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Operator in training cert /OIT Exam actual questions study guide
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Operator in training cert /OIT Exam actualquestions study guide
What are colloids? - Very small particles suspended in water which are resistant to settling.
What is turbidity measured in? - Nephelometric Turbidity Units (NTU)
What is the turbidity measurement that is visible to the naked eye? - 5 NTU
What is an important indicator of treatment efficiency and particularly the efficiency of filters and
disinfection processes? - Turbidity
Why are particles that cause turbidity harmful? - They can hide or entrap harmful organisms so
that the disinfectant is unable to reach them. It calls increases CL demand which can be
carcinogenic
What are the 2 types of sampling? - Grab samples and composite samples
What are grab samples and when is it used? - A single sample taken at one place and time.
Used when water quality and quantity are not variable
What is a composite sample and when is it used? - A series of samples taken over a period of
time which are combined to form a single sample. Necessary if water quality changes greatly
over time.
What is voltage? - Electrical potential or potential difference between two points. Indicated the
strength of the "push" on current
What is current and what are its units? - Flow off electric charge. Measured in amperes
What is the typical rate of change (Hz) or alternating current? - 60 cycles per second
What happens when wires or appliances carry more than their rated capacity of current? - May
overheat and cause fires. Circuit breakers stop this
What is the equation for voltage? - V=IR
What is Power (P), what is is measured in and what is the formula? - The rate at which work is
done or energy is produced.
Measured in Watts
P=VI
,What is the symbol for flow and what is the formula for it? - Flow (Q)
Q= AV
What can flow provide info on? - Dentention time in tanks, flow between various processes or
sections, chemical feed rates, etc.
What are the types of flow measurement determined by? - Whether water is flowing in a closed
pipe of an open channel
What is used to measure flow in an open channel? - Weirs or flumes. Flow is determined by the
height of water at a particular point
What is a flume? - A specially shaped constriction in the channel
What is a weir? - A dam or obstruction in the channel
What are venturi meters, ultrasonic meters, magnetic meters, doppler meters and orifice meters
used for? - Measuring flow in closed pipes.
What is static pressure? - The force exerted when water is at rest and not flowing
What is the pressure exerted by flowing water known as? - Dynamic pressure
What is the force exerted when water is at rest and not flowing? - Static pressure
What is the rise of water in a tube known as? - The head
What is the pressure loss due to friction as water flows through a pipe/filter etc? - Headloss
What is headloss? - the pressure loss due to friction as water flows through a pipe/filter etc
What can decrease head loss? - Larger diameter and smoother interior surface
How can you make up for head loss? - Energy inputs (pumping)
When does water hammer occur? - When a moving fluid suddenly stops, can destroy piping and
appurtenances
How can you avoid water hammer? - Operate valves slowly and start and stop valves gradually
What is cavitation and how does it occur? - The formation and collapse of a bobble or gas
pocket. Can result from very low pressure within pump which causes water to boil, releasing tiny
bubbles. The bubbles then collapse with enough force to damage the pump impeller
, What are indications that cavitation is occurring? - A vibration noise similar to hammering of the
pump impeller
What are the 2 basic types of pumps? - Centrifugal and displacement
What is a centrifugal pump? - Pressurizes water by "throwing it" at high speeds from the centre
of the impeller to the outside.
What is an impeller and what does it do? - A rotating disk with a set of vanes coupled to the
engine/motor shaft that produces centrifugal force within the pump casing.
What is a volute? - A specially designed chamber that widens within the pump that liquid
accelerates out of
What is the name of the chamber of a centrifugal pump? - Volute
What is the name of the spinner in a centrifugal pump? - Impeller
How are centrifugal pumps classified? - By their shapes
What are radial vane, Francis vane, mixed flow and axial flow examples of? - Centrifugal pumps
How do positive displacement pumps work? - Push fluid mechanically. Starts with a suction
valve and discharge valve open
What are screw, gear, piston, diaphragm, and progressive cavity examples of? - Positive
displacement pumps
What are packing glands? - Seals which prevent the pumped fluid from leaking from a pump
and prevent air from entering
What is the name of the seals which prevent the pumped fluid from leaking from a pump and
prevent air from entering - Packing glands
What types of pipes can be used? - -cast iron (CI)
-ductile iron (DI)
-steel and reinforced concrete (CP)
-asbestos cement (AC)
-plastic (PVC, HDPE, ABS)
-copper
What is the most common type of pipe used in water systems? - Cast iron, but PVC and HDPE
are used more recently for smaller pipes
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