Tank
Blanketing:
A Versatile
Tool for Tank
Protection
This information is proprietary to the Protectoseal Co., and is not
to be duplicated or distributed without prior written consent.
Tank Blanketing is the process of applying an
inert gas to the vapor space of a storage tank,
vessel or container. Tank blanketing is also
referred to as tank padding.
WHY USE TANK BLANKETING?
To protect the product in the tank from oxidation (limits degradation or
spoiling of the product)
Protect the inside of the tank from oxidizing / rusting
Limit product evaporation
Reduce the possibility of an explosive vapor in the tank
Effectively control volatile organic compounds (VOC’s) emitted to the
atmosphere.
This information is proprietary to the Protectoseal Co., and is not
to be duplicated or distributed without prior written consent.
HOW IS THIS DONE?
By preventing air, moisture and other
contaminants from getting in the tank
HOW DOES A BLANKETING VALVE WORK?
The Blanketing Valve works by delivering an inert gas into the tank
during tank in-breathing. This gas is also called a “make-up” gas.
In-breathing occurs when liquid is being pumped from the
tank, and/or when vapors condense in the tank due to a
decrease in temperature causing a vacuum in the tank.
The inert gas is delivered into the tank only during tank
inbreathing cycles.
This information is proprietary to the Protectoseal Co., and is not
to be duplicated or distributed without prior written consent.
HOW DOES A BLANKETING VALVE WORK?
THE MOST COMMON INERT GASES USED IN BLANKETING ARE:
Nitrogen
Carbon Dioxide
Other gases which are also used:
Natural Gas
Argon
This information is proprietary to the Protectoseal Co., and is not
to be duplicated or distributed without prior written consent.
HOW DOES A BLANKETING VALVE WORK?
Depending upon the specific application, the selection of the
inerting gas is often based upon one or more of the following
characteristics:
NON-FLAMMABILITY
NON-CONTAMINATING
CHEMICALLY COMPATIBLE
NON-TOXIC
COST
AVAILABILITY
This information is proprietary to the Protectoseal Co., and is not
to be duplicated or distributed without prior written consent.
WHAT ARE THE BENEFITS OF TANK BLANKETING?
-Protect the product in the tank from oxidizing
Limits product spoilage & Ensures quality feedstock for production process
-Protect the inside of the tank from oxidizing / rusting
Do not have to replace the tank
-Limit product evaporation from the tank
Increases profitability
-Reduce the possibility of an explosive vapor in the tank
Eliminates air in the tank and therefore reduces the possibility of a fire
-Effectively control volatile organic compounds (VOC’s) emitted to the atmosphere
Gets EPA of your back
This information is proprietary to the Protectoseal Co., and is not
to be duplicated or distributed without prior written consent.
Tank blanketing valves are used in wide variety of liquid
processing and storage tank applications which include:
Chemical Process Facilities
Petroleum Refineries
Bulk Liquid Storage Terminals
Food / Pharmaceutical Plants
Digester Systems
Vapor Recovery Systems
Semiconductor Industry
This information is proprietary to the Protectoseal Co., and is not
to be duplicated or distributed without prior written consent.
Blanketing Valve
A device that senses the pressure in the vapor space
of a storage tank and controls the flow of an inert gas
(usually Nitrogen) into the vapor space so that the
tank pressure can be maintained within an acceptable
range.
Deadband
The total pressure difference between the
blanketing valve opening pressure (or set point)
and resealing pressure. This applies to the main
valve. Some minor leakage through the pilot will
occur above the main valve resealing pressure.
Dome Pressure
In a pilot operated blanketing valve, the
pressure in the dome volume.
Dome Volume
In a pilot operated blanketing valve, the
chamber between the poppet in the pilot valve
and the piston in the main valve.
Flow Plug
A small cylinder which may be installed in the
valve to partially block the flow of inert gas
through the valve.
This information is proprietary to the Protectoseal Co., and is not
to be duplicated or distributed without prior written consent.
Main Valve
The portion of the valve through which the supply gas
flows into the storage tank.
Pilot Valve
In a pilot operated valve, the portion of the valve
that senses tank pressure and controls the
opening and closing of the main valve.
Poppet
The component in the valve which moves in
response to changes in pressure in the sensing
diaphragm chamber and which, when unseated,
allows flow through the device.
Pressure Balanced
Poppet
A poppet designed so that the supply pressure
will not have an effect on its opening or closing
characteristics. All Protectoseal blanketing
vales have pressure balanced poppets.
