FanAir Company

Industrial Fan Silencers

For Large Fans, A Special IB Fan Silencer Should Be Used

Since the cost of even a few decibels of noise reduction is high with large fans, it pays to tailor the silencer to the exact requirements of the fan, when the flow per silencer exceeds about 200,000 CFM. We are prepared to do this.
   Please E-Mail us the following information or fax us back the above PDF Inquiry / request to quote form.

1. Fan Size, make, RPM, wheel diameter, number of blades, and BHP.
2. Inlet box for fan inlet size.
3. CFM and density of air.
4. Pressure Drop allowance for silencer.
5. Acoustic criterion required.
6. Fan noise generation by octave band (from fan manufacturer). If not available, we can estimate same from fan RPM, number of blades and wheel diameter.

MODEL IB For Fans with Inlet Boxes

The internal configuration of this model silencer is designed so that the silencer exit matches the fan inlet box thereby eliminating the need for a separate transition piece.
   Each silencer has a pressure drop of 1.00" of water at its rated flow.
   The silencer includes a 3/4" mesh galvanized inlet screen, silencer section and flanged discharge, sized and drilled to match your inlet box.

MODEL DF Fan Discharge Silencers

We have designed a series of fan discharge silencers for use when the fan inlet is connected to the process, and the discharge to the atmosphere.
   The required silencers are generally larger than the fan discharge connection, and transitions from the fan discharge to the silencer are not included, however, both inlet and discharge transitions are available on request.
   The pressure drop at the rated flow is 1.00 inches of water. This pressure drop has been corrected for the pressure recovery from the fan discharge velocity. A 50% diffusion efficiency is assumed for the transition from the fan to the silencer.
   Model DF silencers can be supplied at extra cost with internals removable for cleaning. This is recommended when the silencer is used with dirty gases.
   Note that transitions from the fan discharge to the silencer inlet must expand at an angle not exceeding 15^o on the fastest expanding side. Also note that "B" dimension must be parallel to the fan shaft for good aerodynamic performance.

MODEL CI For Single Inlet Fans Without Inlet Boxes

Model CI Fan Silencers are designed to bolt directly onto the fan inlet flange. The Silencer includes a silencing element, followed by a plenum section, with one or two removable plates to allow access to the bolts, and 3/4" mesh inlet screen.
   Each Silencer has a resistance of 1.00" of water at its rated flow.

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MODEL SI For Single Inlet Fans

Without Inlet Boxes -- 90^o Inlet

Model SI fan inlet silencer is designed to bolt directly to the fan inlet flange. This silencer includes the silencing section, followed by a plenum section large enough to accommodate the fan inlet opening. A removable plate is incorporated to allow access to the plenum for installation. A 3/4" mesh galvanized inlet screen is standard.
Model SI has a built-in, all-metal, inlet box.

MODEL CIF FILTER ASSEMBLIES Model CI fan inlet silencers can be supplied with a matching inlet filter. When clean, these filters will add a of .15" H2O to the silencer  at the silencer rated flow. Filter elements are removable and can be reused after cleaning. Filter is a cleanable viscous type of all galvanized construction and has a filtering efficiency of 93% at rated flow on 10 micron particles. CIF model numbers correspond to CI silencer model numbers.

RAINHOODS For Vertical IB, SI and DF Fan Silencers Rainhoods which will provide uniform flow at the silencer face thereby resulting in a minimum increase in pressure drop when used with an Blower inlet silencer.  Rainhoods for vertical down installation will add .25" H2O at silencer rated flow.