Abstract: A rotary valve assembly which includes of a pair of valve parts with flat faces which, when pressed together and rotated, provide valving action between various ports incorporated in one of the valve parts. The first valve part contains two circular arrays of through openings, each of which is connected to a conduit. The second valve part contains several passages which provide communication between various openings of the first valve part and valve ports located in the second valve part. The second valve part also contains one or more passages which provide communication between members of one array of openings. The valve assembly can be effectively used to automate operation of a gas or liquid adsorption system comprising two or more adsorption vessels, the number of vessels being equivalent to the total number of openings in either array. Use of the valve assembly in an adsorption system eliminates the need for many of the valves required in conventional multivessel adsorption systems.

Abstract: A process and a system for producing helium from a helium-bearing feed gas that is purified in a cryogenic processing unit to produce cryogenic crude helium containing at least 10% helium. The cryogenic crude helium is directly introduced into a thermal swing helium refinery where it is refined. Refrigeration is supplied to the refinery by the cryogenic crude helium from the cryogenic processing unit.

Abstract: A process for treatment of a secondary gas including ozone, comprising the steps of:a) adding an adjacent gas including CO.sub.2 to the secondary gas to form a mixture of secondary gas and adjacent gas;b) passing the mixture of secondary gas and of adjacent gas obtained at the end of stage a) into at least one stock of adsorbent, where the ozone is completely or partly adsorbed;c) sweeping the stock of adsorbent with the aid of a desorbing gas including CO.sub.2, and discharging from an outlet of the stock an output gas including ozone, wherein the ozone has a concentration which is higher in the output gas than the ozone concentration of the secondary gas.

Abstract: A process and apparatus for the preparation of a cryogenic fluid in the high purity liquid state, such as liquid argon, liquid helium or liquid nitrogen of high purity, substantially free from at least one of the impurities which it contains. The cryogenic fluid in the liquid state to be purified is placed in contact with an adsorbent permitting the adsorption of at least one of the impurities, and the cryogenic fluid is recovered in the high purity liquid state, characterized in that cooling of at least a proportion of the adsorbent is maintained with purified cryogenic fluid in the liquid state during at least a part of the duration of the stoppage stage separating a purification cycle N and a purification cycle N+1, which are successive.

Abstract: A device for separation of gas by adsorption, of the so-called VSA or MPSA type, comprises, between a utilization line (L) and a source (S) of gaseous mixture to be separated, at least one module (M) comprising in series a reversible rotary machine (R), typically a Roots machine, an adsorber (A) and a shut-off valve (V), the rotary machine (R) being alternately actuated, in one direction during a first phase of pressurization and of production and then, in the other direction, during a second phase of depressurization and desorption. Used particularly in the production of small and medium volumes of oxygen in modular installations.

Abstract: The present invention is a method of selective adsorptively separating nitrogen from oxygen using a crystalline metallosilicate having a ZSM-2 structure with a Si/Al ratio less than 2.0 and a lithium cation exchange of at least 50%, wherein the composition has the chemical formula:M.sub.2/n O:X.sub.2 O.sub.3 :(2.0 to <4.0)SiO.sub.2wherein M=one or more metal cations having a valence of n, and X is selected from the group consisting of aluminum, gallium and boron, preferably aluminum. The method is conducted at a bed temperature in the range of approximately -100.degree. C. to 100.degree. C.

Abstract: A single stage secondary oxygen concentrator for receiving a gas mixture from a first stage oxygen concentrator and a method of use therefor is disclosed. The concentrator includes a first carbon molecular sieve bed and a second carbon molecular sieve bed. A first inlet valve is connected to an inlet of the first carbon molecular sieve bed and a second inlet valve is connected to the inlet of the second carbon molecular sieve bed. A first product outlet valve is connected to the outlet of the first carbon molecular sieve bed and a second product outlet valve is connected to the product outlet of the carbon molecular sieve bed. The oxygen concentrator has control means for controlling a first cycle in which the first carbon molecular sieve bed is being charged with the gas mixture and the second carbon molecular sieve bed is being desorbed.

