Why must a recovery cylinder never be filled to more than 80 percent of its capacity?

Safety · EPA 608 Core. The correct answer, and the reasoning behind it.

Exposure risks, protective equipment, the 80% cylinder limit and nitrogen for leak testing.

The question

Why must a recovery cylinder never be filled to more than 80 percent of its capacity?

• AThe recovery machine cannot push refrigerant above 80 percent
• BWarming liquid expands and could burst the cylinderCorrect answer
• CRefrigerant above 80 percent turns to vapor and vents
• DDOT allows only 80 percent so the cylinder weighs less

Why “Warming liquid expands and could burst the cylinder” is correct

As temperature rises, liquid refrigerant expands. A cylinder that is too full can become completely liquid-filled, and further warming then builds pressure very quickly and can rupture it. Leaving at least 20 percent vapor space prevents this.

Source: EPA: Test Topics

Why the other answers are wrong

• The recovery machine cannot push refrigerant above 80 percent — The limit is about cylinder safety, not machine capacity.
• Refrigerant above 80 percent turns to vapor and vents — Refrigerant above 80 percent does not simply vent; the danger is hydrostatic pressure.
• DOT allows only 80 percent so the cylinder weighs less — The limit protects against rupture, not shipping weight.

Practice more of this

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