The Storage of Acetylene at High Pressure.
M. Moskowitz, of Indianapolis, an expert of the Prest-O-Lite Company, and a representative of the International Acetylene Association, was recently in Minneapolis investigating the explosion on the premises of the Minneapolis Acetylene Company,
With a view to assisting in a proper understanding of acetylene generation so that if a regulating ordinance is drawn up for Minneapolis it will be in accord with those in other cities of Europe and America, Mr. Moskowitz held a conference with City Attorney Ilealy.
The suggestions, volunteered by Mr. Moskowitz are summed up as follows:
First—That acetylene be generated at a pressure not to exceed 15 pounds per square inch at 70 degrees Fahrenheit, for the reason that free acetylene at a pressure in excess of 15 pounds is liable to decompose spontaneously if heated to a degree that is possible in the apparatus known as pressure generators.
Second—Acetylene, when generated at a pressure under 15 pounds must be in machines permitted by the committee of consulting engineers of the National Board of Fire Underwriters, and all such generators shall be provided with water seals, safety valves, or other automatic apparatus which limits the pressure of acetylene in the generator to 15 pounds per square inch at 70 degrees Fahrenheit.
Third—Every building in which acetylene is manufactured, collected and compressed at pres sures exceeding 15 pounds, shall be fireproof throughout, and be used for no other purpose, nor shall any such building be located nearer than 150 feet to other buildings or structures. No room in any such building shall have any open artificial lights, and every room must be properly ventilated. No room shall be artificially heated other than by steam or hot water and no open fire or flame shall be permitted.
Fourth—The transportation, storage, sale and use of acetylene compressed not exceeding 300 pounds to the square inch, shall be allowed within the city limits when such gas is dissolved in acetone or other approved solvent and simultaneously absorbed in porous material and compressed in steel cylinders, tanks, or receptacles of approved design and construction.
The explosions in St. Paul and Minneapolis originated in so-called “pressure generators,” said Mr. Moskowitz. “This type of apparatus is prohibited in Europe and in America wherever the matter has been given legislative attention. The International Acetylene Association, Union Carbide Company, and the National Board of hire Underwriters, through their experimental station, have all condemned the generation of acetylene at pressures in excess of 15 pounds, because in such apparatus the gas is in a free state at pressures above one atmosphere per square inch, and if carbide gets unduly heated, which is always possible in such apparatus, the gas becomes ignited and dissociation takes place with destructive effect and consequent explosion.”
Mr. Moskowitz stated that the proper method for gas generation is to utilize approved generators, in which carbide is immersed in an excess of water permitting cool generation and at pressures not exceeding three or four ounces per square inch. After such generation the gas is sent to regulation gas holders from which it is drawn through suitable drying and purifying devices by suction into three-stage gas compressors where the gas is compressed by steps through inter coolers so as to kep cool until ready to enter the tanks at requisite pressures.
“These tanks arc packed with asbestos disks,” he explained, “and the gas is rendered absolutely safe by being dissolved in a liquid called acetone which has the peculiar property of absorbing 250 times its own volume at the pressure to which the tanks are finally charged. In use the gas is released from the liquid, which is held in suspension in the porous asbestos, when tanks are opened to consuming devices on railway coaches, automobiles, signal lights, etc.”
As for the ordinary form of acetylene house generators, Mr. Moskowitz said they were In an absolutely different category from pressure generators, as such house machines are not operated at pressures in excess of a few ounces, and are necessarily equipped with escape pipes and pressure reliefs constructed strictly in accordance with the rules of the National Board of Fire Underwriters and have been installed in from 300,000 to 400.000 homes throughout the country displacing kerosene and gasoline lamps, which he claims constitute a greater fire risk.