Abstract: A process for determining the amount of argon contamination present in high purity oxygen employing a combination apparatus including a gas chromatography apparatus, a pressure swing adsorption apparatus, and a conduit connecting the two apparatus to each other. The gas chromatography apparatus can be run with its column at about 70.degree. F. (21.1.degree. C.) or higher. A sample of the high purity oxygen is fed to the pressure swing adsorption apparatus, where a portion of the oxygen is removed, and then the thus modified sample is fed through the conduit to the gas chromatography apparatus. Since some of the oxygen has been removed with the pressure swing adsorption apparatus, the graph generated by the gas chromatography apparatus shows 2 resolved peaks, namely a small argon peak preceding a large oxygen peak, even though the column of the gas chromatography apparatus is not being cooled to cryogenic temperatures with a cryogen.

Abstract: Oxygen is recovered from a hot, compressed oxygen-containing gas, preferably air, by an oxygen-selective ion transport membrane system. Hot, pressurized non-permeate gas from the membrane is cooled and useful work is recovered therefrom by expansion at temperatures below the operating temperature of the membrane. The recovered work is used together with the oxygen permeate product in applications such as oxygen-enriched combustion of liquid fuels, wood pulping processes, steel production from scrap in mini-mills, and metal fabrication operations. Oxygen permeate product can be compressed utilizing a gas booster compressor driven by expansion of cooled, pressurized non-permeate gas.

Abstract: A process for pressure swing adsorption of oxygen from a gas mixture containing at least oxygen and nitrogen to recover an unadsorbed nitrogen enriched product from a plurality of parallel piped adsorbent beds undergoing adsorption, depressurization and repressurization wherein the improvement is conducting a pressure transfer from one bed to another from an intermediate point of the bed finishing adsorption to a point closer to the feed end of a bed that is repressurizing to improve productivity and recovery of nitrogen enriched gas in the process.

Abstract: A PSA method incorporating the invention is applicable to the separation of a preferred gas from a mixture of the preferred gas and a less preferred gas. The PSA method uses an adsorbent bed including one or more layers of O.sub.2 equilibrium selective adsorbents, and comprises the steps of: pressurizing the adsorbent bed to a high pressure with a feed of air to enable the adsorbent bed to adsorb O.sub.2 ; extracting from the bed at bed pressure, a flow of N.sub.2 and storing at least some of the flow in a product tank; desorbing O.sub.2 from the adsorbent bed by feeding void gas in the bed enclosure to a storage tank and venting the adsorbent bed to a low pressure region; purging the adsorbent bed by feeding thereto the void gas from the storage tank; and repressurizing the adsorbent bed to an intermediate pressure with a flow of void gas from the storage tank.

Abstract: The flow rate of a nonadsorbed product gas stream from a multiple unit PSA plant can be reduced in response to a reduced product demand by isolating all units in the plant and inserting an idle step into the adsorption cycle immediately following bed equalization steps of the cycle. In a preferred embodiment, the duration of the idle step is inversely proportional to the percentage reduction in the product demand. To maintain the product gas purity at the desired level, minor adjustments of the idle step duration can be made following adjustment to the idle step in response to a change in product demand.

Abstract: A process for concentrating ozone, which includes switching a plurality of adsorption columns each packed with an adsorbent capable of preferentially adsorbing ozone thereon sequentially to an adsorption step where the adsorbent is maintained at a low temperature to adsorb ozone thereon; a desorption step where the adsorbent is heated to desorb ozone therefrom, and a scavenger gas is introduced in a substantially fixed amount into the adsorption column to discharge the thus desorbed ozone being carried on the scavenger gas; and a cooling step where the adsorbent having completed the desorption step is cooled to the same low temperature level as in the adsorption step. Heating of the adsorbent in the desorption step is carried out depending on the time elapsed after desorption is started or on the ozone concentration of the gas discharged from the adsorption column performing the desorption step. A gas having a predetermined pressure is employed as the scavenger gas in the desorption step.

Abstract: A process for separating a mixture of gases by selective adsorption, in which pressure swing is used to induce both desorption and the flow of gas through at least one simulated moving chromatographic column.

Abstract: A method and apparatus for the purification and collection of hydrogen isotopes in a flowing inert gaseous mixture containing impurities, wherein metal alloy getters having the capability of sorbing non-hydrogen impurities such as oxygen, carbon dioxide, carbon monoxide, methane, ammonia, nitrogen and water vapor are utilized to purify the gaseous mixture of impurities. After purification hydrogen isotopes may be more efficiently collected. A plurality of parallel process lines utilizing metal getter alloys can be used to provide for the continuous purification and collection of the hydrogen isotopes.

