CFESA Warewashing Equipment

Question 1

What is the minimum final rinse temperature required at the dish surface for a high-temperature commercial dishwasher to achieve proper sanitization?

Accepted Answer

180°F (82°C)

Answer

NSF/ANSI 3 and FDA Food Code require a minimum 180°F (82°C) at the dish surface during the final rinse cycle to achieve sanitization in high-temperature machines. The booster heater raises incoming water to meet this threshold.

Question 2

A flight-type dishwasher is producing cloudy glassware despite correct water temperature. Which cause should be investigated FIRST?

Accepted Answer

Insufficient rinse-aid concentration or malfunctioning chemical dispenser

Answer

Cloudy or spotted glassware in an otherwise correctly-temped machine is the classic symptom of inadequate rinse-aid. The surfactant in rinse-aid sheets water off the glass surface; without it, mineral deposits and detergent film dry on the glass.

Question 3

A undercounter glasswasher is tripping its thermal overload repeatedly. After confirming the motor windings are good, what is the most likely mechanical cause?

Accepted Answer

Pump impeller jammed with broken glass or debris

Answer

A jam in the wash/rinse pump impeller causes the motor to draw locked-rotor amperage, rapidly heating the windings and tripping the thermal overload. Broken glass, bottle caps, and silverware are common culprits in glasswashers.

Question 4

When sizing a booster heater for a commercial dishwasher, which specification is the PRIMARY determining factor?

Accepted Answer

The volume of final-rinse water per hour and the required temperature rise (ΔT)

Answer

Booster heater capacity (kW) must be matched to the gallons-per-hour of final-rinse flow multiplied by the BTU/hr required to raise incoming water temperature to 180°F. Undersizing results in chronic sanitization failures.

Question 5

What is the purpose of the scrap screen or pre-flush trough in a commercial conveyor dishwasher?

Accepted Answer

To remove food soil from dishes before the main wash cycle to prevent tank contamination

Answer

The scrap screen/pre-flush zone removes gross food debris from dishes before they enter the wash tank. Without it, soil would rapidly contaminate the wash water, reducing detergent effectiveness and requiring more frequent tank changes.

CFESA - Commercial Food Equipment Service Association Practice Test

CFESA - Commercial Food Equipment Service Association Practice Test

CFESA Warewashing Equipment