VENT SILENCERS - noise enclosures - blowers

1 WilliamsSTEEL DIVISIONBUILDING SOUND SOLUTIONS referencecatalogue6 VENT SILENCERSLDFLOWOPTIONALOUTLETSTACKINLET NOZZLEINFORMATION ON VENT SILENCERS1 Avent silencer or a blow off silencer is a device used toreduce unwanted noise created by gas or steam flow in apipeline discharging directly into the atmosphere. Thisnoise can be generated due to the high velocity flowthrough the valve and turbulence created around anyobstacle in the line that suddenly restricts or changes thedirection of flow such as valve or an orifice. Vent SILENCERS find wide applications in high pressurevents, steam vents , safety relief valve outlets, system blowdowns and purge outlets etc. Vent and blow down noise is a function of upstreampressure and temperature, type of gas being vented, thevalve size and type, plus the effect of down stream piping.

2 Each vent silencer is designed to attenuate the noise levelto the required sound pressure level criteria at a givendistance from the silencer. This is the reason that vent and blow down SILENCERS are seldom a catalogue details given here can be considered as a our experienced engineers to recommend asilencer best suited for your application for vertical orhorizontal installations. In any steam or gas venting / blow off system, the primaryrelease of noise energy occurs at the open stack exit. Theblow off silencer is installed either within the stack or at thestack outlet to intercept this noise before it escapes intothe environment. There are two fundamental noise reduction principles usedin passive silencer design.

3 Dissipative components (usingsound absorbing material) provide balanced noisereduction over a broad frequency range. Reactivecomponents, using resonant reflections within tunedchambers and passages, provide peak noise reduction in a more concentrated frequency band. The SV series ventsilencers combines both dissipative and reactivetechnology in a highly efficient REQUIRED TO SELECT VENT SILENCER Application (Vent, Blow down, Relief Valve etc.) Fluid Composition (Steam, Gas, Air) Molecular Weight or Specific Gravity Process conditions upstream of valve Flow rate (W)and units (lb/hr, SCFM, ACFM), Temperature (T 1),Pressure (P 1) Atmospheric pressure ( P a ) and down streamtemperature (T 2) if known.

4 Line size between valve and silencer and connection type. Line size from silencer discharge Unsilenced octave band noise levels, if known Attenuation required (silencer performance) Allowable pressure dropSIZING OF A VENT SILENCER Typical examples of sizing a SV series vent silencer areshown here. The diameter of a silencer is a function of flowrate of the gas it can safely pass without eroding theacoustical packing or regenerating noise . The silencer lengthis a function of the degree of noise reduction to be STEAME xample 1: Service conditions: W max. = 60000 lb / steam, P 1 = 250 psia, T = 500 F, Pa = psia. Require 40 dB steam tables, using P 1 (250 psia) and T 1 (500 F),find the upstream enthalpy, h 1 = btu / lb.

5 B. Assuming constant enthalpy expansion h1 = h2, fromsteam tables determine the down stream specificvolume v2 using h2 (1265 btu / lb and P a ( psia), v2 = cu. Ft. / lb. c. Calculate actual down stream flow rate Q d (ACFM),actual cubic feet per minute using equationQ d = W X V260Q d = 60000 X 36750 ACFM d. Select silencer using Table 1, having capacity equal toor greater than Q d. Therefore SV-36-2 is 1 can be used to select SV type for desiredattenuation or contact our engineers for selection. Example 2: Service Conditions : W max. = 120000 lb / hr. of saturated steam, P 1 = 300 psia. T1 = 417 F, P a = 15 psia. Require minimum of 55 dB attenuation. Using the same procedure as example 1 above.)

6 A. From steam tables h 1 = btu / lb = h2 b. For h 2 = 1203 btu / lb and P a = 15 psia , V 2 isdetermined to be 31 cu. Ft. / lb. c. Using equation: Q d = W X V 260Q d = 120000 X 3160= 62000 ACFM d. From table 1, SV-48-4 is selected. B. GASS ervice conditions: W max. = 200000 lb / hr. Nitrogen, (or Q = 45022 SCFM), Specific gravity ( ) = , T 2 =200 F and P a = psia. Require 40 to 50 dB attenuation. a. If flow is given in lb / hr., calculate Q d (ACFM) usingequation : Q d = W X ( T2 + 460 )162 X P a X Q d = 200000 X ( 200 + 460 )162 X X 58742 ACFM b. If flow is given in SCFM, calculate Q d (ACFM) usingequation : Q d = Q X ( T2 + 460 ) X P a Q d = 45022 X ( 200 + 460 ) X = 58742 ACFM c.

7 From Table 1, SV-48-3 is selected. Intermediate and larger sizes available onrequest, consult factory. Dimensions and weights are approximate andmay change slightly with production models. Dimension in inches. Weight in specialize in custom designsand also provide various nozzleorientations to suit your NOZZLESV2 SPECIFICATIONSSV SERIES VENT SILENCERS The SV series vent SILENCERS are recommended for reducing excessivenoise caused by the discharge of high pressure gas, steam or air intothe atmosphere. The SILENCERS are of reactive / absorptive type design. The gas andnoise enters the silencer through the single stage or multi stage diffuserwhere it is permitted to expand through many small holes into theexpansion chamber.

8 The design of diffuser and size of the expansionchamber provides a tuned reactive section. The diffuser also provides afrequency shift to higher frequencies which are best attenuated by theabsorptive section. The gas then passes through the absorptive sectionwhich consists of multiple perforated flow tubes surrounded by denseacoustical packing providing a broad range of attenuation in the mid tohigh frequency standard construction is a rigid all welded carbon steel shellassembly, flow tube bundle and inlet / diffuser with acoustical packing ofdense long strand fiberglass suitable for service temperatures of flow tubes and number of tube bundles is dependent ondegree of silencing required. The silencer thickness includes 1/16 corrosion allowance and finished with rust inhibitive primer.

9 The optionalfeatures include multiple inlets, special materials or finishes, mountingbrackets and code 1 VENTSIZE &TYPEO ctave Band Center Frequency, Hz631252505001000200040008000SV110182733 39403530SV21223344249504337SV31429425360 605144SV41634496370696050 TYPICAL PERFORMANCE ( Dynamic Insertion Loss ) dBINLETNOZZLESIZEMAX. SILENCERCAPACITY, ACFMSHELLDIA. SVOUTLETSTACKTYPE SV1 TYPE SV2 TYPE SV3 TYPE WilliamsSTEELDIVISIONBUILDING SOUND SOLUTIONS OTHERPRODUCTS AVAILABLE: ROTARY POSITIVE BLOWER INTAKE ANDDISCHARGE SILENCERS reference catalogue 1 BASE SILENCERS FOR ROTARY POSITIVEBLOWERS reference catalogue 2 COMBINATION SILENCERS FOR ROTARYPOSITIVE blowers reference catalogue 3 FAN SILENCERS reference catalogue 4 CENTRIFUGAL COMPRESSOR SILENCERS reference catalogue 5 VENT SILENCERS reference catalogue 6 ENGINE SILENCERS reference catalogue 7 noise enclosures reference catalogue 8 PUCK SILENCERS reference catalogue 9 YOUR ONE STOP CENTER FORALL INDUSTRIAL.

10 264 FAIRALL STREET, AJAX, ONTARIO L1S 1R6 CANADATEL (905) 428 0950 FAX (905) 428 8343