A restaurant near the ocean has lost two evaporator coils in five years, each to tiny pinholes scattered through the copper tubing rather than at any joint. What condition produces that pattern?
Correct Answer
A) Corrosion attacking the tubing from outside in a chemically aggressive atmosphere
Pinholes scattered across a coil rather than clustered at joints point to attack from the outside. Salt-laden and chemically contaminated air, common near the coast and near kitchens and cleaning chemicals, drives corrosion that tunnels through thin copper tube walls and produces the small, widely spread perforations technicians call pinholes. Coated coils and better washdown practice are what extends the life of a replacement.
Why This Is the Correct Answer
Copper tubing in a corrosive atmosphere is attacked from the outside, and the damage takes the form of many tiny perforations spread over the coil rather than a single failure at a joint. Coastal salt air and airborne chemicals from kitchens or cleaning are the usual drivers. Because the attack is external and general, replacing the coil with a coated one addresses the cause rather than only the symptom.
Why the Other Options Are Wrong
Option B: Refrigerant velocity gradually eroding the inside wall of the tubing
Erosion from refrigerant velocity attacks specific locations such as the outlet of a metering device, not the whole coil evenly.
Option C: Acid formed in the oil eating through the tube wall from the inside
Acid in the oil attacks motor windings and bearing surfaces from within the circuit. It does not perforate evaporator tube walls in a scattered pattern.
Option D: Vibration from the fan motors work hardening the tube wall until it splits
Vibration failures show up as splits and rub-throughs at fixed points where tubing contacts a bracket, not as pinholes distributed across the coil.
Memory Technique
Many small holes everywhere means the air did it. One hole in one place means the machine did it.
Reference Hint
Coastal and chemically loaded air corrodes copper coils from the outside, producing scattered pinhole leaks.
More epa-608-type-2 Questions
A walk-in cooler condensing unit holds a full charge of twenty-five pounds of R-404A, which is below the fifty pound threshold that brings an appliance under the leak repair provisions. What still applies to this unit?
An office building has thirty water source heat pumps on a common water loop, and each one left the factory assembled, hermetically sealed and charged with four pounds of R-410A. How is one of those units classified?
A data sheet for an unfamiliar refrigerant lists a boiling point of about fifty-five degrees Fahrenheit at atmospheric pressure. What does that tell a technician holding Core and Type II certification?
A technician holds Core, Type I and Type III certification and is sent to recover the charge from a twenty ton rooftop unit charged with R-410A. What does that combination of sections allow on this job?
A fleet garage technician holds only the vehicle air conditioning certification issued under Section 609 and is asked to recover the charge from the shop's own rooftop air conditioner. What does that credential allow?
A split system's outdoor unit, indoor coil and the line set the installer ran and brazed between them are being considered. For the purposes of the refrigerant rules, what makes up the appliance here?
On a new installation the line set is brazed to a factory charged outdoor unit and an indoor coil shipped under a nitrogen holding charge, with the outdoor unit's service valves still closed. What does the recovery requirement call for before that brazing?
A rooftop unit's data plate has weathered until the charge figure cannot be read, and the technician needs the full charge to place the appliance under the evacuation and leak provisions. Where should that figure come from?
A computer room air conditioning unit holds forty pounds of R-407C and connects to a remote air cooled condenser through refrigerant piping run and brazed by the installer. How is that unit classified?
A shop's office manager, who holds no technician certification, is sent to a supply house to pick up a new recovery machine for the commercial crew. What does the sales restriction require at that counter?
People Also Study
Business & Financial Management
120 questions · 70% to pass
Contract Administration
60 questions · 70% to pass
Project Management
60 questions · 70% to pass
Related Study Resources
Previous Question
A leak above the action level is found on an industrial process refrigeration system, and the repair cannot be made without shutting down the process the system serves. How much time does the regulation allow for that repair?
Next Question
A technician has finished pulling the liquid charge out of a large system, and the sight glass in the recovery hose has gone clear. What still has to be done before the system may be opened?