Sense Chamber
The space below the diaphragm chamber to
which the sense line pressure, from the tank, is
directed. The pressure in the sense chamber
controls the opening and closing of the poppet.
This information is proprietary to the Protectoseal Co., and is not
to be duplicated or distributed without prior written consent.
Sense Diaphragm
A thin, non-metallic disc in the diaphragm chamber
which flexes in response to changes in the sense line
pressure
Sense Line
A tube running from the tank’s vapor space to
the sense port of the blanketing valve. This tube
transmits tank pressure to the sense chamber.
Set Point
The pressure at which the main valve opens
and flows.
This information is proprietary to the Protectoseal Co., and is not
to be duplicated or distributed without prior written consent.
PROTECTOSEAL MANUFACTURES
TWO TYPES OF BLANKETING VALVES
F20T Pilot Operated, 1 inch
F30B Direct Acting, 1/2 inch
This information is proprietary to the Protectoseal Co., and is not
to be duplicated or distributed without prior written consent.
Designed specifically for tank blanketing
SERIES 20
Pilot operated design provides very tight
operating band
Compact, light-weight design
1” NPT inlet and outlet standard
Optional inlet and outlet connections available
Accommodates inlet gas pressures from
20 PSIG to 200 PSIG
Delivers up to 83,108 SCFH of N2
Set points from –0.5” WC to 69.2” WC
Optional flow plugs to meet specific flow
requirements
Fully field serviceable
This information is proprietary to the Protectoseal Co., and is not
to be duplicated or distributed without prior written consent.
F20T PILOT OPERATED BLANKETING VALVES
Consists of two separate valves operating in
tandem, the pilot valve and the main valve.
The pilot valve senses the tank pressure
which causes the pilot valve to open and to
close which then controls the opening and
closing of the main valve.
When the main valve opens it allows the flow
of the blanketing gas through the valve from
the supply source into the tank.
Series 20 in open position
The pilot valve will open and close gradually
(movement is small).
The pilot valve movement is controlled by a flexible diaphragm which is spring loaded on
one side and the tank pressure on the other.
The main valve will open and close quickly responding to changes in “dome pressure”
which is controlled by the pilot valve.
This information is proprietary to the Protectoseal Co., and is not
to be duplicated or distributed without prior written consent.
Pilot Operated Design
Pressure Sense Chamber (C)
Controls the opening and closing
of the valve
Vertical Moving Poppet (D)
Movement causes valve to open
and close
Piston (E)
Movement controls the inert gas flow
This information is proprietary to the Protectoseal Co., and is not
to be duplicated or distributed without prior written consent.
Emergency Vent Full Open
Blanketing Valve
Operating Ranges
Emergency Vent Set Point
Pressure Vent Fully Open
Pressure Vent Set Point
Blanketing Valve Closed
Deadband
Blanketing Valve Open
Blanketing Valve
Set Point
Vacuum Vent Set Point
Vacuum Vent Fully Open
This information is proprietary to the Protectoseal Co., and is not
to be duplicated or distributed without prior written consent.
BLANKETING
VALVE OPERATING
CYCLE
TANK PRESSURE
Pilot Valve Seals
Pilot Valve Cracks
Main Valve Seals
DEADBAND
Main Valve Opens
This information is proprietary to the Protectoseal Co., and is not
to be duplicated or distributed without prior written consent.
Designed specifically for tank blanketing
SERIES 30
Compact, light-weight design
1/2” NPT inlet and outlet standard
Optional flanged or threaded connections
available
Accommodates inlet gas pressures from 10
PSIG to 200 PSIG
Delivers up to 2,170 SCFH of N2
Set points from -0.1” WC to 69.2” WC
Optional flow plugs to meet specific flow
requirements
Fully field serviceable
This information is proprietary to the Protectoseal Co., and is not
to be duplicated or distributed without prior written consent.
F30B DIRECT ACTING BLANKETING VALVES
A valve assembly connected to a flexible
diaphragm, similar to a pilot valve, moves up
and down gradually responding to tank
pressure.
As the valve moves away from its seated
position, flow through from the blanketing
gas supply source begins.
Direct acting valves tend to have
considerable more ‘droop” than pilot
operated valves.
Droop is defined as the amount of pressure
drop below the set point required to cause
the gas blanketing valve to open.
Series 30 in open position
This information is proprietary to the Protectoseal Co., and is not
to be duplicated or distributed without prior written consent.
Direct Acting Design
Pressure Sense Chamber (D)
Controls the opening and closing
of the valve
Vertical Moving Poppet (B)
Movement causes valve to
open and close
This information is proprietary to the Protectoseal Co., and is not
to be duplicated or distributed without prior written consent.
