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Vacuum Pumps are designed primarily to handle agas, such as air. They normally operate with anopen discharge to the atmosphere. Water is usuallyused as a liquid compressant on vacuum pumpsand the amount of water varies depending on thedegree of vacuum that is required. Since the vac-uum pump discharges both air and water to theatmosphere, there are two problems involved: dis-carding the water, and silencing the air noise flow-ing from the discharge.
Intake Silencers are seldom required in vacuumpump operations unless removal of process liquidis required, prior to entry into the pump. A pumpor “barometric leg” is required to remove the liquidfrom the intake separator, because of the vacuum con-ditions. All Intake Silencers are designed for full vacu-um service.
Discharge Separator Silencers are normally used onwet vacuum systems to reduce the discharge noise
and simultaneously separate the liquid, which canbe recovered or piped to a drain.
Stoddard Silencers can furnish separator silencersin sizes required for all vacuum systems.
Below is an application guide, engineered to best fityour requirements.
Separator Silencer Application Guide
Select size of Intake and Discharge SeparatorSilencer from table below. (Sizing is based on
start-up conditions [6000 FPM Maximum] to elim-inate carry over.)
Intake and Discharge Separator Silencer Pressure Drop CalculationsPressure Drop is the governing consideration formost vacuum systems. There are two conditionsto consider — start-up and operating conditions.The size is controlled by air flow with a maximum
velocity of 6,000 fpm for complete separation.This velocity must be determined for START-UPconditions since maximum air flow and pressuredrop occur at this time.
Selection Chart
Pressure Drop Procedure for Start-Up Conditions (Intake or Discharge)
StoddardSilencers
Liquid Ring Vacuum Pump Separator SilencersF O R W A T E R S E A L E D P - D V A C U U M P U M P S E PA R A T O R S I L E N C E R S S E E PA G E 4
3
Sizing and Pressure Drop Procedures
Pressure Drop = _____________ x 4.0 x PTR = _____________ inches of water
For Models V32H and V32HA
Pressure Drop = _____________ x 5.5 x PTR = _____________ inches of water
Silencer Selection Procedure1. Determine Silencer Model. (V22H = 95% water removal V33H = 99% water removal)2. Select Silencer Size from Chart “A” based on ACFM and Vacuum.3. Select Silencer Size from Chart “B” based on Blower Displacement. (ICFM ÷ RPM)4. Use largest size determined from Chart “A” and “B”.
Inlet Separator Silencers
5
V12H
ApplicationIntake Separator Silencer for wet vacuum systems.
DesignRemoves entrained liquid from air in a vacuum system. Air flows through a sepa-ration chamber where 95% of the liquid is removed. Water pump or barometricleg is required on water outlet. Alternate designs for 99% separation are available.
ConstructionSeparator Silencer is all-welded construction designed to handle a full-vacuum sys-tem. Exterior surfaces painted with a high quality primer.
Typical Attenuation Curve
V12H
K
M
WATER OUTLET
G
C
A
E
B
A
FL
OW
6
Inlet Separator SilencersV12T
ApplicationIntake Separator Silencer for wet vacuum systems.
DesignRemoves entrained liquid from air in a vacuum system. Air flows through a separationchamber where 95% of the liquid is removed. Water pump or barometric leg is required onwater outlet. Alternate designs for 99% separation are available.
ConstructionSeparator Silencer is all-welded construction designed to handle a full-vacuum system.Exterior surfaces painted with a high quality primer.
Typical Attenuation Curve
IPS
IPS
IPS
V12T
B
C
A
E
G
FL
OW
H
A
M
K
7
Discharge Separator SilencersLiquid Ring Pumps
V31H
ApplicationDischarge Separator for liquid ring vacuum pumps. They may be used on water-sealed vacuum pumps where silencing is not critical.
DesignA highly effective single-chamber Separator Silencer which attenuates a wide bandof frequencies through a separation section and removes 99+% of the free liquid.
ConstructionAll-welded heavy-duty steel construction. Exterior surfaces are painted with a highquality primer.
E
F
K
J
A
A
B
C
H
G
FLOW
M — N.P.T. WATER OUTLET
V31H
Typical Attenuation Curve
8
Discharge Separator SilencersLiquid Ring Pumps
ApplicationDischarge Separator for liquid-ring vacuum pumps. They may be used on water-sealed vacuum pumps where a high degree of silencing is required.
DesignA two-chamber Separator Silencer that attenuates a wide band of frequencies andremoves entrained liquid air. Air flows through a separation chamber where 99+% ofthe free liquid is removed centrifigually.
ConstructionAll-welded heavy-duty steel construction. Exterior surfaces are painted with a highquality primer.
Typical Attenuation Curve
E
F
K
J
A
A
B
C
H
G
M — N.P.T. WATER OUTLET
V32H
V32H
9
Discharge Separator SilencersLiquid Ring Pumps
ApplicationDischarge Separator for liquid-ring vacuum pumps. They may be used on water-sealed vacuum pumps where a high degree of silencing is required.
