on their external surfaces with a suitable material, i.e. laminated aluminium foil/epoxy skin or a glass reinforced plastics skin, these units then being placed between the high pressure inlet and low pressure outlet.
The baffles may be used alone or in conjunction with an additional mechanical reducing valve and/or with other types of baffle.
A preferred embodiment of the invention is hereinafter described with reference to the accompanying drawing in which FIG. 1 shows a diagrammatic cross section of a first embodiment;
FIG. 2 is a cross section of an alternate embodimenthaving contiguous annular discs and a spaced apart inner section, and FIG. 3 is a further embodiment having spaced apart discs.
The preferred embodiment shown in FIG. 1 comprises a cylindrical inlet and a coaxial cylindrical outlet 1 1 having a substantially larger diameter than the inlet 10.
Disposed between the inlet 10 and outlet 11 is a porous baffle made up of independent inner and outer portions. The outer portion 30 is in the form of a female cone, of relatively fine pore foam metal, which has a central bore 32. The inner portion 31 is in the form of a male cone of relatively coarse pore foam metal, and is located in the central bore 32 in contact with the outer portion 30.
The whole arrangement is sealed in tube 33 by a ring of 55 inch thick, pore/inch polyurethane foam (not shown) which is adhered to the pressure reducing device and is compressed when the device is fitted in the tube.
A pressure reducing device of the type described above was constructed in which: the male cone which forms the inner portion has base diameter 76 mm and height 102 mm-and is made from foam metal having 8 pores per inch; the female cone which forms the outer portion has diameter 76 mm and an overall length of 127 mm, and is made from foam metal having 80 pores per inch.
The noise level produced by a stream of air in the above pressure reducing device was measured using air velocity of 7.4 m/sec. In the absence of the diaphram the sound level was measured as 96 dB, whereas the arrangement described above produced a sound level of 79 dB and also silenced the high pitched whistle which was characteristic of the empty pipe.
When the above device was used together with three foam metal discs 76 mm in diameter and 13 mm thick made from 80 pores per inch foam, these discs being sealed in the outlet pipe 77 mm, 191 mm and 305 mm respectively, after the base of the male cone, the noise level was reduced to 75 dB. However, the air velocity was also reduced to 7.1 mm/sec.
In the embodiment shown in FIG. 2, the tube 37 contains a plurality of contiguous annular discs 35 of increasing internal diameter as an outer portion and an inner portion 34 which is spaced therefrom. In the embodiment shown in FIG. 3, the annular discs 35 are separated by spaces 36, the inner portion 31 being similar to that shown in FIG. 1. In any of the embidiments, the baffles may be coated on their external surfaces with a material such as a laminate such as aluminum foil and a plastics material or a glass reinforced plastics material.
Having now described my invention what I claim is:
l. A pressure reducing device comprises an inlet for high pressure gas, an outlet for low pressure gas and a path therebetween for flow of gas from inlet to outlet, said path including at least one porous bafile having at least two portions, the first being a relatively coarse pore inner portion disposed in an inner zone of said path and the other being a relatively fine pore outer portion in an outer zone of said path.
2. A pressure reducing device according to claim 1 in which the inner and outer portions are in contact with one another.
3. A pressure reducing device according to claim 2 in which the inner and outer portions are integral.
4. A pressure reducing device according to claim 1 in which the inner and outer portions are spaced apart.
5. A pressure reducing device according to claim 1 in which the outer portion is formed by a female cone of porous material, having an axial bore.
' 6. A pressure reducing device according to claim 1 in which the outer portion is formed by a series of coaxial annular discs of increasing internal diameter.
7. A pressure reducing device according to claim 6 in which the discs are contiguous with one another.
8. A pressure reducing device according to claim 6 in which the discs are spaced apart.
9. A pressure reducing device according to claim 1 in which the outer portion has at least one cavity which is enclosed at least in part by porous material.
10. A pressure reducing device according to claim 1 in which the inner portion is thicker in its central region than in its outer region.
11. A pressure reducing device according to claim 1 in which the inner portion is at least partly curved.
12. A pressure reducing device according to claim 1 in which each baffle is disposed within at least one duct.
13. A pressure reducing device according to claim I in which the baffles are coated on their external surfaces.
14. A pressure reducing device according to claim 13 in which the coating is a laminate of aluminum foil and a plastics material.
15. The device of claim 1 in which the relatively coarse inner portion has less than 10 pores per inch and the relatively fine outer portion has at least 50 pores per inch.
16. The device of claim 1 in which the relatively coarse inner portion has about 8 pores per inch and the relatively fine outer portion has about 80 pores per inch.
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|U.S. Classification||138/42, 137/625.3, 138/40, 138/44|
|International Classification||F16L55/02, F01N1/08, F16L55/00, F16L55/027|
|Cooperative Classification||F16L55/02745, F01N1/082, F16L55/02709|
|European Classification||F16L55/027G, F16L55/027B, F01N1/08C|