Gemini VII
Rapid & Precise Surface Area Analysis
- Gemini utilizes a unique adaptive rate dosing algorithm and is a special case of the static volumetric technique
- Gemini’s capabilities lie in its unique and innovative design which makes for not only a reliable and accurate instrument but also offers an easy to use operating system with intuitive reporting
- Rapid surface area measurements with precision &Â No thermal-diffusion errors
- Capable of measuring low surface area materials with N2
- Common mode rejection of free-space error effects
- Three model options to accommodate needs
Micromeritics’ Gemini VII 2390 Series of surface area analyzers rapidly and reliably produces accurate and repeatable surface area and porosity results. Their low cost, speed, simplicity of use, reliability, and ruggedness have earned the Gemini a place in laboratories worldwide as an essential tool in research and quality control environments.
Features and Benefits:
The clear advantage of the Gemini’s capabilities lie in its unique and innovative design which makes for not only a reliable and accurate instrument but also offers an easy to use operating system with intuitive reporting.
- Innovation: Gemini utilizes a unique adaptive rate dosing algorithm and is a special case of the static volumetric technique. Speed and sensitivity are unsurpassed by other static volumetric instruments.
- Accuracy: Micromeritics invented the balance tube design, which negates freespace errors introduced by thermal gradient variations or by initial mismeasurement of free space. The Gemini permits low surface area measurements without requiring krypton and the use of a servo valve controls the rate of gas flow into the sample tube to accurately attain target pressures without pressure overshoot.
- Faster Results: The sample controls the rate at which the gas is delivered thus accelerating delivery of the analysis gas. This results in a surface area analyzer that is as fast as the physics of adsorption allows. How-to videos provide on-screen instruction on instrument operation reducing training time for new users. Easy-to- follow installation videos and system verification tests ensure optimum performance and reliability.
- Flexibility: Three choices of software control: Embedded software allows for operation without an external PC through the keypad Windows 7 or greater operating system Gemini VII Confirm™ 21 CFR Part 11 option for regulated pharmaceutical applications
Three Instrument Options:
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- Gemini VII 2390a: Ideal for rapid and accurate surface area determinations by single-point and multipoint BET and Langmuir methods. In addition, provides standard methods for total pore volume, micropore analysis by the t-method, and much more. Included is the capability to determine statistical thickness surface area (STSA) of carbon blacks. (Refer to ASTM D 6556, ASTM D 3765, ISO/DIS 18852.2, or ISO/CD 4652-2/3.)
- Gemini VII 2390p: Provides additional precision with the addition of a saturation pressure (Po) tube that allows the system to monitor the saturation pressure of the adsorptive on a continuous basis during an analysis. This design feature permits a rapid measurement of the adsorption isotherm to near-saturation, as well as determination of pore size distribution.
- Gemini VII 2390t: Has all the ability of the 2390p, including a Po tube, with the addition of a larger Dewar and longer sample tubes for extended analyses. This provides the additional capability to measure the total adsorption-desorption process. With this data set, one can perform a BJH or Dollimore-Heal pore size distribution using up to 1000 data points.
