2 Refrigerant Pressures and Pressure-Temperature Charts Free Online FlashCards

How does pressure affect a refrigerant’s saturation temperature?

For a given refrigerant, increasing pressure raises its saturation temperature, and decreasing pressure lowers it.

What does a refrigerant P–T chart show?

It translates between a refrigerant’s saturation pressure and saturation temperature during boiling or condensing.

Can a P–T chart alone confirm correct refrigerant charge?

No. A P–T chart describes saturation, but does not by itself show whether the system is correctly charged or operating properly.

What is temperature glide in a refrigerant blend?

Temperature glide is the temperature change some refrigerant blends undergo while evaporating or condensing at nearly constant pressure.

What system conditions do suction and discharge pressures reflect?

Suction pressure reflects conditions around the evaporator; discharge or condensing pressure reflects conditions around the condenser.

Why is pressure alone not a reliable way to diagnose or charge a system?

No single pressure is correct for every system or every condition. Compare readings with manufacturer specifications and operating conditions, using temperatures and other relevant measurements; pressure alone is not a reliable diagnosis or charging method.

What can coexist at refrigerant saturation?

At saturation, liquid and vapor can coexist.

Which refrigerant data should you use on a P–T chart?

Use the column or data for the refrigerant in the system; different refrigerants have different pressure–temperature relationships.

What pressure reference does the cited Sporlan chart use?

The cited chart reports psig at sea level. Gauge pressure is relative to atmospheric pressure; absolute pressure includes atmospheric pressure.

Which saturation temperature is used to determine superheat?

Use the vapor saturation temperature when determining superheat.

Which saturation temperature is used to determine subcooling?

Use the liquid saturation temperature when determining subcooling.

What is the dew point for a refrigerant blend?

The dew point is the saturated-vapor boundary; use it when calculating superheat.