Brand: Fisher

Fisher T205 Series Tank Blanketing Regulator

Name: Fisher T205 Tank Blanketing Regulator
Brand: Fisher
SKU: T205

Description

Fisher T205 tank blanketing regulator series

The Fisher T205 series is a direct-operated, spring-loaded regulator built for tank blanketing. It feeds a small, steady flow of gas such as nitrogen into the vapor space of a storage tank to keep a slight positive pressure, which stops the stored liquid from vaporizing into the atmosphere, reduces combustibility and keeps air and moisture out of the product. The same positive pressure also helps prevent tank wall collapse during pump-out.

Seven Star LLC supplies the Fisher T205 series in Oman and the GCC as an independent supplier in Muscat. The four type codes are decoded here so the correct one is quoted.

Decoding the T205 types

Type	Construction	Key point
T205	Internal pressure registration, no control line	Outlet 1 in. w.c. to 7 psig in seven spring ranges
T205M	Blocked throat, external registration via downstream control line	Control line 1/2 NPT
T205H	Like T205, inlet equals casing pressure of 150 psig / 10.3 bar	Low temperature to -20 °F / -29 °C
T205HM	Like T205M with the H pressure rating	150 psig / 10.3 bar

Fisher T205 technical specifications

Parameter	Specification
Manufacturer / part number	Fisher (Emerson) / T205 Series (Bulletin 74.1, D103747X012, May 2024)
Outlet (control) pressure	1 in. w.c. to 7 psig / 2.5 mbar to 0.48 bar, seven spring ranges
Body sizes	3/4 or 1 in. (DN 20 or 25); 3/4 x 1 in. flanged uses the 3/4 in. body
End connections	NPT; CL150 RF, CL300 RF, PN 16/25/40 RF flanged (welded flanges)
Max allowable inlet	Gray cast iron 150 psig / 10.3 bar; steel and stainless 200 psig / 13.8 bar (150 psig for H types)
Max outlet (casing)	T205 and T205M: gray iron 35 psig / 2.4 bar; steel or stainless 75 psig / 5.2 bar. H types: 150 psig / 10.3 bar
Body materials	Gray cast iron, WCC carbon steel, LCC carbon steel, CF8M/CF3M stainless steel
Shutoff	Class VI soft seat per ANSI/FCI 70-3-2004
Elastomer temperature	Nitrile -40 to 180 °F / -40 to 82 °C; FEP -20 to 180 °F; FKM 40 to 300 °F; EPDM -20 to 225 °F; FFKM 0 to 300 °F
Low temperature	Special constructions to -76 °F / -60 °C available by request
Gases	Air, nitrogen, natural gas, sour gas (NACE MR0175-2002 construction), butane, propane
Spring case vent	1/4 NPT
Approximate weight	17.7 lb / 8 kg
Hygienic options	Types T205 and T205M available with FDA / USP Class VI / ADI-free elastomers

How the T205 keeps a blanket pressure

The T205 compares tank pressure with a control spring through a large diaphragm. With the spring set for a few inches of water column, any small fall in tank pressure, for instance when liquid is pumped out, makes the spring open the disk through a lever and nitrogen flows in. When the pressure returns to the setting, the disk closes tightly with a small lockup pressure. The large diaphragm area and lever style give fine throttling control at low settings and a response to demand changes that is quick for a direct-operated unit.

In the T205 and T205H the regulator senses outlet pressure internally with a pitot tube. In the M versions the throat is blocked and a downstream line brings the tank pressure to the diaphragm, which is the better choice when pressure drop through the outlet piping would distort the reading.

