GT1000 Series

GT1000 Series Glass Tube Variable Area Flow Meters

Simple design. Rugged performance for high flow rates.

Models 1020N / 1024N / 1026N / 1027N

The GT1000 Series glass tube VA flow meter from Brooks Instrument is easy to read and uses simplicity of design with rugged, long-lasting flow measurement performance for a wide range of high-flow gas and liquid applications where viewing the process is important.

Featuring a clear and easy-to-read scale, the GT1000 Series O-ring seal design minimizes process downtime by allowing for convenient in-line removal of the glass tube for cleaning and maintenance. Reliable, with only one moving part, it is globally approved for use in hazardous environments.


  • Wide range of flow ratings
  • Operating temperature range 33 to 125°F (1°C to 52°C)
  • Pressure ratings up to 500 psig / 34 bar
  • Two accuracy levels to choose from: 2% or 1% Full Scale
  • Optional high and low-flow reed switch or inductive alarm, also for safe use in explosive hazardous areas
  • Calibrated to process conditions with 127mm or high resolution 250mm direct reading scales
  • Brass or 316L stainless steel end fittings
  • Flanged or threaded connections
  • Horizontal or vertical connections
  • Horizontal end fittings 360° rotatable
  • 180° viewing window
  • Rugged, vented polycarbonate enclosure available on most models
  • Tube and float can be re-ranged in line, minimizing process downtime
  • Rotatable connections for easy installation at any angle
  • Packing gland or O-ring sealing to meet piping requirements or customer preference
  • No power required; reduces installation cost and provides flow measurement in hazardous areas
  • Low-pressure drop allows for economical pump selection
  • Optional needle valve mounted to inlet or outlet for setting the desired flow
  • Optional economical brass fittings for delicate applications (e.g. avoidance of hydrogen embrittlement)
  • Industrial processes
  • Pharmaceutical production
  • Oil and gas pumping and refining processes
  • Chemical manufacturing
  • Burner control
  • Water treatment and distribution systems

Product Type

Glass Tube VA Flow Meter
Applications: Clean liquids and gases


Removable borosilicate glass metering tube for easy service without removing the meter, minimize downtime
Process connections can be rotated 360°, 180° viewing window, panel mount option
One or two flow alarms are available, alarms are safe use in explosive atmospheres
Reliable o-ring seal design for leak free process connections
Optional needle valves mounted to inlet or outlet for precision flow control


Flow Range (Full Scale Capacity)

98 gpm / 22,000 lph

270 scfm / 440 m3n/hr

See Capacity Tables in Data Sheet

Pressure Drop

See Capacities & Pressure Drop Tables in Data Sheet


+/- 2% Full Scale / Class 2.5 VDI / VDE
+/- 1% Full Scale / Class 1.6 VDI / VDE


Less than 0.5% Full Scale


Metering Tube Material

Borosilicate Glass


Single or Dual Detachable Aluminum Plate

Scale Length

127mm, 200mm and 250mm

Scale Graduations

Choice of direct reading units, millimeter or percentage of maximum flow with factor tag.

Window Material

Polycarbonate with UV Inhibitor

Float Material

Size 2 and 6: Glass, Sapphire, Carboloy, 316 Stainless Steel
Size 7: Glass, 316 Stainless Steel
Size 8 to 13: 316 Stainless Steel

Float Stops

Sizes 2 through 13: Teflon


Cast Aluminum with Epoxy Paint Coating

End Block Options

Brass or 316 Stainless Steel (1.4404)

O-Ring Materials

Viton® fluoroelastomer
Kalrez® 4079 fluoroelastomer

Connection Materials

Brass or 316 Stainless Steel (1.4404)

Process Connections

Brass Construction: NPT, BSPT / Rc Female connections
316 Stainless Steel Construction: NPT, BSPT / Rc Female connections or 150# Flanges per ASME B16.5

Optional Equipment


Max Pressure

Refer to Maximum Pressure Ratings Table in Data Sheet

Max Temperature

121oC (250oF)

PED Categories

See PED Categories Table in Data Sheet
Sizes 2 through 10 meet PED Category SEP
Sizes 12 & 13 do not conform to PED


International Calibration Certificate (ICC)
Material certification
Pressure Test certificate
Oxygen Cleaning certificate
Certificate of Conformance



Reed Switch – Sizes 7 to 13
Inductive Switch – Sizes 2 & 6

Diagnostics & Display

Fluid Temperature Range

33 to 250°F  /  1 to 121°C

Alarm Option
Reed Switch: 33 to 250°F  /  1 – 121°C

Inductive Switch: 33 to 167°F  /  1 – 75°C

Ambient Temperature Range

33 to 125°F / 1 to 52°C

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