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

Specications ....................................................................... 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

Specications

This section lists the specications of the T208 Series Tank Blanketing Vapor Recovery Regulator. Factory specication, such
as maximum temperature, maximum inlet and outlet pressures, spring range and seat or orice size are stamped on the

nameplate fastened on the regulator at the factory.

Available Congurations

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 Coefcients

See Table 4

Cv Coefcients and Flow Capacities

See Table 5

Orice 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

Peruoroelastomer (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 orice, 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 orice, 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 orice,
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

Bulletin 74.2:T208

Table 2. Available Construction and Trim Materials

AVAILABLE CONSTRUCTION MATERIAL AVAILABLE TRIM OPTION

Body and 

Casing

Gray cast iron,

WCC Carbon

steel or

CF8M/CF3M

Stainless steel

1. Pipe nipples and anges are 316 Stainless steel for anged body assemblies.

Table 3. Control Pressure Ranges and Spring Information

2.0 to 7.0

3.0 to 13.0

10.0 to 26.0 25 to 65 Yellow 0.114 2.9 4.31 109

0.9 to 2.5 psig 62 to 172 Green 0.156 4.0 4.06 103

1.3 to 4.5 psig 90 to 310 Light Blue 0.187 4.8 3.94 100

3.8 to 7.0 psig 0.26 to 0.48 bar Black 0.218 5.5 3.98 101

1. To achieve the published control pressure range the spring case must be installed pointing down.

2. Do not use Fluorocarbon (FKM) diaphragm with these springs at diaphragm temperatures lower than 60°F / 16°C.

Table 4. Flow and Sizing Coefcients

Guide Insert, 

Stem and 

Pusher Post

316 Stainless

Steel

(1)

CONTROL PRESSURE RANGE

In. w.c. mbar In. mm In. mm

(1)(2)

(1)(2)

ORIFICE SIZE REGULATING WIDE-OPEN

In. mm C

7/16 11 94 2.7 35.0 97 2.8 35.0

Diaphragm 

Head

304 Stainless

Steel

(1)(2)

5 to 17

(1)(2)

7 to 32

Lever 

Assembly

302 Stainless

Steel

Trim Option 

Code

Standard Nitrile (NBR) Nitrile (NBR) -40 to 180°F / -40 to 82°C

VV Fluorocarbon (FKM) Fluorocarbon (FKM) 40 to 300°F / 4 to 149°C
TV Fluorinated Ethylene Propylene (FEP) Fluorocarbon (FKM) 40 to 180°F / 4 to 82°C
TN Fluorinated Ethylene Propylene (FEP) Nitrile (NBR) -20 to 180°F / -29 to 82°C
TK Fluorinated Ethylene Propylene (FEP) Peruoroelastomer (FFKM) 0 to 180°F / -18 to 82°C
TE Fluorinated Ethylene Propylene (FEP) Ethylene Propylene Diene (EPDM) -20 to 180°F / -29 to 82°C

SPRING COLOR

Red 0.085 2.2 3.63 92.2

Unpainted 0.105 2.7 3.75 95.3

g

Diaphragm Material Disk and O-ring Material

SPRING WIRE DIAMETER SPRING FREE LENGTH

C

v

C

1

C

g

C

v

Operating Temperature 

Range

C

1

Table 5. T208 Series Cv Coefcient and Flow Capacity

CONTROL PRESSURE 

RANGE AND 

SPRING COLOR

2.0 to 7.0 in. w.c. /
5 to 17 mbar

Red

3.0 to 13.0 in. w.c. /
7 to 32 mbar

Unpainted

10.0 to 26.0 in. w.c. /

25 to 65 mbar

Yellow

0.9 to 2.5 psig /
62 to 172 mbar

Green

1.3 to 4.5 psig /
90 to 310 mbar

Light Blue

3.8 to 7.0 psig /

0.26 to 0.48 bar
Black

SET PRESSURE MINIMUM BUILDUP TO WIDE-OPEN VACUUM OUTLET PRESSURE

In. w.c. mbar In. w.c. mbar psig barg SCFH Nm3/h

2.0 5.0 4.02 10

4.0 10.0 3.62 9

10.0 25 5.99 15

15 37 8.89 22.1

1 psig 70 0.78 psig 54

2 psig 140 1.49 psig 103

5 psig 340 2.79 psig 192

Installation

Install the T208 Series regulator using a straight run pipe of
the same size or larger as the regulator body. Flow through

the regulator body is indicated by the ow arrow attached
to the body. If a block valve is required, install a full ow

valve between the regulator and the blanketed vessel. To
achieve the established regulator capacities, the regulators
should be installed with the spring case barrel pointed down
(See Figure 1).