Specifications
Applicability
| Surface Area | From 0.1 m², total; From 0.01 m²/g, specific |
| Pore Volume | 4 x 10-6 cmÂł/g |
Pressure Measurement
| Pressure Measurement Range | 0 to 950 mm Hg |
| P/Po Resolution | <10-4 |
| Relative Pressure Range | 0 to 1.0 P/Po (adsorption only) |
| Pressure Resolution | <0.1 mmHg |
| Accuracy and Linearity (transducer manufacturer’s specification) |
Better than ± 0.5% Full Scale |
Operating Environment
| Temperature | 10 to 35 °C (50 to 96 °F) operating; 0 to 50 °C (32 to 122 °F) non-operating |
| Humidity | 20% to 80% relative, non-condensing |
Gases
| Adsorbate | Optimized for nitrogen in a liquid nitrogen sample bath; Gemini may be used with non-corrosive adsorbate gases having vapor pressures at both room and bath temperatures that are acceptably high relative to the resolution of the 1000-mmHg pressure transducer. Typically, oxygen, argon, carbon dioxide, butane, methane, and other light hydrocarbons will produce useful data above absolute pressures of a few mmHg. Helium inlet also provided |
Vacuum System
| Vacuum source achieving 20 x 10-3 mmHg (or better) at the instrument inlet; having a device to reduce oil vapor backstreaming is recommended. The system must have an anti-suckback valve to prevent oil from being admitted into the Gemini should there be a power failure. |
Sample Tube/Dewar
| Standard Tube | Gemini VII 2390a and 2390p: 0.95 cm (3/8 in.) outside diameter by 15.5 cm (6.1 in) with 6.5 cmÂł of volume. Sample capacity is approximately 2.0 cmÂłGemini VII 2390t: 0.95 cm (3/8 in) outside diameter by 20.5 cm (8.1 in.) with 8.9 cmÂł of volume. Sample capacity is approximately 2.0 cmÂł |
| Dewar | ~ 8 hours; Gemini VII 2390a and 2390p; ~ 24 hours; Gemini VII 2390t |
Electrical
| Voltage | 85 to 265 VAC |
| Frequency | 50/60Hz |
| Power | 150 VA, operating, max. plus vacuum pump |
Physical
| Height | 59 cm (23 in); Gemini VII 2390a and 2390p; 74 cm (29 in); Gemini VII 2390t |
| Width | 40 cm (16 in) |
| Depth | 51 cm (20 in) |
| Weight | 32 kg (70 lbs); Gemini VII 2390a and 2390p; 35 kg (78 lbs); Gemini VII 2390t |
Unique Design: The Gemini Technique
Configurations
Gemini VII 2390a
Gemini VII 2390a
The Gemini VII 2390a model is ideal for rapid and accurate surface area determinations by single-point and multipoint BET and Langmuir methods. In addition, it provides standard methods for total micropore volume using the t-plot method. Included in this model’s capabilities is the ability to determine statistical thickness surface area (STSA) of carbon blacks. (Refer to ASTM D 6556, ISO/DIS 18852.2, or ISO/CD 4652-2/3.)
Gemini VII 2390p
Gemini VII 2390p
The Gemini VII 2390p model provides additional precision with the addition of a saturation pressure (Po) tube that allows the system to monitor the saturation pressure of the adsorptive on a continuous basis during an analysis using a dedicated pressure transducer. This design feature permits a rapid measurement of the adsorption isotherm to near-saturation, as well as determination of pore size distribution.
Gemini VII 2390t
Gemini VII 2390t
The Gemini VII 2390t model has all of the facilities of the 2390p with the addition of a larger dewar and longer sample tubes for extended analysis times. This provides the additional capability to measure the complete adsorption-desorption isotherm and perform pore size distribution measurements by BJH or DH using up to 1000 data points.
Accessories
Quote Accessories
Sample Preparation Devices
Sample Preparation Devices
Micromeritics offers numerous sample preparation devices for surface area and pore volume analysis. These devices combine flowing gas and/or vacuum with heat to remove atmospheric contaminants, such as water vapor and adsorbed gas, from the surface and pores of the sample. The quality of the data produced by surface area and pore volume analyses depends greatly on the cleanliness of the sample surface. All of Micromeritics sample preparation devices accept He, N2 , Ar, and other non-corrosive gases.
The FlowPrep™ 060Â
The FlowPrep™ 060 applies both heat and a stream of inert gas to the sample. The heat causes contaminants to desorb from the surface and the stream of inert gas sweeps them out of the sample tube. The unit lets you choose the temperature, gas, and flow rate best suited for your sample material and application. Needle valves allow you to introduce the flowing gas slowly to prevent fluidization of samples.
The VacPrep™ 061
The VacPrep™ 061 offers two methods for removing contaminants. In addition to flowing gas, it enables vacuum to be applied to prepare samples by heating and evacuation. This combination allows you to choose the preparation method that is best suited to your material or application. The VacPrep features six degassing stations, and a choice of vacuum or gas flow preparation on each of the six stations. Needle valves are also provided allowing you to introduce slowly the flowing gas or vacuum to prevent fluidization of samples.