Spring ranges for the Fisher T205

Outlet range	Spring color	Remark
1 to 2.5 in. w.c. / 2.5 to 6.2 mbar	Orange	Spring case must point down for the full range
2.5 to 7 in. w.c. / 6.2 to 17 mbar	Red	Spring case pointing down
7 to 16 in. w.c. / 17 to 40 mbar	Unpainted
0.5 to 1.2 psig / 34 to 83 mbar	Yellow
1.2 to 2.5 psig / 83 to 172 mbar	Green
2.5 to 4.5 psig / 0.17 to 0.31 bar	Light blue
4.5 to 7 psig / 0.31 to 0.48 bar	Black

For the first two ranges, do not use an FKM diaphragm below 60 °F / 16 °C diaphragm temperature. Related Fisher regulators for other duties include the CS800 series and the 299H series, which handle gas supply rather than blanketing.

Fisher T205 selection and ordering checklist

Type: T205, T205M, T205H or T205HM, based on registration and casing pressure.
Setpoint and spring range, plus the lowest tank pressure change you must control.
Inlet pressure of the blanketing gas against the maximum operating inlet table for the chosen orifice.
Body size and connection, and body material for site corrosion and temperature (LCC or stainless for cold sites).
Elastomer: nitrile standard, or FKM, EPDM, FEP, FFKM for chemical compatibility.
Gas: nitrogen, air, natural gas, sour gas (NACE construction), butane or propane.
Hydrogen duty: the maker lists T205 Series configurations evaluated for hydrogen use; state this when ordering.
Orientation of body and vent, with the vent pointing down on horizontal lines for drainage.

Installation and maintenance of the Fisher T205

Install the T205 in a clean gas supply line to the tank, ahead of a vent or relief arrangement that handles the tank breathing separately. On external registration units, run the control line to a point on the tank away from turbulence. Make sure the spring case vent screen is clear; the casing drains through the vent, so the vent orientation shown in the bulletin should be followed to keep water out.

Easy conversion is built in: the T205 and T205H convert to the T205M and T205HM with two O-rings and one machine screw. At service, replace diaphragm, disk and O-rings, check the lever and pusher post for wear, and then reset and verify the setpoint with a low-range gauge.

Applications in Oman and the GCC

Tank blanketing appears in refineries, petrochemical plants, chemical storage terminals and fuel terminals, as well as food and pharmaceutical tanks that need an inert atmosphere. In Oman and the GCC, high ambient heat makes tank breathing and vapor loss large, so a regulator that holds a few inches of water column is useful for solvent, aromatics and product tanks. The FDA and USP Class VI elastomer option points to clean-service use, and the NACE sour gas construction to gas treatment locations.

Information to send with a Fisher T205 RFQ

Type (T205, M, H or HM) and nameplate photo if replacing.
Blanketing gas, supply pressure and tank setpoint.
Maximum flow demand during pump-out and thermal breathing.
Ambient and process temperature range.
Body material, size, connection and elastomer preference.
Spare diaphragms, disks and springs.

Documents and quotation

The T205 series bulletin is attached on this page as a datasheet.

Send the T205 type and your tank data to Seven Star LLC in Muscat, and we will quote against the confirmed configuration.

Datasheets & Documents

Datasheet Fisher T205 Series Bulletin Download

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About brand

Fisher is the control valve brand of Emerson. Its history starts in 1880 in Marshalltown, Iowa, where William Fisher, working at the town waterworks, invented a constant-pressure pump governor and founded a company to make it. Emerson bought Fisher Controls in 1992, and Marshalltown remains a main engineering and manufacturing site for Fisher valves. The brand covers control valves, actuators, FIELDVUE digital valve controllers, regulators and level controllers.

Seven Star LLC is an independent supplier listing Fisher control valves, actuators, positioners, regulators and spare parts for buyers in Oman and the GCC. Replacement valves and trim are matched from the serial number on the valve nameplate.

