Basic Mechanical Engineering (3110006)

• Water level indicator
• Pressure gauge
• Safety valves
• Steam stop valve
• Feed check valve
• Blow off cock
• Fusible plug
• Man hole, mud holes or sight holes

Function

Construction

• This fitting may be seen in front end of the boiler, and are generally two in number.
• It consists of three cocks and a glass tube. The glass tube is protected by means of cover, and made of specially toughened glass as shown in Figure.
• The steam cock keeps the glass tube in connection with the steam space. The water cock puts the glass tube in connection with the water in the boiler and the drain cock is used to drain out the water from glass tube at frequent intervals to ascertain that the steam and water cocks are clear.

Construction

• When steam cock and water cock opened, steam rushed from upper passage and water rushed from lower passage of the glass tube and the drain cock is closed.
• This will indiacte the level of the water in the boiler. In this case handles of cocks are placed in a vertical position.
• Two balls are placed at the junction of metal tubes. Under normal operating conditions, two balls are kept as shown in Fig. 6.4 with full line circle.
• In case the glass tube is broken, the two balls are carried along its passages to the ends of the glass tube. It is thus obvious, that water and steam will not escape out.
• The glass tube can be easily replaced by closing the steam and water cocks and opening the drain cock.