This invention relates to improvements in malodorous compositions of matter in conjunction with pressurized air systems to warn persons, such as miners in mines, of danger by smelling the released odor.
The malodorous compositions of matter disclosed in U.S. Pat. No. 3,861,350 used widely available nonflammable solvents which eventually were found to cause ozone depletion of the earth's atmosphere and in U.S. Pat. No. 5,552,088 used nonflammable solvents which had the potential of increasing climate change of the earth's atmosphere. These solvents all contained chlorine, and included trichloro-mono-fluoromethane, trichlorotrifluoroethane, 1,1,1 trichloroethane, methylene chloride, trichloroethylene, and perchloroethylene and/or 1,1,1,2-tetrafluoroethane. Applicants are unaware of any prior art combining trans-1,3,3,3-tetrafluoroprop-1-ene, as a nonflammable solvent, and trans-1-chloro-3,3,3-trifluoropropene, as a flame suppression component, for a malodorous composition of matter for use in a warning system, and which are reduce climate change over the prior art.
This invention comprises an improved warning system having a malodorous composition of matter that uses a mixture that is a nonflammable solvent in conjunction with a suitable mercaptan and an inert gas under pressure. This mixture is trans-1,3,3,3-tetrafluoroprop-1-ene, as a nonflammable solvent, and trans-1-chloro-3,3,3-trifluoropropene, as a flame suppression component.
When this mixture is mixed with a suitable mercaptan and a suitable inert gas under pressure is added, the resulting composition of matter produces a nonflammable blend which eliminates the ozone depletion problem caused by previous formulations as disclosed in U.S. Pat. No. 3,861,350 and the climate change problem caused by the previous formulation U.S. Pat. No. 5,552,088 both of which are incorporated by reference in their entities as if fully set forth herein.
Suitable mercaptans are preferably liquid at ambient temperatures and include methyl mercaptan, ethyl mercaptan, n-propyl and isopropyl mercaptan, butyl mercaptan, both secondary and tertiary, and tetrahydrothiophene.
Other suitable malodorous compounds which may be used to make up a workable malodorous composition of matter are dimethyl sulfide and ethyl iso-propyl sulfide.
Since these malodorous compounds are either flammable or explosive or both, a nonflammable solvent such as a mixture of trans-1,3,3,3-tetrafluoroprop-1-ene, as a nonflammable solvent, and trans-1-chloro-3,3,3-trifluoropropene, as a flame suppression component, is required and is essential because of its climate change reducing nature, in particular reduction of Global Warming Potential (GWP) and no ozone depletion potential (ODP). Further, this mixture has a suitable vapor pressure which is not over 80 pounds per square inch at sea level and at a maximum temperature of 25 degrees Centigrade.
Preferably, the composition of the malodorous composition of matter is a mixture of Ethyl Mercaptan trans-1,3,3,3-tetrafluoroprop-1-ene between more than 11% and less than 56%, and trans-1-chloro-3,3,3-trifluoropropene between less than 56% and more than 11%. Most preferably, the malodorous composition of matter has a composition of Ethyl Mercaptan 33% trans-1,3,3,3-tetrafluoroprop-1-ene and trans-1-chloro-3,3,3-trifluoropropene between which renders the mixture non-flammable. The malodorous composition of matter is then pressurized with an inert gas, preferably nitrogen gas.
The most suitable inert gas for use in the malodorous composition of matter is nitrogen gas. The container for the malodorous composition of matter is charged to an internal pressure of up to 500 pounds per square inch at room temperature with nitrogen gas so that sufficient pressure exists to expel the malodorous composition of matter into pressurized air breathing systems commonly maintained in mines in the United States at about 150 pounds per square inch. Carbon dioxide might also be used.
Containers used for the malodorous composition of matter must be high pressure cylinders with a capability of withstanding up to 500 pounds per square inch of pressure at sea level. Such containers may be equipped with either a high pressure needle valve which has a corrosion resistant seat, or with a ball valve having corrosion resistant capability.
The warning system is created when the container, after being filled with the malodorous composition of matter under pressure of nitrogen gas or carbon dioxide, is then equipped with an adapter and feeder tube means for connection to a valve of a pressurized air breathing system or pressurized pneumatic tool system and is then connected.
An object of this invention is to provide a malodorous composition of matter which is nonflammable and non-explosive and climate change reducing, in particular reduction of Global Warming Potential (GWP) and no ozone depletion potential (ODP).
Another object of this invention is to provide a malodorous composition of matter which can be pressured in a container with an inert gas for delivery to a pressurized air breathing system or pneumatic tool system, thereby forming a warning system.
These and other objects will be more readily understood by reference to the following specification and claims, taken in conjunction with the accompanying drawing.
A suitable malodorous composition of matter which is nonflammable and reduces climate change may be prepared at room temperatures with ethyl mercaptan as the malodorous ingredient and with a mixture of trans-1,3,3,3-tetrafluoroprop-1-ene, as a nonflammable solvent, and trans-1-chloro-3,3,3-trifluoropropene, as a flame suppression component.
