Emerson T208 Data Sheet
Bulletin 74.2:T208
T208 Series Tank Blanketing Vapor
Recovery Regulators
October 2014
Figure 1. Type T208 Tank Blanketing Vapor Recovery Regulator
Contents
Features ............................................................................... 1
Introduction ........................................................................... 2
Specications ....................................................................... 2
Principle of Operation ........................................................... 2
Installation ............................................................................ 4
Overpressure Protection....................................................... 4
Capacity Information............................................................. 5
Ordering Information............................................................. 7
Ordering Guide ..................................................................... 7
Features
• Accurate Control—Large diaphragm area provides very
accurate throttling control at low pressure settings.
• Easy Conversion—Changes easily from the
Type T208 to the Type T208M with two O-rings and a
machine screw.
• Rugged Construction—Heavy duty casings and internal
parts are designed to reduce vibration and shock and
give this regulator the ability to withstand up to 35 psig /
2.4 bar (with Nitrile (NBR) and Fluorocarbon (FKM)
diaphragms) and 10 psig / 0.69 bar (with Fluorinated
Ethylene Propylene (FEP) diaphragm) with no internal
parts damage.
• Simplicity—Direct-operated, straightforward stem
and lever design minimizes the number of parts while
providing excellent regulation of pressure.
• Sour Gas Service Capability—Available construction to
meet NACE MR0175-2002.
www.fisherregulators.com
D103751X012
Bulletin 74.2:T208
Specications
This section lists the specications of the T208 Series Tank Blanketing Vapor Recovery Regulator. Factory specication, such
as maximum temperature, maximum inlet and outlet pressures, spring range and seat or orice size are stamped on the
nameplate fastened on the regulator at the factory.
Available Congurations
Type T208: Tank Blanketing Vapor Recovery regulator
with control pressure range of 2 in.w.c. to 7 psig /
5 mbar to 0.48 bar in six different spring ranges
and has internal pressure registration requiring no
control line.
Type T208M: Similar to Type T208 but has a blocked
throat and a control line connection for external
pressure registration.
Body Sizes and End Connection Styles
See Table 1
Maximum Allowable Inlet (Casing) Pressure
(1)
See Table 1
Maximum Outlet Pressure
(1)
35 psig / 2.4 bar
Maximum Emergency Inlet Pressure to Avoid Internal
Parts Damage
(1)
With Nitrile (NBR) or Fluorocarbon (FKM)
diaphragm: 35 psig / 2.4 bar
With Fluorinated Ethylene Propylene (FEP)
diaphragm: 10 psig / 0.69 bar
Control Pressure Ranges
(1)
See Table 3
Flow and Sizing Coefcients
See Table 4
Cv Coefcients and Flow Capacities
See Table 5
Orice Size
7/16 in. / 11 mm
Body and Casing Materials
Gray Cast Iron, WCC Carbon Steel and
CF8M/CF3M Stainless Steel
(2)
Trim Materials
See Table 2
Material Temperature Capabilities
(1)(3)
Elastomer Parts
Nitrile (NBR): -40 to 180°F / -40 to 82°C
Fluorinated Ethylene Propylene (FEP): -20 to 180°F /
-29 to 82°C
Fluorocarbon (FKM): 40 to 300°F / 4 to 149°C
Ethylene Propylene Diene (EPDM): -20 to 225°F /
-29 to 107°C
Peruoroelastomer (FFKM): 0 to 300°F / -18 to 149°C
Body Materials
Gray Cast Iron: -20 to 300°F / -29 to 149°C
WCC Carbon Steel: -20 to 300°F / -29 to 149°C
CF8M/CF3M Stainless Steel: -40 to 300°F /
-40 to 149°C
Spring Case Vent Connection
1/4 NPT
Diaphragm Case Control Line Connection (Type T208M)
1/2 NPT
Approximate Weight
17.7 lbs / 8 kg
1. The pressure/temperature limits in this Bulletin and any applicable standard or code limitation should not be exceeded.
2. Pipe nipples and anges are 316 Stainless steel for anged body assemblies.
3. See Table 2 for operating temperature ranges for available trim combinations.
Table 1. Body Sizes, End Connection Styles and Maximum Allowable Inlet (Casing) Pressures
BODY SIZE
In. DN psig bar
3/4 or 1 20 or 25
1. All flanges are welded. Weld-on flange dimension is 14 in. / 356 mm face-to-face.
2. Pipe nipples and anges are 316 Stainless steel for anged body assemblies.
BODY MATERIAL END CONNECTION STYLE
Gray cast iron NPT 35 2.4
WCC Carbon steel
CF8M/CF3M Stainless steel
NPT, CL150 RF, CL300 RF or
(2)
PN 16/25/40 RF
(1)
MAXIMUM ALLOWABLE INLET (CASING) PRESSURE
75 5.2
Introduction
The T208 Series are direct-operated tank blanketing vapor
recovery regulators. These regulators are used to sense
an increase in vessel pressure and vent excessive internal
tank pressure to an appropriate vapor recovery disposal
or reclamation system. T208 Series may also be used as
backpressure regulators or relief valves.
Principle of Operation
Type T208 vapor recovery regulator senses the change in
tank pressure internally (see Figure 2), while Type T208M
regulator senses the change in tank pressure through a
1/2 NPT control line tapped in its lower casing (see Figure 3).
When vessel pressure increases above the setpoint of the
regulator due to thermal heating or pump-in of the product, the
pressure on the diaphragm overcomes the force of the control
spring. The disk moves away from the orice, allowing gas to
ow from the vessel to the vapor recovery system.
As vessel pressure is reduced, the force of the back disk spring
causes the disk to move toward the orice, decreasing the ow
of gas out of the vessel. As vessel pressure drops below the
setpoint of the regulator, the disk will seat against the orice,
shutting off the gas ow.
2
DISK
BACK DISK SPRING
ORIFICE
CONTROL SPRING
STEM
Bulletin 74.2:T208
PIPE PLUG
LEVER
DIAPHRAGM
ERSA02737
INLET PRESSURE
OUTLET PRESSURE
ATMOSPHERIC PRESSURE
Figure 2. Type T208 with Internal Pressure Registration Operational Schematics
STEM SEAL O-RING
LEVER
THROAT SEAL
DISK
BACK DISK SPRING
ORIFICE
UMBRELLA VENT
CONTROL LINE CONNECTION
DIAPHRAGM
CONTROL SPRING
ERSA02738
INLET PRESSURE
OUTLET PRESSURE
ATMOSPHERIC PRESSURE
Figure 3. Type T208M with External Pressure Registration Operational Schematics
UMBRELLA VENT
3
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