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US 5,074,146 AGranted
Gas comparison pycnometer
AssigneeMicromeritics Instrument Corporation
InventorsClyde Orr, Ronnie W. Camp, Kathryn H. Gibson
Life of this patent
Estimating the term…
Abstract
A gas comparison pycnometer is disclosed which provides a method and apparatus for determining and checking the accuracy of the volume of a solid substance. The pycnometer is also outfitted with a unique cap assembly which fixes the volume in the pycnometer's sample chamber from run to run. The pycnometer also employs a series of purges with a suitable gas to carry unwanted moisture and vapors out of the system. This pycnometer solves many problems in the prior art by quickly and accurately determining the volume of a solid substance.
Claims29
An apparatus for determining the volume of a solid substance comprising:
- a sample chamber containing said substance;
- an integral expansion chamber connected by a passageway to said sample chamber;
- gas supply means for introducing a gas under pressure into one of said chambers;
- valve means for controlling flow of gas through said passageway;
- vent means for venting either of said chambers to atmosphere;
- means for measuring the pressure of gas within said one of said chambers;
- and
- control means for:
- (a) operating said gas supply means to pressurize with a gas the one of said chambers containing said pressure measuring means;
- (b) operating said pressure measuring means to measure the pressure in said one chamber;
- (c) operating said valve means to allow expansion of said gas through said passageway into said other chamber;
- (d) operating said pressure measuring means to measure the pressure in said connected chambers;
- (e) calculating a first volume of said sample;
- (f) storing said first volume;
- (g) operating said vent means to vent said chambers to atmosphere;
- (h) repeating (a) through (d);
- (i) calculating an additional volume of said sample;
- (j) comparing two or more of said volumes;
- (k) responsive to said compared volumes being within a predetermined tolerance, accepting one of said compared volumes as the volume of said sample;
- and
- (l) responsive to said compared volumes being outside said predetermined tolerance, repeating steps (h)-(j) until said compared volumes are within said predetermined tolerance.
18 more elements
A method for determining the volume of a solid substance contained in a sample chamber of a pycnometer having an integral expansion chamber and a passageway connecting said chambers comprising the steps of:
- (a) pressurizing one of said chambers with a gas;
- (b) measuring the pressure in said pressurized chamber;
- (c) allowing expansion of said gas into said other chamber;
- (d) measuring the pressure in said connected chambers;
- (e) calculating a first volume;
- (f) storing said first volume;
- (g) venting said chambers to atmosphere;
- (h) repeating steps (a) through (d);
- (i) calculating an additional volume of said sample;
- (j) comparing two or more of said volumes;
- (k) accepting one of said compared volumes as the volume of said sample if said compared volumes are within a predetermined tolerance;
- and
- (l) repeating steps (h) through (j) if said compared volumes are outside said predetermined tolerance until said compared volumes are within said tolerance.
10 more elements
A pycnometer apparatus comprising:
- a sample chamber containing a substance;
- an integral expansion chamber connected by a passageway to said sample chamber;
- gas supply means for introducing a gas under pressure into one of said chambers through a gas supply valve;
- expansion valve means for controlling flow of gas through said passageway;
- vent valve means for venting either of said chambers to atmosphere;
- means for measuring the pressure of gas within said one of said chambers;
- and
- control means for:
- (a) operating said supply valve so as to admit gas into said one chamber until the pressure within said one chamber approaches a predetermined fill pressure in said one chamber within a predetermined tolerance of said fill pressure;
- (b) closing said supply valve;
- (c) operating said pressure measuring means;
- (d) generating an error signal if the pressure in said one chamber exceeds said fill pressure by more than said tolerance;
- (e) momentarily admitting additional gas if the pressure in said one chamber is lower than said fill pressure by more than said tolerance;
- (f) repeating functions (b) through (e) until the pressure in said one chamber is within said tolerance;
- and
- (g) operating said expansion valve means to allow expansion of said gas through said passageway into said other chamber.
13 more elements
A method for determining the volume of a substance contained in a sample chamber of a pycnometer having an integral expansion chamber and a passageway connecting said chambers comprising the steps of:
- (a) pressurizing one of said chambers with a gas to establish a predetermined fill pressure in said one chamber within a predetermined tolerance of said fill pressure;
- (b) admitting said gas until the pressure in said one chamber approaches said predetermined fill pressure;
- (c) measuring the pressure in said one chamber;
- (d) generating an error signal if the pressure in said one chamber exceeds said fill pressure by more than said tolerance;
- (e) momentarily admitting additional gas if the pressure in said one chamber is lower than said fill pressure by more than said tolerance;
- (f) repeating steps (b) through (e) until the pressure in said one chamber is within said tolerance;
- (g) allowing expansion of said gas into said other chamber;
- (h) measuring the pressure in said connected chambers;
- (i) calculating the volume of said substance.
6 more elements
A pycnometer apparatus comprising:
- a block of highly thermally conductive material;
- a sample chamber bored into the center of said block and defining an opening of said sample chamber communicating with the exterior of said block;
- an expansion chamber bored into the center of said block and connected by a first passageway to said sample chamber, said expansion chamber positioned in close proximity to said sample chamber;
- means for selectively closing said opening so as to define an identical volume within said sample chamber each time said sample chamber is closed;
- gas supply means for introducing a gas under pressure through an inlet valve into said sample chamber through a second passageway;
- expansion valve means for controlling flow of gas through said first passageway;
- vent means connected to said expansion chamber by a third passageway for venting said expansion chamber to atmosphere;
- means connected to said sample chamber by a fourth passageway for measuring pressure within said sample chamber;
- and
- purging control means for:
- (a) opening said expansion valve means;
- (b) operating said gas supply means to open said inlet valve and pressurize said sample chamber and said expansion chamber with a gas to a pressure above atmospheric pressure;
- (c) closing said inlet valve after pressurization of said chambers;
- (d) waiting for a predetermined period of time;
- (e) opening said vent means to allow said gas to expand to atmosphere;
- (f) repeating functions (b) through (e);
- said passageways being located in the interior of said block.
14 more elements
A pycnometer apparatus, comprising:
- a sample chamber;
- an expansion chamber connected by a passageway to said sample chamber, said sample and expansion chambers being positioned within an integral environment of high thermal conductivity;
- gas supply means for introducing a gas under pressure into one of said chambers;
- valve means for controlling flow of gas through said passageway;
- vent means for venting either of said chambers to atmosphere;
- and
- means for measuring the pressure of gas within said one of said chambers.
4 more elements
A pycnometer apparatus, comprising:
- a sample chamber defining a sample loading opening;
- an expansion chamber connected by a passageway to said sample chamber, said sample and expansion chambers being positioned adjacent to one another within an integral environment of high thermal conductivity;
- means for selectively closing said sample loading opening so as to define an identical volume within said sample chamber each time said sample chamber is closed;
- gas supply means for introducing a gas under pressure into one of said chambers;
- valve means for controlling flow of gas through said passageway;
- vent means for venting either of said chambers to atmosphere;
- means for measuring the pressure of gas within said one of said chambers;
- and
- purging means for repeatedly pressurizing said chambers with a purging gas;
- said passageway being located essentially entirely within said environment.
7 more elements
Dependencies are inferred from the claim text.