Intermediate Hydraulics Practice Test

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• What is a surge arrester and where is it used in hydraulic systems?
• A pump suction has static head z_s = 2 m, suction line head loss h_f = 3 m, vapor pressure head p_v/ρg = 0.8 m, atmospheric head p_atm/ρg = 10 m. Compute NPSH_available.
• For a pipe with Darcy friction factor f doubling, how does major head loss h_f change for the same flow?
• An integral P-port check valve is commonly used to build back pressure for shifting which devices?
• Which expression defines Reynolds number in terms of fluid properties and dimensions?
• In the hydraulic jump scenario, Fr1 ≈ 1.91; which is the upstream flow regime?
• When would you prefer Darcy–Weisbach over Hazen–Williams for head loss calculations?
• The part of a pilot-operated relief valve that controls the flow of oil is the ___________.
• When the needle valve is completely closed, pressure rises at the relief valve inlet, increasing the ___________ across the relief spool.
• Given a discharge Q and diameter D, which expression correctly gives the velocity V in the pipe?
• A hydraulic pilot-operated DCV typically uses which to actuate the main valve?
• Given A=2.0×10^-3 m^2, h=4 m, g=9.81 m/s^2, and Cd=0.68, what is Q? (Cd = Q / (A sqrt(2 g h)))
• A nozzle with Cd = 0.98 discharges into atmosphere. If head h = 5 m and nozzle area A = π(0.025)^2 ≈ 0.0019635 m^2, compute Q.
• Unloading a pump can be accomplished using which valve arrangement?
• If EGL = 28 m and velocity head = 6 m, what is HGL?
• Double-rod cylinders are commonly used in which type of circuits?
• A sudden valve closure in a pipe of fluid with density 1000 kg/m^3 and wave speed a = 1000 m/s and initial velocity V = 2 m/s. If ΔV = 2 m/s, compute maximum surge pressure ΔP using ΔP = ρ a ΔV.
• Cavitation occurs when NPSHa and NPSHr satisfy which condition?
• Actuator relaxation in a multi-actuator circuit is _________.
• Why must NPSHa exceed NPSHr in pumping applications?
• Calculate Reynolds number for water at 20 C with velocity 2.0 m/s in a pipe of diameter 0.15 m, using ν = 1.0×10^-6 m^2/s.
• Which method turns a 4/2 hydraulic DCV into a 3/2 DCV?
• What is the effect of vena contracta on discharge measurement across an orifice?
• How many ports does a double pilot-operated check valve have?
• Which parameter is used to express major head loss in the Darcy–Weisbach equation?
• Which statement correctly describes the continuity condition at a junction in a pipe network?
• In a rectangular channel, area A = B*y. If B = 3 m and y = 1.2 m, what is A?
• In a wide rectangular channel, compute critical depth y_c for Q = 3 m^3/s, width B = 4 m, g = 9.81 using y_c = [Q^2/(g B^2)]^(1/3).
• How do you compute acceleration head in a vertical lift suction line and why does it matter for pump suction?
• If the pilot pressure to a pilot-operated check valve repeatedly drops momentarily, the cylinder will
• What is the circuit that controls fast approach, followed by a decrease in speed called?
• For a nozzle with area A and head h, the ideal discharge Q_th = A sqrt(2 g h). If Cd = 0.95 and h doubles, how does Q change?
• What is the primary benefit of a bladder tank in a water distribution system?
• In the Venturi problem, the throat velocity is approximately 7.1 m/s and the upstream velocity is approximately 3.14 m/s. Which of the following is the upstream velocity?
• Which statement best describes NPSHa in relation to cavitation risk?
• A P-port check valve that is built into a DCV is called _________.
• A 4/2 DCV offset P to B _______ when de-energized.
• Which statement expresses energy conservation around a loop in pipe flow problems?
• A pump curve is H_p(Q) = 60 - 0.8 Q (m). System head loss is H_f(Q) = 20 + 0.5 Q^2 (m). Find the operating point Q.
• When equal pressure exists on both sides of a standard cylinder, what is the effect described in the material?
• The circuit described as rapid-traverse, slow feed moves the actuator how?
• In regeneration, the cylinder will extend ___________.
• All else equal for a broad-crested weir, if crest length L doubles with head h constant, how does discharge Q change?