Emerson Process Management Regulator Technologies, Inc.
(Emerson™) provides an instruction manual with every

Cv COEFFICIENT 

0 0 3.1 192 5.1

2.5 0.17 3.5 1161 31.1
5 0.34 3.5 1488 39.9
0 0 2.6 226 6.1

2.5 0.17 3.5 1178 31.6
5 0.34 3.5 1500 40.2
0 0 2.0 268 7.2

2.5 0.17 3.5 1232 33.0
5 0.34 3.5 1539 41.2
0 0 2.0 331 8.9

2.5 0.17 3.5 1279 34.3
5 0.34 3.5 1574 42.2
0 0 2.2 499 13.4

2.5 0.17 3.6 1426 38.2
5 0.34 3.6 1687 45.2
0 0 2.3 752 20.2

2.5 0.17 3.8 1694 45.4
5 0.34 3.7 1904 51.0
0 0 2.2 1139 30.5

2.5 0.17 3.8 2286 61.3
5 0.34 3.8 2242 60.1

CAPACITIES OF AIR

regulator shipped. Refer to this for complete installation,
operation and maintenance instructions. Included is a complete
listing of individual parts and recommended spare parts.

Overpressure Protection

Vapor recovery regulators are used to maintain a constant

inlet (blanket) pressure with the outlet owing to a system

whose pressure is lower than that at the inlet. The recovery

regulators are not intended to be used as an ASME certied

relief device for overpressure protection on a tank. They are to

4

Bulletin 74.2:T208

POSITION 2 POSITION 3 POSITION 4

BODY POSITION

A (STANDARD)

POSITION 1 (STANDARD) POSITION 2

POSITION 3 POSITION 4

BODY POSITION

Figure 4. Body and Vent Position

be used as part of a gas blanketing system to control outow of

blanketing gas under normal conditions and collect tank vapors
for the vapor disposal or reclamation system. Provide alternate
methods of emergency overpressure protection.

Universal NACE Compliance

Optional materials are available for applications handling

where,
Q
Q
Q

Capacity Information

sour gases. These constructions comply with the
recommendations of National Association of Corrosion
Engineers (NACE) sour service standards.

The manufacturing processes and materials used by

Emerson™ assure that all products specied for sour gas

service comply with the chemical, physical and metallurgical
requirements of NACE MR0175-2002. Customers have the
responsibility to specify correct materials. Environmental
limitations may apply and shall be determined by the user.

Table 5 shows the T208 Series Cv coefcient and ow
capacities of air at selected set pressure. Flows are in SCFH
(at 60°F and 14.7 psia) and Nm3/h (at 0°C and 1.01325 bar)

of 1.0 specic gravity air. For gases of other specic

gravities, divide the given capacity of air by the square root

of the appropriate specic gravity of the gas required. To

determine regulating capacities at pressure settings not

given or to determine wide-open ow capacities, use the

following formula:

D

C

VENT POSITION

Q

= Q

total

: Required Flow Rate

total

: Required Flow Rate due to pump in

pump

: Required Flow Rate due to thermal heating

thermal

pump

+ Q

thermal

B

Sizing Blanketing Systems

When sizing a gas vapor recovery regulator system,
consider the volume of blanketing gas that must be

displaced from the vessel when either lling the vessel with

liquid (pump-in) or the expansion of vapors inside the vessel
during atmospheric thermal heating.

Using the established procedures from American Petroleum

Institute Standard 2000 (API 2000), determine the ow rate

for outbreathing:

520

Q = CgP1SIN

GT

3417

C

1

∆P

P

DEG

1

where:

Q = ow rate, SCFH
G = gas specic gravity

T = absolute temperature of gas at inlet, °Rankine
C
P
C

= gas sizing coefcient, Table 4

g

= absolute inlet pressure, psia

1

= Cg/Cv, ow coefcient, Table 4

1

ΔP = pressure drop across the regulator, psi

5

Bulletin 74.2:T208

8.38 / 212.9

1/4 NPT VENT

1/2 NPT CONTROL

LINE CONNECTION

10.37 / 263.4

T208 SERIES WITH NPT END CONNECTION

6.18 / 157

NPT

1.84 /

46.7

5.58 /

141.6

2.25 /

57.2

4.12 /

104.6

FLANGED

14 /

355.6

SPRING ADJUSTMENT ASSEMBLY OPTION

Figure 5. Dimensions

6

8.07 / 205

MAXIMUM

7.19 /

182.6

T208 SERIES WITH

FLANGED END CONNECTION

IN. / mm

Ordering Information

Bulletin 74.2:T208

When ordering, complete the ordering guide on this page.

