Eternal flame for John F. Kennedy moved temporarily

WASHINGTON (CNN) -- The eternal flame dedicated to John F. Kennedy at Arlington National Cemetery has been moved to a temporary location, according to a release from the cemetery.

This is only the second time a temporary burner has been used at the gravesite. The first occurred when Kennedy was laid to rest, 49 years ago on November 25, 1963, when a temporary burner was used until 1967.

The flame will continue to be eternal - by burning on the temporary burner - while the permanent burner is "undergoing significant upgrades to make the flame system more modern, energy efficient and easier to maintain," the press release announces.

The upgrades include new gas lines and an energy-efficient gas management system, as well as a new burner.

Kennedy became the fourth president assassinated when he was shot and killed in Dallas, Texas on November 22, 1963. His state funeral took place three days later on November 25.

Before the funeral, first lady Jacqueline Kennedy instructed the cemetery to "mark the president's grave with an eternal flame similar to that of the French Unknown Soldier in Paris."

According to the cemetery, the Washington Gas Company was given one day to design a propane-fed torch that could be lit during Kennedy's funeral. During the state funeral, the first lady and Robert Kennedy, the president's brother and Attorney General, lit the temporary eternal flame.

After the funeral, a permanent burner was designed.

"The burner is a specially designed apparatus created by the Institute of Gas Technology of Chicago," the cemetery says on their website. "A constantly flashing electric spark near the tip of the nozzle relights the gas should the flame be extinguished by rain, wind or accident. The fuel is natural gas and is mixed with a controlled quantity of air to achieve the color and shape of the flame."

The upgrades to the burner are expected to take three weeks, at which time the flame will be relit.