Industrial Noise Control Silencers for Blowers and Fans.
INDUSTRIAL FAN SILENCERS
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A fan radiates noise equally through its
inlet and its discharge. Usually either the inlet or outlet of a fan is connected to some
sort of equipment which contains and/or absorbs the noise from that side of the fan.
Normally only the inlet or the discharge side has to be silenced. One exception is that
type of air conditioning system in which both the fan inlet and discharge are ducted into
occupied spaces. In these installations silencers are often required on both the inlet and
discharge sides of the fan. Fan / Blower silencers are available in a wide variety of sizes and capacities which are compatible with popular size airfoil blade and other type fans to reduce fan noise to required or legal levels. Also available are rainhoods, flow measuring piezometer tubes, and filter assemblies. A discussion of methods for computing fan silencing requirements and listings of standard centrifugal fan inlet & discharge silencers is available in our literature. In addition, fans are sometimes enclosed in acoustical enclosures or concrete enclosures with splitter silencers quieting the air inlet ducts to the enclosures. If the fan discharges into a stack, a stack stuffer may be used. Large axial fans are silenced by means of splitter 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
- Fan Size, make, RPM, wheel diameter, number of blades, and BHP.
- Inlet box for fan inlet size.
- CFM and density of air.
- Pressure Drop allowance for silencer.
- Acoustic criterion required.
- 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 15o on the fastest expanding side. Also note
that "B" dimension must be parallel to the fan shaft for good
aerodynamic performance.
MODEL CI For Blowers or Micro turbines
Model CI Fan Silencers
are designed to bolt directly onto the Blower or Turbine inlet flange
directly. 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.
MODEL SI vertical inlet silencers
Without Inlet Boxes -- 90o 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 ASSEMBLIESModel CI fan inlet silencers can be supplied with a matching inlet
filter. When clean, these filters will add aprox .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.
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RAINHOODS For Vertical IB, SI and DF Fan SilencersRainhoods 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.
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