Abstract: The present invention relates to the separation of one or more components from a multi-component gaseous stream. The component(s) being separated are relatively small molecular diameter gas components. They are separated by sorption techniques wherein the sorbent is a unique class of layered nanostructure materials, such as carbon nanofibers, characterized as having; (i) a surface area from about 0.2 to 3,000 m.sup.2 /g as determined by N.sub.2 adsorption at -196.degree. C., (ii) a crystallinity from about 5% to about 100%, and (iii) interstices from about 0.335 nm to about 0.67 nm.

Abstract: A method and apparatus for removing oxygen from a crude inert gas containing oxygen as a contaminant is disclosed. The inert gas is passed through a reactor containing an oxidizable material. The reactor is then regenerated via a gaseous reducing agent such as hydrogen. The hydrogen can be generated on site via water or steam hydrolysis.

Abstract: High purity argon is produced by subjecting a two-phase liquid-vapor mixture containing up to 3 volume % of nitrogen and/or up to 5 volume % oxygen to cryogenic temperature swing adsorption in an adsorption bed containing one or more adsorbents selective for nitrogen and/or oxygen at a temperature between the bubble point and the dew point of the two-phase mixture.

Abstract: The present invention is a synthesis, product and process for activated carbon and preferably carbon molecular sieve separation of air to produce a nitrogen product wherein a carbon is partially pyrolyzed, impregnated with a transition metal salt and further pyrolyzed to develop enhanced microporosity. The resulting microporous carbon can then be activated with carbon dioxide or steam and then pore-sized by cracking of hydrocarbons on the carbon to produce a carbon molecular sieve.

Abstract: An adsorbent and a process for its use in removing trace oxygen from an inert gas. The adsorbent comprises a porous reducing support such as activated carbon, carbon black, coal, petroleum coke and titania which is impregnated with about 10% to about 90% by weight of an alkali metal oxide or an alkaline earth metal oxide.

Abstract: Oxygen of uniform purity is produced in a two-bed air-fed oxygen pressure swing adsorption process in which the beds are operated out of phase. The steps of the adsorption cycle include a pressurization/production step and a bed regeneration step, with the bed undergoing regeneration being purged with a low pressure stream of the oxygen-enriched gas produced as the nonadsorbed product of the process. The oxygen concentration in the purged gas effluent is continuously periodically monitored, and the maximum oxygen concentration in the effluent during selected purge steps is compared with the maximum oxygen concentration in the effluent during a previous purge step, and the difference is used to adjust the timing and duration of a purge step following the selected purge step in a manner that reduces the difference between the oxygen concentration in the sequential purge steps.

Abstract: The components of a gas mixture are separated by pressure swing adsorption in a plurality of adsorption vessels. In the first step of the half-cycle adsorption takes place in a first bed while the second bed undergoes countercurrent desorption. At the end of the first step the first bed is vented countercurrently and the first and second beds undergo, as a first bed equalization step, outlet-to-outlet equalization or outlet to both inlet and outlet equalization. The vent step may precede or be concurrent with the first bed equalization step. In a second equalization step the beds simultaneously undergo inlet-to-inlet and outlet-to-outlet equalization. The second bed is then further pressurized with nonadsorbed product gas. The half cycle is then repeated but with the first bed being substituted for the second bed and vice versa.

Abstract: A method of treating a material with ozone including the steps of passing oxygen rich gas from a PSA plant 2 through an ozonizer 4 and then passing the ozonized oxygen thus formed directly back to the PSA plant where the ozone is adsorbed in a bed of silica gel contained within a vessel. During the desorption step nitrogen adsorbed in a bed of zeolite also located in the vessel desorbs the ozone from the bed of silica gel and a nitrogen-ozone gas leaves the PSA plant via a line in the feed end. The material is treated with the nitrogen-ozone gas.

Abstract: A method of separating nitrogen-enriched gas is performed by PSA with the use of an apparatus which comprises a plurality of adsorbers (1, 2), a balance tank (3), and a product receiver (4). The method is characterized by comprising the steps of (a) passing, at a predetermined flow rate, high-purity nitrogen gas from the balance tank (3) to an outlet of an adsorber (2) undergoing regeneration; (b) establishing communication between the outlets of both adsorbers (1, 2) through a pressure equalization line while opening the inlets of both adsorbers to atmospheric pressure; (c) after the above step (b), causing a predetermined amount of high-purity nitrogen gas in the balance tank (3) to reversely pass via the outlet of the adsorber (2) which is to be switched from regeneration to adsorption while also supplying the crude gas through its inlet.

