Questions

2.4 Steam Quality

1 Steam supplied at 6.5 bar g contains 20% air by volume. What is the temperature of the mixture?
a) 165°C
b) 127°C
c) 167°C
d) 159°C
2 Why is a boiler feedtank heated to approximately 85°C?
a) To reduce the energy required to raise steam
b) To reduce the content of total dissolved solids in the water supplied to the boiler
c) To reduce the gas content of the water
d) To reduce the content of suspended solids in the water
3 What is used to dry steam?
a) A separator
b) A strainer
c) A steam trap
d) A tee piece
4 What causes waterhammer?
a) Suspended water droplets
b) An air/water mixture
c) Strainers fitted on their sides
d) Slugs of water in the steam
5 How does air enter a steam system?
a) Through joints, on shut down of the steam system
b) With make-up water to the boiler feedtank
c) With condensate entering the boiler feedtank
d) All of the above
6 Why should strainers installed on steam lines be fitted on their sides?
a) To prevent the build-up of water in the strainer body
b) To trap more dirt
c) To reduce the frequency of cleaning
d) To provide maximum screening area for the steam