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T205VB Series
Specifications
The Specifications section on this page provides the ratings and other specifications for the T205VB Series.
Factory specification such as type, maximum inlet pressure, maximum temperature, maximum outlet pressure,
spring range and orifice size are stamped on the nameplate fastened on the vacuum breaker at the factory.
BODY SIZE
BODY MATERIAL
END CONNECTION
STYLE
(1)
NPS
DN
3/4 or 1
20 or 25
Gray cast iron
NPT
316/316L Stainless steel,
Carbon steel
NPT or CL150 RF
1. All flanges are welded. Weld-on flange dimension is 14 in. / 356 mm face-to-face.
Available Configurations
Type T205VB:
Direct-operated vacuum breaker
with internal pressure registration.
Type T205VBM:
Direct-operated vacuum breaker
equipped with a blocked throat and control line
connection for external pressure registration.
Body Sizes
NPS 3/4 / DN 20
NPS 1 / DN 25
End Connection Styles
Maximum Operating Inlet Pressure
(1)
150 psig / 10.3 bar
Maximum Outlet (Casing) Pressure
(1)
Cast Iron:
35 psig / 2.41 bar
Steel/Stainless steel:
75 psig / 5.17 bar
Maximum Emergency Outlet (Casing) Pressure to
Avoid Internal Parts Damage
(1)
35 psig / 2.41 bar
Maximum Set Points for Achieving Wide-Open Flow
See Table 2
Maximum Vacuum Pressure
Full Vacuum
Vacuum Control Pressure Ranges
(1)
See Table 1
Temperature Capabilities
(1)
Nitrile (NBR)
Cast Iron/Steel Body:
-20 to 180°F / 29 to 82°C
Stainless steel Body:
-40 to 180°F / -40 to 82°C
Fluorocarbon (FKM):
40 to 300°F / 4 to 149°C
Spring Case Connection
1/4 NPT
Diaphragm Case Connection
1/2 NPT
Orifice Size
1/4 in. / 6.4 mm
1/2 in. / 13 mm
Pressure Registration
Type T205VB:
Internal
Type T205VBM:
External
Approximate Weight
18.7 lbs / 8.5 kg
1. The pressure/temperature limits in this Instruction Manual and any applicable standard or code limitation should not be exceeded.
WARNING
Failure to follow these instructions or
to properly install and maintain this
equipment could result in an explosion,
fire and/or chemical contamination
causing property damage and personal
injury or death.
Fisher™ vacuum breakers must be
installed, operated and maintained
in accordance with federal, state and
local codes, rules and regulations
and Emerson Process Management
Regulator Technologies, Inc.
(Emerson) instructions.
If the vacuum breaker discharges
process fluid or a leak develops in
the system, service to the unit may be
required. Failure to correct trouble could
result in a hazardous condition.
Call a qualified service person to service
the unit. Installation, operation and
maintenance procedures
performed by unqualified person may
result in improper adjustment and
unsafe operation. Either condition
may result in equipment damage
or personal injury. Only a qualified
person shall install or service the
T205VB Series vacuum breakers.
Principle of Operation
The T205VB Series vacuum breakers are used in
applications where an increase in vacuum must be
limited, see Figure 2. An increase in vacuum (decrease
in absolute pressure) is sensed on the under side
of the diaphragm, opening the disk assembly. This
permits positive pressure, atmosphere or an upstream
vacuum that has higher absolute pressure than the
downstream vacuum to enter the system and restore
the controlled vacuum to its original pressure setting.
On the Type T205VB, the pressure registers internally
underneath the diaphragm. The Type T205VBM has
a control line connecting the diaphragm casing to the
vacuum line and a throat seal allowing for registration
only through the control line connection.
