The principle of Reflex Level Gauges is based on the difference in the refractive indices of liquid and vapor. The liquid column is contained within the recess of the liquid chamber behind the sight glass, which is clamped to the gauge body. The sight glass has prismatic right-angled grooves on the side facing the liquid and vapor space. Light rays entering from outside the gauge are either absorbed or reflected depending upon whether they enter the liquid or vapor space. When the ray of light encounters the surface of one of the grooves in the vapor space, it is reflected to the opposite surface of the grooves and from there, totally reflected back to the direction of observation.
Thus, vapor space appears as silvery white. When the light ray encounters the surface of the grooves in the liquid space, it is totally absorbed, thereby making the liquid behind the glass appear black. These gauges are used for measuring the level in a vessel. Maximum pressure of up to 400 bar and a maximum temperature of 4000 C.
- Constructional features include, three-meter single piece construction with multiple glasses between process connections.
C/C Distance: Up to 3000mm, single piece liquid chamber
- Materials: Carbon Steel or Stainless Steel; Monel – 400, Hastelloy ‘C’, Polypropylene, HDPE, PTFE / Rubber lined as optional
- Glass: Toughened borosilicate
- Connections: Flanged, screwed or socket weld.
- Gauge Valve: Auto-shut-off ball check, offset pattern, bolted or screwed bonnet.
- Drain Valve: Gate or Needle type
- Packing: Grafoil*/ PTFE
- Fasteners: ASTM A-193 Gr. B7 / A-194 Gr. 2H.
- Anti-frost extension for low temperature service
- Heating / Cooling arrangements.
- Saturated steam: Up to 464 psig (32 bar)
- Other media: Up to 3190 psig (220 bar) at 752° F (4000 ° C)