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Description
Micromeritics’ Gemini® VII 2390 Series of surface area analyzers rapidly and reliably produces accurate and repeatable surface area and porosity results. Their low cost, high speed, simplicity of use, reliability, and ruggedness have earned the Gemini a place in research and quality control laboratories worldwide Determines single- and multpoint BET and Langmuir surface areas, total pore volume, and micropore analysis by the t-method. Universal electrical input.
Surface Area, Total Pore Volume, and Pore Volume Distribution
Accurate, Fast and Economical Micromeritics’ Gemini VII 2390 Series of surface area analyzers rapidly and reliably produces accurate and repeatable surface area and porosity results.
Unique Capabilities
The design of the Gemini provides unique capabilities found only in more expensive products. Many error sources inherent in traditional static volumetric instruments are eliminated through common mode rejection. This provides a more accurate, more precise and more stable measurement tool, therefore providing unique capabilities. For example, using nitrogen, the Gemini is capable of performing measurements on materials with a very low surface area, where similar instruments would require the use of krypton. Krypton is not only more expensive, but for a typical analyzer, measuring a krypton isotherm requires lower pressures than can be achieved with low-cost pumps and requires additional components within the instrument to measure these lower pressures. Without the additional requirements, both the Gemini’s price and operating costs remain low.
•The Windows® version includes easy-to-follow installation videos and system verification tests to ensure optimum performance and reliability. How-to videos provide on screen instruction on instrument operation.
•The patented twin-tube design negates free-space errors introduced by thermal gradient variations or by initial mismeasurement of free space.
•Permits low surface area measurements without requiring krypton by essentially eliminating free-space error, the limiting factor in typical static volumetric systems.
• Accelerates delivery of the analysis gas because sample uptake rate is used to control the rate at which the gas is delivered to the sample. This results in a surface area analyzer that is as fast as the physics of adsorption allows.
• The use of a servo valve to control the rate of gas flow into the sample tube assures accurate attainment of target pressures without pressure overshoot. Since this is not a ‘pulse-and-equilibrate’ method, there is no over-dosing.
• Three choices of software control: embedded software with a keypad enabling the Gemini VII to be operated without an external PC, Windows® XP or Vista operating system, or the Gemini VII confirm™ 21 CFR Part 11 option.
Three Gemini VII Model Options
Gemini VII 2390a
This option is ideal for rapid and accurate surface area determinations Also provides standard methods for: single-point and Langmuir surface areas, 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 P0 (saturation pressure) tube allowing the user to monitor the saturation pressure of the adsorptive on a continuous basis. The instrument is designed to provide a rapid measurement of the adsorption isotherm.
Gemini VII 2390t
Gemini Has all the capability of the 2390 with the additional ability to perform a BJH or Dollimore Heal pore size distribution using both adsorption and desorption isotherms of up to 1000 points. This instrument also features a P0 tube as well as a larger Dewar and longer sample tubes for extended analysis.
The Gemini Series of surface area analyzers uses the Static Volumetric Technique to generate high-speed surface area and porosity data.
Features
•Low cost
•Fully automatic operation
•High throughput – up to four Geminis can be operated with single computer
•Capable of measuring low surface area materials
•Keypad or computer-operated with Windows-driven software
•Choice of analysis mode (scan or equilibrate)
•No pressure overshoot
•Common mode rejection of free-space error effects
•No thermal-diffusion errors
•Optional stainless-steel Dewars
• 21 CFR Part 11 software option
• IQ/OQ Validation service (optional)
Analysis Technique
The Gemini uses an adaptive rate, static volumetric technique of operation. It is the first gas sorption method which adapts the required rate at which gas is supplied for equilibration. The Gemini has, as illustrated in Figure 1 (below), two gas reservoirs (A) which are filled with equal volumes of the desired adsorptive, usually nitrogen. From the reservoirs, gas is dosed into the sample and balance tubes. A transducer (B) on the sample side monitors for the target pressure. As the sample adsorbs gas, the pressure would tend to decrease in the sample tube were it not that transducer (B) causes a fast response servo valve (C) to hold the pressure constant. Transducer (D) located between the sample and balance tubes detects any pressure difference between the two tubes and causes another servo valve (E) to balance the pressures in both tubes. A third pressure transducer (F) monitors the pressure between the two reservoirs to determine the amount of gas that is adsorbed on the sample. This method of dosing and accounting for the volume of gas uptake enables the Gemini to produce highly accurate, highly reproducible results in the minimum time.
Twin-tube design
The sample and balance tubes are identical in every way. Conditions within one tube exactly reproduce the conditions within the other, the only difference being associated with the presence of the sample in the sample tube. Free-space errors introduced by thermal gradient variations are canceled because the balance tube essentially has the same free space variation as the sample tube and no pressure differential is produced. Since free-space error is the limiting factor in measuring low surfaces with nitrogen, common mode rejection of free-space variation in the Gemini allows accurate measurements to be performed on low surface area materials that by other static volumetric techniques would require the use krypton.
Accelerated dosing of the analysis gas In the unique Gemini design, the sample uptake rate controls the rate at which the gas is delivered through a servo valve, therefore the adsorptive is delivered as fast as the sample can adsorb it. In this manner of dosing, there is no under-dosing in which the sample waits for more adsorptive, nor over-dosing in which case the target pressure is exceeded. The result is a surface area analyzer that is as fast as the physics of adsorption allows and yet retains accuracy and reproducibility. Gemini analyzers can be operated from the keypad (included with the analyzer) or, optionally, from a computer. Using computer control, you can operate up to four Geminis simultaneously from a single computer.
Two categories of software control
Embedded software: The Gemini V Series continues to be a stand-alone physical adsorption analyzer. The Gemini V Series offers two versions of embedded software that allow the unit to be operated without the need for an external PC. Each Gemini V embedded software version provides a wider range of analysis choices and data reduction capabilities than in previous Gemini models.
Intuitive and powerful Windows-based software:
The optional Windows-based software allows the Gemini V Series to be controlled from a PC, thus providing more versatility in data archiving, networking, and printer options. In addition, the Windows software extends the choices of data reduction methods in each Gemini model.
For applications that fall under FDA’s 21CFR11 rule, the Gemini V Windows confirm™ software option provides the security features and audit trails required by this regulation.
Windows Option Software Features
The easy-to-use Gemini software utilizes a Windows interface to help 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. Features include cut-and-paste graphics and tables, scalable-and-editable graphs, and customizable report formats.
Windows Option Analyses and Reports
The new Gemini Windows software includes powerful data reduction software.
- Single- and Multipoint BET (Brunauer, Emmett, and Teller) surface area
- Langmuir surface area
- Pore volume and pore area distributions in the mesopore and macropore ranges by the BJH (Barrett, Joyner, and Halenda) method using a variety of thickness equations including a user-defined, standard isotherm (2380 model)
- Pore volume (distribution and total pore volume) in a user-defined pore size range
- Micropore distribution by the MP-method (2380 model) and total micropore volume by the t-Plot and as Plot methods
- Halsey, Harkins-Jura, Carbon Black STSA, Broekhoff-de Boer and user-entered thickness curves
The 2380 model also includes
- Dubinin-Radushkevich (D-R)
- Dubinin-Astakhov (D-A)
- Fixed pore size tables
- Linear & Log Plots (isotherm, pore volume, pore area)
- Cumulative and Differential data
- Plot overlays, any type
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.
Specification
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