Regenair® - Gast Manufacturing, Inc.

ReferenceREGENAIR ® Regenerative BlowersSound Pressure Level Decreases With Distance According To This Formula:(SPL)2 = (SPL)1 - 20LOG (d2/d1)Where:(SPL)2 = New Sound Pressure Level(SPL)1 = Original Sound Pressure Leveld2 = New distance from sound generatord1 = Original distance from sound generatorThus, each doubling of distance results in 6 dBa reduction in Sound Pressure LevelNOTE: this formula assumes that no noise is reflected. In a room that reflects most sound energy (having walls with a low noise reductionco-efficient) much less reduction in noise level with increased distance will be observed than is predicted with this formula.Noise Q & AQ. How do I decrease blower noise?A. Common methods used to decrease blower noise include:• Having the cover side face where you want thereduction in noise to be and having sound absorbingmaterial diminish sound reflected from the motor sideof the blower• Checking the supporting structure for rattling• Controlling reflected noise with sound absorbing material• Moving the blower away from the operator, in anotherroom, possibly in a different area or outside.Q. Typically how much does the noise output of Gastblowers vary with changes in pressure or vacuum?A. This varies a lot from model to model with some models littleor no change and with others, as much as 9 dBa.Q. Tyically how much does the noise output of Gast blowerschange between 60 Hz and 50 Hz?A. Generally 50 Hz is 3 dBa quieter than 60Hz but this variesfrom model to model.Q. On Gast dual blowers when do I need the large accessorymuffler?A. These blowers provide silencing for either the inlet or exhaustbut not both. If, for example, the discharge of the bloweris underwater or in some location where the noise passingthrough the pipe is contained and not objectionable noadditional silencer is needed. Where this ringing noise is notcontained and noise control is needed, we manufacture accessorymufflers to greatly reduce noise levels.Q. What happens to the noise when I locate two blowersclose together?A. If the blowers are of the same design they produce soundfrequencies that are close together. These may cause a“beating” change in volume of the blower noise. This isbecause the units are not synchronized. If two small blowersare needed this change in volume can be reduced by movingthem further apart. With larger blowers a dual blower withtwo blowers on one motor will solve this problem.Q. What causes the noise relief valves make?A. Air rush through the valve.Q. How do I control relief valve or bleed off valve noise?A. Attach AJ121 Series silencer on the port of the relief valvethat is open to atmosphere.Contact Gast at 269-926-6171 or www.gastmfg.com with anyfurther questions you may have on reducing blower noise in yourapplication.74 Gast Regenair® Regenerative Blowers www.gastmfg.com