• In a system using a pressure-compensated flow control valve, what is maintained constant when both upstream and downstream pressures rise?
• For the same sudden expansion, what is the approximate head loss h_L due to the velocity change?
• How does increasing water temperature generally affect pipe friction for a given flow?
• Which mounting method is commonly used for cylinders that are attached to flat surfaces and frequent in machine tool setups?
• Which formula correctly expresses the head loss across a sudden expansion in terms of V1, V2, and g?
• Which pump type is typically associated with high Ns?
• Why should you avoid operating a pump at shut-off (zero flow) and what happens to the head?
• Which statement best describes cavitation risk assessment in pumps?
• The term P-port in a hydraulic valve refers to which port?
• In a rectangular open-channel with width B = 3 m, depth y = 1.2 m, discharge Q = 4 m^3/s, compute velocity V and specific energy E at the section.
• If a cross-section area A=0.01 m^2 experiences a pressure difference Δp=2000 Pa, what is the force due to this pressure difference?
• The _________ of a pilot-operated relief valve can be used to change the pressure setting of a relief valve from a remote location.
• What is vena contracta in open-channel flow and how does it affect flow measurement across an orifice?
• Which statement is true about combined scaling using both N and D according to the provided material?
• The symbol for a PCFC valve is different from a non-compensated valve by the addition of a(n) _____________.
• When both upstream and downstream pressures of a pressure-compensated flow control valve increase, the flow rate _________.
• What is the Reynolds number formula for flow in a pipe?
• In Manning's equation Q = (1/n) A R^(2/3) S^(1/2), which parameter is raised to the 2/3 power?
• Which of the following is a potential advantage of cylinder regeneration?
• Each cylinder bore size that contains the smallest rod is called the ________ cylinder.
• What approach ensures that the highest hydraulic pressure in a system does not exceed equipment limits?
• To avoid cavitation, which inequality relates NPSH_available and NPSH_required according to the material?
• 4/2 DCVs are use in applications that must allow the actuator to ________.
• Hydraulic pilot-operated DCVs are used in applications requiring high ______.
• What does vapor pressure refer to in the context of cavitation?
• Which of the following is NOT listed as a method to prevent cavitation in a pump-suction system?
• The dimensionless discharge Cd for an orifice is defined as Cd = Q / (A sqrt(2 g h)). If Q=0.012 m^3/s, A = 2.0×10^-3 m^2, h = 4 m, compute Cd.
• List typical sources of minor losses and give example K-values for common components.
• In a 4/3 pilot-operated DCV, the spool is always which center type?
• What is the best method to synchronize cylinders?
• The piston area of a pilot-operated check valve is always larger than the _____________.
• If the head h in Q ≈ Cd L sqrt(2 g h) increases by a factor of 4, by what factor does the discharge Q change?
• A Venturi meter has upstream diameter 0.15 m and throat diameter 0.10 m. If Δp between upstream and throat is 20 kPa, compute the discharge Q (ρ = 1000 kg/m^3, neglect losses).
• Cylinders are synchronized when they finish their strokes simultaneously.
• Which relation correctly connects cross-sectional area A to diameter D for a circular pipe?
• Three-way, 2-position DCVs are used to ________.
• A rectangular open-channel section has width B = 5 m and depth y = 1 m. If a step increase of discharge doubles V, how does Froude number change qualitatively?
• The advantage of a pilot-operated relief valve over a direct-acting relief valve is____________.
• How is the total head loss in a pipe with both major and minor losses computed?
• In the energy equation for steady, incompressible flow, what does head loss h_L represent?
• A double pilot-operated check valve is particularly useful for which of the following?
• NPSHr is provided by the pump manufacturer for a given flow; it indicates the minimum suction head to avoid cavitation; ensure NPSHa > NPSHr.
• What is a true basic concept of fluid power?
• What is a key functional difference between open-channel flow and closed-conduit flow in hydraulics?
• In the head loss formula h_L = (V1 - V2)^2 /(2g), which of the following expresses the correct units for h_L?
• ____________ pilot-operated check valves is/are used in load-lock circuits when forces act in both directions on a cylinder or forces act to retract a cylinder.
• A sudden contraction from D1 = 0.30 m to D2 = 0.15 m is analyzed in a pipe with Q such that V1 = 0.80 m/s. Compute V2.