The Smart VacPrep™ 067
The Smart VacPrep™ 067 is an advanced six-port system that utilizes vacuum to prepare samples by heating and evacuation. Each of the ports may be operated independently. Samples may be added or removed from degas ports without disturbing the treatment of other samples undergoing preparation. Degassing automatically terminates when the samples have completed all programmed steps.
Cryogen Transfer System
Cryogen Transfer System
The Micromeritics Cryogen Transfer System allows transferring liquid nitrogen or liquid argon from a nonpressurized storage dewar into smaller containers used in laboratory experiments. Additional accessories are available for special applications.
Consumables & Supplies
Consumables & Supplies
Superior Data Presentation Capability
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Operating Software
Operating Software
Gemini analyzers can be operated from a keypad by way of embedded software or from a computer using the more-powerful and versatile Gemini Windows optional software.
The embedded software includes:
- System verification tests
- Single- and Multipoint BET (Brunauer, Emmett, and Teller) surface area
- Langmuir surface area
- Total pore volume
- Total micropore volume and area by the t-Plot method using Halsey, Harkins-Jura, or Carbon Black STSA thickness curves
- Horvath-Kawazoe for micropore distribution
- BJH pore size distribution using adsorption isotherm (Gemini 2390p and 2390t only)
- BJH adsorption and desorption isotherm, 1000 data points (Gemini 2390t only).
Optional Gemini Windows Software
The easy-to-use Gemini Windows 7 interface enhances the capabilities to plan, launch, and control the analysis. You can collect, organize, archive and reduce raw data, and store standardized sample information and analysis conditions for easy access during later applications.
Finished reports may be generated to screen, paper, or to files in various formats. Features include cut-and-paste graphics and tables, scalable-and-editable graphs, and customizable report formats. Using computer control, you can operate up to four Gemini analyzers simultaneously from a single computer
Gemini Windows® Features
Gemini Windows software provides additional features not included with the embedded software.
Features such as:
- Installation and how-to videos
- Reduction of user-entered data
- Automatically generated pressure tables with user-selected endpoints
- Storage of all historical sample data for retrieval
- User-defined pressure table
- Summary report
- Sample log
- Isotherm plot overlays
- Autoscaling x- and y-axes
- Cut-and-paste graphics and tables
- Data export to ASCII and spreadsheet formats
- User-defined thickness curve (manually entered or from data file)
- Fixed pore size tables
- Linear and log plots (isotherm, pore volume, pore area)
- Cumulative and differential data
- Broekhoff-de Boer thickness curve
21 CFR Part 11 Option
21 CFR Part 11 Option
Also available is Confirm™ software, which addresses the many requirements specified by 21 CFR Part 11 validation, security, audit trails, reporting, and more.
Micromeritics Gas Adsorption Reports
Micromeritics Gas Adsorption Reports
Windows software with all Micromeritics’ gas adsorption instruments contains the following reports:
Isotherm Reports:
- tabular
- graphical
- pressure composition isotherm
Isotherm modeling and surface area:
- BET
- Langmuir
- Temkin
- Freundlich
Standard isotherm models:
- t-plot: micropore volume, micropore area, external surface area
- alpha-s method
- f-ratio method
Classic models for mesopore volume, area, and distribution:
- BJH*
- Dollimore-Heal*
Classic models for micropore distribution:
- Dubinin-Radushkevich and Astakhov
- Horvath-Kawazoe
- Saito-Foley
- Cheng-Yang
- MP method
Density Functional Theory for pore size modeling:
- Slit-shaped pores using N2 , Ar, or CO2
- Cylindrical pores for alkalineexchanged zeolites using N2 or Ar
- Cylindrical pores for hydrogen–or ammonium-exchanged zeolites using N2 or Ar
- Windows-shaped model for pillared clay
Density Functional Theory for surface energy:
- Surface area and energy distributions using nitrogen at 77 K
- Surface area and energy distributions using argon at 87 K
* BJH and Dollimore-Heal require the Gemini VII 2390t to take full advantage of pore size reports based upon the desorption isotherm
Gemini VII Resources
Application Notes
- Characterization of Medicinal Tablet Surface Area with the Gemini Series
- Optimize Free-Space Correction for Low Surface Area Samples Using the Gemini Analyzer
Standard Methods
Gemini VII Photo Gallery
