Positive And Non Positive Displacment Pumps And Fans Flashcards
Which of the following pumps is not dynamic:
Reciprocating
Centrifugal
Mixed flow
Axial flow
Reciprocating
When liquid is vaporized when pumping, what will happen?
Cavitation will occur
The capacity of the pump varies __________ when operated at a constant speed?
Directly with impeller diameter
When the pump inlet is above the level of the liquid in the supply reservoir, the pump has a suction ________?
Lift
What source of energy is available to allow liquid to enter a pump with suction lift?
Sucking action of the impeller to start the flow and atmospheric pressure to keep the flow moving
The impeller that helps push the liquid to the pump inlet?
Inducer
The NPSH available must be ______ or higher then the NPSH required to prevent cavitation?
10% or more
Pumps convert mechanical energy to______?
Hydraulic energy
Diffusers in pumps are mounted where?
Around the impeller
Gauge pressure is?
Atmospheric pressure minus absolute pressure
Absolute pressure is 14.7
Cavitation can be caused by ?
An increase in intake velocity or to large of a suction lift.
Bernoulli’s principle relates to dynamic pump systems in that they have?
Pressure head from the pressure acting upon the liquid
Velocity head from the speed of the liquid through the pipe
As pressure is increased, the boiling point of the liquid _______?
Increases
Pump performance curves are based on handling ________ water, and a specific gravity S.G of _____?
Cold
1
Friction losses through pipes depend on:
Inside diameter of the pipe
Fluid velocity
Surface finish
What things can happen if you install the pump with the wrong impeller rotation?
Inadequate discharge
Excessive power consumption
Pump won’t deliver fluid
An excessive suction lift can cause?
Insufficient atmospheric pressure at the intake
A suction piping condition to avoid is?
Reduced or restricted pipe diameter
Water hammer is a result of?
Opening and closing valves
Hydraulic slap is the result of ?
Check valve closing to quickly
Dynamic pump wear rings should be replaced when?
The clearance is increased 3 times the initial clearance
The screws of multiple screw pumps can use _______ to help stop the rotors from contacting each other.
The positon of timing gears
Pump motor power consumption may increase if the?
Pump packing gland is over tightened
Recirculation of fluid in the pump causes ?
Vortices and cavitation to be created
Changing impeller’s diameter effects?
Pump capacity and pressure
The dial indicator touching the face of a shoulder on a shaft will tell you?
Shaft end float
When blinding piping for pump removal, blinds should be placed on the down stream of the suction valve and upstream of the _________ valve
Discharge
Mechanical seal faces that have uneven wear patterns on them will indicate ?
Misalignment
Valve packing controls leakage between?
Plunger and chamber or between piston and cylinder wall
Internal wear rings can be removed by?
Welding on the inside diameter of the ring
When taking a back pullout design centrifugal pump apart, you should first refer to the ________?
Manufactures instructions
If you need to break a partial vacuum when taking a positive displacement pump apart, you need to ______?
Remove the drain plug from the casing
Pump shaft runout is measured with?
Dial indicators
When rebuilding a centrifugal pump, the last thing you would check would be if?
The rotor turns over
What is used in a positive displacement pumping circuit to help eliminate vibrations and absorb cyclical flow variations?
Pulsation dampener
On a vertical plunger pump, the pump is attached to the ______?
Crosshead
Which of the following vane pumps use an oval rotor in a concentric housing?
Flexible
Balanced
External
Unbalanced
External
Which of the following reciprocating pumps can run dry?
Plunger
Single acting piston pump
Double acting piston pump
Diaphragm pump
Diaphragm pump
High pressure diaphragm pumps (up to 5000psi) use _________ to activate them?
Hydraulic fluid
A flexible pump uses a _________ to squeeze the flexible tube?
Compression ring
When a relief valve is forced open because of high pressure in a pumping system, the liquid is returned to the ______?
Suction side
What type of check valve would be most suitable for liquids contains solids?
Flap
A sand which diaphragm on a hydraulically activated diaphragm pump is used to help prevent product escape by using a ________ sensor that lets you know when 1 diaphragm leaks.
Rupture
Which type of pump requires timing gears?
Gear
Lobe
Flexible vane
External vane
Lobe
Which pump has a cam inserted between the discharge and inlet ports?
Flexible vane
Which pump has an eccentric rotor?
Flexible liner
The impeller with the lowest specific speed is?
Radial flow
Inducers have ________ flow?
Axial
In a volute pump, the impeller can be reduced by _______% before hydraulic losses affect pump efficiency?
20
The type of impeller that has a double curvature vane is the?
Francis
The multi stage barrel pump(double casing) have what bennefit?
Stop leakage to atmosphere of high pressure pump systems
Double suction single stage pumps have a single suction inlet that splits to allow ____________?
Flow to both sides
Wear rings will last longer by?
Making both rings out of a hard material when immersed in a abrasive liquid.
Being immersed in a clean pumping liquid.
A combination disc and drum balancing device will?
Balance out the suction and discharge pressure helping lower axial thrust.
Calculate the pressure of a column of water 30 feet tall.
PSI = ft X .433 x S.g
SG water is 1
PSI = 30 x .433 X 1
Psi = 12.99
Calculate 40 ft of oil with a s.g .8 to the equivalent height of water?
Ft = psi / .433 x S.G
PSI = ft x .433 x S.G
40 x .433 x .8 = 11.86 psi
11.86/.433 x 1 = 32 ft of water
Convert 54 psi of oils with a s.g of .9 to the ft of head of oil?
Ft = psi / .433 x s.g
54 / .433 x .9
54 / .3897 = 138.6 feet
A pump is supplying a plant with water 300ft above it. The pump needs to be running with a pressure of 200 psi after supplying the water to the 300 ft level what will the discharge pressure at the pump be.
