A safety shut-off device is provided for a liquid gas system for vehicles and/or vehicle trailers, in order to avoid an inadvertent release of gas. The device includes an electromagnetic gas valve for supplying/shutting off the gas, an electronic unit for activating the electromagnetic gas valve, and a flow sensor for determining a current gas flow being discharged from a storage tank. Furthermore, the device includes an evaluation unit for comparing the current gas flow to a previous gas flow or to a gas flow which is indicated by the gas consumers and is to be expected. If, during use, the evaluation unit determines a current gas flow which differs by more than a maximum permissible rate of change from the previous gas flow or from an expected gas flow, the electromagnetic gas valve is activated via the electric unit in order to shut off the supply of gas.

The present invention provides methods of reducing friction on a surface of an apparatus that stores or transports a gas, comprising: (a) contacting the surface either directly or through an intermediate organometallic layer with a fluorinated material in a diluent, wherein the fluorinated material has the following structure: ##STR00001##
wherein A is an oxygen radical or a chemical bond; n is 1 to 20; Y is H, F, C.sub.nH.sub.2n+1 or C.sub.nF.sub.2n+1; X is H or F; b is at least 1, m is 0 to 50, p is 1 to 20, and Z is an acid group or an acid derivative; (b) forming a hydrophobic surface layer on the surface; and (c) introducing the gas into the apparatus.

There is provided a method for storing a fluorine-containing nitrogen compound that prevents the progress of a reaction of the fluorine-containing nitrogen compound during storage. A fluorine-containing nitrogen compound containing nitrosyl fluoride and nitroyl fluoride contains or does not contain at least one type among sodium, potassium, magnesium, and calcium as metal impurities. When any of the foregoing is contained, the fluorine-containing nitrogen compound is stored in a container with the total concentration of the sodium, the potassium, the magnesium, and the calcium set to 1000 ppb by mass or less.

The present invention provides treated gravel pack screens comprising a metal surface and a hydrophobic surface layer applied thereto, directly or through an intermediate layer. The surface layer comprises a self-assembled monolayer prepared from a fluorinated material having the structure: ##STR00001##
wherein A is an oxygen radical or a chemical bond; n is 1 to 20; Y is H, F, C.sub.nH.sub.2n+1 or C.sub.nF.sub.2n+1; X is H or F; b is at least 1, m is 0 to 50, p is 1 to 20, and Z is an acid group or an acid derivative. Also provided is a method of reducing deposition of a contaminant on a metal surface of a gravel pack screen, comprising: contacting the surface with the above fluorinated material in a diluent, directly or through an intermediate layer; forming a hydrophobic surface layer on the surface; and introducing a fluid through the gravel pack screen.

A foot valve assembly according to the present invention includes: a cylindrical adapter attached to a lower opening end of a cylindrical pump column configured to accommodate a pump configured to be submerged in a handling liquid, the adapter configured to accommodate a suction port of the pump; a disc-shaped valve disc configured to open and close a lower opening of the adapter corresponding to raising and lowering of the pump; a biasing member that biases the valve disc toward the adapter; and an auxiliary valve configured to open and close corresponding to the raising and lowering of the pump and configured to assist in opening the valve disc when the valve disc is closed.

There is provided a method for storing fluoroalkene in which, even when stabilizers for suppressing reactions of fluoroalkene are not added, the reactions of the fluoroalkene hardly occur and the purity of the fluoroalkene hardly decreases during storage. Fluoroalkene having a bromine atom or an iodine atom in the molecule is at least one type of fluoroethylene represented by a first general formula C.sub.2H.sub.pF.sub.qX.sub.r and fluoropropene represented by a second general formula C.sub.3H.sub.3F.sub.tX.sub.u (X represents a bromine atom or an iodine atom), and contains or does not contain at least one type among manganese, cobalt, nickel, and silicon as metal impurities. When any of the foregoing is contained, the fluoroalkene is stored in a container with the total concentration of the manganese, the cobalt, the nickel, and the silicon set to 1000 ppb by mass or less.

A pressurization method for increasing a pressure within a propellant tank containing hydrogen peroxide H.sub.2O.sub.2. The pressurization method includes irradiating at least some of the hydrogen peroxide H.sub.2O.sub.2 with ultraviolet light emitted by at least one ultraviolet light source. With the UV light, a photolysis is actively provoked which causes the irradiated hydrogen peroxide H.sub.2O.sub.2 to at least partially decompose into water H.sub.2O and gaseous oxygen O.sub.2. Also a filling method for at least partially filling a receiving propellant tank with the pressurization method, a tank assembly, a filling system, and a spacecraft.

A steel is for making containers, such as for reservoirs or tanks for the storage and transport of liquid ammonia.