Rotary Positive BlowersThe Rotary Positive Blower is a two impellercompressor that delivers a large quantity ofgas or air relative to the individual pulses.Blower capacities are expressed in CFM atinlet conditions (ICFM). Blower size is usuallyexpressed as gear diameter by rotor length.Pitch Line Velocity (PLV) is the peripheralvelocity of the timing gear—equal to theproduct of the gear circumference and therotative speed of the blower, usuallyexpressed in feet per minute (FPM).

The blower presents two problems:1) pulsation within the piping system and,2) noise radiation in the vicinity of the blowerand piping.

The importance of these relative to each otheris a function of blower size and speed; bothincrease proportionately to the blower sizeand the square of the speed.

Pulsation is more pronounced on thedischarge side. Peak pulse pressures are quitesevere and can result in unsilenced dischargesound power levels up to 140–145 dB. Theinlet, although producing less severe pulsationand noise, receives equal attention since theinlet is usually open to atmosphere and thenoise much more apparent.

SilencersThere is little question that silencers are anecessity on any blower installation.Regardless of the size or speed of the blower,silencers of some type are nearly always used.

In the selection of blower silencers, there aretwo basic considerations: 1) the silencer mustbe the correct size (i.e., sufficient capacity forthe volume flow) and, 2) the silencer must bethe proper type for the application. Thenominal silencer size need only be based onthe gas volume, (i.e., the CFM of the gas orair at the operating conditions). However, thesilencer (design) must be selected withconsideration of the blower size andoperating speed. Complete application andcapacity information is given on page 2.3.

There are two types of silencers commonlyused on positive blowers: a reactive typesilencer which consists of a series ofexpansion chambers having interconnecting

tubes, a more sophisticated silencer design.is the combination chamber-absorptive type.This combination silencer is similar to thereactive type with the exception that anacoustically-packed, sound absorbingsection is included, comprising an extensionof the silencer connection closest to theblower. The inlet of a discharge silencer andthe outlet of an inlet silencer are the endshaving the packed section.

A third basic type of silencer—the simple,straight-through packed type—is occasionallyused on blowers. This type of silencer is usuallyused on small, high speed machines whichcharacteristically produce significant highfrequency noise and relatively mild pulsations.

The PLV is normally the criterion forsilencer type selection. If the blower isoperating in the critical PLV range, it willgenerate objectionable high frequency noisewhich may cause shell ring or tank hammerin the piping and silencer. These critical PLV conditions will always require acombination chamber-absorptive silencerfor satisfactory results.

Inlet SilencersFor inlet service, a PLV of 3,300 ft/min orgreater is considered critical. This transitionspeed is empirically established and issomewhat arbitrary, however, it is commonlyaccepted that blowers operating at or above3,300 ft/min are considered critical for thepurpose of inlet silencer application. Thoseoperating below 3,300 ft/min are consideredsubcritical. Subcritical PLV applications canusually be silenced adequately with achamber-type silencer, such as Universal URBor UCI Series. Blowers operating above thecritical PLV of 3,300 ft/min will invariablyrequire the RIS Series combination chamber-absorptive type silencer. Inlet Filters or FilterSilencers are commonly used on blowerinlets, either individually or in series with aseparate inlet silencer. Please reference theFilters and Filter Silencers section of thiscatalog for further information.

Discharge SilencersFor the more severe discharge conditions oftypical blower installations, a PLV of2,700 ft/min is accepted as the criticaltransition speed. Blowers operating below2,700 ft/min are considered subcritical andcan usually be adequately silenced on thedischarge side by use of a chamber-typesilencer UCD or URD Series. Machinesoperating above the 2700 ft/min transitionspeed will require combination chamber-absorptive silencers such as SD or RD Series.

In some larger blower installations, pipingrequirements or space restrictions maypreclude the use of a large, single dischargesilencer such as the SD or RD Series.

Where two or more blowers discharge into acommon header, individual silencers upstreamof the header are required to subdue theindividual blower pulsations. Otherwise, thepulsations tend to beat with each other andcan be extremely objectionable.

Note: Silencers should be mounted as closeto the blower as possible since any pipingbetween the blower and silencer will radiatenoise. Standard silencer connections are notdesigned to carry external piping or valveloads, so good piping support practicesshould be used to prevent stresses thatcause fatigue and eventual fracture of thesilencer or piping. It is also good practice toisolate the blower from the silencer with aflexible expansion joint. Contact UniversalSilencer for special design considerationswhere loading is a factor.

Attenuation CurvesNoise attenuation curves are given for thevarious models within this section. The curves represent insertion loss ofairborne noise for typical applications underaverage conditions. It is not feasible to chartthe expected performance of a silencer overa wide range of applications and conditions,therefore, the curves must be used withdiscretion. Structure-borne noise (seeabove) may be a consideration and willrequire separate analysis, since it is notairborne noise and not used for silencerperformance rating.

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GeneralInformationBlower Silencers

In a closed blower discharge system,structure-borne noise—such as that radiatedby pipe wall and silencer shell—may be aconsideration, particularly where a stringent,close-proximity noise specification applies. For these applications, various means areavailable to treat the pipe and shell radiatednoise, such that most reasonablespecifications may be met.

For instance, it is possible to lag the silencer

shell externally and reduce any shell noisecontribution to below the casing and mechanicalnoise of the blower and driving machinery.

Universal Silencer invites your inquiriesconcerning special applications where EPA,OSHA or other noise specifications apply.Special applications are handled on anindividual basis and recommendations aremade according to specific requirements ofthe installation.

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GeneralInformation

Rotary Positive Blowers

The silencers shown below are more fullydescribed on the individual catalog pages.These units are designed specifically for useon Rotary Positive Blowers.

There are fundamental similarities betweenblower silencers and other types, particularlyreciprocating engine silencers, which alsorequire a silencer design that provideseffective pulse control as well as noise

attenuation. However, blower silencersgenerally must be constructed moreruggedly to withstand prolonged exposure tosevere pulsations produced by the blower.

All silencers described are of standard withend in, end-out design. Low or high sideinlet and outlet connections are availableand are described on the individual catalog pages.

