Flanged Double Window 300 PSI

DOUGLASS flow sight glasses made of steel allow a view of the fluid in the line. They can be manufactured with a 150 PSI or 300 PSI flanged connection.


Douglass presents the Double Window Sight Flow Indicator, engineered for robust applications up to 300 PSI. Designed for clear fluid movement visualization, this tool excels in high-pressure environments, offering durability and performance for industries that demand accurate flow monitoring.

This versatile model features dual windows for optimal visibility and can be customized with:

  • Flappers for measuring flow rates,
  • Spinners to indicate fluid or gas movement,
  • Drip Indicators for precise gas flow detection

Ideal for a range of applications, from petrochemical to energy production, it ensures reliable monitoring of both liquid and gas flows.

Measurement 1” 1-1/2” 2”
A Distance between faces 7” (177.8 mm) 8” (203.2 mm) 9” (228.6 mm)
B Distance between covers 5” (127.0 mm) 5.5” (139.7 mm) 5.5” (139.7 mm)
C Visible process 2” (50.8 mm) 2.5” (63.5 mm) 3” (76.2mm)
D Diameter of covers 4” (101.6 mm) 4.5” (114.3 mm) 5” (127.0 mm)
Total diameter of glass 2.5” (63.5 mm) 3” (76.2 mm) 3.5” (88.9 mm)
Thickness of glass 5/8” (15.87 mm) 5/8” (15.87 mm) 5/8” (15.87 mm)

Connection Type Flanged #150 / #300
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 1450°C

Depending on the type of fluid, they can have a free passage type view, where the flow is appreciable and anomalies are sought to be inspected; rotor type, where the fluid is translucent and inspection is sought to ensure that there is flow; fin type, an alternative to the rotor that measures the intensity of the flow; and drip type, for gases.

The indicators are forged in one piece, which guarantees excellent resistance to pressure and more adverse conditions.

They are manufactured for flanges of 1″, 1-1/2″, 2″ and 3″. Depending on the operating conditions, types of gaskets and glass will be recommended.

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