About 100 to 500 grams of ethyl mercaptan is placed inside a high pressure cylinder 10, capable of withstanding internal pressures of from 240 to 500 pounds per square inch at sea level, and equipped with a high pressure needle valve 12. The cylinder 10 may have an internal capacity of from 75 to 189 cubic inches.
Then, from 200 to 2500 grams of a mixture of trans-1,3,3,3-tetrafluoroprop-1-ene, as a nonflammable solvent, and trans-1-chloro-3,3,3-trifluoropropene, as a flame suppression component, is added to the ethyl mercaptan in the cylinder 10 as the nonflammable and climate change reducing mixture to form the malodorous composition of matter 13.
Thereafter, nitrogen gas or carbon dioxide 15 under pressure is introduced into the cylinder 10 through needle valve 12 in an amount sufficient to produce an internal pressure of from 240 to 500 pounds per square inch, depending upon the particular capacity of the cylinder 10.
Cylinder 10 is preferably equipped with an adapter 18 whose lower end is threaded in the neck portion of cylinder 10 and closes its inner end. The adapter's upper end is threaded into needle valve 12 whose outer end receives a threaded male hexagonal connector 20. A hexagonal cap nut 22 closes the outer end of connector 20. The filled and capped cylinder 10 may then be stored at ambient temperatures until it is placed in operation.
In use, the cylinder 10 is positioned vertical with the needle valve 12 at the bottom. The cap nut 22 is removed and one end of a feeder tube 24 having a flared threaded fitting 26 is connected to the connector 20. The other end of the feeder tube 24 having a flared threaded fitting 27 is connected to an adapter 28 to pipe nipple 29 of valve 30 of the pressurized air breathing system 32 which is to receive warning. Needle valve 12 is equipped with a handle 34 to open and close it. Upon opening the needle valve 12, all of the liquid contents of the cylinder 10 will be metered into the pressurized air breathing system or pneumatic tool system 32 by metering valve 39 in short amount of time (could be as little as 5 seconds) due to the greater pressure in cylinder 10 in comparison with the air breathing system or pneumatic tool system. A substantial part of the inert nitrogen gas 15 will also be exhausted into the pressurized air breathing system or pneumatic tool system 32 until equilibrium of pressure is reached. Valve 30 of the pressurized air breathing system or pneumatic tool system 32 is then closed and if it is desired to remove the cylinder 10 from its connection to the air breathing system or pneumatic tool system 32, the needle valve 12 is closed and cylinder 10 is separated from air breathing system or pneumatic tool system 32.
For air breathing systems or pneumatic tool systems having a pressure of about 150 pounds per square inch, the above procedure producing a warning system can be performed at ambient temperatures ranging from about 50 degrees F. to about 130 degrees F. without any heating or cooling of cylinder 10 or any special preparation.
The steps of Example 1 are repeated except for using a cylinder 10 equipped with a ball valve 36 having a handle 38 to open and close ball valve 36, instead of a needle valve 12.
The same results are obtained as in Example 1.
The ratio of parts by weight of the liquid malodorous substance and the mixture may vary from 1 part of the ethyl mercaptan to 3 parts of the mixture comprising trans-1,3,3,3-tetrafluoroprop-1-ene, as a nonflammable solvent, and trans-1-chloro-3,3,3-trifluoropropene, as a flame suppression component wherein the amount of trans-1,3,3,3-tetrafluoroprop-1-ene varies from 0.1 parts to 4.0 parts with balance of the mixture being trans-1-chloro-3,3,3-trifluoropropene to equal 1-3 parts of the mixture. The amount of inert gas may vary from 0.1 to 1.0 parts by weight, thereby producing a variance in internal pressure of a 75 cubic inch high pressure cylinder from about 240 pounds per square inch to about 400 pounds per square inch at room temperatures of about 70 degrees F. without adversely affecting the results. Suitable high pressure cylinders which are capable of withstanding such higher pressures must be used.
To use high pressure cylinders of capacities other than 75 cubic inches internally, the various amounts of ingredients may be adjusted in proportion to the increased or diminished capacity of the cylinder so that effective operating pressures may be obtained internally over the temperature range of 50 degrees to 130 degrees F.
However, the proper operation of the invention requires that the internal pressure of the charged cylinder always must be greater than that of the pressurized air breathing system that will use the invention.
Although we have described preferred embodiments of the invention, it is understood that the scope of the invention is not to be limited thereby, but numerous variations in ingredients and procedures are possible without departing from the spirit and scope of the invention as claimed herein.
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Entry |
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William H. Pomroy and Terry L. Muldoon; “Improved Stench Fire Warning for Underground MInes”; United States Department of Interior; Bureau of Mines Information Circular 1985; Information Circular 9016. |