UCI SeriesInlet SilencerChamber-type inlet silencer for use on sub-critical PLV applications. Available in pipesizes 8"–30". Smaller sizes use URB Series.Available with side connections andmounting brackets.

SD SeriesRD SeriesDischarge SilencersCombination chamber-absorptive typedischarge silencers for critical PLVapplications. Available in pipe sizes 2"–30".Low, high, or opposed side connections andmounting brackets available on most sizes.

UCD SeriesURB/URD SeriesDischarge SilencersChamber-type discharge silencer for use onsub-critical PLV applications. Available inpipe sizes 8"–30". (Smaller sizes use URBSeries). Low, high, or opposed sideconnections and mounting brackets available.

RIS SeriesInlet SilencerCombustion chamber-absorptive type inletsilencer for critical PLV applications.Available in pipe sizes 2"–30". Low or highside outlet and mounting brackets availableon most sizes.

Accessories,Special Features

Mounting Brackets

Inspection Openings

Pressure Vessel Construction

Oversize Flanges

Special Finishes

Special Materials

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Transition Speed-RPM

Application,Capacity,Pressure Drop DataBlower Silencers

BlowerGear Size Inlet Discharge

22¹⁄₂

345678

1012141618202224

6,3005,0404,2003,1502,5202,1001,8001,5751,2601,050

900785700630570525

5,1554,1253,4352,5752,0601,7201,4701,2901,030

860735645570515470430

Blower Transition Speed1

Pitch LineVelocity

BelowTransition

InletSilencer

UCI, URB

DischargeSilencer

URB, UCD,URD

AboveTransition RIS SD, RD

Silencer Model Specifications2

� ���P = V

4005

2c

��P � � � c � �V

4005P

14.7530T

Silencer RecommendationsAs mentioned on page 2.1 pitch line velocity(PLV) is the speed of the timing gear in feetper minute (ft/min). For purposes of silencerapplication. PLV is considered “critical” at3,300 ft/min for intake and 2,700 ft/min fordischarge.

Table 1 gives transition speeds in RPM.Blowers running at these speeds or greaterwill have critical PLV. Operating speeds belowtransition will be in the sub-critical range.Blowers operating in the sub-critical speedrange usually require only simple chamber-type silencers while those in the critical rangerequire combination chamber-absorptive typesilencers. If there is doubt, it is best to usethe combination-type silencers. When gearsize and operating speeds are known, theproper type silencer is easily selected.

Silencer Size Selection, CapacityTable 3 gives the nominal capacity of thevarious size silencers. “Size” in this tablerefers to the silencer “nominal size,” or its“inlet size.” Capacities are expressed in inletCFM (ICFM), thus, discharge silencers arerated at higher capacities than inlet silencerssince the air is compressed to reducedvolume at the discharge operating pressure.

A From Table 1 determine whether blowerRPM is above or below the transitionspeed for critical PLV.

B Consult Table 2 for recommendedsilencer models.

Pressure DropThe following formulas may be used tocalculate pressure drop through thesilencers covered in this catalog.

Inlet:

(assumes silencer inletis open to atmosphere)

Discharge:

��P = pressure drop through silencer,inches of water

V = air velocity through silencer,ft/min*

c = individual silencer restrictioncoefficient—empirical constant(see Table 4)

P = discharge pressure, PSIA(operating pressure in PSIG + 14.7)

T = discharge temperature, ˚Rabsolute (operating temperature in˚F + 460)

* To calculate velocity through silencer, divide flow inACFM by cross-sectional area of silencer inlet diameterin square feet.

2

Size

11¹⁄₂

22¹⁄₂

33¹⁄₂

4568

1012141618202224262830

Est Temp.

3070

120190270370480750

1,0801,9203,0004,3005,9007,7009,700

12,00014,50017,30020,30023,50027,000

70˚F

3580

140220320430560880

1,2602,2503,5205,0706,8909,000

11,40014,00017,00020,20023,80027,60031,700115˚F

4085

150235335455600935

1,3402,3903,7305,3707,3109,550

12,10014,90018,10021,50025,20029,30033,600140˚F

4090

160245355480630985

1,4102,5103,9305,6607,700

10,00012,70015,70019,00022,60026,60030,80035,400165˚F

4095

165255370505660

1,0301,4802,6304,1105,9208,060

10,50013,30016,40019,90023,70027,80032,20037,000190˚F

45105185285415560735

1,1501,6502,9404,5906,6008,990

11,80014,90018,40022,20026,40031,00036,00041,300240˚F

Silencer Capacity3

Inlet Silencer4 PSIG

Discharge Silencer

Capacity (Inlet CFM 14.7 PSIA at 70˚F)

6 PSIG 8 PSIG 10 PSIG 15 PSIG

URB, URBYUCI, UCIY, UCIHRIS, RISY, RISHUCD, UCDYURD, URDY, URDHSD, SDY, SDHRD, RDY, RDHRDS, SDS, URDS

4.24.24.24.24.24.24.27.0

Model Pressure DropCoefficient (C)

Pressure Drop Coefficients4

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SpecificationsUCI Group

Chamber TypeInlet Silencer

40

50

63 125 250 500 1K 2K 4K 8K

30

Octave Band Center Frequency, Hz

Attenuation, dB

Typical Attenuation Curve

10

0

20

The UCI Series Inlet Silencer is a heavy-duty, all welded unit constructed of carbonsteel sheet and plate. It provides pulsecontrol and silencing for most subcriticalPLV applications. Sizes 8" and larger areequipped with flanged connections drilled to

125/150 lb ANSI specifications. Exteriorsurfaces receive a shop coat of rust-inhibitive primer and may be finish paintedin the field if desired. The UCI Series is thebasic inlet model and is the conventionalend-in,end-out version. The low side inlet

DrainP

N

N

L H D

K

Y

K

Y

UCI Series UCIY Series(Low Side Outlet)

UCIH Series(High Side Outlet)

model is designated UCIY Series and thehigh side inlet type is designated UCIHSeries. The three types are fundamentallyalike and performance is identical. Mountingbrackets and other options are available—see page 2.11.