Abstract: There is diclosed a process for purifying hydrogen gas which comprises removing impurities such as nitrogen, oxygen, methane, carbon monoxide, carbon dioxide and moisture contained in a crude hydrogen gas by bringing the crude hydrogen gas into contact under heating with a hydride of a zirconium alloy such as Zr-V, Zr-V-Ni, Zr-V-Cr, Zr-V-Co, Zr-V-Fe, Zr-V-Cu, Zr-V-Ni-Cr, Zr-V-Ni-Co and Zr-V-Cr-Fe. By virtue of using the above Zr alloy hydride, the process enables highly advanced purification of crude hydrogen gas by removing such impurities as above to a level as low as 1 ppb or less in high safety and efficiency at low installation and running costs.

Abstract: A nitrogen PSA system uses a back-fill step only on start-up conditions or when a minor fault has caused the plant to temporarily lose purity. The plant utilizes an oxygen analyzer which controls valves allowing the initiation and cancellation of the back-fill step.

Abstract: A sorbent capable of removing trace amounts of oxygen (ppt) from a gas stream at a high temperature above 200.degree. C. comprising a porous alumina silicate support such as zeolite containing from 1 to 10 percent by weight of ion exchanged transition metal such as copper or cobalt ions and 0.05 to 1.0 percent by weight of an activator selected from a platinum group metal such as platinum. The activation temperature, oxygen sorption and reducibility are all improved by the presence of the platinum activator.

Abstract: The present invention discloses an improved method of producing a low-cost, nitrogen-based inert atmosphere suitable for radiation curing of resins, coatings, etc. from non-cryogenically generated nitrogen. According to the disclosed method, residual oxygen present in non-cryogenically generated nitrogen is converted to either moisture or a mixture of moisture and carbon dioxide by reaction with a reducing gas in a catalytic reactor prior to using the nitrogen-based atmosphere for radiation curing of moisture insensitive materials such as resins and coatings.

Abstract: A process for supplying nitrogen to at least two user stations, whose requirements as to nitrogen purity are different. Compressed air is passed from an air compressor (12) to at least one air treatment station (13) permitting effecting at least one of the following treatments of oil removal, filtering out a major portion of the particles, drying, and bringing the air to the desired temperature. The compressed air is then sent to a centralized gas separation unit (14), so as to produce at the outlet of the unit impure nitrogen of intermediate purity. The gas from the centralized separation unit (14) is directed to at least two utilization lines (3-5), each comprising a local gas separation unit (6-8), in which the gas is again treated, so as to obtain at the outlet of each local separation unit nitrogen of a purity suitable for the uses of each of the user stations (9, 10) at the end of the line.

Abstract: A system for controlling the atmosphere of a container for use in the storage and/or transportation of perishable goods which includes adsorption apparatus for the selective adsorption in whole or in part and in a predeterminded order of any water vapor, carbon dioxide, oxygen or ethylene contained within the atmosphere, a blower for urging the atmosphere to the adsorption apparatus, and a conduiting for returning the controlled atmosphere to the container.

Abstract: An oxygen selective adsorbent and a method for making an oxygen selective adsorbent wherein a porous carbon substrate such as a carbon molecular sieve, activated carbon, carbon black, coal, or petroleum coke, is impregnated with a solution of an acidic species and the impregnated substrate is dried. The oxygen selective adsorbent can be used in a pressure swing adsorption process for the separation of oxygen from nitrogen, for example, in air.

Abstract: The present invention is a nitrogen pressure swing adsorption process for separating gas mixtures containing nitrogen and oxygen, such as air, using a unique gas transfer process step, continuous feed gas introduction and an appropriate isolation step with continued product purge/repressurization to achieve high purity nitrogen product of 99.9% or greater by volume nitrogen, preferably 99.99% or greater by volume of nitrogen.

