District Of Columbia (DC) Journeyman AC & Refrigeration 312 Practice
Exam | 100 Q&A | Detailed Explanations
Subject/Course: HVAC, Refrigeration, Mechanical Systems, Licensing
Exams
Tags: HVAC License, DCRA, Refrigeration Systems, EPA Certification,
Electrical Codes, Mechanical Codes, HVAC/R, Ductwork, Load
Calculations, Refrigerants
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===========================
EXAM QUESTIONS
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===========================
1. According to DC mechanical codes, what is the minimum clearance
required between a condenser unit and any obstruction?
A. 12 inches
B. 24 inches
C. 36 inches
D. 48 inches
Answer: C
Explanation: DC Mechanical Code requires a minimum of 36 inches
clearance on all sides of condenser units for proper airflow and service
access.
2. What is the maximum allowable pressure drop in a refrigerant suction line
for a system with a 50-foot equivalent length?
, A. 1 psi
B. 2 psi
C. 3 psi
D. 4 psi
Answer: B
Explanation: Industry standards typically limit suction line pressure drop
to 2 psi or equivalent to 2°F saturation temperature drop for proper system
operation.
3. Which EPA certification is required to handle R-410A refrigerant?
A. Type I
B. Type II
C. Type III
D. Universal
Answer: D
Explanation: R-410A is an HFC refrigerant requiring Universal
certification under EPA Section 608 regulations.
4. According to the DC Electrical Code, what size overcurrent protection is
required for a 5-ton air conditioner with an MCA of 28 amps?
A. 30 amps
B. 35 amps
C. 40 amps
D. 45 amps
, Answer: C
Explanation: NEC Article 440 requires overcurrent protection at 175% of
RLA or 225% of compressor nameplate, with 40 amps being the standard for
a 5-ton unit with 28 amp MCA.
5. What is the minimum ventilation rate required for a mechanical
equipment room according to DC codes?
A. 0.5 cfm per square foot
B. 1.0 cfm per square foot
C. 1.5 cfm per square foot
D. 2.0 cfm per square foot
Answer: B
Explanation: DC Mechanical Code requires minimum ventilation of 1.0
cfm per square foot for mechanical rooms to prevent refrigerant
accumulation.
6. When brazing copper refrigerant lines, what type of flux should be used?
A. Acid flux
B. Rosin flux
C. No flux
D. Silver-bearing flux
Answer: C
Explanation: No flux should be used when brazing refrigerant lines as flux
can contaminate the system; nitrogen purge should be used instead.
, 7. What is the recommended superheat for a properly operating R-410A air
conditioning system?
A. 8-12°F
B. 10-15°F
C. 15-20°F
D. 20-25°F
Answer: B
Explanation: R-410A systems typically operate with 10-15°F superheat at
the evaporator outlet under normal conditions.
8. According to ASHRAE 15, what is the maximum refrigerant charge for a
direct expansion system in an occupied space without special ventilation?
A. 25 lbs
B. 50 lbs
C. 75 lbs
D. 100 lbs
Answer: A
Explanation: ASHRAE Standard 15 limits refrigerant charge to 25 lbs for
occupied spaces without additional ventilation or refrigerant detection
systems.
9. What is the minimum working pressure for R-410A discharge lines?
A. 250 psig
B. 350 psig
C. 450 psig
Exam | 100 Q&A | Detailed Explanations
Subject/Course: HVAC, Refrigeration, Mechanical Systems, Licensing
Exams
Tags: HVAC License, DCRA, Refrigeration Systems, EPA Certification,
Electrical Codes, Mechanical Codes, HVAC/R, Ductwork, Load
Calculations, Refrigerants
=========================================================
===========================
EXAM QUESTIONS
=========================================================
===========================
1. According to DC mechanical codes, what is the minimum clearance
required between a condenser unit and any obstruction?
A. 12 inches
B. 24 inches
C. 36 inches
D. 48 inches
Answer: C
Explanation: DC Mechanical Code requires a minimum of 36 inches
clearance on all sides of condenser units for proper airflow and service
access.
2. What is the maximum allowable pressure drop in a refrigerant suction line
for a system with a 50-foot equivalent length?
, A. 1 psi
B. 2 psi
C. 3 psi
D. 4 psi
Answer: B
Explanation: Industry standards typically limit suction line pressure drop
to 2 psi or equivalent to 2°F saturation temperature drop for proper system
operation.
3. Which EPA certification is required to handle R-410A refrigerant?
A. Type I
B. Type II
C. Type III
D. Universal
Answer: D
Explanation: R-410A is an HFC refrigerant requiring Universal
certification under EPA Section 608 regulations.
4. According to the DC Electrical Code, what size overcurrent protection is
required for a 5-ton air conditioner with an MCA of 28 amps?
A. 30 amps
B. 35 amps
C. 40 amps
D. 45 amps
, Answer: C
Explanation: NEC Article 440 requires overcurrent protection at 175% of
RLA or 225% of compressor nameplate, with 40 amps being the standard for
a 5-ton unit with 28 amp MCA.
5. What is the minimum ventilation rate required for a mechanical
equipment room according to DC codes?
A. 0.5 cfm per square foot
B. 1.0 cfm per square foot
C. 1.5 cfm per square foot
D. 2.0 cfm per square foot
Answer: B
Explanation: DC Mechanical Code requires minimum ventilation of 1.0
cfm per square foot for mechanical rooms to prevent refrigerant
accumulation.
6. When brazing copper refrigerant lines, what type of flux should be used?
A. Acid flux
B. Rosin flux
C. No flux
D. Silver-bearing flux
Answer: C
Explanation: No flux should be used when brazing refrigerant lines as flux
can contaminate the system; nitrogen purge should be used instead.
, 7. What is the recommended superheat for a properly operating R-410A air
conditioning system?
A. 8-12°F
B. 10-15°F
C. 15-20°F
D. 20-25°F
Answer: B
Explanation: R-410A systems typically operate with 10-15°F superheat at
the evaporator outlet under normal conditions.
8. According to ASHRAE 15, what is the maximum refrigerant charge for a
direct expansion system in an occupied space without special ventilation?
A. 25 lbs
B. 50 lbs
C. 75 lbs
D. 100 lbs
Answer: A
Explanation: ASHRAE Standard 15 limits refrigerant charge to 25 lbs for
occupied spaces without additional ventilation or refrigerant detection
systems.
9. What is the minimum working pressure for R-410A discharge lines?
A. 250 psig
B. 350 psig
C. 450 psig