PartNumber D L N H K

Min Max

P(Size)

Min Max

UCIY UCIH

Y

Weight

Chamber Type Inlet Silencers

Sizes 1"–6" Use URB Series (page 2.7)

Note: Dimensions and weights are nominal and may vary slightly with production models.Request certified drawings of specific models for exact dimensions.

53-108-AA53-110-AA53-112-AA53-114-AA53-116-AA53-118-AA53-120-AA

53-124-AA53-126-AA53-128-AA53-130-AA

2226303036424248545460

45¹⁄₂

6980¹⁄₂

91¹⁄₂

103¹⁄₂

114126138149161173

250360550

9501,2001,3501,9502,5002,7503,4004,650

11¹⁄₂

22¹⁄₂

33¹⁄₂

4568

101214161820

24262830

61748799

113126140153167179193

3¹⁄₂

3¹⁄₂

3¹⁄₂

3¹⁄₂

3¹⁄₂

3¹⁄₂

4¹⁄₂

4¹⁄₂

4¹⁄₂

4¹⁄₂

4¹⁄₂

54678092

106119131144158170184197

14¹⁄₂

16¹⁄₂

18¹⁄₂

21¹⁄₂

24¹⁄₂

25¹⁄₂

28¹⁄₂

31¹⁄₂

31¹⁄₂

34¹⁄₂

37¹⁄₂

911

13¹⁄₂

15¹⁄₂

17¹⁄₂

1920¹⁄₂

22¹⁄₂

23¹⁄₂

25¹⁄₂

27¹⁄₂

2127

404855¹⁄₂

60¹⁄₂

66¹⁄₂

7285

9587

28¹⁄₂

34¹⁄₂

47¹⁄₂

53¹⁄₂

59¹⁄₂

67758384

10091

206 4¹⁄₂66

53-122-AA22

650

57413412¹⁄₂18¹⁄₂

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SpecificationsRIS GroupCombination Chamber-Absorptive TypeInlet Silencer

PartNumber D L N H

54-102-AA54-125-AA54-103-AA54-135-AA54-104-AA54-105-AA54-106-AA54-108-AA54-110-AA54-112-AA54-114-AA54-116-AA54-118-AA54-120-AA54-122-AA54-124-AA54-126-AA54-128-AA54-130-AA

888

10101214182226303642424854546066

28¹⁄₂

333939¹⁄₂

4557¹⁄₂

64728598

111113126140153167179193206

33333333¹⁄₂

3¹⁄₂

3¹⁄₂

3¹⁄₂

3¹⁄₂

3¹⁄₂

4¹⁄₂

4¹⁄₂

4¹⁄₂

4¹⁄₂

4¹⁄₂

4¹⁄₂

22¹⁄₂

273333¹⁄₂

3951¹⁄₂

58657891

104106119131144158170184197

8¹⁄₂

9101112¹⁄₂

15¹⁄₂

1721¹⁄₂

25¹⁄₂

29¹⁄₂

3035¹⁄₂

414746¹⁄₂

5455¹⁄₂

6166¹⁄₂

————

14¹⁄₂

17¹⁄₂

2026¹⁄₂

32¹⁄₂

384049¹⁄₂

57¹⁄₂

62¹⁄₂

65¹⁄₂

75¹⁄₂

7684¹⁄₂

93¹⁄₂

————

2¹⁄₄

2³⁄₄

3¹⁄₄

4567¹⁄₂

00000000

FIXED AT 6

2¹⁄₂" THRU 3¹⁄₂"AVAILABLE ON

SPECIAL ORDER

FIXED AT 7FIXED AT 7FIXED AT 8

7¹⁄₂

99

1213¹⁄₂

1516¹⁄₂

18¹⁄₂

20¹⁄₂

2223¹⁄₂

25¹⁄₂

25¹⁄₂

29¹⁄₂

30¹⁄₂

16¹⁄₂

2325¹⁄₂

30¹⁄₂

3744505158¹⁄₂

63¹⁄₂

69¹⁄₂

75879198

30¹⁄₂

4043¹⁄₂

49¹⁄₂

61¹⁄₂

698156¹⁄₂

62¹⁄₂

7078868695

103

P(Size)

11¹⁄₂

22¹⁄₂

33¹⁄₂

4568

1012141618202224262830

RISY RISH

KE

Min Max

RISY RISH

Y

Min Max

Weight

32¹⁄₂

43¹⁄₂

495465¹⁄₂

7789¹⁄₂

88¹⁄₂

100¹⁄₂

111123135147157170

252530405080

110190380550800

1,0501,3501,5002,1002,7003,0503,8505,150

Combination Chamber-Absorptive Type Inlet Silencers

Sizes 1"–1¹⁄₂" use U5 Series (page 3.2)

The RIS Series Inlet Silencer is a heavy-duty, all welded unit constructed of carbonsteel sheet and plate. It features anacoustically-treated outlet and will providepulse control and silencing suitable forcritical PLV applications. Sizes 4" and largerare equipped with flanged connectionsdrilled to 125/150 lb ANSI specifications.

Smaller sizes are standard with malethreaded pipe nipples. Units sized 4" and 5"are available in either flanged or male pipethreads. Exterior surfaces receive a shopcoat of rust inhibitive primer and may befinish painted in the field if desired. The RIS Series is the basic model, havingconventional end-in, end-out configuration.

P

N

N

L H D

K

Y

K

Y

E

Note: Dimensions and weights are nominal and may vary slightly with production models.Request certified drawings of specific models for exact dimensions.

*Specify -TT for male pipe threaded units.

40

50

63 125 250 500 1K 2K 4K 8KOctave Band Center Frequency, Hz

Attenuation, dB

Typical Attenuation Curve

30

10

0

20

RIS Series RISY Series(Low Side Outlet)

RISH Series(High Side Outlet)

A low side outlet version is designated RISYSeries and high side outlet configuration isdesignated RISH Series. The three types arefundamentally alike and performance isidentical. Mounting brackets and otheroptions are available—see page 2.11.

