Sorption analysis apparatus and method

Claim 2

In an apparatus for selectively indicating the surface area and the pore volume distribution of a sample of porous material in a sample flask in response to the quantity of gas adsorbed or desorbed by the sample when the sample and the gas are at a predetermined temperature in the sample flask and the gas is at a predetermined pressure in the sample flask; temperature control means for maintaining a sample flask and a sample and a gas within said sample flask at a predetermined temperature; means for substantially evacuating the atmosphere within said sample flask; opEration control means for changing the quantity of said gas within said sample flask by successive increments of gas, the amount of each of said increments of gas being responsive to the adsorbed or desorbed quantity of said gas within said sample flask resulting from a previous one of said increments of gas and the total quantity of gas changed by all of said increments of gas being sufficiently large to cause said gas within said sample flask to be at a predetermined pressure; and indicating means responsive to said total quantity of gas changed by all of said increments of gas for selectively indicating the surface area and the pore volume distribution of said sample.

Claim 3

The apparatus of claim 1 in which said operation control means is operative to change the quantity of said gas by selectively adding said increments to said sample flask or removing said increments from said sample flask.

Claim 4

The apparatus of claim 1 in which said operation control means is operative to select a plurality of said predetermined pressures in certain predetermined sequence.

Claim 5

The apparatus of claim 1 in which said sample flask is one of a plurality of sample flasks positioned in a mounting means for mounting said plurality of sample flasks, in which said temperature control means is simultaneously operative with respect to all of said sample flasks, and in which said operation control means and said indicating means are selectively operative with respect to each of said plurality of sample flasks.

Claim 6

The apparatus of claim 4 including means for indicating the one of said plurality of sample flasks with respect to which said operation control means and said indicating means are operative.

Claim 7

The apparatus of claim 4 including means responsive to a leak in said mounting relative to one of said plurality of sample flasks for causing said operation control means to be inoperative as to said one of said plurality of same flasks.

Claim 8

The apparatus of claim 1 in which said operation control means includes a first means for changing the quantity of a first gas within a first sample flask in successive increments of gas and a second means including said evacuating means for simultaneously removing substantially all of a second gas from a second sample flask.

Claim 9

The apparatus of claim 7 in which said second means removes said second gas from said second sample flask at successively different rates and including heating means for heating said second sample flask and a sample within said second sample flask.

Claim 10

The apparatus of claim 8 including means responsive to said rates for rendering said second means inoperative when any of said rates is in excess of a predetermined rate.

Claim 11

The apparatus of claim 7 in which said second means includes a mechanical vacuum pump, an oil diffusion pump and a cold trap selectively operative to remove said second gas from said second sample flask.

Claim 12

The apparatus of claim 7 in which said second sample flask is one of a plurality of second sample flasks and in which said second means simultaneously removes a gas from all of said plurality of second sample flasks.

Claim 13

The apparatus of claim 7 in which said operation control means includes a gas supply means for supplying a replacement gas to said second sample flask.

Claim 14

The apparatus of claim 1 in which said gas is selectively one of an available plurality of gases.

Claim 15

The apparatus of claim 1 in which said temperature control means includes a vessel for receiving liquid nitrogen, level sensing means for sensing the level of liquid nitrogen in said vessel, and transfer means responsive to said sensed level of liquid nitrogen in said vessel for transferring liquid nitrogen from a storage means for liquid nitrogen when said level of liquid nitrogen is below a predetermined level, and in which said operation control means raises said vessel from a first position to a second position in which said sample flask is partially immersed in said liquid nitrogen.

Claim 16

The apparatUs of claim 14 including gas absorbing means immersed in said liquid nitrogen for determining a reference saturation pressure of liquid nitrogen.

Claim 17

The apparatus of claim 14 in which said operation control means is responsive to said pressure of said gas within said sample flask relative to a reference pressure to provide a successive increment of said gas at a pressure proportional to said sample flask gas pressure, and including reference pressure means for providing said reference pressure, said reference pressure means having an enclosure positioned within said liquid nitrogen, an adsorbing means for adsorbing gases within said enclosure, and pumping means for removing gases from said enclosure and said adsorbing means.

