EHEDG hygienic design training · International (Europe-based) · European Hygienic Engineering & Design Group
Original practice questions written to the published syllabus · not past papersTurning a process into a plant that is hygienic, efficient and safe: hygienic equipment and building design, plant layout, process flow and equipment selection, steam, water, compressed air and refrigeration utilities, instrumentation and automation, energy audit and scale-up. Agricultural Engineering's food-quality-safety-plant-design covers plant location, layout and feasibility reports; this subject adds hygienic engineering (EHEDG and 3-A principles), utilities, automation and energy management in depth.
In the exams: ICAR AIEEA-PG Code 18 Unit II (process equipment design, steam generation, compressed air, automation and process control, food plant layout and design, energy audit); ICAR AICE 41 Units 8–9
How our questions for EHEDG hygienic design training spread across the units of Food Plant Design, Hygienic Engineering, Utilities & Automation. Difficulty: 6 easy, 12 medium, 2 hard.
| Hygienic design of buildings: floors, drains, walls and air handling | 9 | |
| Hygienic design of equipment: EHEDG and 3-A principles | 8 | |
| Plant layout: product, process and hygienic zoning | 3 |
Choose an answer, then open the working. Each explanation says why the right answer is right and why the others are not.
In a ready-meal plant, where is the boundary between low-risk and high-risk areas ideally placed?
C. At the lethal step itself, such as a through-wall oven loaded on the raw side and emptied on the cooked side
The best barrier is the cooking equipment: raw product enters on the low-risk side and cooked product leaves on the high-risk side, so nothing crosses the wall uncooked. A single shared zone or a boundary at the canteen or dock leaves cooked product exposed to raw-side contamination.
Further reading: See the manual sources: EHEDG guidelines; 3-A Sanitary Standards; Codex General Principles of Food Hygiene; food plant design and process control textbooks
What is a dead leg in a hygienic pipeline?
C. A stagnant pipe section that cleaning flow cannot reach
A dead leg is a stagnant branch, such as a capped tee, which CIP flow does not sweep, so soil and biofilm build up. Supports, falls in the flow direction and double-seat valves are normal hygienic features, not dead legs.
Further reading: See the manual sources: EHEDG guidelines; 3-A Sanitary Standards; Codex General Principles of Food Hygiene; food plant design and process control textbooks
Why is a mix-proof double-seat valve used where product and cleaning lines meet?
A. A leakage chamber vented to drain between two seats keeps a seat leak from mixing them
Between the two seats is a chamber vented to drain; if either seat leaks, the leak shows at the drain instead of contaminating product. Mixing the fluids is exactly what it prevents; it is costly and its seats are cleaned by seat-lifting; ball valves with cavities are unhygienic.
Further reading: See the manual sources: EHEDG guidelines; 3-A Sanitary Standards; Codex General Principles of Food Hygiene; food plant design and process control textbooks
An open conveyor frame is being specified. Which construction meets hygienic design principles?
B. Open frame of round tubes, minimal horizontal surfaces and floor clearance for cleaning beneath
Round tubes shed water and soil, open frames can be seen and cleaned, and clearance from the floor allows cleaning beneath. Hollow box sections and angle iron trap soil and are hard to inspect, horizontal ledges collect debris, and frames flush to the floor create inaccessible crevices.
Further reading: See the manual sources: EHEDG guidelines; 3-A Sanitary Standards; Codex General Principles of Food Hygiene; food plant design and process control textbooks
Welds in product-contact pipework are found to be uneven with incomplete penetration on the inside. Why is this a hygiene problem?
C. Crevices and rough internal beads harbour soil and bacteria that cleaning cannot remove
Product-zone welds must be continuous, full-penetration and ground flush, ideally orbital-welded, because pits and crevices inside the pipe hold soil and biofilm out of reach of cleaning. The pressure-drop effect is small, welds do not make austenitic steel a detection issue downstream, and the defect described is on the inside.
Further reading: See the manual sources: EHEDG guidelines; 3-A Sanitary Standards; Codex General Principles of Food Hygiene; food plant design and process control textbooks
Which elastomers are commonly used for hygienic seals and gaskets in food equipment?
D. EPDM, FKM, silicone and PTFE
Approved elastomers and plastics such as EPDM, FKM, silicone and PTFE resist product, cleaning chemicals and temperature. Cork, leather and felt are absorbent; asbestos is banned; untreated rubber degrades.
Further reading: See the manual sources: EHEDG guidelines; 3-A Sanitary Standards; Codex General Principles of Food Hygiene; food plant design and process control textbooks
Why must bearings and lubrication points on food machinery be placed outside the product zone, with food-grade lubricants where incidental contact is possible?
A. To keep lubricant and wear debris out of the food
Bearings shed lubricant and metal particles; keeping them outside the product zone and using lubricants registered for incidental food contact limits chemical and physical contamination. Temperature, price and painting are not the reason.
Further reading: See the manual sources: EHEDG guidelines; 3-A Sanitary Standards; Codex General Principles of Food Hygiene; food plant design and process control textbooks
A floor slopes to a drain at a fall of 1 in 50. How much lower is the floor at the drain than at a point 6 m away?
A. 120 mm
Fall = run ÷ 50 = 6,000 mm ÷ 50 = 120 mm. A 1-in-100 fall would give 60 mm; 300 mm multiplies instead of divides; 12 mm is a factor-of-ten slip. Falls of about 1 in 50 to 1 in 100 are common, steeper in very wet areas.
Further reading: See the manual sources: EHEDG guidelines; 3-A Sanitary Standards; Codex General Principles of Food Hygiene; food plant design and process control textbooks
High-care rooms are kept at positive air pressure relative to adjacent areas. What does this achieve?
A. Air flows outward through openings, so unfiltered air from less clean areas does not enter
Supplying more filtered air than is extracted makes air leak outward through doors and gaps, keeping less clean air out. The pressure difference is tiny and does not change boiling point or remove all humidity.
Further reading: See the manual sources: EHEDG guidelines; 3-A Sanitary Standards; Codex General Principles of Food Hygiene; food plant design and process control textbooks
Where are HEPA filters typically used in food plants?
C. Over aseptic fillers and in some high-care rooms
High-efficiency particulate air filters are used where the highest air cleanliness is required, such as aseptic filling. They do not remove gases such as CO2 or water vapour and are not used on liquid effluent.
Further reading: See the manual sources: EHEDG guidelines; 3-A Sanitary Standards; Codex General Principles of Food Hygiene; food plant design and process control textbooks
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