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SpecificationsUCD Group

Chamber TypeDischarge Silencer

The UCD Series Discharge Silencer is aheavy-duty, all welded unit constructed ofcarbon steel sheet and plate. It providespulse control and silencing for subcriticalPLV applications where the higherperformance of the URD Series on page 2.7

is not warranted. Sizes 8" and larger areequipped with flanged connections drilled to125/150 lb ANSI specifications. Exteriorsurfaces receive a shop coat of rust-inhibitive primer and may be finish paintedin the field if desired. The UCD Series is the

PartNumber D L N H K

56-108-AA56-110-AA56-112-AA56-114-AA56-116-AA56-118-AA56-120-AA56-122-AA56-124-AA56-126-AA56-128-AA56-130-AA

222630303642424854546066

61748799

113126140153167179193206

3¹⁄₂

3¹⁄₂

3¹⁄₂

3¹⁄₂

3¹⁄₂

3¹⁄₂

4¹⁄₂

4¹⁄₂

4¹⁄₂

4¹⁄₂

4¹⁄₂

4¹⁄₂

54678092

106119131144158170184197

14¹⁄₂

16¹⁄₂

18¹⁄₂

18¹⁄₂

21¹⁄₂

24¹⁄₂

25¹⁄₂

28¹⁄₂

31¹⁄₂

31¹⁄₂

34¹⁄₂

37¹⁄₂

P(Size)

11¹⁄₂

22¹⁄₂

33¹⁄₂

4568

1012141618202224262830

Min

91112¹⁄₂

13¹⁄₂

15¹⁄₂

17¹⁄₂

1920¹⁄₂

22¹⁄₂

23¹⁄₂

25¹⁄₂

27¹⁄₂

Max

Y

212734404855¹⁄₂

60¹⁄₂

66¹⁄₂

72858795

Weight

250360550650900

1,2001,3501,9502,5002,7503,4004,650

Chamber Type Discharge Silencers

DrainP

N

N

L H D

K

Y

Sizes 1"–6" use URB Series (page 2.7)

Note: Dimensions and weights are nominal and may vary slightly with production models.Request certified drawings of specific models for exact dimensions.

40

50

63 125 250 500 1K 2K 4K 8KOctave Band Center Frequency, Hz

Attenuation, dB

Typical Attenuation Curve

30

10

0

20

UCD Series UCDY Series(Low Side Inlet)

basic end-in, end-out configuration. A lowside inlet version is designated UCDY Series.The two types are fundamentally alike andperformance characteristics are identical.Mounting brackets and other options areavailable—see page 2.11.

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SpecificationsURB GroupURD GroupChamber TypeDischarge Silencer

Note: Dimensions and weights are nominal and may vary slightly with production models.Request certified drawings of specific models for exact dimensions.

*Specify -TT for male pipe threaded units.

PartNumber D L N H

55-101-AA55-115-AA55-102-AA55-125-AA55-103-AA55-135-AA55-104-AA55-105-AA55-106-AA55-108-AA55-110-AA55-112-AA55-114-AA55-116-AA55-118-AA55-120-AA55-122-AA55-124-AA55-126-AA55-128-AA55-130-AA

4¹⁄₂

6¹⁄₂

8101012141618222630364248485454606672

21243334465253657297

122135161181188202204239259279304

2233333333¹⁄₂

3¹⁄₂

3¹⁄₂

3¹⁄₂

3¹⁄₂

3¹⁄₂

4¹⁄₂

4¹⁄₂

4¹⁄₂

4¹⁄₂

4¹⁄₂

4¹⁄₂

17202728404647596690

115128154174181193195230250270295

——7889

10111214¹⁄₂

16¹⁄₂

18¹⁄₂

21¹⁄₂

24¹⁄₂

27¹⁄₂

28¹⁄₂

31¹⁄₂

31¹⁄₂

34¹⁄₂

37¹⁄₂

40¹⁄₂

——

66¹⁄₂

89

1112¹⁄₂

14¹⁄₂

16¹⁄₂

18¹⁄₂

19¹⁄₂

21¹⁄₂

22¹⁄₂

252729

——

2229324863¹⁄₂

698192¹⁄₂

98103103126132144161

—————————82

106117¹⁄₂

141158¹⁄₂

164¹⁄₂

175¹⁄₂

175¹⁄₂

210¹⁄₂

228246272

—————————

6276¹⁄₂

88107119¹⁄₂

126¹⁄₂

134137156¹⁄₂

175188203

——————89

10121415¹⁄₂

17¹⁄₂

19¹⁄₂

21¹⁄₂

22¹⁄₂

24¹⁄₂

25¹⁄₂

273132

K

Min

URBY, URDY URDH URDS

Y

Max Min Max Min Max

Weight

——————

1619222940¹⁄₂

424955¹⁄₂

56¹⁄₂

616076¹⁄₂

788596

10152030405570

120160370550800

1,2501,6002,3002,5002,9503,4504,4006,1507,250

Chamber Type Discharge Silencers

The URB/URD Series Discharge Silencer isa heavy-duty, all welded unit constructed ofcarbon steel sheet and plate. It providespulse control and silencing for subcriticalPLV applications. Sizes 4" and larger areequipped with flanged connections drilled to125/150 lb ANSI specifications. Smallersizes are standard with male threaded pipe

nipples. Units sized 4" and 5" are available ineither flanged or male pipe threads. Exteriorsurfaces receive a shop coat of rust-inhibitive primer and may be finish paintedin the field if desired. The URB/URD Seriesis the basic end-in, end-out configuration. A low side inlet version is designatedURBY/URDY Series; high side inlet is

P

N

N

L H D

P(Size)

11¹⁄₂

22¹⁄₂

33¹⁄₂

4568

1012141618202224262830

K

Y

K

Y

K

Y

K

Note: Sizes 1"–6" are URB Series;sizes 8"–30" are URD Series. Both series arefundamentally the same in design and theperformance characteristics are identical.

FIXED AT 6FIXED AT 7FIXED AT 7FIXED AT 8

40

50

63 125 250 500 1K 2K 4K 8KOctave Band Center Frequency, Hz

Attenuation, dB

Typical Attenuation Curve

30

10

0

20

URB,URD Series

URBY,URDY Series(Low Side Inlet)

URDH Series(High Side Inlet)

URDS Series(Opposed Connections)

designated URDH Series; and low opposedconnection is designated URDS Series. Thefour types are fundamentally alike andperformance characteristics are identical.Mounting brackets and other options areavailable—see page 2.11.

