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Brand: Brooks Instrument
Brooks Instrument MT3809G Metal Tube Variable Area Flow Meter
Description
An all-metal variable area meter for high pressure and extreme temperature
The MT3809G is the Brooks Instrument all-metal variable area flow meter that the datasheet calls the go-to meter for decades and a regular choice of engineering, procurement and construction companies. It measures gas, liquid and steam on the variable area principle and is aimed at services where high pressure or high temperature rules out glass-tube meters. The primary meter is available in 316/316L dual-certified stainless steel and with an ETFE liner, and Brooks lists premium materials such as Alloy 625, Hastelloy C and titanium for aggressive fluids.
The G revision brings a redesigned 316 stainless steel flameproof housing, a three-line LCD that can be adjusted with a magnet in hazardous areas, improved gasket sealing surfaces that meet ASME so special gaskets are not required, and weldneck flanges that allow full-penetration welds. The mechanical indicator needs no power, and the optional alarm design meets SIL 2.
Technical specifications
| Parameter | Specification |
|---|---|
| Measuring principle | Variable area, metal metering tube with magnetically coupled indicator |
| Fluids | Gas, liquid and steam |
| Fluid temperature | -198 to +420 C (-325 to +788 F) with the flameproof housing, transmitter and alarm options; maximum 300 C / 570 F on some constructions |
| Model 3809G | Vertical inlet, vertical outlet; 2% of full scale or 2.5 VDI/VDE class |
| Model 3810G | Vertical inlet, vertical outlet; 5% of full scale or 6 VDI/VDE class |
| Rangeability | 10:1 on most sizes; see capacity tables for each size |
| Wetted materials | 316/316L dual-certified stainless steel; ETFE/TFE lined 316/316L; Hastelloy C-276, Inconel 625 or titanium grade II options; Kalrez, Viton or Teflon O-rings |
| Process connections | ASME B16.5 equivalent flanges 1/2 to 4 inch 150#, 1/2 to 2 inch 900/1500# and 2500# RTJ; DIN PN40; female NPT/Rc 1/2 to 2 inch; male NPT |
| Flange design | Weldneck, designed to ASME B31.3, 3.2 to 6.3 micrometre Ra finish |
| Housing | Cast 316L stainless steel or die-cast aluminium with epoxy paint; IP66/67 and NEMA 4X |
| Hazardous area | Flameproof Ex db IIC T6 to T1 Gb (ATEX/IECEx), intrinsically safe and CSA options; IIC / Class I Div 1 |
| Transmitter | 4-20 mA with HART 7, or FOUNDATION Fieldbus; 21 to 30 Vdc, 2-wire loop; loop current 3.8 to 22 mA |
| Transmitter functions | Two totalizers, scalable pulse output, high and low flow alarms, open-collector alarm output |
| Safety | Mechanical and alarm design meets SIL 2 |
| Approvals listed | CCOE, CE (EMC, RoHS, PED), CRN, ECAS, IP66/IP67, KOSHA, NAMUR, NEMA 4X, SIL 2 on alarms, TR-CU |
| Installation | Vertical, within 5% of true vertical, bottom inlet, top outlet |
| Minimum pressure for gas | 7 psig / 0.48 bar; TFE-lined gas service above 29 psia / 2 bar(a) |
| Accessories | Needle control valves, flow controllers, inductive alarms, high-temperature or stainless indicator housings |
How the model code works
The first positions define the base model (3809 or 3810) and the revision G. Position VI chooses material and certification: 316L dual certified, with or without a 3.1 material certificate, a Code 5 certificate for pressure-bound material from Western Europe, Japan, Canada or the USA, a CRN version, an ETFE/TFE lined body, titanium float, or Hastelloy C-276, Inconel 625 or titanium bodies. Position VII sets the construction: raised-face flange in standard, oversized or two to four times standard connection size, or threaded female or male, including a 2500 lb threaded female design. Meter size and connection size, then the electronics and housing codes, complete the order number.
What to confirm before ordering
Send the fluid with density or molecular weight and viscosity, minimum, normal and maximum flow, operating pressure and temperature, connection size and rating, indicator type (mechanical, HART or Fieldbus), alarm requirements and the area classification. The datasheet capacity tables list the flow of air and water by meter size and pressure drop, and the supplied meter should be sized to the actual fluid. Flange and temperature limits for the chosen construction should be read from the pressure and temperature tables in the datasheet.
How the Brooks Instrument MT3809G works
The fluid flows up through a metal tube and lifts a float. The float rises until the flow area around it passes the flow. A magnet in the float drives an indicator outside the tube, so the reading follows the float height.
Where the MT3809G is used
- High pressure gas lines
- Steam lines
- Hot liquid lines
- Aggressive fluids
- Engineering and construction projects
Selection checklist for the MT3809G
- Fluid type
- Flow range
- Process temperature
- Process pressure
- Wetted materials
- Process connection
- Indicator or transmitter
- Alarm need
Installation, commissioning and maintenance notes for the MT3809G
Mount the meter vertically with the flow going up. Fit the flanges and check the gasket faces. Check the indicator and the float at regular intervals.
Requesting a quotation for the Brooks Instrument MT3809G
Please send the fluid, the flow range, the pressure and the temperature. Seven Star LLC serves industrial customers in Oman and the GCC and replies with a quotation based on the information provided.
MT3809G meter type
It is an all-metal variable area flow meter.
MT3809G maker
It is made by Brooks Instrument.
MT3809G fluids
It measures gas, liquid and steam.
MT3809G indicator
The mechanical indicator needs no power.
MT3809G magnetic coupling
The indicator is magnetically coupled to the float.
