NPT Threaded Double Window Sight Flow Indicator Brass

DOUGLASS flow indicators made of brass allow a view of the fluid in the line. Depending on the type of fluid, they can have a free-flow view, where the flow is appreciable and anomalies are inspected; rotor type, where the fluid is translucent and flow inspection is sought; fin type, an alternative to the rotor that measures the intensity of the flow; and drip type, for gases.


Douglass offers the Double Window Threaded Sight Flow Indicator in Brass, tailored for versatile applications
across industries. This durable brass-constructed indicator is designed for environments where corrosion resistance and longevity are paramount. It features dual windows for comprehensive visibility of fluid dynamics, ensuring accurate flow monitoring.

Customizable with:

  • Flappers for direct flow rate insights,
  • Spinners to visually confirm fluid movement,
  • Drip Indicators for detecting gas flow,

It’s an indispensable tool for sectors from manufacturing to utilities, providing essential flow data. The brass threaded model combines traditional durability with modern functionality, catering to the sophisticated demands of our clients.

Connection Type NPT Threaded
Types of flow indication Free passage, rotor type, fin type, drip type
Working pressure From 0 to 300 PSI
Working temperature -45°C up to 270°C

Measurement 1/4” NPT 3/8” NPT 1/2” NPT 3/4” NPT 1” NPT
A Total height 3.25” (82.55mm) 3.25” (82.55mm) 3.25” (82.55mm) 4.25” (107.95mm) 4.25” (107.95mm)
B Distance between covers 2.25” (57.15mm) 2.25” (57.15mm) 2.25” (57.15mm) 3.25” (82.55mm) 3.25” (82.55mm)
C Total thickness 1.75” (44.45mm) 1.75” (44.45mm) 1.75” (44.45mm) 2.25” (57.15mm) 2.25” (57.15mm)
D Visible diameter 1” (25.40mm) 1” (25.40mm) 1” (25.40mm) 1.5” (38.10mm) 1.5” (38.10mm)


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