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Note: Dimensions and weights are nominal and may vary slightly with production models.Request certified drawings of specific models for exact dimensions.

*Specify -TT for male pipe threaded units.

SpecificationsSD Group

Combination Chamber-Absorptive Type

Discharge Silencer

The SD Series Discharge Silencer is aheavy-duty, all welded unit constructed ofcarbon steel sheet and plate. It will provideexcellent pulse control and is equipped withan acoustically-treated inlet for use oncritical PLV applications. Its pulse and noiseperformance is recommended for all but themost demanding applications, which mayrequire the RD Series on page 2.9. Sizes 4"

and larger are equipped with flangedconnections drilled to 125/150 lb ANSIspecifications. Smaller sizes are standardwith male threaded pipe nipples. Units sized4" and 5" are available in either flanged ormale pipe threads. Exterior surfaces receivea shop coat of rust-inhibitive primer andmay be finish painted in the field if desired.The SD Series is the basic end-in, end-out

DrainP

N

N

L H D

K

Y

E

K

Y

KB

Y

Acoustical packing is suitable for 325˚F

P(Size)

11¹⁄₂

22¹⁄₂

33¹⁄₂

4568

1012141618202224262830

Part Number

54-102-AA54-125-AA54-103-AA54-135-AA54-104-AA*54-105-AA*54-106-AA54-108-AA54-110-AA54-112-AA54-114-AA58-116-AA58-118-AA58-120-AA58-122-AA58-124-AA58-126-AA58-128-AA58-130-AA

D

888

10101214182226303642424848545460

L

28¹⁄₂

333939¹⁄₂

4557¹⁄₂

64728598

111137150176195213233250276

N

33333333¹⁄₂

3¹⁄₂

3¹⁄₂

3¹⁄₂

3¹⁄₂

3¹⁄₂

4¹⁄₂

4¹⁄₂

4¹⁄₂

4¹⁄₂

4¹⁄₂

4¹⁄₂

H

22¹⁄₂

273333¹⁄₂

3951¹⁄₂

58657891

104130143167186204224241267

K

8¹⁄₂

9101112¹⁄₂

15¹⁄₂

1721¹⁄₂

25¹⁄₂

29¹⁄₂

3035¹⁄₂

41474755¹⁄₂

556268

————

14¹⁄₂

17¹⁄₂

2026¹⁄₂

32¹⁄₂

38404752626172768190

SDY SDH SDS

————

14¹⁄₂

17¹⁄₂

2026¹⁄₂

32¹⁄₂

38404752626172768190

B

————89

1012¹⁄₂

14¹⁄₂

16¹⁄₂

18¹⁄₂

21¹⁄₂

24¹⁄₂

25¹⁄₂

28¹⁄₂

28¹⁄₂

31¹⁄₂

31¹⁄₂

34¹⁄₂

E

————2¹⁄₄

2³⁄₄

3¹⁄₄

4567¹⁄₂

9¹⁄₂

11¹⁄₂

10¹⁄₂

12¹⁄₂

11¹⁄₂

13¹⁄₂

12¹⁄₂

14¹⁄₂

Min

SDY

Min

————7¹⁄₂

99

1213¹⁄₂

1516¹⁄₂

18¹⁄₂

20¹⁄₂

21¹⁄₂

23¹⁄₂

24¹⁄₂

2628¹⁄₂

29¹⁄₂

Max

Max

————16¹⁄₂

2325¹⁄₂

30¹⁄₂

3744506570¹⁄₂

87¹⁄₂

93¹⁄₂

110¹⁄₂

117126¹⁄₂

139

Min

SDS

Min

————7¹⁄₂

9101213¹⁄₂

1516¹⁄₂

18¹⁄₂

20¹⁄₂

21¹⁄₂

23¹⁄₂

24¹⁄₂

2628¹⁄₂

29¹⁄₂

Max

Max

————9¹⁄₂

12¹⁄₂

15¹⁄₂

16¹⁄₂

1824253640¹⁄₂

48¹⁄₂

50¹⁄₂

60¹⁄₂

7071¹⁄₂

81

Min

SDH

Min

————30¹⁄₂

4043¹⁄₂

49¹⁄₂

61¹⁄₂

698196

104¹⁄₂

120¹⁄₂

138¹⁄₂

146¹⁄₂

157¹⁄₂

173¹⁄₂

190

Max

Max

————32¹⁄₂

43¹⁄₂

495465¹⁄₂

7789¹⁄₂

113¹⁄₂

124¹⁄₂

147¹⁄₂

165¹⁄₂

182¹⁄₂

201¹⁄₂

216¹⁄₂

241¹⁄₂

Weight

152530405080

110190380550800

1,2501,6001,9002,7003,0003,9004,4005,400

Y

Combination Chamber-Absorptive Type Discharge Silencers

40

50

63 125 250 500 1K 2K 4K 8KOctave Band Center Frequency, Hz

Attenuation, dB

Typical Attenuation Curve

30

10

0

20

SD Series SDY Series(Low Side Inlet)

SDH Series(High Side Inlet)

SDS Series(Opposed Connection)

configuration. A low side inlet is designatedthe SDY Series; high side inlet, SDH Series;and low opposed connection, SDS Series.The four types are fundamentally alike andperformance characteristics are identical.Mounting brackets and other options areavailable—see page 2.11.

Sizes 1" and 1¹⁄₂" use URB Series (page 2.7)

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Note: Dimensions and weights are nominal and may vary slightly with production models.Request certified drawings of specific models for exact dimensions.

*Specify -TT for male pipe threaded units.

