FPS®Aquarian® Equipment - Visual Level Gauge (Sight Glass)

Aquarian® 3000 Visual Bi-Color Water Level Gauge

The Aquarian 3000 Visual Bi-Color Water Level Gauge is rated to 3000 psi (207 bar) and produces a red/green image to indicate the water level in a high-pressure steam drum.

With a one-piece trapezoidal shape body, light projected through steam produces a red image. Light projected through water is refracted and produces a green image.

Viewable from wide angles, the solid-state LED Illuminator provides a clear red/green image and offers a 10-year maintenance-free service life. Two discs of premium V-1 quality mica protect and extend the glass life and the Belleville washers eliminate hot re-torqueing. With nipple ends or flanged connections, this gauge fulfills the requirements of the ASME Boiler and Pressure Vessel Code.

The standard features of this high-performance gauge reduce plant maintenance and the total cost of operation. Optional Intrinsic Safety Protection and Explosion Proof Protection is available to meet hazardous area classification requirements.

Aquarian® 650R Reflex Gauge

The Aquarian 650R Reflex Gauge is rated for 975 psi (350 psi/24 bar for steam) and provides excellent visibility of liquid level. Light refracting grooves in the glass cause the liquid to appear black and steam to appear white.

The high contrast between water and steam allows gauges to be stacked on top of one another without concern for blind spots between gauges. Recessed gasket surfaces in both the cover and body facilitate glass and gasket alignment and also help prevent gasket blowout. Belleville spring washers maintain constant gasket loading under thermal and pressure cycles.

Aquarian® 1000T High Pressure Flat Glass Gauge

The Aquarian 1000T High Pressure Flat Glass Gauge is rated for 1000 psi (69 bar) and is structurally designed with a thicker and wider body to resist deflection. The design meets the most recent changes of the ASME Boiler and Pressure Vessel Code, which no longer permits the use of cross webbing. Belleville spring washers maintain constant gasket loading under thermal and pressure cycles.

Precision tempered and ground Borosilicate glass provides high strength and clear visibility, while mica shields protect the glass from the effects of erosion for an extended service life.

Visual Gauge

A Visual Gauge, commonly referred to as a Sight Glass or Level Gauge, is the only technology available to provide “Direct” indication of steam drum water level thus satisfying the ASME Boiler and Pressure Vessel Code requirements.

Did You Know?

FPS Ported Gauge Components - Babcock & Wilcox

The ASME Boiler and Pressure Code (Section 1 Para. PG-60.1.1) states: “Boilers having a maximum allowable working pressure of 400 psi (27 bar) or less shall have at least one gage glass in service at all times. Boilers having a maximum allowable working pressure exceeding 400 psi (27 bar) shall have two gage glasses.

Instead of one of the two required gage glasses, two independent remote water level indicators (two discrete systems that continuously measure, transmit and display water level) may be provided and the required gage glass may be shut off, but shall be maintained in serviceable condition.”


  • Power Boiler Steam Drum Visual Level Gauge
  • Power Boiler Steam Drum Electronic Level Gauge
  • Steam Drum Level Gauges for Hazardous Locations
  • Feedwater Heater Electronic Level Switches
  • Turbine Water Induction Protection (TWIP)
  • Combined Cycle Power Plant Visual Level Gauges for HRSG Applications
  • Hot well alarms
  • Blow-down flash tank alarm
  • Condensate Detection in High Temperature Air Systems
  • Generator Coolant Liquid Level