FEP (fluorinated ethylene propylene) is a tough, flexible copolymer of tetrafluoroethylene and hexafluoropropylene. It is often used for flexible tubing and fluid processing equipment when chemical resistance, high purity, and low stiffness are required. FEP has outstanding electrical properties and UV resistance.

The two columns on the PT chart give the liquid and vapor pressures at the listed temperatures. Single component refrigerants and azeotropic blends have bubble points and dew points equal to each other, and we simply call this the boiling point. When there is only one column on the PT chart, low glide blends would have very similar numbers in the two columns, and often the PT chart will only have ...

A single component refrigerant always had a "boiling point." Zeotropic blends change composition when they boil or condense, and therefore have a continuously changing boiling point. The most useful temperatures to know are where the boiling starts and ends. Bubble point and dew point are terms used in the chemical industry to define these two temperatures.Bubble point is the temperature where the...

There are several reasons for bubbles in the sight glass. If one of the traditional refrigerants showed vapor in the sight glass it often meant there wasn't enough liquid refrigerant being fed to the valve, and more refrigerant was added to the system.Blends could show flashing for the same reason, however, they can also flash when there is plenty of liquid in the receiver. Ironically, this liquid...

It depends. Studies were done a few years ago to show how higher glide blends behave during leakage and they showed significant fractionation, which affected the properties of the blend. When the system was topped off, the properties came back close to original. The cycle was repeated to see how many times the system could leak before topping off became a problem (the recommendation was not more t...

You can feed vapor, however, at any point in time the compressor will be seeing the wrong composition gas. At first the vapor will be rich in the higher pressure, higher capacity component. This will cause high discharge pressure and temperature, high motor amps, etc. As the cylinder empties, the compressor will see the lower capacity gas which is left behind, changing the operating conditions the...

In a cylinder, a zeotropic blend will have a different vapor composition sitting above the bulk of the liquid. If you remove this vapor, you will: 1) take the wrong composition refrigerant out of the cylinder, and 2) leave behind the wrong composition refrigerant for future use. Liquid must be removed from the cylinder in order to avoid this fractionation effect. Somewhere between the cylinder and...

To begin, HFCs (134a and 404a / 507) MUST have some of the mineral oil replaced with polyolester (POE). Most manufacturers recommend less than 5% residual mineral oil, although that is an arbitrary number and recent studies have show larger amounts of residual mineral oil will still work fine. Some blends contain hydrocarbons, which help with mineral oil circulation even though the HFC blend will ...