INSTALLATION, OPERATION AND MAINTENANCE MANUAL
Model 3200
Pressure / Vacuum Relief Vent
w/ Pipeaway Connection
SECTION I
I. 3000 SERIES DESIGN AND FUNCTION
IOM-3200
08-10
MODEL P V DESCRIPTION
3100 P V Vent to Atmosphere
3200 P V Vent to Header
3300 V Top Mounted
3400 P Vent to Atmosphere
3500 P Vent to Header
3600 V Side Mounted
3700 P Emergency/Manhole Cover
3800 P Emergency/Top Guided Relief
Models 3100 through 3600 Pressure and /or Vacuum
Vents are used for the normal venting requirements.
Normal venting is defi ned as venting required
because of operational requirements (i.e. fi lling and
emptying the tank) or atmospheric changes. Models
3700 and 3800 Emergency Relief Vents are used to
meet venting required when an abnormal condition,
such as an external fi re or such as ruptured internal
heating coils, exist either outside or inside the tank.
All of these devices are sized in accordance with API
Standard 2000. Improperly specifi ed relief vents may
result in structural damage to the tank or system and
can cause severe personal injury or death.
Figure 1 illustrates the operation of the Pressure/
Vacuum Relief Vent under overpressure conditions.
As the tank pressure increases as a result of product
being pumped into the tank and/or because of thermal
expansion of the product and vapors, the pressure
pallet remains closed until the set pressure of the
vent is reached. When the tank pressure reaches the
pressure setting of the vent, the pressure pallet lifts
allowing the tank pressure to bleed off.
Figure 2 illustrates the operation of the Pressure/
Vacuum Relief Vent under vacuum conditions.
As the tank pressure decreases as a result of product
being pumped out of the tank and/or because of
thermal contraction of the product and vapors, the
vacuum pallet remains closed until the set vacuum of
the vent is reached. When the tank vacuum reaches
the vacuum setting of the vent, the vacuum pallet lifts
allowing air to be drawn into the tank.
Figure 1 - Pressure Relief
Figure 2 - Vacuum Relief
II. SAFETY WARNINGS
SECTION II
Tank or system protection is the primary function of
the weight loaded Pressure and/or Vacuum Relief
Vent. It must be selected to meet the total pressure
and vacuum fl ow requirements within the Maximum
Allowable Working Pressure and Vacuum of the
system on which it is installed. Consult API Standard
2000 for tank protection sizing procedures. Improperly
specifi ed relief vents may result in structural damage
to the tank or system and can cause severe personal
injury or death.
CAUTION
DO NOT attempt to remove the vent from the tank or
process vessel without fi rst bleeding all pressure from
the system. ALTERNATIVE MEANS OF PRESSURE
RELIEF MUST BE PROVIDED WHEN THE VENT IS OUT
OF SERVICE.
SECTION III
III. INSPECTION AND STORAGE
When Pipe-Away relief vents are used, backpressure
in the header system will affect the set point of
weight loaded vents by the amount of the header
pressure. Maximum possible header pressure must
be considered when sizing the pressure relief vent.
CAUTION
DO NOT change pressure ratings by adding additional weights to the pallet assembly without consulting
Cashco Inc. or your VCI representative.
CAUTION
DO NOT mix pressure/vacuum weight assemblies. Failure to ensure that both weight assemblies are installed
in the correct location can change the pressure and
vacuum relief settings. This can cause tank failure.
The pressure/vacuum relief vent is carefully packaged
to prevent damage or contamination during shipping.
Inspect the equipment when it is received and report
any damage to the carrier immediately. The vent
should be stored with all the protective fl ange covers
SECTION IV
IV. INSTALLATION
WARNING
The vent must be installed in a vertical position as
shown in Figure 1. The tank nozzle on which the vent
is mounted should have the same nominal diameter as
the venting device. It is recommended that the tank
nozzle fl ange face be within 1 degree of horizontal for
best performance of the venting device.