Psi = 300ft x ,433 x 1 = 129.9
Psi + running psi = total psi
129.9 + 200 = 329.9
A pressure gauge reads 350 psi. If it was pumping water what would the feet of head be?
350 / .433 x 1
350 / .433
808 feet
A pressure gauge reads 500psi. If it was pumping oil with a s.g of .75 what would the feet of head be?
500 / .433 x .75
500 / .32475
1540 feet of head
A pump displaces 350 psi . Line pressure at the plant is 100 psi. How much higher is the plant above the pump?
350 - 100 = 250 psi.
250 / .433 x 1
250 / .433
Equals 577 feet above the pump
If you were using a pump graph what informations would not be available?
Feet of head
NPSHa
Brake HP
Gpm
NPSHa
Net positive suction head available
When dealing with fans, 1psig will support ________ column.
27.7” of water
Static pressure developed by a fan is?
Pressure that air exerts on the inside of the duct walls
Velocity pressure is ?
Equal to total pressure minus static pressure
Air travelling through a restriction will show what changes?
Decrease in static pressure, increase in velocity pressure
All fan pressures can be read with?
A manometer hooked up to the side of the ducting and the other end hooked up to atmospheres
Manometer hooked up to the side of the ducting and the other end inside the ducting facing the air flow
The manometer hooked up inside the ducting and the other end open to the atmosphere
You need to do all of the above and read the fan pressures
When the damper is closed, all pressure in the system is changed to?
Static
All fans need to be _________ to help stop arcing through bearings?
Grounded
Centrifugal fans
Have radial flow
Use forward curved and backward curved incline blades
Have a scroll
When fans are mounted in series, they
Increase pressure
The centrifugal fan changes velocity pressure to static pressure in the_______
Scroll
Forced draft is when the fan is controlling the air flow into the furnace and_______
Pressurizes the furnace
The velocity of the air in the fan can be increased (while running) with which type of blades?
Variable pitch
Open wheel radial blades can handle
Small wood blocks
Silage
Paper trim
An inlet bell with an internal guide vanes will help centrifugal fans ________ air swirl
Decrease
The use of diffuser rings in centrifugal fans should not be used?
True or false
True
Axial fans compared to radial fans?
Require less power at the maximum air delivery
Cooling towers can use
Atmospheric pressure for the air flow
Forced draft
Induced draft
On fan discharge piping you need a straight section of ducting to help
Velocity pressure
Laminar flow
Vibration isolators are needed to
Help absorb mechanical air flow imbalances
Be mounted between the baseplate and the foundation
Cusion vibrations
Valves are made of what materials?
Bronze
Cast iron
Stainless steel
Aluminum
Valve ratings tell you the working pressure when the valve is used for steam or water and oils and gas
True or false
True
What does CWP stand for
Cold working pressure
Gate valves can come in rising stem and non-rising stem. These valves are not used used for throttling because?
Wire drawing
Erosion
The large butterfly valve uses a power actuator to rotate the disc because of the large pressure differential across it?
True
Needle valves are used for pre ice fluid control?
True
Globe valves have the fluid change directions _____ time through it?
2
Balance valves can be the single or double seated type and require less force to operate then conventional globe valves
True
Diaphragm valves are used in corrosive and toxic fluids because they can produce a bubble tight and drip tight closure?
True
Check valves prevent reverse flow through them by
Reverse of fluid flow closing the ball or flap
Gravity acting on the ball or flap
Pressure relief valve start opening at a preset pressure which is called ________ pressure?
Cracking
Pressure override is the difference between ________ and __________ pressure
Cracking and full flow
Rupture disc relief valves rupture at a pre set pressure and are used with a _______ valve to stop the fluid flow.
Gate or plug
Large hand and wheel valves (for two handed operation) usually have a worm and wheel gear reduction to get the mechanical advantage to open the valve?
True
Limit switches are employed with cylinder actuators to confirm full travel.
True
Lapping to mating surfaces on valves allows the valve to have a positive seal and no leakage.
True
When lubricating valve stem packing, also apply a few drops of oil onto the valve stem and any exposed threads. This will greatly extend the life of the valve packing.
True
When repacking valve stuffing boxes, you will add oil after packing some of stuffing box making sure the slits are 90 degrees from each other
All valves must be checked for leakage. The valves would be tested according to the valve class and simulate the valve operating conditions.
True
The bonnet is the part of the valve thru which the stem extends. It contains the means for sealing the fluid in the valve.
True
Environmental pollution is any discharge of material or energy in the:
Land
Air
Water
The most efficient approach to pollution control is?
To change the process
If there is acid effluent in water treatment, the acid must be neutralized with chemicals
True
Air particles are removed with _________ which have the highest removal efficiency?
Bag house
Cyclones rely on _______ to help separate out particulates:
Inertial forces
Centrifugal forces
Gravity
Cyclones are less efficient when the dust density is _______
High
The cleaned air is expelled from the _______ of the revers flow cyclone?
Top
When using a bag house, you will choose the type of filter bags based on?
Temperature
Chemical composition of the gas
Type and make up of particulates
When reconditioning (cleaning) the filters of a bag house, you can _________ to do the job
Mechanically shake them
Use reverse air flow
Use pulse jet
To attract particles when using electrostatic precipitator, you would use a ________ charged electrode and a _______ charged plate which attracts the particles.
Negative
Positive
Dry dynamic precipitators have the particle laden gas stream driven against the ________ and then deposited into the hopper
Fan blades
A scrubber is a ______collector and can use a _______ or ________ to disperse the droplets?
Wet
Fan
Pump