Abstract: The present invention is a pressure swing adsorption process for separating a more strongly adsorbed gas component from a less strongly adsorbed gas component in a feed gas mixture at higher recoveries and productivity and less capital cost by the use of void space gas recycle, membrane based nitrogen enrichment of feed gas and the elimination of pressure equalization steps. The process is particularly amenable to air separation wherein nitrogen product is recovered and an oxygen byproduct is removed.

Abstract: A filter material based on a polyarylene thioether having repeating units of the formula--[(Ar.sup.1).sub.n --X)].sub.m --[(Ar.sup.2).sub.i --Y)].sub.j --[(Ar.sup.3).sub.k --Z)].sub.l --[(Ar.sup.4).sub.o --W)].sub.p --(I)in which Ar.sup.1, Ar.sup.2, Ar.sup.3, Ar.sup.4, W, X, Y and Z, independently of each other, are identical or different, the indices n, m, i, j, k, l, o and p, independently of each other, are zero or integers 1, 2, 3 or 4, their sum being at least 2, Ar.sup.1, Ar.sup.2, Ar.sup.3 and Ar.sup.4 are arylene systems having 6 to 18 carbon atoms, and W, X, Y and Z are divalent linking groups, selected from --SO.sub.2 --, --S--, --SO--, --CO--, --O--, --CO.sub.2 --, or alkylene groups or alkylidene groups having 1 to 6 carbon atoms is suitable for removing ozone from gases or liquids. The removal proceeds quantitatively, no volatile products being formed.

Abstract: A method for separating gases wherein the gases to be separated are contacted with a particulate composite material with a carbon matrix to selectively adsorb gases. The material contains a microporous phase which is essentially carbon with a microporous volume between 0.1 cm.sup.2 /g and 1 cm.sup.2 /g, which is associated with an amorphous mineral dispersed phase containing an oxide of silicon, aluminum, titanium or magnesium disposed on the carbon phase at a thickness of less than 10 nm.

Abstract: A two stage pressure swing adsorption process is set forth for producing high purity oxygen from a feed air stream wherein carbon dioxide, water and preferably nitrogen are removed in the first stage and wherein an oxygen selective adsorbent is used to adsorb oxygen in the second stage. The oxygen product is recovered upon depressurization of the second stage. The high purity of the oxygen product is achieved by rinsing the oxygen selective adsorbent with oxygen prior to the depressurization step. A key to the present invention is that the effluent streams from the second stage feed and rinse steps are used to regenerate the first stage adsorbent(s) in a specific regeneration scheme.

Abstract: Processes and systems for purifying high purity helium group gas which may have been contaminated with water, oxygen and/or hydrogen during its transmission to customers' sites.

Abstract: A method is disclosed for using a pressure swing adsorption separator system to provide an oxygen-depleted gaseous effluent for injecting into a suitable solid carbonaceous subterranean formation, such as a coalbed, to enhance the recovery of methane from the formation.

Abstract: A two stage pressure swing adsorption process is set forth for producing the less strongly adsorbed component of a feed gas mixture wherein the first stage utilizes a first adsorbent for bulk removal of the more strongly adsorbed component and wherein the second stage utilizes a second adsorbent for trace removal of the more strongly adsorbed component. A further feature of the present invention is that the desorbed gas from the second stage's depressurization step (consisting primarily of the desired less strongly adsorbed component) is recycled to the first stage in order to improve its performance. In a preferred embodiment of the present invention, high purity nitrogen (less than 1000 ppm oxygen, preferably less than 100 ppm oxygen) is produced from an air feed using a kinetically controlled carbon molecular sieve adsorbent in the first stage and an equilibrium controlled metal complex-based adsorbent in the second stage.

Abstract: A method for detection of impurities at very low levels in hydrogen, oxygen or specialty gases comprises the metered mixture with high purity helium and subsequent selective separation of hydrogen, oxygen or specialty gas with the detection of impurities remaining in the helium by ionization spectrometry.

Abstract: A process for separating nitrogen which comprises, with a nitrogen gas separation apparatus of a pressure-swing adsorption type, a gas transfer step between an adsorber having completed an adsorption step with another adsorber having completed a regeneration step. The gas transfer step further comprising discharging part of the gas being transferred out of the system. This process provides, with compact equipment, high-purity product nitrogen with a purity of at least 99.99%, which has been considered difficult to obtain with conventional pressure-swing adsorption apparatuses.

