Private first class

Private first class (PFC) is a military rank held by junior enlisted persons.

United States

United States Army

In the United States Army, recruits usually enter service as a private, in pay grade E-1. Private (E-2), designated by a single chevron, is typically an automatic promotion after six months of service, or for those who have achieved the rank of Eagle Scout in the Boy Scouts or have been awarded the Girl Scout Gold Award in the Girl Scouts of the USA, or have completed 30 semester units of college courses. Private first class (E-3), equivalent to NATO grade OR-3, is designated by a single chevron and a rocker stripe and is more common among soldiers who have served in the U.S. Army for one year or more. Soldiers who have achieved an associate degree or its equivalent are entitled to enter the Army at this pay grade. Advancement from private first class is typically to specialist, although occasionally it may be to corporal.

The rank of private first class has existed since 1866 and, prior to 1919, its insignia consisted of the branch of service insignia without any arcs or chevrons. The Secretary of War approved "an arc of one bar" (i.e., a "rocker") under the branch of service or trade insignia for privates first class on 22 July 1919. From August 5, 1920 to May 28, 1968, the rank insignia for private first class was a single chevron, per War Department Circular No. 303. On May 28, 1968, the insignia was changed to its current form, consisting of a single chevron with one arc.

PFC

PFC may refer to:

Science

Economy

Sports

Football (soccer) clubs

Other uses

Hexafluoroethane

Hexafluoroethane is a fluorocarbon counterpart to the hydrocarbon ethane. It is a non-flammable gas negligibly soluble in water and slightly soluble in alcohol.

Physical properties

Hexafluoroethane's solid phase has two polymorphs. In the scientific literature, different phase transition temperatures have been stated. The latest works assign it at 103 K (−170 °C). Below 103 K it has a slightly disordered structure, and over the transition point, it has a body centered cubic structure.

Table of densities:

Vapor density is 4.823 (air = 1), specific gravity at 21 °C is 4.773 (air = 1) and specific volume at 21 °C is 0.1748 m³/kg.

Uses

Hexafluoroethane is used as a versatile etchant in semiconductor manufacturing. It can be used for selective etching of metal silicides and oxides versus their metal substrates and also for etching of silicon dioxide over silicon. The primary aluminium and the semiconductor manufacturing industries are the major emitters of hexafluoroethane.

Together with trifluoromethane it is used in refrigerants R508A (61%) and R508B (54%).