• What happens when NPSHa equals NPSHr?
• A pilot-operated check valve is used on a cylinder to _______.
• In the energy equation, what is the sign convention for elevation z and head losses?
• The Swamee-Jain formula is used to estimate the Darcy friction factor directly for turbulent flow in pipes.
• How does viscosity affect Reynolds number and the transition between laminar and turbulent flow?
• How do you compute the net suction head available for a centrifugal pump in a suction lift arrangement?
• In a wide open channel of width B = 4 m, with depth y = 2 m, slope S = 0.001, Manning n = 0.030, compute discharge Q.
• Three-way, 2-position DCVs are used to power actuators in one direction.
• A __________ valve is used to fill large volume cylinders as they extend by gravity or suction instead of using large volume pumps.
• Which pump type is typically associated with low Ns?
• In a rectangular channel with Q=2 m^3/s and width B=2 m, depth y, the Fr number is defined as Fr = V/√(g y) with V = Q/A and A=By. Which expression correctly gives Fr in terms of y?
• In a double-rod cylinder, what is true about the motion of the two rods?
• XP on a hydraulic pilot-operated DCV means ____________.
• What is Hardy-Cross method used for in hydraulics?
• Which method is Hardy Cross used for?
• Compare node analysis and loop (Hardy Cross) methods for pipe networks.
• Why must NPSH_available exceed NPSH_required in a pump suction to avoid cavitation?
• In Manning's equation, what does the symbol n represent?
• Which statement best describes how node analysis and Hardy Cross differ in pipe-network practice?
• What is the Hazen-Williams C coefficient used for in water distribution pipelines?
• Which statement describes the typical laminar-turbulent criterion for pipe flow based on Reynolds number?
• A sharp-edged entrance into a pipe has K = 0.5. If the pipe velocity is 0.8 m/s, compute the entrance head loss h_L.
• Which option would convert a 4/2 DCV into a 3/2 DCV?
• In a straight pipe with major and minor losses, which expression represents the total head loss?
• ____________ is the increase in pressure in a part of the circuit above the system pressure at the pump outlet.
• A hydraulic jump occurs when a supercritical flow transitions to subcritical flow. If the upstream depth y1 = 0.40 m and downstream depth y2 = 0.90 m in a wide channel, compute r = y2/y1 and Fr1^2 using r, then comment on the flow regime.
• Which of the following formulas is used to calculate the pressure used to open a POC valve when no pressure is supplied to the cylinder?
• Estimate the head loss across a 90-degree bend and a throttling globe valve, given velocity head V^2/(2g).
• Darcy-Weisbach head loss h_f = f (L/D) (V^2/(2g)). If V doubles, by what factor does h_f change (assuming f constant)?
• The term external pilot refers to:
• Write the Chezy–Manning equation used for open-channel flow and define the roughness coefficient.
• What is the function of a hydropneumatic (bladder) tank in a water distribution system?
• Equal pressure on both sides of a standard cylinder will_______________.
• For a sharp-edged orifice with area A = 1.0×10^-4 m^2, Cd = 0.62, upstream head h = 3.0 m, compute discharge Q using Q = Cd A sqrt(2 g h).
• A pilot-operated check valve is used instead of a DCV with a closed center spool to hold a cylinder because ____________.
• Which statement correctly describes the relationship between the Hydraulic Grade Line (HGL) and the Energy Grade Line (EGL)?
• What is the main purpose of a pressure-compensated flow control valve?
• The speed of a cylinder in regeneration is determined by how fast the __________.
• If LP = 90 psi, PP = 15 psi, CR = 0.4, what is the maximum pressure in the POC circuit?
• If LP = 100 psi, PR = 25 psi, Z = 7 psi, what is PP according to PP = (LP/PR) + Z?
• In a rectangular open channel with width B and depth y, the hydraulic radius R = A/P. Given A = B y and wetted perimeter P = B + 2 y, what is R?
• The most basic load-lock circuit uses a single ____________ in one of the cylinder lines to resist the movement of the cylinder by the load.
• What is the purpose of a pressure-regulating device in a hydraulic system?
• The DCV spool that connects all ports in the center position is called __________.
• What are typical K-values for a 90-degree elbow, a throttling globe valve, and a sudden enlargement?
• In a cylinder circuit, when the pilot signal is removed, the pilot-operated check valve _______.