DesignA multi-chamber silencer containing a high-frequency absorption device to attenu-ate the noise over a wide frequency range. Air flows through a separation chamberwhere 99+% of the free liquid is removed centrifigually.
ConstructionAll-welded heavy-duty steel construction. Exterior surfaces are painted with a high-quality primer.
ApplicationDischarge Silencer for water sealed vacuum blowers, and dry type vacuum blowers.
DesignA highly effective two-chamber silencer which attenuates a wide band of frequen-cies. Gas passes through a separation section, a ported tube, and final silencer sec-tion. 95% of the free liquid is removed at the inlet section.
ConstructionAll-welded heavy-duty steel construction. Exterior surfaces are painted with a highquality primer.
ApplicationDischarge Separator for water-sealed Rotary Positive Vacuum Blowers requiring highdegree of silencing.
DesignA highly effective three-chamber Separator Silencer which attenuates a wide band of fre-quencies. Gas passes through a separation section, a ported tube, and final Silencer sec-tions. 99+% of the free liquid is removed at the inlet chamber.
ConstructionAll-welded heavy-duty steel construction. Exterior surfaces are painted with a high-quality primer.
V33H
V33H
Other Stoddard Silencers Products
Bulletin Series/Title ContentsSeries PD Discharge Silencer and Base The PD is a discharge silencer for blowers on which the blower, motor
and belt guard are mounted as an integral part of the silencer.
Series L Rotary Blower Intake Silencers Intake silencers effectively reduce the noise and destructive low fre-quency pulsations that can be detrimental to surrounding equipmentand personnel, as well as neighbors.
Series D Rotary Blower Discharge Silencers Discharge silencers are essential to good system performance on allrotary blower systems. The belief that the discharge creates less noisethan the inlet is erroneous because the discharge pulsations and noiseare normally contained in a closed system.
Series E Engine Exhaust Silencers The selection of the correct type of engine intake and dischargesilencer is determined by the type of engine, the end use of the engine,and the degree of silencing required. Various models are availablewhich can meet the above requirements. Special performance can bedesigned into existing models upon request.
Series C Centrifugal Compressor Silencers Effective treatment of the intake and discharge noise generated by thecentrifugal compressor is accomplished through the use of the lowpressure-drop absorption-type silencers.
Series CF Fan Silencers Effective treatment of the intake and discharge noise generated by theblower fan is accomplished by using a high volume, low pressure drop,absorption type silencer which can control the noise as a unit.
Series F Air Intake Filters and Filter Silencers Air intake filter and filter silencer requirements vary with installationlocations and type of foreign matter being removed from the air.
Series F64 Air Intake Filters and Filter Silencers The series F64 Air Intake Filter and Filter Silencer is designed to mountdirectly on the inlet of an engine, blower, or compressor.
Series F65 Inline Air Filters The series F65 Filter is designed to mount directly in the air piping sys-tem for engines, blowers or compressors.
Series B Vent Silencers To effectively treat the noise generated due to turbulence, high veloci-ty of the gas stream must be reduced. This is achieved through the useof one or two stage diffusers located at the silencer inlet.
Series D90/D93 Rotary Blower Combination Silencers The D90/D93 silencer is a combination intake and discharge silencer,designed into a single silencer, in which the blower and motor aremounted as an integral part of the silencer.This enables the blower system to be pretested, before installation atthe job site.
Silencers effectively reduce the noise and destruc-tive low frequency pulsations that can be detrimen-tal to surrounding equipment and personnel, as wellas neighbors. The noise and/or pulsation energygenerated by the blower is a function of both blow-er speed and blower size.
It is an established fact that the smaller size blow-ers do not develop destructive low frequency puls-es, where as larger blowers do. To properly elimi-nate these destructive pulsations, a chamber-typesilencer with a minimum volume of 15 items theblower displacement is required. This parameter
has been incorporated in all application recommen-dations.
Blower speed plays an important part in the correctselection of a silencer. For slow speed blowers, thechamber-type silencer performs best on all sizes.
For high-speed blowers (i.e., blowers with operatingspeeds above the transition speed) a chamber-absorption type silencer is required. This combina-tion design is necessary to reduce the increasedhigh-frequency noise energy that is developedabove the transition speed and also effectively treatthe energy contained in the low frequencies.
Intake Silencers Model Selection Chart “A” Discharge Silencer Model Selection Chart “B”
Size Selection Chart “C”
Inlet ATMOSPHERIC DISCHARGE SILENCERSSilencer Max. ICFM at Blower Inlet
VACUUM BLOWER DISPLACEMENT — CUBIC FEET PER REVOLUTION
Silencer Selection Procedure1. Determine Silencer Model from Chart “A” and “B” based on Blower Gear Size and RPM.2. Select Discharge Silencer Size from Chart “C” based on ICFM and Vacuum.3. Select Discharge Silencer Size from Chart “D” based on Blower Displacement. (ICFM ÷ RPM)4. Use largest size determined from Chart “C” and “D”.
Silencer Selection
Silencer Basic Configurations
Flanged, NPT and plain pipe tubes inlet,outlet are available
See Accessory Bulletin “A” for optionalmounting brackets, raincaps, and otheraccessories