Refer to the Specications section on page 2. Review
the description to the right of each specication and the

Ordering Guide

Type (Select One)
T208, Internal pressure registration***
T208M, External pressure registration***

Body Size (Select One)
3/4 in. / DN 20***
1 in. / DN 25***

Body Material and End Connection Style (Select One)
  Gray Cast Iron
NPT***
  WCC Carbon Steel

NPT***
CL150 RF***
CL300 RF***
PN 16/25/40 RF*** specify rating _________

  CF8M/CF3M Stainless Steel

NPT***
CL150 RF***
CL300 RF***
PN 16/25/40 RF*** specify rating _________

Control Pressure Range (Select One)

2.0 to 7.0 in. w.c. / 5 to 17 mbar, Red***

3.0 to 13.0 in. w.c. / 7 to 32 mbar, Unpainted***

10.0 to 26.0 in. w.c. / 25 to 65 mbar, Yellow***

0.9 to 2.5 psig / 62 to 172 mbar, Green***

1.3 to 4.5 psig / 90 to 310 bar, Light Blue***

3.8 to 7 psig / 0.26 to 0.48 bar, Black***

Trim Material (See Table 2, Select One)
Standard***
VV***
TV***
TN***
TK***
TE***

(1)

information in each referenced table or gure. Specify your

choice whenever a selection is offered.

Adjusting Screw (Select One)
Internal Flat Circular (standard)***
External Square Head (Available for Green, Light blue

and Black springs only. Steel closing cap is automatically
supplied in this option)***

Closing Cap Material (Select One)
Plastic (standard) (not available for Green,

Light blue and Black springs)***
Steel (standard for Green, Light blue and Black springs)***
Stainless steel***

Body Position (See Figure 4, Select One)
Position 1 (standard)***
Position 2***
Position 3***
Position 4***

Spring Case Orientation/Vent Type (Select One)
Spring Case Down (Type Y602-1) (standard)***
Spring Case Up (Type Y602-11)***

Vent Position (See Figure 4) (Select One)
Position A (standard)***
Position B***
Position C***
Position D***

NACE Standard MR0175-2002 Construction (Select One)
Yes
No

Replacement Parts Kit (Optional)
Yes, send one replacement parts kit to match this order.

1. Pipe nipples and anges are 316 Stainless steel for anged body assemblies.

7

Bulletin 74.2:T208

Ordering Guide (continued)

Regulators Quick Order Guide

* * * Readily Available for Shipment

* * Allow Additional Time for Shipment

Special Order, Constructed from Non-Stocked Parts.

*

Consult your local Sales Ofce for Availability.

Availability of the product being ordered is determined by the component with the
longest shipping time for the requested construction.

Specication Worksheet

Application (Please designate units):

Specic Use

Line Size

Fluid Type and Specic Gravity

Fluid Temperature
Does the Application Require Overpressure Protection?
Yes No If yes, which is preferred:
Relief Valve Monitor Regulator Shutoff Device
Is overpressure protection equipment selection assistance
desired?

Pressure:

Maximum Inlet Pressure
Minimum Inlet Pressure
Differential Pressure
Set Pressure
Maximum Flow (Q

max

)

Performance Required:

Accuracy Requirements?
Less than or Equal to:
5% 10% 20% Wide Open

Other Requirements:

Industrial Regulators

Emerson Process Management
Regulator Technologies, Inc.

USA - Headquarters
McKinney, Texas 75070 USA
Tel: [phone]
Outside U.S. [phone]

Asia-Pacic

Shanghai 201206, China
Tel: [phone]

Europe
Bologna 40013, Italy
Tel: [phone]

Middle East and Africa
Dubai, United Arab Emirates
Tel: [phone]

For further information visit www.fisherregulators.com

The Emerson logo is a trademark and service mark of Emerson Electric Co. All other marks are the property of their prospective owners. Fisher is a mark owned by Fisher Controls International LLC,
a business of Emerson Process Management.

The contents of this publication are presented for informational purposes only, and while every effort has been made to ensure their accuracy, they are not to be construed as warranties or

guarantees, express or implied, regarding the products or services described herein or their use or applicability. We reserve the right to modify or improve the designs or specications of such

products at any time without notice.

Emerson Process Management Regulator Technologies, Inc. does not assume responsibility for the selection, use or maintenance of any product. Responsibility for proper selection, use and
maintenance of any Emerson Process Management Regulator Technologies, Inc. product remains solely with the purchaser.

Natural Gas Technologies

Emerson Process Management
Regulator Technologies, Inc.

USA - Headquarters
McKinney, Texas 75070 USA
Tel: [phone]
Outside U.S. [phone]

Asia-Pacic

Singapore 128461, Singapore
Tel: [phone]

Europe
Bologna 40013, Italy
Tel: [phone]
Chartres 28008, France
Tel: [phone]

Middle East and Africa
Dubai, United Arab Emirates
Tel: [phone]

TESCOM

Emerson Process Management
Tescom Corporation

USA - Headquarters
Elk River, Minnesota 55330-2445, USA
Tels: [phone]
[phone]

Europe
Selmsdorf 23923, Germany
Tel: [phone]

Asia-Pacic

Shanghai 201206, China
Tel: [phone]

The distinctive diamond shape cast into every
spring case uniquely identifies the regulator
as part of the Fisher® brand and assures you
of the highest-quality engineering, durability,
performance, and support.

©Emerson Process Management Regulator Technologies, Inc., 2013, 2014; All Rights Reserved