C33 Paint Application Equipment 5 — Questions and Answers
Question 1: What is the function of a 'whip hose' (short flexible hose) at the airless spray gun connection?
- It boosts fluid pressure at the gun tip
- It filters debris before it reaches the spray tip
- It reduces vibration and operator fatigue from the rigid high-pressure hose (Correct answer)
- It allows the operator to change tips without stopping the pump
Correct answer: It reduces vibration and operator fatigue from the rigid high-pressure hose
A whip hose is a short, flexible section of hose between the main high-pressure line and the spray gun that absorbs vibration and reduces hand fatigue.
Question 2: Which type of spray gun tip is specifically designed to reverse 180° for field cleaning of clogs without removing the tip from the gun?
- Conventional fluid tip
- Reversible airless tip (RAC tip) (Correct answer)
- External mix air cap
- Pressure feed tip
Correct answer: Reversible airless tip (RAC tip)
Reversible Airless Cartridge (RAC) tips can be rotated 180° so that fluid pressure blows the clog back out through the reversed tip.
Question 3: A painting contractor is applying an elastomeric coating to a concrete block wall. Which application method is most appropriate?
- Conventional air spray with a fine finish tip
- Airless spray with a large orifice tip (0.021–0.031) and back-rolling (Correct answer)
- HVLP turbine spray for maximum transfer efficiency
- Brush application only to ensure penetration
Correct answer: Airless spray with a large orifice tip (0.021–0.031) and back-rolling
Elastomeric coatings are thick, high-build materials that require a large-orifice airless tip, and back-rolling ensures the coating bridges surface voids.
Question 4: What does a 517 airless spray tip designation indicate?
- 5 inch fan width and 0.017 inch orifice
- 10 inch fan width and 0.017 inch orifice (Correct answer)
- 5 inch fan width and 0.170 inch orifice
- 17 degree spray angle and 0.05 inch orifice
Correct answer: 10 inch fan width and 0.017 inch orifice
In a three-digit airless tip number, the first digit multiplied by 2 gives the fan width in inches, and the last two digits give the orifice size in thousandths of an inch — so 517 = 10" fan, 0.017" orifice.
Question 5: When cleaning an airless spray system that was used with latex paint, which solvent should be used for flushing?
- Mineral spirits or paint thinner
- Lacquer thinner
- Warm water followed by pump armor (Correct answer)
- Acetone
Correct answer: Warm water followed by pump armor
Latex paint is water-based, so warm water is used to flush the system, followed by pump armor or mineral spirits to protect seals from drying.
Question 6: What is the primary risk of holding an airless spray gun tip too close to the skin?
- Chemical burns from solvents in the coating
- High-pressure fluid injection injury that can cause serious tissue damage (Correct answer)
- Electric shock from the spray gun motor
- Inhalation of overspray at close range
Correct answer: High-pressure fluid injection injury that can cause serious tissue damage
Airless spray systems operate at 2,000–3,500 PSI, and the fluid jet can penetrate skin and inject coating material deep into tissue, requiring emergency surgery.
Question 7: Which factor most directly determines the recommended tip size when selecting an airless spray tip for a specific coating?
- The color of the coating being applied
- The viscosity and recommended application rate of the coating (Correct answer)
- The ambient temperature on the day of application
- The brand of the airless spray pump being used
Correct answer: The viscosity and recommended application rate of the coating
Coating viscosity and the manufacturer's recommended mil thickness determine the orifice size needed to deliver the correct flow rate without excessive pressure.
C33 Paint Application Equipment 5
What is the function of a 'whip hose' (short flexible hose) at the airless spray gun connection?