OIT Practice and Application 3 — Questions and Answers
Question 1: In a pneumatic system, a pressure relief valve is set at 150 psi but the system regularly operates at 140 psi. What is the likely result?
- The relief valve will open frequently causing pressure loss
- The system will operate safely with adequate margin (Correct answer)
- The compressor will shut down automatically
- The relief valve will become permanently open
Correct answer: The system will operate safely with adequate margin
A 10 psi margin between operating pressure and relief valve setting provides adequate safety without causing nuisance valve openings.
Question 2: Which WHMIS 2015 pictogram indicates a substance is an oxidizer?
- Skull and crossbones
- Flame over circle (Correct answer)
- Exclamation mark
- Health hazard (silhouette)
Correct answer: Flame over circle
The flame over circle pictogram (GHS03) specifically identifies oxidizing gases, liquids, and solids under WHMIS 2015/GHS.
Question 3: A hydraulic press is producing parts that vary inconsistently in thickness. The hydraulic fluid level is normal. What is the most likely cause?
- Worn seals causing internal leakage (Correct answer)
- Excessive pump speed
- Too much hydraulic fluid
- A faulty pressure gauge
Correct answer: Worn seals causing internal leakage
Worn seals cause internal bypass leakage, resulting in inconsistent pressure delivery and variable press force, leading to dimensional inconsistency.
Question 4: When using an angle grinder on a metal workpiece, which PPE is mandatory in addition to safety glasses?
- Hearing protection only
- Face shield, gloves, and hearing protection (Correct answer)
- Only a face shield
- Respirator and gloves only
Correct answer: Face shield, gloves, and hearing protection
Angle grinder use requires a full face shield (in addition to safety glasses), gloves for grip and heat, and hearing protection due to high noise levels.
Question 5: A refrigeration system's suction pressure is lower than normal while discharge pressure is normal. What does this typically indicate?
- Refrigerant overcharge
- Restriction in the liquid line
- Low refrigerant charge or evaporator icing (Correct answer)
- Condenser fouling
Correct answer: Low refrigerant charge or evaporator icing
Low suction pressure with normal discharge pressure typically indicates insufficient refrigerant or a restricted/iced evaporator reducing refrigerant flow.
Question 6: On a technical drawing, what does the symbol GD&T 'flatness' control?
- The parallelism of a surface to a datum
- All points of a surface lying within two parallel planes (Correct answer)
- The perpendicularity of a surface to a datum
- The angularity of a surface feature
Correct answer: All points of a surface lying within two parallel planes
Flatness is a form control that requires all points on a surface to lie within a tolerance zone defined by two parallel planes, with no datum reference required.
Question 7: In Ontario, which regulation under the OHSA specifically governs industrial establishments?
- Regulation 851 (Correct answer)
- Regulation 213/91
- Regulation 490/09
- Regulation 67/93
Correct answer: Regulation 851
Ontario Regulation 851 (Industrial Establishments) sets out specific health and safety requirements for industrial workplaces under the OHSA.
OIT Practice and Application 3
In a pneumatic system, a pressure relief valve is set at 150 psi but the system regularly operates at 140 psi.
What is the likely result?