Figure 6-42. - A cutaway view of an automatic ice machine.

Q20. What design factor makes remote refrigeration equipment different from self-contained equipment?

Q21. Reach-in refrigerators are operated at a temperature that falls within what range, in degrees Fahrenheit?

Q22. Reach-in refrigeration units are equipped with what type of evaporator?

Q23. Why are walk-in refrigerators manufactured and constructed in sections?

Q24. Domestic refrigerators come in what two design configurations?

Q25. What are the two types of automatic defrosting in the two-door refrigerator-freezer combination unit?

Q26. What component of a water cooler precools the fresh water line to the evaporator?

Q27. What design factor is the primary difference in the different types of ice machines?

INSTALLATION OF REFRIGERATION EQUIPMENT

Learning Objective: Recall refrigeration requirements and the types of installation for refrigeration equipment.

Utilitiesman are often tasked to installation refrigeration systems. Therefore, it is important for you to understand the basic requirements applicable to the installation of the various types of the equipment.

When installing a refrigeration or air-conditioning plant, you must not allow dirt, scale, sand, or moisture to enter any part of the refrigerant system. Since air contains moisture, its entrance into the circuit should be controlled as much as possible during installation. Most maintenance problems come from careless erection and installation. All openings to the refrigerant circuit - piping, controls, compressor, condensers, and so on - must be adequately sealed when work on them is not in progress. The R-12 refrigerant is a powerful solvent that readily dissolves foreign matter and moisture that may have entered the system during installation. This material is soon carried to the operating valves and the compressor. It becomes a distinct menace to bearings, pistons, cylinder walls, valves, and the lubricating oil. Scoring of moving parts frequently occurs when the equipment is first operated, starting with minor scratches that increase until the operation of the compressor is seriously affected.

Under existing specifications, copper tubing and copper piping needed for installation should be cleaned, deoxidized, and sealed. When there is a question about cleanliness of tubing or piping to be used, each length of pipe should be thoroughly blown out. Use a strong blast of dry air when blowing out, and clean the tubing with a cloth swab attached to copper wire pulled back and forth in the tube until it is clean and shiny. Then the ends of the tubes should be sealed until connected to the rest of the system.

EFFECTS OF MOISTURE

As little as 15 to 20 parts of moisture per million parts of R-12 can cause severe corrosion in a system. The corrosion results from hydrochloric acid formed by R-12 in contact with water. A chemical reaction takes place between the acid and the iron and copper in 6-28