Steam boiler use water level indication to detect the water level in steam drum. Steam drum usually uses gauge glass as its indicator. A lot of rules determine to use and arrange two gauge glasses especially for steam boiler which has maximum allowable working pressure above 400 psi or above 28 bar to reduce possibility of breakage which can cause the operator in danger. Gauge glass is a tool consisting prismatic glass which is design to resist high pressure (see figure 1) and allow the operator to see water level in the normal condition, under normal and above normal water level.
|Fig. 1: Water Level Gauge Glass in Steam Boiler|
Source: Book - The Boiler House - The steam and condensate lopp - spirax sarco
Water level can be designed for remote or direct viewing. Sometimes water level is difficult to be seen clearly because there are steam and many bubbles at the water surface and high pressure / temperature make more water fluctuation.
Water level indicator has two types for direct viewing and remote viewing. Each type has kind of product type:
1. Water level indicator for direct viewing
- Tubular gauge glass
- Reflex type gauge glass
- Transparent gauge
- Bicolor gauge
- Port type bicolor gauge
- Multiple gauge
2. Water level indicator remote viewing
- Manometric gauge
- Electronic gauge