Fisher company profile

Origin	William Fisher's constant-pressure pump governor, Marshalltown, Iowa, USA (1880)
Ownership	Owned by Monsanto from 1969; sold to Emerson in 1992 and combined with Rosemount as Fisher-Rosemount, later Emerson Process Management. Today a brand of Emerson.
Main site	Marshalltown, Iowa, USA
Product families	Sliding-stem and rotary control valves, spring-diaphragm and piston actuators, FIELDVUE digital valve controllers, pressure regulators, displacer and digital level controllers
Typical duty	Throttling control of liquids, gas and steam, high-pressure and severe service, instrument supply and gas pressure reduction

Milestones

1880: William Fisher builds a constant-pressure pump governor in Marshalltown, Iowa.
1969: Monsanto acquires Fisher Controls.
1992: Emerson buys Fisher and combines it with Rosemount as Fisher-Rosemount, later Emerson Process Management.

Fisher valves, actuators and instruments

Series	Type	Typical use
easy-e ES, ET, EZ	Sliding-stem globe and angle valves	Cage-guided globe valves: ES with unbalanced plug, ET with balanced trim for higher pressure drop; EZ unbalanced with a seat ring retainer for viscous or dirty fluids
GX	Compact globe valve with integral actuator	Standard chemical and process duty where a compact valve package is preferred
HPT, HPAT	High-pressure globe and angle valves	Pressure classes up to ASME CL2500, compressor recycle and high-pressure letdown
V150, V200, V300, V250	Vee-Ball segmented ball and full-bore ball control valves	High-capacity control of liquids, gas and fibrous or slurry service
CV500	Eccentric rotating plug valve	Erosive, coking and dirty service
8560, 8580	High-performance butterfly valves	Large-line throttling and on-off control
657, 667, 1052, 1061, easy-Drive	Spring-diaphragm, piston and electric actuators	657 and 667 for sliding-stem valves; 1052 and 1061 for rotary valves; easy-Drive where no air is available
FIELDVUE DVC6200, DVC2000, 3610J	Digital valve controllers and positioners	HART positioning with valve diagnostics; 3610J pneumatic positioner for rotary actuators
627, 1098-EGR, 67C	Pressure regulators	Gas pressure reduction, pilot-operated regulation and instrument air supply
DLC3100, 2500	Digital and pneumatic level controllers	Displacer level and interface on separators and scrubbers

Where Fisher valves are used

Fisher control valves and regulators are standard equipment in oil and gas production, refineries, gas processing and LNG, petrochemicals, power plants and water systems. Typical loops are separator level and pressure, compressor anti-surge and recycle, fuel gas pressure reduction, feedwater and steam control, and chemical dosing. FIELDVUE controllers add diagnostics that help plan valve maintenance before a turnaround.

Ordering Fisher valves and spare parts: what we need

For spares, send the serial number from the valve nameplate together with the valve type, size, pressure class, trim and actuator type and size. Emerson keeps the build record behind the serial number, so plug, seat ring, cage, packing and diaphragm kits can be matched without guesswork. For a FIELDVUE or regulator, send the full model and type number and the mounting details. For a new valve add the process data: fluid, flow range, inlet and outlet pressure, temperature, leakage class, fail position, air supply and signal.

Facts checked against Emerson Fisher product information and published company histories, October 2026.

Browse Fisher products by category: Control Valves, Valve Actuator, Valve Positioner, Regulators, Level Transmitter.

FAQ

Questions about the Fisher T205 Series Tank Blanketing Regulator

Answers from our engineering team on installation, compatibility and integration.

01What does the Fisher T205 do?

It maintains a slight positive pressure of inert or other gas in a tank vapor space, reducing vapor loss and keeping air out.

02What outlet range does the T205 cover?

1 in. w.c. to 7 psig (2.5 mbar to 0.48 bar) across seven spring ranges.

03What is the difference between T205 and T205M?

T205 senses pressure internally. T205M has a blocked throat and uses an external control line (1/2 NPT) for sensing.

04What do the H types mean?

T205H and T205HM have inlet equal to casing pressure of 150 psig / 10.3 bar and a low temperature limit of -20 °F / -29 °C.

05What shutoff class does it have?

Class VI soft seat shutoff per ANSI/FCI 70-3-2004.