SpecificationsRD GroupCombination Chamber-Absorptive TypeDischarge Silencer

The RD Series Discharge Silencer is a heavy-duty, all welded unit constructed of carbonsteel sheet and plate. It provides excellentpulse control and is equipped with anacoustically treated inlet for use on criticalPLV applications. Pulse control and noiseattenuation provided by the RD Series is theultimate and is necessary for only the most

demanding installations. Sizes 4" and largerare equipped with flanged connections drilledto 125/150 lb ANSI specifications. Smallersizes are standard with male threaded pipenipples. Units sized 4" and 5" are available ineither flanged or male pipe threads. Exteriorsurfaces receive a shop coat of rust inhibitiveprimer and may be finish painted in the field

DrainP

N

N

L H D

K

Y

E

K

Y

KB

Y

Combination Chamber-Absorptive Type Discharge Silencers

Acoustical packing is suitable for 325˚F

40

50

63 125 250 500 1K 2K 4K 8KOctave Band Center Frequency, Hz

Attenuation, dB

Typical Attenuation Curve

30

10

0

20

RD Series RDY Series(Low Side Inlet)

RDH Series(High Side Inlet)

RDS Series(Opposed Connection)

if desired. The RD Series is the basic end-in,end-out configuration. A low side inlet isdesignated the RDY Series; high side inlet,RDH Series; and low opposed connections,RDS Series. The four types are fundamentallyalike and performance is identical. Mountingbrackets and other options are available—see page 2.11.

P(Size)

11¹⁄₂

22¹⁄₂

33¹⁄₂

4568

1012141618202224262830

Part Number

57-102-AA57-125-AA57-103-AA57-135-AA57-104-AA*57-105-AA*57-106-AA57-108-AA57-110-AA57-112-AA57-114-AA57-116-AA57-118-AA57-120-AA57-122-AA57-124-AA57-126-AA57-128-AA57-130-AA

D

8101012141618222630364248485454606672

L

3334465253657297

122135161181188202204239259279304

N

33333333¹⁄₂

3¹⁄₂

3¹⁄₂

3¹⁄₂

3¹⁄₂

3¹⁄₂

4¹⁄₂

4¹⁄₂

4¹⁄₂

4¹⁄₂

4¹⁄₂

4¹⁄₂

H

2728404647596690

115128154174181193195230250270295

K

910101114¹⁄₂

16¹⁄₂

20¹⁄₂

24¹⁄₂

28¹⁄₂

3540¹⁄₂

44¹⁄₂

4753¹⁄₂

59¹⁄₂

66727878

————

161822¹⁄₂

28¹⁄₂

344247¹⁄₂

52¹⁄₂

54657281¹⁄₂

8793¹⁄₂

95¹⁄₂

RDY RDH RDS

————

14¹⁄₂

16¹⁄₂

20¹⁄₂

263239¹⁄₂

45¹⁄₂

5052¹⁄₂

63¹⁄₂

7079¹⁄₂

859194

B

————

10111214¹⁄₂

16¹⁄₂

18¹⁄₂

21¹⁄₂

24¹⁄₂

27¹⁄₂

28¹⁄₂

31¹⁄₂

31¹⁄₂

34¹⁄₂

37¹⁄₂

40¹⁄₂

E

————44¹⁄₂

5678

10¹⁄₂

12¹⁄₂

14¹⁄₂

13¹⁄₂

15¹⁄₂

14¹⁄₂

16¹⁄₂

18¹⁄₂

20¹⁄₂

RDY

Min

89

10121415¹⁄₂

17¹⁄₂

19¹⁄₂

21¹⁄₂

22¹⁄₂

24¹⁄₂

25¹⁄₂

273132

Max

2026¹⁄₂

304560¹⁄₂

667889¹⁄₂

95100100123130140158

RDS

Min

————89

10121415¹⁄₂

17¹⁄₂

19¹⁄₂

21¹⁄₂

22¹⁄₂

24¹⁄₂

25¹⁄₂

273132

Max

————

1416¹⁄₂

202637¹⁄₂

394652¹⁄₂

53¹⁄₂

585773¹⁄₂

768193

RDH

Min

————3343¹⁄₂

466579¹⁄₂

91110122¹⁄₂

129¹⁄₂

13740

159¹⁄₂

177192205

Max

————39515679

103114¹⁄₂

138155¹⁄₂

161¹⁄₂

172¹⁄₂

172¹⁄₂

207¹⁄₂

226242266

Weight

2535406080

130160410600900

1,4001,8002,5502,7503,3003,8505,0006,9508,100

Sizes 1"–1¹⁄₂" use URB Series (page 2.7) or use U5 Series: (page 3.2)

FIXED AT 6FIXED AT 7FIXED AT 7FIXED AT 8

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SURS Series blower silencers are heavy-duty, all welded steel construction, suitablefor application as either and inlet ordischarge silencer on rotary positive. Theseunits are designed for blowers runningabove critical transition speed, andtherefore, no acoustic packing material isincluded in the design. Instead, these unitshave a specially designed, high-performance, three chamber system whichincorporates a diffuser on the blower side of

the silencer units. The unit will provideexcellent pulse control and is designed forthe most demanding applications.

Sizes smaller than four inches are equippedwith standard male threaded pipe nipples,while the 4” and larger units have flangedconnections drilled to 125/150 lb ANSIspecifications. As with other blower silencers,the SURS Series employs a high-heataluminum paint system.

DrainP

N

N

L H D

K

Y

SURS Series SURSY Series(Low Side Inlet)

The SURS is a basic end-in, end-outconfiguration. A low-side inlet model isdesignated as the SURSY Series; theSURSY is fundamentally identical to theSURS series in both dimension andattenuation performance. Both series aredesigned to operate at pressures to 15 psi.Mounting brackets, shell lagging and otheraccessories are available for both series ofblower silencers.