• When nozzle area is doubled while head h remains the same, what happens to the ideal discharge Q_th?
• A Pitot tube measurement yields dynamic head Δh = 2.5 m; compute flow velocity V.
• If D1 = 0.1 m, D2 = 0.2 m, and V1 = 3.0 m/s, what is V2?
• Equal-sized cylinders will not operate in synchronization because of ___________.
• According to the provided affinity laws, how does Q, H, and P change with a speed increase by a factor N?
• The cross-sectional area A of a circular pipe is proportional to the square of its diameter D. Which option correctly reflects this statement?
• For open-channel specific energy, which expression gives E in terms of depth y and velocity V?
• In an open-channel, Fr = V / sqrt(g y). If velocity is constant and depth y doubles, what happens to Fr?
• Which statement correctly defines dynamic pressure and its appearance in head loss expressions?
• The _______ has a rod the same diameter as the cylinder bore.
• ________ mounted cylinders are easily attached to flat surfaces, common with machine tools.
• How do you read a manometer for differential pressure and what does it indicate in a hydraulic system?
• Which description best characterizes the Hardy Cross method?
• In hydraulic circuits, the path of least resistance means:
• If HGL = 15 m and velocity head = 4 m, what is EGL?
• Which expression correctly relates Δp/γ to elevations, velocity heads, and head losses in the energy equation?
• In the Darcy-Weisbach equation h_f = f (L/D) (V^2/(2g)), h_f is proportional to which combination?
• Which action reduces vapor pressure and helps prevent cavitation?
• In a closed loop of pipe segments, what is the algebraic condition on head losses around the loop?
• What is the Darcy–Weisbach head loss formula?
• In a load-lock circuit, how many pilot-operated check valves are used when force can act in both directions?
• Which port on a pilot-operated relief valve is used to change the relief setting from a remote location?
• In a sudden expansion, if the upstream diameter doubles, how does the fluid velocity change?
• What is the Colebrook–White equation used for?
• What component is used in a pilot-operated check valve to eliminate hydraulic shock?
• The minimum pressure head required to avoid cavitation is represented by which of the following?
• If the energy grade line is rising along a pipe with no external energy addition, what does this imply about losses and elevations?
• A double POC valve has two pilot-operated check valves built into one housing and requires ________ lines to be connected.
• Define the cavitation number sigma and its relation to NPSH and vapor pressure.
• When comparing a DCV with an integrated P-port check valve to one without, the difference is that the P-port has built-in check valve capability.
• A decompression poppet is used in a pilot-operated check valve to eliminate ____________.
• A pump with Q = 0.05 m^3/s, head H_p = 60 m; ρ = 1000 kg/m^3; g = 9.81; compute hydraulic power P_h.
• In a network with two parallel pipes D1 = 0.15 m and D2 = 0.20 m, same length and roughness, to have equal head loss; If total Q = 0.6 m^3/s, compute Q1 and Q2.
• Which device is typically installed as surge protection and can be an air chamber or surge tank?
• Which feature differentiates a PCFC valve symbol from a non-compensated valve?
• Cylinder regeneration _____________.
• Define the specific speed of a pump and what its value indicates about the type of pump.
• Given a discharge Q and maximum allowable velocity Vmax, how is the minimum pipe diameter determined?
• Multiple pressure relief valve operation__________.
• Which statement correctly indicates the cavitation risk when sigma is lower?
• Define suction dynamic head and explain why velocity in the suction line is important for pump suction performance?
• Compute the relative roughness ε/D for a pipe with ε = 0.045 mm and D = 100 mm.
• Which mechanism is used to synchronize hydraulic cylinders in a system?
• A broad-crested weir with crest length L and head h uses Q ≈ Cd L sqrt(2 g h) with Cd ≈ 0.6. If L=3 m and h=0.5 m, approximate Q.
• A ___________ can be used to avoid momentary drops in system pressure as the work cylinder is cycled.
• Estimate the Reynolds number for a pipe given ρ=1000 kg/m^3, V=2 m/s, D=0.25 m, and μ=1.0×10^-6 Pa·s, and state the flow regime.
• In the wide open channel described, what is the hydraulic radius R?
• What is the typical effect of adding a pilot-operated check valve on retract speed?
• How does head loss change with pipe length in fully developed flow?