Abstract: A process for separating dioxygen from a gaseous mixture containing dioxygen, which entails:a) absorbing dioxygen by one or more transition metal complexes at a low oxidation state of the formula (A):(L.sub.n (M.sup.+p).sub.m (X.sup.-z).sub.x.sup.mp-xz (A)the absorption causing formation of a peroxo dihapto deoxygenated product complex of the formula (B):(L.sub.n '(M.sup.p+2 O.sub.2).sub.m' (X.sup.-z).sub.x).sup.m'p-x'z(B)b) desorbing oxygen from the complex by electrochemically oxidizing the peroxo dihapto product complex obtained by reaction of the complex of the formula (A) wiht O.sub.2 : andc) recovering the absorbed oxygen.

Abstract: The present invention concerns a polyphase particulate composite material containing a microporous phase which is essentially carbon whose microporous volume is between 0.1 cm.sup.3 /g and 1 cm.sup.3 /g, which is associated with an amorphous mineral dispersed phase essentially consisting of an oxide of silicon, aluminum, titanium or magnesium disposed on the carbon phase, at a thickness of less than 10 nm. The invention is also concerned with a process for the preparation of these composite materials, and the use thereof as a molecular sieve.

Abstract: Process for obtaining nitrogen from air or nitrogen-containing gases by pressure exchange adsorption and desorption on two alternately operated adsorbers filled with carbon molecular sieves, whereby air is passed through the adsorber so that the oxygen is adsorbed and enriched nitrogen is obtained, while at the same time the other adsorber is regenerated by pressure relief, whereby in a first carbon molecular sieve layer (on the air intake side) of the two adsorbers, making up 1/20 to 1/2 of the entire carbon molecular sieve layer, a carbon molecular sieve A is introduced which serves simultaneously for the adsorption of the residual humidity and gas separation, and that in a second (on the air-outlet side) carbon molecular sieve layer a carbon molecular sieve B is introduced serving exclusively for gas separation, and that the carbon molecular sieve A has a relative volume of 3.0 to 3.4 and the carbon molecular sieve B has a relative volume of 2.3 to 2.95.

Abstract: An oxygen-absorbing composition containing particulate annealed electrolytically reduced iron of between about 100 mesh and 325 mesh in an amount of about up to 99.6% by weight, a salt such as sodium chloride in an amount by weight of about up to 3.5%, and optionally a water-attracting and supplying component such as silica gel of a mesh size of between about 30 mesh and 325 mesh in an amount by weight of up to about 80%. A packet for absorbing oxygen including a stain and grease resistant envelope containing the oxygen-absorbing composition. A grease and stain resistant laminate consisting of plies of various plastics and grease and stain resisting paper.

Abstract: Apparatus and process for the production of a purified product gas at a user specified product gas demand from a feed gas containing impurities which includes at least one treatment zone having an inlet and outlet region, a sensing device for detecting a change in product gas demand, a device for generating a first signal, a device for translating the first signal and comparing the same to a standard, and a device for converting the translated signal to a second signal which operates a valve to vary the feed rate of the gas entering the system.

Abstract: A process for producing carbon molecular sieves for the separation of oxygen and nitrogen, whereby finely ground hard coal particles are oxidized with air in a fluidized bed, the coal is then formed after the addition of water and binders and carbonized at temperatures of 800.degree.-900.degree. C., subsequently activated with steam at temperatures of 800.degree.-900.degree. C. and the preliminary product of the low-level activation is treated with carbon splitting hydrocarbons. Starches obtained by reacting agglutinized starches with sulphamates are used as binders.

Abstract: Nitrogen is produced by separating air in a pressure swing adsorption process using a high capacity kinetically O.sub.2 selective material as the adsorbent. An example of such an adsorbent is a carbon molecular sieve made from coconut shell char. Such a coconut shell char having a high oxygen volumetric capacity is provided by crushing and sizing coconut shells to form granules which are then heated in flowing inert gas at a temperature ramp rate of about 2 to 12.degree. C. per minute to a peak temperature of 775 to 900.degree. C. which is then held so that the total heating time is up to 8 hours and thereafter the granular char is cooled in an inert gas atmosphere. The granular char thus produced is kinetically selective for O.sub.2 over N.sub.2 without further modification to narrow the openings of its micropores and has an oxygen volumetric capacity in excess of 8.0 cc/cc at 1 atm. and ambient temperature.