Kawaki FS-II Sight Flow Indicator With Flapper – ANSI 150LB Raised Face
Overview
The Kawaki FS-II Sight Flow Indicator with Flapper is a visual flow-verification device that lets operators confirm the presence, direction, and relative rate of liquid or gas flow in a pipeline at a glance, using a rotating flapper vane visible through a sight-glass window. It is used by process engineers and operators across Oman and the GCC on piping systems in refineries, chemical plants, and utility installations where continuous visual confirmation of flow is a practical, low-cost complement to instrumented flow measurement.
The “II” designation in the FS-II identifies the flapper-type configuration within Kawaki’s FS sight-flow indicator range, distinguishing it from drip-type or bull’s-eye variants that show flow through droplet formation or window fogging rather than a moving mechanical vane.
Operating Principle
As fluid passes through the indicator body, it deflects an internal flapper vane, which is directly visible through a transparent sight-glass window mounted in the housing. The degree and speed of flapper movement gives operators an immediate visual indication of flow presence and relative velocity, and on FS-II variants, the window can be marked with outline flow-rate scale graduations for a rough visual read of flow magnitude, not just flow/no-flow status.
Engineering Design of the Kawaki FS-II
This unit is supplied to ANSI 150LB raised-face flange configuration, with a body available in cast iron (FC250), high-tensile cast iron (FC450), bronze (CAC406), carbon steel (SS400), or stainless steel (SUS304/SUS316) depending on process compatibility requirements. The sight-glass window uses phosphor bronze (C2801P) or stainless steel (SUS304/SUS316) framing with a transparent viewing glass. The indicator is rated to withstand 1.0 MPa pressure at temperatures up to 80°C under standard specifications, and is available in bore sizes from 3/8B to 6B in flange configuration (special order up to 12B) or 3/8B to 2B in screw-connection configuration.
Key Features
- Flapper-type visual flow indication through sight-glass window
- ANSI 150LB raised-face flange connection
- Body materials: FC250, FC450, CAC406, SS400, SUS304, SUS316
- Sight-glass frame: C2801P (phosphor bronze), SUS304, or SUS316
- Pressure rating 1.0 MPa, temperature to 80°C
- Size range 3/8B-6B (flange), 3/8B-2B (screw), special order to 12B
- Optional flow-rate scale graduations on the sight window
Industrial Applications
Across Muscat, Sohar, and Salalah, the Kawaki FS-II is used in refineries, petrochemical plants, and utility piping systems as a low-maintenance, no-power visual check point for confirming flow at pump discharges, drain lines, sample points, and process transfer lines. Its mechanical simplicity makes it a reliable backup indicator alongside instrumented flow meters, giving operators an immediate visual cross-check during rounds or troubleshooting.
The stainless-steel body and window variants are also specified for corrosive or hygienic process lines in chemical and water-treatment facilities across the region, where material compatibility with the process fluid is the primary selection criterion.
Technical Specifications
| Parameter | Specification |
|---|---|
| Type | Flapper-type sight flow indicator |
| Connection | ANSI 150LB raised face |
| Body Material | FC250, FC450, CAC406, SS400, SUS304, SUS316 |
| Sight Window Frame | C2801P, SUS304, or SUS316 |
| Pressure Rating | 1.0 MPa |
| Temperature Rating | ≤80°C |
| Size Range | 3/8B-6B (flange), 3/8B-2B (screw); special order to 12B |
Request a Quote for Kawaki FS-II Sight Flow Indicator With Flapper – ANSI 150LB Raised Face
Seven Star LLC supplies the Kawaki FS-II sight flow indicator as an authorized channel partner to process industries across Oman and the GCC. Contact our engineering team for a formal quotation and material selection support for your pipeline application.
Kawaki is a Japanese manufacturer specializing in industrial flow indication and fluid monitoring equipment for process piping systems. The company designs and produces sight flow indicators, strainers and related fluid control components engineered for reliable visual monitoring of liquid flow conditions in industrial pipelines.
Kawaki products are widely used across chemical processing, oil & gas facilities, water treatment plants, power generation systems and general industrial piping installations where real-time visual confirmation of flow is essential for safe and efficient operation. Built with durable materials such as stainless steel and corrosion-resistant alloys, Kawaki solutions provide dependable performance under high pressure and temperature conditions.
With a focus on mechanical reliability and straightforward installation, Kawaki equipment supports process monitoring, maintenance planning and operational safety in industrial fluid handling systems.
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