INSTALLATION, OPERATION AND MAINTENANCE MANUAL
Model 3100
Pressure / Vacuum Relief Vent
IOM-3100
01-17
ISO Registered Company
SECTION I
I. 3000 SERIES DESIGN AND FUNCTION
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
Models 3100 through 3600 Pressure and /or Vacuum
Vents are used for the normal venting requirements.
Normal venting is defined as venting required
because of operational requirements (i.e. filling and
emptying the tank) or atmospheric changes. Model
3700 Emergency Relief Vent is used to meet venting
required when an abnormal condition, such as an
external fire or such as ruptured internal heating
coils, exist either outside or inside the tank.
Figure 1 illustrates the operation of the Pressure
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 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.
All of these devices are sized in accordance with API
Standard 2000. Improperly specified relief vents may
result in structural damage to the tank or system and
can cause severe personal injury or death.
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 flow 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
specified 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 first 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, back
pressure 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 or vacuum setpoints 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 flange 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 flange 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 flange. Torque guidelines are provided
in Table 1. These vents are NOT rated for full flange
pressure and do not require high bolting torque.
Before installing any 3000 Series Vent, remove all
packing materials from inside and outside the vent.
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 weights on the appropriate
pallets. Tighten cover dome cap screws to 15 ft.-lbs.
Inspect the gasket seating surface of the tank nozzle
flange. It must be clean, free of scratches, corrosion,
tool marks and flat.
FRP and Aluminum vents are furnished with flat
faced flanges. It is recommended that they be
installed on mating flat face flanges with a full faced
gasket. If the flat face of the vent is sealing against
a raised face steel flange, a spacer or filler ring must
be used to fill the annular space of the raised face
steel flange.
Make sure the gasket is suitable for the application.
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IOM-3100
WARNING
Minimum clearance between tank roof and vacuum
inlet port must be at least equal to the vents’
nominal flange bore. Tank nozzle bore must be
greater than or equal to vent inlet flange bore.
Inlet and outlet piping loads must be supported by
appropriate structural supports, NOT by the vent
body.
Fiberglass flanges 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
flange, align the bolt holes and carefully set the vent
on the flange nozzle.
NOTE: At installation, the vent valve should be
carefully lifted into position using the lifting brackets
(2) on the body.
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 flange faces.
Misalignment of flange faces will cause bending
stresses at the flange and flange 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”
3” 4 5/8” - 11 2.75” 2
4” 8 5/8” - 11 2.75” 4
6”
8” 8 3/4” - 10 3.00” 4
10”
12” 12 7/8” - 9 3.50” 6
BOLT TORQUE -
Ft. lbs.
47
83
134
NUMBER
BOLTS
TOTAL
4 5/8” - 11 2.50” 2
8 3/4” - 10 3.00” 4
12 7/8” - 9 3.50” 6
THREAD UNC STUD LENGTH *QUANTITY
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
NUMBER
BOLTS TOTAL
STUD SPECIFICATIONS
*
QUANTITY
*
Blind tapped holes only (Models 3100, 3200, and 3300). Use standard ASME stud length for other holes.
*
IOM-3100
3
V. MAINTENANCE
SECTION V
Tank or system protection is the primary function
of the weight loaded Pressure and/or Vacuum
Relief Vent. As a safety device, it is very important
that maintenance/inspection be done on a regular
interval. Maintenance should only be done by a
qualified technician. Valve Concepts recommends
that all service be performed at the factory or a
factory authorized repair center. For information on
repair centers in your area, please contact factory.
Maintenance procedures hereinafter are based
upon removal of the relief vent unit from the tank
where installed.
Owner should refer to Owner’s procedures for re mov al,
handling and cleaning of non re us able parts, i.e.
gaskets, suitable sol vents, etc.
NOTE: Item Numbers that are specific to FRP body
material are in parenthesis and underscored; i.e. (8).
See Figure 11. Item Numbers that are generic to all
body materials are not un der scored; i.e. (1). See
Figures 3 thru 9 where applicable.
To Dis-assemble: Remove the weatherhood wing
nuts (12), (10 & 33) lift off weatherhood (13) and
screen (31).
Remove vacuum cover cap screws (10), vacuum
cover (8) and the TFE tape / rope seal (34).
Inspect weatherhood (13), screen (31), and cover
(8) for corrosion, damage or foreign material. Clean
with a suitable solvent, replace as necessary.
NOTE: During re-assembly, install new TFE tape /
rope (34). For FRP material - nuts (10) for cover (8)
should be tightened to 50 in. - lbs. (5.6 Nm).
