NDDB and dairy cooperative recruitment · India · National Dairy Development Board; state cooperative milk federations
Original practice questions written to the published syllabus · not past papersDrawing, workshop, mechanics, materials and electricity as used in a milk plant. Go to the agricultural engineering track (engineering-drawing-cad, workshop-technology, basic-electrical-electronics) for depth.
In the exams: ICAR AIEEA-PG group 17 Unit III (mechanics, strength of materials, Hooke's law, materials, machine tools, electrical engineering, AC fundamentals)
How our questions for NDDB and dairy cooperative recruitment spread across the units of Engineering Fundamentals for Dairy Technologists. Difficulty: 2 easy, 25 medium, 0 hard.
| Electrical safety and earthing | 6 | |
| Lubrication and maintenance of machines | 6 | |
| Corrosion and its control in dairy plants | 4 | |
| Engineering drawing and reading plant drawings | 3 | |
| Workshop practice: fitting, welding and sheet-metal work | 3 | |
| Stainless steels and other dairy plant materials | 2 | |
| Electric motors and starters in dairy plants | 2 | |
| Power transmission: belts, gears and couplings | 1 |
Choose an answer, then open the working. Each explanation says why the right answer is right and why the others are not.
Hygienic-design guidance commonly specifies product-contact surfaces with a roughness of:
B. Ra no more than 0.8 µm
Smooth surfaces of Ra ≤ 0.8 µm resist bacterial attachment and clean more easily. Rougher surfaces harbour soil and organisms.
Further reading: EHEDG Doc. 8
Stainless-steel dairy pipework is normally welded by:
A. TIG welding with argon shielding
Gas tungsten arc (TIG) welding, often orbital, gives clean, fully penetrated welds. Solder and brass are unacceptable for product contact.
Further reading: 3-A and EHEDG welding guidance
For welded tanks and pipework handling salted whey, the best common choice among these grades is:
B. 316L
316L combines molybdenum for chloride resistance with low carbon to avoid sensitisation at welds. 430 is ferritic; 420 is a martensitic cutlery grade.
Further reading: Nickel Institute, Stainless steels in the food and beverage industry
Using PREN = %Cr + 3.3 %Mo + 16 %N, what is the PREN of a steel with 17% Cr, 2.5% Mo and 0.05% N?
A. 26.1
PREN = 17 + 3.3 × 2.5 + 16 × 0.05 = 17 + 8.25 + 0.8 = 26.1. Ignoring nitrogen gives 25.25.
Further reading: Nickel Institute, Stainless steels in the food and beverage industry
A centrifugal milk pump repeatedly destroys its mechanical seal and bearings within weeks. The first thing to check is:
B. Alignment of the motor and pump shafts at the coupling
Misalignment is the commonest cause of coupling, bearing and seal failures; it is checked with dial indicators or laser tools.
Further reading: Tufail Ahmad, Dairy Plant Engineering and Management
The main purpose of earthing the metal frame of a motor is to:
C. Let fault current flow so the protective device trips fast
A low-impedance earth path ensures an insulation fault draws enough current to trip the fuse or breaker.
Further reading: IEC 60364
Why is the electrical shock risk higher in a dairy processing hall than in an office?
A. Wet skin and floors lower body resistance
Water lowers contact resistance, raising current for a given voltage; conductive metal surrounds the worker.
Further reading: IEC 60364-7
Equipotential bonding of tanks, pipes and platforms in a wet dairy area is done to:
B. Keep touchable metal parts at the same potential
Bonding keeps simultaneously accessible metal at the same potential during a fault.
Further reading: IEC 60364
A filler has a mean time between failures of 95 h and a mean time to repair of 5 h. What is its inherent availability?
B. 95%
A = MTBF/(MTBF + MTTR) = 95/100 = 95%.
Further reading: Reliability-centred maintenance literature
After maintenance work on a filler in a product area, production should restart only when:
D. Tools are accounted for and quality staff release the cleaned machine
Maintenance is a food-safety activity: tool and part control, removal of debris, cleaning and formal hygiene release prevent foreign bodies and contamination.
Further reading: Codex General Principles of Food Hygiene
Ten here, 27 in the app. The Laisha app has every practice question we have written to NDDB and dairy cooperative recruitment in this subject, marked as you go, with timed papers, a jump-to-unanswered list and a certificate when you pass at 70 per cent.
Free for ten days, then one subscription of US$10 a month. We would rather say so here than have you find it later.
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