In 1797 the first known application experiment for lifting fluids with compressed gas in a laboratory was conducted in Germany. In 1846 an American engineer utilized compressed air to lift oil from wells in Pennsylvania.

20 years later the first US patent was registered for a system called the oil ejector. Gas was injected through the annulus and into the production string via an open 'goose neck' ejector positioned into the flow stream.

From 1864 to 1900 the era consisted of lifting by compressed air injected through the annulus or tubing. In addition to oil production several flooded mine shafts were unloaded using this method.

In this era numerous patents were applied for and issued, but it took nearly 20 years before gas lift became an acceptable lifting method. From 1929 -1945 nearly 25,000 different flow valves were patented. More efficient rates of production as well as proration caused a continuing development of flow valves.

Since the end of world-war II the pressure operated valve has practically replaced all other types of gas lift valves. The first WL retrievable gas lift valve was introduced in 1957. Kick-off valves were next employed to provide for means to for closing off gas after a lower valve was uncovered.

These pressure differential spring valves were operated with approx. 100 psi differential pressure. This kick-off valve was the crude forerunner of modern gas lift flow valves. Note that in the early days gas lift was predominantly used to allow dead wells to flow.

With the introduction of the bellows charged gas lift valve in 1940 (W.R. King patent) gas lifting of low pressure wells with a controlled change in the surface injection pressure was achieved. King had good insight into valve construction when he designed this valve. He recognized the need for complete bellows protection, including an anti chatter mechanism.

The success of the King valve is evidence by the fact that the basic principles used in the design were quickly adopt by almost all valve manufacturers and are still used with little modification today.

Note that these valves were prone to leakage and not qualified as well barriers. In today's market were gas lift is predominantly used to boost (enhance) production from live pressurized wells, valve requirements has changed.

PTC is part of the new era valves being qualified as fully integrated barriers in the tubing string and with erosion protected metal/metal seal areas.