THE INJECTOR AND PERPETUAL MOTION


| May/June 1983



Boiler

108 Garfield Avenue Madison, New Jersey 07940

How many times have we all watched the man on the engine operate the injector to fill the boiler? There would be some steam coming from the overflow followed by some water then that unmistakable sound of an injector working. Steam from the boiler was being used to put water into the same boiler. Isn't that perpetual motion? Not quite, as we shall see.

The principles involved and their discovery go back many years to perhaps as far as Bernulli and Venturi. If we are not careful, however, we'll be having Adam and Eve as the inventors of the atom bomb. So let us begin with outlining just what it is that the injector does. That is, let's dissect the steps.

First, it must draw water from the supply tank and bring it to the injector. We can call that priming although many will recognize it as lift. Then the pressure is increased to something above that of the boiler onto which the water is to be injected. For the first part, the prime or lift, we can thank the Marquis Mannuary d'Ectot, who in 1818, was granted a French patent for a steam jet apparatus for pumping water from one height to another. Or, said another way, from one pressure to another.

His device contained all of the components that we now associate with an injector. That is, a combining tube and a delivery tube. But he was not thinking of a boiler feed device. It was Henri J. Giffard that put it all together and was the one to receive a patent from the French government in May, 1858, for a boiler feed device. At first his development was looked upon with skepticism for it was thought that he was trying to invent a perpetual motion machine. Truth did triumph and he received an award from the Academy of Science in Paris; their mechanical grand prize for 1859.

But just what had prompted M. Giffard to develop such a device? But of course it was for his airship! True. Giffard is the inventor of the dirigible. The steer able balloon or dirigere from the Latin. On September 24, 1852, he flew his 143 foot long by 39 foot diameter cigar shaped balloon powered by a 3 horsepower steam engine weighing 350 pounds some seventeen miles. As we all know, it really was necessary for internal combustion engines having much greater horsepower to weight ratios to be developed before flight was to become completely practical. But, as Giffard was a man of great technical capability it is fitting that he should be the one credited with devising a boiler feed device of such physical simplicity but of such thermodynamic complexity.