MT3809G temperature range
Fluid temperature runs from minus 198 to plus 420 degrees C.
MT3809G housing
The G revision has a redesigned 316 stainless steel housing.
MT3809G display
A three-line LCD is available.
MT3809G magnet adjustment
The LCD can be adjusted with a magnet.
MT3809G gasket surfaces
The gasket sealing surfaces are improved so special gaskets are not required.
MT3809G flanges
Weldneck flanges allow full-penetration welds.
MT3809G model 3810G
The 3810G is the companion model with vertical inlet and outlet.
MT3809G rangeability
Rangeability is 10:1 on most sizes.
MT3809G body material
The primary meter is 316/316L stainless steel.
MT3809G lined option
An ETFE lined version is available.
MT3809G premium materials
Alloy 625, Hastelloy C and titanium are available.
MT3809G O-rings
O-rings can be Kalrez, Viton or Teflon.
MT3809G flange sizes
Flange sizes run from 1/2 to 4 inch.
MT3809G threaded connections
Female NPT connections run from 1/2 to 2 inch.
MT3809G transmitter
The transmitter output is 4-20 mA with HART 7.
MT3809G alarm
An optional alarm is available.
Flow meter records for the MT3809G
Record the float position, the fluid and the date of each inspection.
Choosing the right MT3809G build
Choose the materials and connections from the fluid, the pressure and the temperature.
Documents and quotation
The manufacturer datasheet (25 pages) is attached to this page as a download. For a quotation, send the full model code and the process data to Seven Star LLC in Muscat; browse more instruments in the Flowmeters category. We supply this item as an independent supplier, so please confirm availability and delivery with us.
Datasheets & Documents
- Datasheet Brooks Instrument MT3809G datasheet Download
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About brand
Brooks Instrument makes mass flow controllers, flowmeters and pressure and vacuum instruments for gases and liquids. The industrial chemist Stephen A. Brooks started the business in 1946 as the Brooks Rotameter Company near Philadelphia, building variable area flowmeters. After many years as part of Emerson, Brooks was sold to American Industrial Partners at the end of 2007 and has been a division of Illinois Tool Works (ITW) since January 2012. It is headquartered in Hatfield, Pennsylvania.
Seven Star LLC is an independent supplier listing Brooks Instrument thermal and Coriolis mass flow controllers and variable area flowmeters for buyers in Oman and the GCC. Instruments are matched from the model code and the gas, range and calibration data on the label.
Brooks Instrument at a glance
| Origin | Founded in 1946 by Stephen A. Brooks as the Brooks Rotameter Company, Lansdale, Pennsylvania |
|---|---|
| Headquarters | Hatfield, Pennsylvania, USA |
| Ownership | Emerson division until 31 December 2007, then American Industrial Partners; part of ITW since January 2012 |
| Product families | Thermal, pressure-based and Coriolis mass flow controllers and meters, metal tube and glass tube variable area flowmeters, pressure and vacuum products |
| Typical duty | Precise gas and liquid flow control in process, laboratory, analyser, fuel cell and semiconductor applications |
Brooks mass flow controllers and flowmeters
| Series | Type | Typical use |
|---|---|---|
| SLA5800, SLAMf | Thermal mass flow controllers and meters | Gas flow control in process and analytical systems; SLAMf with an IP66 enclosure for harsh or outdoor locations |
| 5800E | Analog thermal mass flow controller | Installed base in older systems; often replaced with the SLA5800 series |
| Quantim QMC | Coriolis mass flow controller | Low-flow liquid and gas control independent of fluid properties |
| GF40, GF80, GF100, GP200 | Metal-sealed thermal and pressure-based mass flow controllers | High-purity and semiconductor gas delivery; MultiFlo allows gas and range changes without recalibration |
| MT3750C, MT3809G | Metal tube variable area flowmeters | Purge, chemical injection and utility flows at higher pressure and temperature, with optional transmitter and alarms |
| GT1600, Sho-Rate 1250/1255 | Glass tube variable area flowmeters | Visual flow indication on purge, sample and laboratory lines |
Where Brooks instruments are used
Brooks mass flow controllers dose gases in analyser systems, catalyst and pilot plant testing, gas blending, burner and combustion control, fuel cell test stands and semiconductor tools. Variable area flowmeters are widely used on purge gas, seal flush, sample and chemical injection lines in oil and gas, refining and petrochemical plants, where a simple local indication without external power is preferred.
Ordering Brooks instruments: what we need
Send the full model code and serial number from the label. Mass flow controllers are calibrated for a specific gas and full-scale flow, so state the gas or gas mixture, flow range, inlet and outlet pressure, temperature, process connection, seal material, signal (analog, RS-485, DeviceNet, EtherNet/IP or other) and any hazardous-area requirement. For variable area meters add the fluid, density, viscosity, flow range, connection size, materials and whether alarms or a 4-20 mA output are needed.
Facts checked against Brooks Instrument company information and product data, October 2026.
Browse Brooks Instrument products by category: Flowmeters.
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Frequently Asked Questions
What fluids can the MT3809G measure?
Gas, liquid and steam, including aggressive services with lined or premium-alloy bodies.
What is the temperature range?
The datasheet states -198 to +420 C for the flameproof housing, transmitter and alarm options.
Does the indicator need power?
No. The mechanical indicator is unpowered; a 4-20 mA HART or Fieldbus transmitter is optional.
What is the difference between 3809G and 3810G?
The model code lists 2 percent (2.5 VDI/VDE) for 3809G and 5 percent (6 VDI/VDE) for 3810G.
Which mounting position is required?
Vertical, within 5 percent of true vertical, with bottom inlet and top outlet.
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