This information is proprietary to the Protectoseal Co., and is not
to be duplicated or distributed without prior written consent.
A TYPICAL TANK BLANKETING INSTALLATION
Make sure that the setting of the vents is between 2” WC and 8” WC higher
than the blanketing system set point.
This insures
that the vents do
not end up being
held open by the
blanketing
systems
operation.
Vacuum Vent
set point should
be 0.5” WC below
the blanketing
system for the
F20T and 1.5”
WC below for the
F30B.
This information is proprietary to the Protectoseal Co., and is not
to be duplicated or distributed without prior written consent.
Sensing Line
Senses any changes in internal
tank pressure and tells the main
valve to either open or close
Inert Gas Supply Line
Feeds the tank’s voided vapor space
It is important that the sense line and the blanketing valves outlet pipe are far enough apart
to ensure the static pressure in the tank is sensed. These lines are usually 2 to 10 feet apart
This information is proprietary to the Protectoseal Co., and is not
to be duplicated or distributed without prior written consent.
INSTALLATION:
The blanketing valve is connected to the top
of the tank and the inert gas is piped from a
supply source to the inlet connection of the valve.
A sensing line from a
remote location on the tank is
connected to the sensing port
of the valve.
The sense line connection to the
tank should not exceed ten feet in
length from the blanketing valve
connection.
This information is proprietary to the Protectoseal Co., and is not
to be duplicated or distributed without prior written consent.
A filter upstream of the blanketing valve is suggested to guarantee
a clean supply of gas to the valve.
If a filter is utilized the flow through the filter must be greater
than the required vacuum flow.
Use of plumber’s tape to connect the gas supply line to
the blanketing valve is recommended. Do not use pipe dope.
Pipe dope can become loose in the pipe and find its way into
the blanketing valve and cause the valve to fail open.
This information is proprietary to the Protectoseal Co., and is not
to be duplicated or distributed without prior written consent.
This information is proprietary to the Protectoseal Co., and is not
to be duplicated or distributed without prior written consent.
Vacuum relief requirements are based on two factors:
Maximum Liquid Movement
out of the tank or
the emptying or pump-out rate
⁺
Thermal effect or
atmospheric cooling
This information is proprietary to the Protectoseal Co., and is not
to be duplicated or distributed without prior written consent.
EXAMPLE – Blanketing Valve*
1. Tank Capacity………………………………………. = 42,000 Gallons
2. Flash Point………………………………………….. = <100° F
3. Maximum Tank Design Pressure…………………. = 6.0”WC
4. Maximum Tank Design Vacuum………………...... = 1.0”WC
5. Pumping In Rate……………………………………. = 100 GPM
6. Pumping Out Rate…………………………………. = 615 GPM
7. Tank Type…………………………………………… = Vertical
8. Tank Diameter…………………………………….... = 12 Feet
9. Tank Height…………………………………………. = 20 Feet
10. Set Point of the Blanketing Valve…………………. = 0.5” WC
11. Minimum Recommended Pressure Set Point…… = 2.5” WC
12. Minimum Recommended Vacuum Set Point……. = 0.865” WC
13. Emergency Set Point………………………………. = 4.0” WC
*Sizing based on API 2000 Version 6, Annex A
This information is proprietary to the Protectoseal Co., and is not
to be duplicated or distributed without prior written consent.
From Pages 4 & 5 in Sales Brochure
STEP #1: Flow Required from Pump Out Rate
• Maximum Emptying Rate = 400 GPM
• 615 GPM x 8.0 (Table 1) = ………………………………………………………..…. 4,920 SCFH
STEP #2: Flow Required from Thermal Cooling
• Add for thermal flow requirement (Table 2)
• 42,000 Gallons = …………………..……………………………………...…..……. 1,000 SCFH
TOTAL VACUUM REQUIREMENT = …….……………………….…….……….…. 5,920 SCFH*
STEP #3: Size the Blanketing Valve: Check Maximum Flows
against Supply Pressure, Page 5
• Determine Blanketing Gas Supply Pressure (Example = 90 psig)
Determine flow at 90 psig with a 100% Flowport =39,855 SCFH Air
Choose a flow plug, if needed, to reduce the flow to “near” the requirement =20%flow port
20% flow port delivers = 7,971 SCFH air (8,105 SCFH N2) which is near the 4,200 SCFH requirement
Final Step – Build Model Number From Page 8 of Sales Brochure
after Determining the Available Options.
This information is proprietary to the Protectoseal Co., and is not
to be duplicated or distributed without prior written consent.