The 3000 Series Vents are designed to mate with a
150 lb ASME fl ange. Torque guidelines are provided
in Table 1. The Vents are NOT rated for full fl ange
pressure and do not require high bolting torque.
in place. Make sure that any loading weights that
might have been shipped separately, to protect the
vent during shipping, are accounted for and stored
with the vent. These weights, when required, will be
installed during installation. See Section IV.
If loading weights were shipped separate from the
vent, make sure to install on the appropriate pallet.
Inspect the gasket seating surface of the tank nozzle
fl ange. It must be clean, free of scratches, corrosion,
tool marks and fl at.
FRP and Aluminum vents are furnished with fl at
faced fl anges. It is recommended that they be
installed on mating fl at face fl anges with a full faced
gasket. If the fl at face of the vent is sealing against
a raised face steel fl ange, a spacer or fi ller ring must
be used to fi ll the annular space of the raised face
steel fl ange.
Before installing the 3000 Series Vent, remove all
packing materials from inside and outside the vent.
2
Make sure the gasket is suitable for the application
and is in good condition.
IOM-3200
WARNING
Minimum clearance between tank roof and vacuum
inlet port must be at least equal to the vents’ nominal fl ange bore. Tank nozzle bore must be greater
than or equal to vent inlet fl ange bore. Inlet and
outlet piping loads must be supported by appropriate structural supports, NOT by the vent body.
Fiberglass fl anges 2 inch to 12 inch require the use
of a full-face 150 lb. gasket. For full face gaskets,
we recommend the use of a 1/8-inch Gortex gasket.
Center the gasket within the bolt circle of the tank
fl ange and carefully set the vent on the fl ange nozzle
and align the bolt holes.
TABLE 1
All Torque Requirements Are Dependant On Gasket Material
Bolt Torque and Stud Specifi cations - ASME #150 Flange Connections
All stud threads must be lubricated to obtain proper
torque results. A washer should be used under each
stud nut.
Install the studs, washers and nuts and tighten nuts
hand tight. Check proper alignment of fl ange faces.
Misalignment of fl ange faces will cause bending
stresses at the fl ange and fl ange joint and damage
may result. Correct any misalignment prior to
applying torque to nuts.
All nuts must be tightened in proper sequence and
equal increments. Proceed through the tightening
sequence until the recommended torque is attained.
Recheck the torque on each bolt in the same
sequence as bolts previously tightened may have
relaxed through the torque sequence.
MOUNTING
FLANGE
2” 30 (0.35) 60 (0.69) 4 5/8” - 11 2.50” 2
3” 54 (0.62) 108 (1.24) 4 5/8” - 11 2.75” 2
4” 42 (0.48) 78 (0.89) 8 5/8” - 11 2.75” 4
6” 90 (1.04) 150 (1.72) 8 3/4” - 10 3.00” 4
8” 126 (1.45) 228 (2.62) 8 3/4” - 10 3.00” 4
10” 138 (1.59) 246 (2.83) 12 7/8” - 9 3.50” 6
12” 186 (2.14) 348 (4.01) 12 7/8” - 9 3.50” 6
BOLT TORQUE - Ft. lbs. NUMBER
RAISED FACE FLAT FACE THREAD UNC STUD LENGTH *QUANTITY
BOLTS
TOTAL
STUD SPECIFICATIONS
Bolt Torque and Stud Specifi cations for FRP Flanges Drilled to ASME #150 Flange Connections
BOLT
MOUNTING
FLANGE
2” 20 4 5/8” - 11 2.50” 2
3” 20 4 5/8” - 11 2.75” 2
4” 20 8 5/8” - 11 2.75” 4
6” 30 8 3/4” - 10 3.00” 4
8” 30 8 3/4” - 10 3.00” 4
10” 30 12 7/8” - 9 3.50” 6
12” 30 12 7/8” - 9 3.50” 6
TORQUE -
Ft. lbs.
FLAT FACE THREAD UNC STUD LENGTH *QUANTITY
NUMBER
BOLTS TO-
TAL
STUD SPECIFICATIONS
*
*
Blind tapped holes only (Models 3100, 3200, and 3300). Use standard ASME stud length for other holes.
*
IOM-3200
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