• A P-port check valve built into a DCV is designed to provide which function?
• Cylinders are said to be synchronized when they __________.
• Unloading a pump can be accomplished using which valve arrangement?
• How do you compute NPSHa from system data and what data do you need?
• Using the Swamee-Jain formula to estimate the friction factor f for Re = 2.0×10^5 and ε/D = 4.5×10^-4, which value is most appropriate?
• What is the Reynolds number definition?
• State Manning's equation for uniform open-channel flow and define each parameter.
• Pilot-operated relief valves have a third port that may be used to __________.
• How does pipe roughness affect the friction factor and head loss?
• In 4/2 DCVs, the actuator is often allowed to coast to a stop rather than stopping abruptly.
• State the definitions of subcritical and supercritical flow using Froude number Fr = V/√(g y).
• Which expression correctly gives V2 for a sudden expansion in terms of V1 and the pipe diameters?
• For a rectangular channel with Q=2 m^3/s, B=2 m, y=0.5 m, compute the Froude number Fr. (Fr = V/√(g y), V = Q/(B y))
• What does the pump head vs flow rate curve represent, and how is it used in system design?
• Which equation represents the pump operating point in a system with a pump head curve and system head loss?
• How can a 4/2 DCV effectively be made into a 3/2 DCV?
• The extend force of a cylinder in regeneration is equal to _________.
• A 200 mm diameter pipe carries Q = 0.02 m^3/s. Using Darcy-Weisbach with f = 0.028, length L = 150 m, compute major head loss h_f.
• What factors contribute to suction losses in a pump system?
• In the POC calculations, which variable represents the pilot pressure?
• A double pilot-operated check valve uses how many pilot signals to control the main valve?
• According to the provided affinity laws, how do Q, H, and P change with a diameter increase by a factor D at constant speed?
• What does the system head curve represent in pump system design?
• For a valve with a head loss coefficient K observed to be proportional to 1/(opening)^2. If the opening is halved, by what factor does K increase?
• Which element in a pilot-operated relief valve is primarily responsible for setting the threshold pressure via a spring?
• A _________ valve is a two-way valve with an external drain and is usually provided with a bypass check valve.
• What is the friction factor for laminar flow in a circular pipe and the Reynolds number criterion?
• A globe valve with K = 4.0 has a flow velocity V = 2.0 m/s in the pipe. Compute head loss h_L.
• What is the Joukowsky equation for pressure rise due to water hammer, and what do the symbols represent?
• An integral P-port check valve can be used to build back pressure for shifting pilot-operated_______________.
• How does roughness affect the friction factor in turbulent pipe flow, and how is it reflected on the Moody chart?
• What transient occurs when a valve closes suddenly on a pressurized line, and what parameter is used to estimate the severity?
• The center position of a DCV that connects all ports is called what?
• For Q = 2.5 m^3/s and B = 2 m, with g = 9.81, the critical depth y_c is approximately:
• What does the system curve illustrate, and how is it used with a pump curve to select an appropriate pump?
• Which component can yield K-values ranging roughly 2-10 depending on opening?
• What determines the operating point of a pump in a piping system?
• Using D1 = 0.15 m and D2 = 0.30 m, what is the ratio V2/V1 for a sudden expansion?
• The ________ cylinder construction is used for heavy-duty applications.
• In a system with a pump delivering head Hp(Q)=50 - 0.5 Q and a pipe with head loss Hf(Q)=10 + 0.3 Q^2, determine the Q where the system is in balance.
• Which cylinder construction is typically used for heavy-duty applications?
• What does the Moody chart relate?
• In a pilot-operated check valve, what component provides the pilot actuation to move the valve element?
• What does NPSH stand for and what does it indicate in pump systems?
• The maximum pressure that will occur in a POC circuit when piloting from the opposite cylinder line is calculated by using:
• The extend force of a cylinder in regeneration is equal to cap pressure times the rod.
• A pilot-operated check valve consists of a standard check valve design with a third port and ____________.
• In a horizontal pipe with a sudden expansion from D1 to D2, given V1 = 2.0 m/s, D1 = 0.15 m, and D2 = 0.30 m, what is V2?
• If velocity doubles in a system with a valve that has loss coefficient K, head loss increases by what factor?
• In a pipe network with a loop, which fundamental equations must be satisfied to solve for the branch flows?