Remove pressure and vacuum pallet assemblies,
including any loading weights (21 & 28) that may
be on the pallets (19,26). NOTE: As the pallets
are removed from the vent, identify each assembly
(including the stack of weights) by tagging as
“pressure” side or “vacuum” side.
Clean and inspect pallet assemblies. Inspect the
diaphragms (18,25) and replace if necessary.
To Replace Diaphragms - Std. Construction:
See Figure 4. Secure pressure or vacuum stem
assembly (23,30) in a soft-jawed vise with short,
threaded end up. Remove washer and nut (14).
For settings above 32oz/in2 See Figure 5. Remove
machine screws (43) CCW.
Lift up to remove diaphragm retainer (17,24),
diaphragm (18,25) and pallet (19,26) and stiffener
plate (20,27). Clean parts with a suitable solvent,
replace as necessary. NOTE: Before re-assembly,
apply TFE paste to threads of the stem and around
center hole on the pallets (19,26).
Place stiffener plate (20,27) over threaded end of
stem. Set diaphragm (18,25) and diaphragm retainer
plate (17,24) over end of stem. Install washer and
nut (14) tight on stem.
2
For settings above 32oz/in
See Figure 5 for
assembly. Install machine screws (43).
Inspect and clean pressure / vacuum seat ring(s)
(16). Check seat surface for any nicks, corrosion,
pitting or foreign material. Seat surfaces must be
clean and smooth for diaphragm and pallet to seal
properly. NOTE: FRP seat surfaces are integral
inside the body.
To Remove Seat Rings (except for FRP body
material): Make a match mark between the seat
ring and the body. Rotate cap screws (15) CCW
and remove. Remove pallet guides (22,29). (Use
flats on the pressure guides or the slot on top of the
vacuum guides and rotate CCW to remove.) Mark
the location of each guide on the seat ring (16)
flange for reference at re-assembly.
Lift up to remove seat rings (16) and TFE tape /
rope seal(s) (34.1). (There is no rope seal on FRP
material.) Inspect guides (22,29) and inside cavity
of the body (1) for any corrosion or product build up.
Clean all parts as necessary.
WARNING
When assembling a P/V vent, always put the pressure
(long stem) and vacuum (short stem) pallet assemblies
back in their original location and ensure that the stem is
straight and fits into the guide in the cover or weatherhood.
If the pressure and vacuum pallet assemblies are mixed
at re-assembly, the settings will be changed and the flow
for the vacuum side will be restricted.
If the stem is cocked at an angle, pallet lift may be completely blocked. An over-pressure can occur if any of
these three conditions happens. This can cause a tank
failure, severe personal injury and material damage.
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IOM-3100
Place new seat ring TFE tape seals (34.1) in grooves
in body (1). See Figure 9. Align match marks for
seat rings (16) with body and re-position seat rings
back in body, resting on rope seals.
Re-install pallet guides (22,29) around the seat rings
as previously marked. Install cap screws (15) - apply
15 ft.-lbs. (20.3 Nm) torque to tighten.
Place a new piece of TFE tape / rope seal (34, 34.1)
on the face of the body flange on the vacuum side.
See Figure 9. Place cover (8) over stem of vacuum
pallet assembly, align bolt holes with the body (1)
and install cap screws (10). Using a star crossing
pattern, tighten nuts to 15 ft. lbs. (20.3 Nm).
See Figure 11. For FRP material - install (10,33)
and tighten to 50 in. - lbs. (5.6 Nm).
Place pressure and vacuum pallet stem assemblies
on the correct seat ring (16).
Select the appropriately tagged set of weights (21,28)
and carefully lower each set of loading weights on
the pallet stem assembly, Exercise care so as not
to damage the pallet diaphragms and seat surfaces.
NOTE: When installing the weatherhood (13)
and vacuum cover (8), ensure the pressure stem
assembly (30) and vacuum stem assembly (23) are
inserted in the guides.
Place screen (31) over the guides (29) and around
the O.D of the seat ring (16). Lay one washer
(33) on top for each support guide. For FRP body
material - the washers (33) are installed after the
weatherhood (13) is put in place.
Position the weatherhood (13) over the threaded
ends of the pallet guides (29) and the stem assembly
(30). Re-install wing nuts (12), hand tighten. For
FRP material - install (10,33) and tighten to 50 in.
- lbs. (5.6 Nm).
To Remove Flame Screen: Rotate cap screws (42)
CCW and remove cap screws and ring (41). Inspect
and clean screen (40), replace as necessary. Resecure screen and ring to body with cap screws.
See Figure 10.
IOM-3100
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