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Vent and BlowdownNoise Control Solutions
Vent and BlowdownNoise Control Solutions
Universal Silencer’s extensive in-house engineering,manufacturing, and testing facilities ensure optimalprocess, mechanical, and acoustic performance for allvent silencer applications.
Universal Silencer’s HV Series Vent and BlowdownSilencers effectively silence high-velocity air, steam, andgas vents and blowdowns to atmosphere, where sonic orcritical conditions exist in the valve. Typical applicationsinclude:� Steam boiler relief valves� Superheater header relief valves� Boiler startup and purge� High-pressure air vents� Natural gas blowdowns� Switch valves� Compressor blowoffs� Autoclaves� Steam ejectors
Design Advantages� Choice of overall attenuation, ranging from 15 dBA
to 70 dBA and beyond.� Unique design options, combined with the latest
manufacturing techniques, ensure optimumperformance and long life, even under demandingconditions.
� Readily customizable.
Standard Features� Welded heavy-duty steel construction.� Inlet plenum covered with acoustic wrap and heavy-
gauge steel shell.� Highly absorptive fiberglass acoustic fill and heavy-
gauge perforated face sheets.� Inlet nozzle and diffuser with flange drilled to 150#
ANSI standards.� Lifting lugs and bottom drain.� Painted exterior.� Vertical or horizontal installation.
Optional Features� High-temperature acoustic fill.� Special materials, such as stainless steel, monel,
or hastelloy.� Inspection openings.� Mounting brackets or other special supports.� Outlet head and nozzle.� Restrictive diffuser built to ASME Section VIII,
Division I, to maintain back pressure or controlblowdown time.
� Elbow, tailpipe, or weatherhood.� Special paint.� Side inlet configuration.
The HV Series’ concentric annular ring design (left) and thewrapped Acousti-Tube vent silencer design (right) offers aunique choice of silencer profiles and configurations to meetspecific needs.
HIGH-EFFICIENCYACOUSTIC PACK
DESIGNEDFOR OPTIMUM
SPACECONSIDERATIONS
ALL-WELDEDSTEEL OUTER
SHELL
PACK RETENTIONWITH PRE-
COMPRESSION
LOWER CHAMBERINSULATION(except HV05,
HV10)
INLETDIFFUSER,
DEPENDING ONAPPLICATION
HV SERIESVent and Blowdown Silencers
Acousti-Tube�
Annular Ring
Why the HV Series?In vent applications, critical flow occurs for most gases atupstream valve pressures greater than twice the outletpressure. Vent and blowdown noise levels increase withincreased pressure drop and are also affected by valveaerodynamic recovery characteristics. Large valve, low-pressure vents will produce relatively broadband low-frequency noise, while high-pressure vents with smallvalves will produce high-frequency noise.
For Any Application Why Universal??
Sub-sonic (or non-critical flow) low-pressure vent andblowdown applications do not require, nor in most cases does the valve have pressure drop available to permit,the use of an inlet diffuser. Contact Universal Silencer forsilencer recommendations when a combination of both lowpressure drop and acoustic requirements must be met.
The HV Series comes with an inlet diffuser or orifice platethat is a critical element to the acoustic and mechanicalperformance of the silencer. Both the inlet nozzle and thediffuser/orifice plate are designed and constructed towithstand the thermal and impact stresses produced inhigh-pressure, high-temperature, continuous orintermittent vent and blowdown service.
The lined inlet plenum (expansion chamber) of the silenceris a double shell separated by a layer of acoustic insulationand sound-deadening material. The inner shell is solid toprevent shell-radiated noise and acoustic fill migration. Thetransmission loss across the plenum and bottom head iscomparable to the silencer attenuation.
Easy to Specify and OrderVent and blowdown silencers are seldom simple catalogselections. However, Universal Silencer makes it easy todetermine whether a standard HV series unit or a customdesigned silencer is best suited to an application.Customers may simply:
1. provide Universal Silencer with detailedspecifications and descriptions of the system, or
2. send the valve manufacturer’s data directly toUniversal Silencer
Universal Silencer’s experienced engineering staff thenquickly generates a technical silencer proposal completewith pricing information.