Model

SURS SURSY

Part Model Part

YP D L N H

K Min. Max Weight

SURS-2SURS-2.5SURS-3SURS-3.5SURS-4SURS-5SURS-6SURS-8SURS-10SURS-12SURS-14SURS-16SURS-18SURS-20

55-A02-SS55-A25-SS55-A03-SS55-A35-SS55-A04-SS*55-A05-SS*55-A06-SS55-A08-SS55-A10-SS55-A12-SS55-A14-SS55-A16-SS55-A18-SS55-A20-SS

SURSY-2SURSY-2.5SURSY-3SURSY-3.5SURSY-4SURSY-5SURSY-6SURSY-8SURSY-10SURSY-12SURSY-14SURSY-16SURSY-18SURSY-20

55-B02-SS55-B25-SS55-B03-SS55-B35-SS55-B04-SS55-B05-SS55-B06-SS55-B08-SS55-B10-SS55-B12-SS55-B14-SS55-B16-SS55-B18-SS55-B20-SS

22¹⁄₂

32¹⁄₂

4568

101214161820

1212121414161826303636424848

40404659597172

111136138168181188214

33333333¹⁄₂

3¹⁄₂

3¹⁄₂

3¹⁄₂

3¹⁄₂

3¹⁄₂

4

34344053536566

104129131161174181205

999

1010111216¹⁄₂

18¹⁄₂

21¹⁄₂

21¹⁄₂

24¹⁄₂

27¹⁄₂

28¹⁄₂

4¹⁄₂

4¹⁄₂

55¹⁄₂

678

10121416182022

1313152020252541515063514856

55556090

100160200520810

1,1301,4001,8002,5002,850

SpecificationsSURS Group

Chamber Type Multi-Use Silencer

40

50

63 125 250 500 1K 2K 4K 8KOctave Band Center Frequency, Hz

Attenuation, dB

Typical Attenuation Curve

30

10

0

20

Combination Chamber Type Multi-Use Discharge Silencers

*Specify -TT for male pipe threaded units.

†

†

†

†

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Accessories andOptional FeaturesUCI, RIS, ICD IRB, IRD, SD, RD,and SURS Blower Silencers

In addition to the standard accessoriesshown here, other special features such asspecial materials and finishes will be quotedon request. Contact Universal Silencer withyour specific requirements.

Mounting BracketsMounting Brackets or legs are available for any of the silencers in this section.Saddle type brackets for horizontal mountand angle legs for vertical mount arestandard. See Spec. Sheet No. 1078. Special design brackets will be quoted withyour specifications.

Inspection OpeningsInspection Openings with bolted andgasketed cover plates are available installedat the time the silencer is fabricated. Theyare designed to withstand the usual range ofpressure encountered with blowers. Oneinspection opening is usually installed ineach silencer chamber for cleaning orinspection. Standard sizes include:3"� 4", 4"� 6", 6"� 8".

Pressure Vessel ConstructionAll silencers shown in this catalog may befabricated in accordance with Div. 1,Section VIII—ASME Code for UnfiredPressure Vessels. Dimensions are similarto standard models, but material types andthicknesses are selected to meet coderequirements. Prices are quoted onapplication to meet your pressure andtemperature conditions.

Oversize FlangesFrequently the blower flange size is largerthan the required silencer’s connection.Rather than use a larger silencer, it isusually more economical to use an oversizereducing flange on the silencer. This is theconventional piping practice and may beused on either inlet or discharge silencers.Example: a 10" flange size silencer hasadequate capacity for a blower with a 12"discharge flange. A flange having a drillingpattern to match the 12" blower flange butwith a 10" bore to match the silencer nozzleis substituted on the silencer inlet.

Two pipe sizes, (e.g. 10" to 14"), is therecommended maximum variation. Priceson request.

Horizontal Vertical

CBF/CBFI SeriesCompact Blower

Inlet Filter-Silencer

Filter and silencer combined in one unit.The CBF and CBFI have the acousticcapabilities of the Universal Silencer RISSeries silencers and the filtrationperformance of CC series filters.

Reduced cost, overall package size, weight,storage space, freight cost and damage.

Approximately one third the size ofconventional blower silencer, with theadded benefit of excellent, high-efficiencyfiltration.

Reduced overall package noise withoutfurther acoustic treatment.

Versatile—Suitable for inlet applications inconfined areas, outdoor or indoor, withoutcompromising acoustic or pressure dropperformance.

500 1K 1.5K 2K 2.5K 3K 3.5K 4K 4.5K 5K 5.5K0

1

2

3

4

5

6

7

Velocity, ft/min

�P, inches of H

2 O

Pressure Drop Curves

70°F200°F300°F

L

WD

H

DP

K

Y

¹⁄₈" NPTpressure tap

Removable weatherhoodfor filter element access

Y

P

H

L

K

D

WDRemovable plate for filter element access

¹⁄₈" NPTpressure tap

CBF Series (outdoor use) CBFI Series (indoor use)

P (nom.)

CBF/CBFI

22¹⁄₂

34568

1012

D

88

12121616243034

89

1015172324¹⁄₂

35¹⁄₂

39¹⁄₂

44³⁄₄

5¹⁄₄

7¹⁄₂

8¹⁄₂

11¹⁄₂

13³⁄₄

17³⁄₄

19³⁄₄

7799

111115¹⁄₂

18¹⁄₂

20¹⁄₂

120175275500750

1,1002,2003,0004,300

34-702-AA34-725-AA34-703-AA34-704-AA34-705-AA34-706-AA34-708-AA34-710-AA34-712-AA

101016162020303640

13¹⁄₄

14³⁄₄

17

21¹⁄₄

263239

46¹⁄₂

54¹⁄₂

2025506085

100200305385

34-G02-AA34-G25-AA34-G03-AA34-G04-AA34-G05-AA34-G06-AA34-G08-AA34-G10-AA34-G12-AA

6¹⁄₂

6¹⁄₂

10101212121824

12³⁄₄

14¹⁄₄

16¹⁄₂

20³⁄₄

25¹⁄₄

31¹⁄₄

39¹⁄₄

45³⁄₄

53³⁄₄

2025506085

100185295370

H Y K CFM CAP Part

CBF

WD L Weight Part

CBFI

B L1 Weight

Models, Dimensions, Weights and Elements

Notes: 1. Non-ASME Code construction suitable for 15" Hg vacuum.2. Weights are approximate and do no include the weight of the filter element.

