1.What is the specific ratio for a blower?
a) <1.1
b) 1.11-1.2
c) >1.2
d) 1.11
Explanation: The ratio of discharge pressure to that of suction pressure is known as the specific ratio. This is 1.1-1.2 for blowers. It is is>1.2 for compressors and <1.1 for fans.
2. Normally what is the pressure under which centrifugal blowers operate?
a) 0.35-0.7 kg/cm2
b) 0.5 -0.7 kg/cm2
c) 0.35 kg/cm2
d) 0.35-0.5kg/cm2
Explanation: The centrifugal blower usually works under the pressure 0.35-0.7 kg/cm2.In some cases it is used to produce negative pressure. This is achieved under vacuum conditions
3. Which blower is used when the system is prone to clogging?
a) Centrifugal blower
b) Positive displacement blower
c) Regenerative blower
d) Helical screw blower
Explanation: Positive displacement blowers are used when the system is prone to clogging. This is because they provide constant air even when the system pressure changes. These are usually belt driven.
4. Centrifugal pumps have a greater speed of rotation when compared to that of positive displacement blower.
a) True
b) False
Explanation: Centrifugal blowers they rotate at a speed up to 15000 rpm. Whereas positive displacement blowers, they rotate at a speed of around <3600 rpm. Also, these are belt driven to facilitate changes in the speed.
5. Dimensionless pressure rise is not dependent on which of the following?
a) Density of the fluid
b) Speed of the blower
c) Diameter of the blower
d) Power of the blower
Explanation: Dimensionless pressure rise is not dependent on the power of the blower. It is equal to pressure rise/ {(Diameter of blower)2 x (speed of the blower)2 x density of the fluid}. It is independent of the flow rate of interest liquid that is handled.
6. What is the maximum discharge pressure of a twin lobe blower?
a) 0.5 kg/cm2
b) 1 kg/cm2
c) 1.5 kg/cm2
d) 0.75 kg/cm2
Explanation: The maximum pressure discharged from a twin lobe blower is 1 kg/cm2. The capacity of these blowers range from 100-8000 cubic meter/hr. These blowers fall under the positive displacement blowers.
7. How is the static pressure drop in the water column related to the air flow rate?
a) Linearly
b) Inversely
c) There is no relation between them
d) A parabolic curve is obtained
Explanation: The static pressure drop in the water column is related linearly to the air pressure. It increases with an increase in air pressure. The air pressure is calculated in terms of ACFM.
8.Which of these is not a characteristic of variable speed drive?
a) Improved speed control of the blower
b) Speed adjustments over a continuous range
c) High cost
d) Can be retrofitted into an existing motor
Explanation: Variable speed drives cannot be retrofitted into an existing motor. Variable frequency drive can be retrofitted into an existing motor. Variable frequency drives are less expensive than variable speed drives.
9. The surface water quality is affected by _______ and infiltration from rainfall.
a) Precipitation
b) Run off
c) Wetlands
d) Farming
Explanation: Even when the catchment area is preserved in its natural condition, the surface water quality is affected by run off and infiltration resulting from rainfall. The impact of these is dependant on the contact of the water with the impurities.
10. Function of the intended uses of water can achieve the desired water quality.
a) True
b) False
Explanation: The function of the land used in catchment area shows the existing water quality. The function of the intended uses for the water shows the desired water quality