Material for valve body and components
Materials for seals and gaskets
Setting range
Filter type – 40 Micron
Flow capacity reduction plugs
Pressure gages
Integral purge
Check valves
Field test setup
This information is proprietary to the Protectoseal Co., and is not
to be duplicated or distributed without prior written consent.
This information is proprietary to the Protectoseal Co., and is not
to be duplicated or distributed without prior written consent.
SERIES 20
FIELD TEST SET-UP
Higher Pressure Set Point
(2.1” to 69.2” WC) Field Test Kit
w/ Outlet Line 3-Way Valve &
Sense Line Shut-Off Valve
This information is proprietary to the Protectoseal Co., and is not
to be duplicated or distributed without prior written consent.
From Pages 4 & 5 in Sales Brochure
STEP #1: Flow Required from Pump Out Rate
• Maximum Emptying Rate = 615 GPM
• 615 GPM x 8.0 (Table 1) = ………………………………………………………..…. 4,920 SCFH
STEP #2: Flow Required from Thermal Cooling
• Add for thermal flow requirement from Table 2
• 42,000 Gallons = …………………..……………………………………...…..……. 1,000 SCFH
TOTAL VACUUM REQUIREMENT = …….……………………….…….……….…. 5,920 SCFH
STEP #3: Check Maximum Flows against Supply Pressure
•
•
•
•
Determine Blanketing Gas Supply Pressure (Example = 90 psig)
Determine if flow plug is needed – To reduce flow to “near” flow requirement
Air @ 90 psig = 39,855 SCFH. (40,528 N₂) is too high
Use 20% flow plug to “choke down” to 7,971 SCFH (air) which is near the 5,920 SCFH required
Final Step – Build Model Number From Page 8 of Sales Brochure
after Determining the Available Options.
This information is proprietary to the Protectoseal Co., and is not
to be duplicated or distributed without prior written consent.
Specifications require 316 stainless steel, pilot-operated Tank Blanketing Valve, with 1 inch
FNPT connections (supply and outlet), set at 0.1 in wc*, with Buna-N Seals and gaskets, 20%
flow plug and an aluminum/zinc pilot filter.
*Notes:
1.) See Table at the bottom of pg. 7. A 2 in WC separation between the TBV Set Point and the pressure
setting on the PVRV vent is suggested.
2.) Protectoseal’s “Set Point” for our tank blanketing valves is the point at which the TBV opens. It closes at
approximately 1.5 in WC higher than the set point.
From Page 8 of Sales Brochure
1) Material
2 – 3) Set Point
4) Revision Level
5) Connections
6) Set Point Range
7) Seals and Gaskets
8) Flow Plug/Flowport
9) Pilot Filter Option
10) Check Valve Option
11) Pressure Gauge Option
12) Integral Purge Option
13) Field Test Option
This information is proprietary to the Protectoseal Co., and is not
to be duplicated or distributed without prior written consent.
Specifications require 316 stainless steel, pilot-operated Tank Blanketing Valve, with 1 inch
FNPT connections (supply and outlet), set at 0.1 in wc*, with Buna-N Seals and gaskets, 20%
flow plug and an aluminum/zinc pilot filter.
*Notes:
1.) See Table at the bottom of pg. 7. A 2 in WC separation between the TBV Set Point and the pressure
setting on the PVRV vent is suggested.
2.) Protectoseal’s “Set Point” for our tank blanketing valves is the point at which the TBV opens. It closes at
approximately 1.5 in WC higher than the set point.
From Page 8 of Sales Brochure
1) Material
2 – 3) Set Point
4) Revision Level
5) Connections
6) Set Point Range
7) Seals and Gaskets
8) Flow Plug/Flowport
9) Pilot Filter Option
10) Check Valve Option
11) Pressure Gauge Option
12) Integral Purge Option
13) Field Test Option
F 20 T A A A E
A 0
0 0
0
This information is proprietary to the Protectoseal Co., and is not
to be duplicated or distributed without prior written consent.
SINGLE PORT OR
DIP TUBE SENSING
This information is proprietary to the Protectoseal Co., and is not
to be duplicated or distributed without prior written consent.
TOTAL TANK PROTECTION CAPABILITIES
Blanketing Valves
End-of-Line
Breather Vents
Pipe-Away
Breather Vents
Vacuum Vents
Emergency Vents
In-Line Flame
Arresters
Combination Vent
w/ Flame Arrester
Detonation
Arresters
This information is proprietary to the Protectoseal Co., and is not
to be duplicated or distributed without prior written consent.