Claim 18

The apparatus of claim 14 including a container means positioned in said liquid nitrogen, a predetermined quantity of a gas in said container means, and means responsive to the pressure of said gas for continuously indicating the temperature of said liquid nitrogen as indicated by the pressure of said gas.

Claim 19

The apparatus of claim 14 in which said storage means is a closed container and in which said transfer means increases the pressure of a second gas above liquid nitrogen in said storage means to cause liquid nitrogen to pass from said storage means to said vessel.

Claim 20

The apparatus of claim 14 including closing means response to said operation control means for selectively closing said vessel with said sample flask within said vessel.

Claim 21

The apparatus of claim 1 including a valve means operative to provide said increments of gas, said valve means being made selectively operative or inoperative in response to corresponding distinct electrical pulses provided by said operation control means, and said valve means being maintained operative or inoperative between said electrical pulses by position maintaining means.

Claim 22

The apparatus of claim 20 in which said valve means includes a plunger having a lower end movable within a cavity which is formed in a base and which is continuous with two gas passages formed in said base, said lower end being positioned to close one of gas passages when said valve means is inoperative.

Claim 23

The apparatus of claim 21 including gas flow restricting means positioned in one of said gas passages to restrict the rate of flow of a gas through said gas passage.

Claim 24

The apparatus of claim 22 wherein said flow restricting means is positioned to be in proximate contact relation with said lower end when said one gas passage is blocked.

Claim 25

The apparatus of claim 20 in which said valve means is one of a plurality of valve means which are operative to control the flow of said gas through a plurality of passages and in which all of said plurality of passages are formed in a single metal block.

Claim 26

The apparatus of claim 1 in which said increments of gas flow through a passage formed in a block of metal maintained at a predetermined temperature by a heating means.

Claim 27

The apparatus of claim 1 in which said operation control means is responsive to a power means being operative and including means responsive to said power means becoming inoperative for causing said operation control means to become inoperative until said power means is again operative.

Claim 28

The apparatus of claim 1 in which said operation control means includes a programmed computer.

Claim 31

The method of claim 28, wherein said second amount of gas is directly proportional to the extent of difference of adsorption or desorption of said first amount of gas and a certain desired amount of adsorption or desorption.

Claim 32

The method of claim 28, wherein: said step of establishing a first amount of gas comprises the steps of establishing an initial predetermined pressure of said gas in a measuring volume selectively isolated from said receptacle; and then establishing gas flow communication between said measuring volume and said receptacle; and then determining a first equilibrium pressure attained in said measuring volume and said receptacle; said step of establishing a second amount of gas comprises the steps of initially establishing a second predetermined pressure of said gas in said selectively isolated measuring volume, said second predetermined pressure determined as a function of the extent by which said first equilibrium pressure differs from a certain desired equilibrium pressure; and then establishing gas flow communication between said measuring volume and said receptacle; and then determining a second equilibrium pressure attained in said measuring volume and said receptacle; and maintaining said measuring volume at a constant predetermined temperature during all of the foregoing steps.

Claim 37

The method of claim 32, wherein said predetermined rate of change of measured pressure is substantially zero.