Application AnalysisUniversal Silencer uses more than a dozen pieces ofinformation from valve data sheets for vent and blowdownsilencer analysis and selection, including:
1. gas type
2. flow rates
3. inlet sizing and pressure rating
4. piping arrangements
5. upstream pressure and temperature
Universal Silencer’s Vent Specification Sheet (available at
and other information in a standard format. Using thisinformation, Universal Silencer prepares computer analyses,such as those shown in Figure 1, and a comprehensivetechnical proposal and price quotation. Silencer selection is based upon optimization of flow velocity, requiredacoustical performance, and pressure drop. UniversalSilencer is skilled in the process engineering principles
needed to successfully meet customer performancerequirements. A key element of a successful vent applicationis proper assignment of pressure drop in the piping, valve andvent silencer. Valve performance and life can be considerablyextended by the appropriate distribution of pressure drop inthe piping system, valve and vent silencer. In many instances,it is possible to reduce the pressure drop across the valvebody (less than critical), thus reducing valve actuatoropen/close force requirements. Reduced valve wear fromcavitation damage and reduced through-valve-body noiseare added benefits of this approach.
Universal Silencer verifies the valve flow and pressure dropcharacteristics from the valve manufacturer’s data sheet,and offers technical services, including determination ofblowdown time; bottled volume calculations; and completevalve, pipe treatment, and vent discharge acousticperformance predictions.
Application NotesThe pipe size immediately downstream from a valve affectsthe noise spectrum octave band distribution; UniversalSilencer balances reactive and absorptive elements in thesilencer design to remedy these effects.
The HV Series annular vent silencers are assembled withstructural members that provide thermal expansion in high-temperature applications. The acoustic fill is long fiber, non-combustible, inert, vermin- and moisture-resistant fiberglassof at least 4 lb/ft3 density, and is protected by both fiberglasscloth and a perforated metal face sheet. The silencer is packedwith a minimum of 10% compression fill; pack retaining ringsare provided to minimize voids and fill settling.
HV Series silencers are designed so the inlet flange anddiffuser are matched to the discharge rating of the valve.Universal Silencer works diligently to obtain the most cost-effective silencing solution by using a restrictive diffuser ororifice plate to stage the system pressure drop. Ventsilencers with restrictive diffusers are designed with pressureratings that match the PSV inlet pressure rating. Customersshould review the valve manufacturer’s data sheet to ensurethe control valve will not malfunction from the rated backpressure of the restrictive diffuser specified. �
Figure 1
www.universalaet.com) is an ideal tool to record this
NOISE CONTROL&& AAIIRR FFIILLTTRRAATTIIOONNfor industrial equipment and gas turbines
Upremiere suppliers of noise control and airfiltration solutions. Since 1959, manufacturers,
packagers and end-users have relied upon USI’sstandard and custom-engineered solutions to quietand protect their equipment on both the inlet andexhaust sides of applications.
USI serves the industrial process, power generation,emissions, marine, and oil and gas markets, providingeffective and efficient acoustic control and air filtrationsystems for gas turbines, engines, fans, blowers andvents. Our product line includes a vast complement ofsilencers, air filtration elements and housings,separators and accessories.
General Mills. With nearly 100 years of engineeringand design experience, you can trust that USI is thebest choice to handle any noise control or filtrationchallenge—from the most basic to the most complex.
USI’s Technology and Research complex is fullyequipped with equipment and instrumentation forsilencer and filter acoustic testing: two semi-anechoicchambers, eight engine test cells (complete withdynamometers), a complete engine emissions andcontrol test area, and several rotary positive blowersand centrifugal fans. Complete facilities andequipment enable USI to develop and test air filtrationproducts, and conduct applied research in acoustics,electronics and controls.
U
243-C 05/05
NOISE CONTROLUNIVERSAL
niversal Silencer (USI) is one of the world’s
P. O. Box 411, Stoughton, Wisconsin 53589608-873-4272 Fax 608-873-4298
UNIVERSAL
www.universalAET.com
OUR SOLUTIONS…YOUR MARKETS,
Our acoustic and filtration experts design solutionsfor such esteemed clients as Boise Cascade,
Power Systems, U.S. Pipe, Cummins PowerGen andSiemens-Westinghouse, Georgia Pacific, GE
