Free PE-A&BE Practice Questions

Question 1

After a storm, a centrifugal irrigation pump develops a gravel-like noise and an unsteady discharge. Reservoir level, water temperature, and pump speed are unchanged. Even at a lower flow than before, the pressure loss across the intake screen is much greater. Briefly reducing discharge flow quiets the pump. A suction-side leak test finds no air ingress. What mechanism best explains these observations?

Accepted Answer

Intake restriction has reduced available suction head, allowing vapor cavities to form.

Answer

Partial closure of a downstream valve has increased discharge-system resistance.

Answer

Impeller wear has increased recirculation through enlarged internal clearances.

Answer

Air entering through the shaft seal is increasing the compressibility of the pumped water.

Question 2

An irrigated crop has an effective root depth of 0.60 m in a uniform soil. Volumetric water contents are 0.32 m³/m³ at field capacity, 0.16 m³/m³ at permanent wilting point, and 0.22 m³/m³ now. The irrigation schedule calls for refilling to field capacity once 50% of total available root-zone water has been depleted. Application efficiency is 80%; rainfall and groundwater contributions are negligible. Application rate is below the soil infiltration limit. Which prescription follows the schedule?

Accepted Answer

Irrigate now with a gross application depth of 75 mm.

Answer

Irrigate now with a gross application depth of 48 mm.

Answer

Irrigate now with a gross application depth of 60 mm.

Answer

Wait for another 36 mm of depletion, then apply 120 mm gross.

Question 3

A loader with a fixed-displacement hydraulic pump began overheating after its directional-valve bank was replaced. With every spool in neutral, the actuators remain stationary, pump pressure stays at the correctly adjusted relief setting, and the relief-valve return line heats rapidly. The suction line and tank return are unrestricted. Actuator speed is satisfactory when a spool is shifted. Which circuit change eliminates the dominant idle heat source?

Accepted Answer

Provide a low-pressure pump-unloading path whenever the directional spools are in neutral.

Answer

Install a larger oil cooler to remove the heat generated during neutral operation.

Answer

Use lower-viscosity oil to reduce friction, retaining the pump and valve arrangement.

Answer

Increase the relief setting so that the relief valve opens less often during neutral operation.

Question 4

A milk-protein-specific swab is positive after a shared mixing line is cleaned for a product formulated without milk. The previous product contained milk, and the swab's assay controls are valid. An adenosine triphosphate (ATP) swab from the same food-contact area reads 9 relative light units, below the facility's 40-unit action limit. The sanitation supervisor argues that the ATP pass should override the protein result. How should the two findings be reconciled?

Accepted Answer

The ATP criterion was met, but the result does not demonstrate that milk protein was removed.

Answer

The ATP pass establishes allergen removal, so the positive protein result can be treated as a false alarm.

Answer

Residual milk protein proves that the microbiological disinfection step failed.

Answer

The ATP action limit should be lowered until the two methods produce matching pass-or-fail decisions.

Question 5

During cold weather, newly weaned pigs crowd away from wall inlets even though the room-average temperature is on target. Smoke testing shows incoming air falling directly into the pens rather than traveling along the ceiling. Measured exhaust flow is already at the minimum needed to control moisture, and the installed fans and heaters have adequate capacity. The ventilation correction should be to:

Accepted Answer

Adjust inlet openings and direction for ceiling-level mixing, retaining minimum exhaust flow.

Answer

Open every inlet fully to reduce entering-air velocity, leaving the exhaust setting unchanged.

Answer

Reduce the minimum exhaust rate until the cold drafts no longer cause the pigs to avoid the inlets.

Answer

Raise the room-temperature setpoint while retaining the existing inlet openings and airflow pattern.

Question 6

"Reset the filler whenever an hourly sample mean misses the target" is proposed as a new rule for a feed-bagging line. The process is centered on target and meets the purchaser's capability requirement. Its established mean and range charts show random variation, with no control-limit violations or other special-cause signals. Which operating policy should the engineer approve?

Accepted Answer

Retain the setting; investigate chart signals rather than each sample's random deviation.

Answer

Trim the setpoint after every off-target sample, using smaller adjustments.

Answer

Recalculate chart limits after each adjustment to reflect the new operating setting.

Answer

Stop and identify the cause of each off-target sample mean.

Question 7

Effluent entering a constructed wetland contains little ammonium, substantial nitrate, and very little readily biodegradable organic carbon. Dissolved oxygen remains above 5 mg/L throughout the treatment cells, and pH is 7.3. Increasing detention time has not appreciably improved nitrogen removal. Which retrofit directly addresses the missing treatment conditions?

Accepted Answer

Add an anoxic treatment zone with a controlled supply of biodegradable carbon.

Answer

Add a settling basin ahead of the wetland's discharge to capture the nitrate.

Answer

Increase aeration throughout the wetland to maintain complete oxidation of the remaining nitrogen.

Answer

Increase alkalinity dosing to improve nitrification throughout the existing aerated treatment volume.

Question 8

At its selected operating conditions, a continuous corn dryer can evaporate at most 700 kg of water per hour. Incoming corn is 28% moisture, and the discharge requirement is 14% moisture, both on a wet basis. Dry-matter losses are negligible, and conveying equipment does not limit throughput. What is the maximum wet-corn feed rate that the evaporation capacity permits?

Accepted Answer

4,300 kg/h

Answer

2,500 kg/h

Answer

3,600 kg/h

Answer

5,000 kg/h

Question 9

A large door is proposed for a post-frame machine shed whose roof diaphragm transfers wind loads to engineered end-wall shear panels. The opening would leave insufficient end-wall shear capacity. The door header and remaining posts pass their gravity-load checks. Before the alteration can be accepted, what additional design provision is essential?

Accepted Answer

Provide a replacement lateral-resisting system with connections carrying diaphragm forces into the foundations.

Answer

Stiffen the roof diaphragm without modifying the remaining end-wall connections.

Answer

Increase the header's gravity-load capacity while retaining its existing end connections.

Answer

Increase footing bearing area beneath the remaining posts without changing their lateral-load connections.

Question 10

An attendant sees a worker collapse inside an enclosed manure reception pit shortly after agitation begins. A remotely sampled atmosphere contains 20.8% oxygen and 650 ppm hydrogen sulfide. No retrieval line is attached to the worker. A coworker is preparing to climb in with a harness, and agitation can be stopped from a safe outside station. What instruction takes priority?

Accepted Answer

Prevent entry, call the trained rescue team, and stop agitation from outside.

Answer

Ventilate until the oxygen reading stabilizes, then allow the harnessed coworker to enter without respiratory protection.

Answer

Delay the rescue call while ventilating, then permit entry once hydrogen sulfide drops below 100 ppm.

Answer

Send the harnessed coworker in with a full-face air-purifying respirator fitted with hydrogen-sulfide cartridges.

Free PE-A&BE Practice Questions

Domain 1: Common System Applications

Question 1

Question 2

Question 3

Domain 2: Natural Resources and Environmental Systems

Question 4

Question 5

Domain 3: Processing Systems

Question 6

Question 7

Domain 4: Facilities and Structures

Question 8

Question 9

Domain 5: Machinery Systems

Question 10

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