Manual selective attenuator

1. An attenuating apparatus for use with a positive displacement compressor, comprising:

a bore formed in a housing of the compressor, the bore being positioned at an angle to a discharge chamber of the compressor and in fluid communication with the compressor discharge chamber;

a plug positioned within the bore, the plug movable after installation within the bore to a preselected position, the plug having a first end in contact with a gas from the compressor discharge chamber and a second, opposite end being accessible from an exterior of the housing;

a seal positioned between the plug and the bore to seal an interface between the plug and the bore to prevent leakage of the gas from the compressor discharge chamber along the interface;

the plug being lockable within the bore at the preselected position;

wherein the preselected position of the plug within the bore determines a bore length in fluid communication with the compressor discharge chamber, the preselected position of the plug determining the bore length that attenuates sound from gas pulsations resulting from discharge of compressed gas from the operation of the compressor.

2. The attenuating apparatus of claim 1 wherein at least a portion of the bore includes threads and at least a portion of the plug includes threads, the bore threads located on an interior diameter of the bore being mateably compatible with the plug threads located on an exterior diameter of the plug.

3. The attenuating apparatus of claim 2 wherein the threaded plug includes a tuning chamber positioned at its first end in fluid communication with the compressor discharge chamber.

4. The attenuating apparatus of claim 1 wherein the bore is positioned in the housing at an angle of about 90 degrees to the discharge chamber and substantially perpendicular to the direction of compressed gas flow.

5. The attenuating apparatus of claim 1 wherein the plug includes a means for adjusting the plug within the bore.

6. The attenuating apparatus of claim 5 wherein the means for adjusting includes a hex head at the second, opposite end.

7. The attenuating apparatus of claim 5 wherein the means for adjusting includes a socket at the second, opposite end.

8. The attenuating apparatus of claim 1 wherein the preselected position of the plug within the bore provides the bore length that is a ¼ wavelength increment of an undesirable, peak sound produced by the gas discharged by the positive displacement compressor.

9. A compressor system having a noise damping capacity, comprising:

a compressor housing;

a positive displacement compressor housed in the compressor housing, the compressor having a discharge chamber at a compressor discharge port, the discharge chamber receiving compressed gas discharged through the compressor discharge port;

a bore formed in the compressor housing, the bore being positioned at an angle to the compressor discharge chamber and in fluid communication with the discharge chamber;

a plug positioned within the bore, the plug movable after installation within the bore to a preselected position, the plug having a first end in contact with the gas from the compressor discharge chamber and a second, opposite end, the second end being accessible from an exterior of the housing;

a seal positioned between the plug and the bore to seal an interface between the plug and the bore to prevent leakage of the gas from the compressor discharge chamber along the interface;

the plug being lockable within the bore at the preselected position;

wherein a volume of the discharge chamber and a volume of the bore together provide a total discharge volume of the compressor; and

wherein the preselected position of the plug within the bore determines the volume of the bore, the preselected position of the plug determining a bore length that attenuates sound from gas pulsations resulting from discharge of compressed gas from the operation of the compressor.

10. The compressor system of claim 9 wherein at least a portion of the bore includes threads and at least a portion of the plug includes threads, the bore threads located on an interior diameter of the bore being mateably compatible with the plug threads located on an exterior diameter of the plug.

11. The compressor system of claim 9 wherein the threaded plug includes a tuning cavity positioned at its first end in fluid communication with the compressor discharge chamber.

12. The compressor system of claim 9 wherein the bore is positioned in the housing at an angle of about 90 degrees to the discharge chamber and substantially perpendicular to the direction of compressed gas flow.

13. The compressor system of claim 9 wherein the plug includes a means for adjusting the plug within the bore.

14. The compressor system of claim 13 wherein the means for adjusting includes a hex head at the second, opposite end.

15. The compressor system of claim 13 wherein the means for adjusting includes a socket at the second, opposite end.

16. The compressor system of claim 9 wherein the preselected position of the plug within the bore provides the bore length that is a ¼ wavelength increment of an undesirable sound produced by the gas discharged by the positive displacement compressor.

17. The compressor system of claim 9 wherein the seal is an o-ring seal.

18. The compressor system of claim 9 wherein the bore further includes a groove for receiving the seal, and the seal is positioned within the groove.

19. The compressor system of claim 9 wherein the plug further includes a groove for receiving the seal, and the seal is positioned within the groove.

20. The compressor system of claim 11 wherein the tuning cavity further includes a passive sound absorptive material.