40

50

63 125 250 500 1K 2K 4K 8KOctave Band Center Frequency, Hz

Attenuation, dB

Typical Attenuation Curve

30

10

0

20

81-0471*81-0471*81-106381-106381-047581-047581-116381-116381-1164

81-1203*81-1203*81-120581-120581-120781-120781-120981-120981-1210

81-1036*81-1036*81-103881-103881-104081-104081-120081-120081-1201

Paper

22¹⁄₂

34568

1012

P (nom.)Element Part Number

Felt Wire

*Pair of elements required (stacked).

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CB SeriesCompact Blower Silencer

Part Number P (nom.) D L H Y K Weight

56-702-AA56-725-AA56-703-AA56-704-AA56-705-AA56-706-AA56-708-AA56-710-AA56-712-AA

22¹⁄₂

34568

1012

88

12121616243034

1112¹⁄₂

13¹⁄₂

182026313943

89¹⁄₂

10¹⁄₂

15172327¹⁄₂

35¹⁄₂

39¹⁄₂

44³⁄₄

5¹⁄₄

7¹⁄₂

8¹⁄₂

11¹⁄₂

13³⁄₄

17³⁄₄

19³⁄₄

7799

111115¹⁄₂

18¹⁄₂

20¹⁄₂

152535457085

170275355

120187270480750

1,0801,9203,0004,320

Model

CB-2CB-2¹⁄₂

CB-3CB-4CB-5CB-6CB-8CB-10CB-12

CFM CAP

Compact Blower Silencers

Y

PH

L

P

D

K

500 1K 1.5K 2K 2.5K 3K 3.5K 4K 4.5K 5K 5.5K0

1

2

3

4

5

6

7

Velocity, ft/min

�P, inches of H

2 O

Pressure Drop Curves

40

50

63 125 250 500 1K 2K 4K 8KOctave Band Center Frequency, Hz

Attenuation, dB

Typical Attenuation Curve

30

10

0

20

70°F200°F300°F

This extremely compact blower silencerworks as either an inlet or dischargesilencer on rotary positive blowers. It isabout one-third the size of a standardsilencer, and reduces overall package size,cost, weight and storage space. The unit’sinternal pack material is suitable fortemperatures up to 325 degrees. The unit is

operable in conditions up to 15 psig.Flanged or threaded connections areavailable. Exterior surfaces receive a shopcoat of rust inhibitive primer.

12

34

56

78

910

UNI-BASEUltra-Wide Base

Plates/ComponentsRotary Positive Blowers

These wide base plate productsaccommodate a variety of blower packagedesigns. The UNI-BASE package and theUSI-BASE base plate use the same basicbase plate and discharge silencer. The UNI-BASE package includes the UniversalSilencer model URBN high-side inlet silencerand CCF inlet air filter, while the UNI-BASE

base plate is only the basic plate and theURBY discharge silencer. Please see page2.7 for performance and sizing informationfor the URBY series silencers, page 2.15 forinformation on the URBN series silencers,and page 8.9 for performance data, weightsand dimensions of CCF filters.

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2.14

UNI-BASE Package

UNI-BASE Base Plate Only

CCF (see page 8.9)

URBN (see page 2.15)

URBY (see page 2.7)

URBY (see page 2.7)

Size UNI-BASE Package

2"2¹⁄₂"3"4"5"6"

80-187380-187480-187580-187680-187780-1878

55-202-ABP55-225-ABP55-203-ABP55-204-ABP55-205-ABP55-206-ABP

55-502-AA55-525-AA55-503-AA55-504-AA55-505-AA55-506-AA

55-202-AA55-225-AA55-203-AA55-204-AA55-205-AA55-206-AA

34-L02-TT*34-L25-TT*34-L03-TT*34-L04-TT*34-L05-TT*34-L06-TT*

Base Plate Only URBN Only URBY Only CCF Only

UNI-BASE Base Plates/Components Part Numbers

UNI-BASEUltra-Wide BasePlates/ComponentsRotary Positive Blowers

P1/P2 (nom.) D1 H1 K1 Y1 Y2 Approx. Weight

22¹⁄₂

3456

81010141618

272840476066

788

101112

677668

3¹⁄₂

4¹⁄₂

4¹⁄₂

5¹⁄₂

6¹⁄₂

7¹⁄₂

25355080

140170

URBN Silencers

CCF Silencers (please see page 8.9)

P (nom.) A B C CD D2 E FS

2

3456

3944¹⁄₂

55¹⁄₂

566666

1¹⁄₂

¹⁄₂

4———

20³⁄₄

20.8831¹⁄₂

37.3143.3852

10.5611.1312.0015.3818¹⁄₄

18¹⁄₄

81010141618

6.316.567¹⁄₂

7.8813³⁄₄

10.38

1314¹⁄₄

15.1316.4414³⁄₄

15.13

23.3827.38

29³⁄₄

3335

35¹⁄₄

16171724¹⁄₂

23¹⁄₂

26¹⁄₂

56689

10¹⁄₄

788

101112

3031435062¹⁄₂

69

3¹⁄₂

44³⁄₄

61112

212526¹⁄₄

29³⁄₄

30¹⁄₂

30¹⁄₂

677

111212

125170270355500645

G H2 J K2 L Q (Dia.) S YApprox.Weight

UNI-BASE Base Plate (w/URBY)

Dimensions and Weights

Notes: 1. Sizes 2"–3" URBY discharge silencers are shipped standard with male pipe threaded connections. 4" and 5" URBY discharge silencers are shipped standard with malepipe threaded discharge connections and plain pipe blower connections. 6" URBY discharge silencers are shipped standard with flanged discharge connection drilledto 125/152 lb. ANSI specifications and plain pipe blower connections.

2. Sizes 2"–3" URBY discharge silencers have a 2" NPT relief valve coupling and plug. Sizes 4"–6" URBY discharge silencers have a 3" NPT relief valve coupling and plug.3. UNI-BASE base plate kit sizes 2"–4" require gussets.

Notes: 1. Sizes 2"–4" URBN inlet silencers are shipped with male pipe threaded inlets and plain pipe outlets. Sizes 5" and 6" URBN inlet silencers are shipped standard withflanged inlet connections drilled to 125/150 lb ANSI specifications and plain pipe outlets.

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1.3

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23

45

67

89

10

2¹⁄₂