The principal of reflex level gauges is based on the difference in the refractive Indices of liquid & vapour. The liquid column is contained within the recess Of 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 vapour space light raise entering from right outside the gauge are either Absorbed or reflected depending upon whether they enter the liquid or vapour Space. When the ray of light encounters the surface of one of the grooves in vapour Space, it is reflected to the opposite space appears as silvery white. When the light Ray encounters the surface of grooves in the liquid space, it is totally absorbed Thereby the liquid behind the glass appear black.Max temperature: 400⁰CMax pressure : 150kg/cm²Pair of valves : SVC-2500 offset integral with bonnet with ball check arrangement.SVC-3500 offset, design bolted bonnet renewable seats and ball Check arrangement.