Claim 38

In an apparatus for selectively indicating the surface area and the pore volume distribution of a sample of porous material in a sample flask in response to the quantity of gas adsorbed or desorbed by the sample when the sample and the gas are at a predetermined temperature in the sample flask and the gas is at a predetermined pressure in the sample flask; temperature control means for maintaining a sample flask and a sample and a gas within said sample flask at a predetermined temperature; means defining a measuring volume for receiving a quantity of said gas; evacuation means; first valve means connected in fluid flow circuit between said measuring volume and said evacuation means; second valve means connected in fluid flow circuit between said measuring volume and the sample flask; third valve means connected in fluid flow circuit between said measuring volume and a source of said adsorbable or desorbable gas; means maintaining said measuring volume, said first valve means, said second valve means, and said third valve means at a constant predetermined temperature; operation control means operatively connected with said first, second, and third valve means and operative to change the quantity of said gas within said sample flask by successively operating said first or third valve means to provide an initial incremental pressure differential within said measuring volume and by then opening said second valve means to communicate such initial incremental pressure differential with said sample flask; pressure responsive means operative to measure the equilibrium pressure of gas within said sample flask after said communication of said initial incremental pressure differential; said operation control means being responsive to said measured pressure and also to a predetermined desired pressure to provide at least one subsequent incremental pressure differential of gas within said measuring volume, and to communicate said subsequent incremental pressure differential with said measuring flask; the amount of said subsequent increment being proportional to the amount of difference between said measured pressure and said predetermined desired pressure and the total of all of said increments being sufficiently large to cause said gas within said sample flask to be at said predetermined desired pressure; and indicating means responsive to said measured pressures of all of said increments of gas for selectively indicating the surface area and the pore volume distribution of said sample.

Claim 39

In an apparatus for selectively indicating the surface area and the pore volume distribution of a sample of porous material in a sample flask in response to the quantity of gas adsorbed or desorbed by the sample when the sample and the gas are at a predetermined temperature in the sample flask and the gas is at a predetermined pressure in the sample flask; temperature control means for maintaining a sample flask and a sample and a gas within said sample flask at a predetermined temperature; means defining a measuring volume for receiving a quantity of said gas; evacuation means; first valve means connected in fluid flow circuit between said measuring volume and said evacuation means; second valve means connected in fluid flow circuit between said measuring volume and the sample flask; third valve means connected in fluid flow circuit between said measuring volume and a source of said adsorbable or desorbable gas; means maintaining said measuring volume, said first valve means, said second valve means, and said third valve means at a constant predetermined temperature; operation control means operatively connected with said first, second, and third valve means and operative to change the quantity of said gas within said sample flask by successively operating said first or third valve means to provide an initial incremental pressure differential within said measuring volume and by then opening said second valve means to communicate such initial incremental pressure differential with said sample flask; pressure responsive means operative to measure the equilibrium pressure of gas within said sample flask after said communication of said initial incremental pressure differential; said operation control means being responsive to said measured pressure and also to a predetermined desired pressure to provide at least one subsequent incremental pressure differential of gas within said measuring volume, and to communicate said subsequent incremental pressure differential with said measuring flask; the amount of said subsequent increment being proportional to the amount of difference between said measured pressure and said predetermined desired pressure and the total of all of said increments being sufficiently large to cause said gas within said sample flask to be at said predetermined desired pressure; and indicating means responsive to said measured pressures of all of said increments of gas for selectively indicating the surface area and the pore volume distribution of said sample.

Claim 40

The apparatus of claim 34, wherein said means defining a measuring volume comprises a block of metal having a passage formed within, and means operative to maintain said block of metal at said fixed predetermined temperature.

Claim 41

The apparatus of claim 34, wherein each of sAid valve means comprises: an annular valve seat surrounding a valve orifice; housing means enclosing a volume on a first side of said valve seat except for a valve member passageway positioned in spaced apart aligned relation with said valve seat; a valve closure member extending through said valve member passageway in fluid tight sealing relation with said housing means for reciprocal movement into and out of sealing contact with said annular valve seat; means selectively operative in response to said operation control means to impart only reciprocal movement to said valve closure member; a first passage communicating with said first side of said valve seat; and a second passage communicating with said valve orifice.

Claim 42

Apparatus as in claim 36, further comprising flow restricting means disposed in the second passage of said third sample valve closely proximate to the location of said sealing contact between said annular valve seat and said valve closure member.

Claim 43

Apparatus as in claim 34, wherein said pressure responsive means is responsive to the rate of change of gas pressure to provide said measurement of equilibrium pressure when said rate of change is a predetermined rate of change.