Pilot freeze-dryer
Floor-mounted unit for small batch production
Epsilon 2-10D LSCplus
The Epsilon 2-10D LSCplus freeze dryer is a general-purpose, high-performance pilot unit featuring stainless steel shelves with internal heat transfer media channels for heating and cooling, enabling it to meet even the most stringent demands of the pharmaceutical and biotechnology industries. The key features of this unit are its drying options using up to seven shelves with a total area of 0.98 m2, adjustable shelf spacing from 38 to 170 mm, and a hydraulic stoppering device with optional stainless steel bellows seal. The Epsilon 2-10D LSCplus is equally ideal for product development and small-scale production activities.
Technical data
| Ice condenser capacity: | 10 kg |
| Ice condenser temperature: | –88 °C |
| Shelf dimensions: | 350 × 400 mm (W × D) |
| Number of shelves: | 1 to 7 |
| Shelf area: | 0,14 m2 to 0,98 m2 |
| Shelf spacing: | 354 mm to 38 mm |
| Shelf temperature: | –55 °C to +60 °C |
| Shelf temperature accuracy: | max. ±1 °C |
| Cooling systems: | 2 independent systems, air cooled (optionally water chilled) |
| Ice condenser cooling system: | 2 compressors, 1.2 kW each, in cascade configuration |
| Shelf cooling system: | 1 compressor, 0.9 kW |
| Unit dimensions: | 1295 × 1190 × 850 mm (H × W × D) |
WTMplus 2.0 – Wireless Temperature Measurement
The WTMplus 2.0 (wireless product temperature measurement system) avoids the disadvantages arising from the use of wired temperature sensors. It is significantly easier to use in practice. There is no need for temperature sensor cables or connectors inside the vacuum chamber. The wireless self-powered sensors are placed manually or automatically when the product vials or dishes are filled and report the corresponding product temperatures to the unit controller during the entire lyophilisation process.
Technical data
| Probe dimensions | Length: 21 mm plus 29 mm flexible antenna Diameter: 2.8 mm |
| Temperature measuring range | –60 °C to +135 °C |
| Measurement accuracy | ±1,0 K |
| Temperature resolution | 0.1 K |
Comparative pressure measurement
In addition to product temperature measurement and pressure rise testing, the simultaneous use of two vacuum sensors with different measuring principles can provide information about the progress of the drying process. The commonly used Pirani gauge indicates higher absolute pressures at the start of the primary drying phase because its operation is dependent on the gas type and large amounts of water vapour are released at the start of the primary drying phase. By contrast, capacitive pressure sensors are independent of the gas type. The approaching end of the primary drying phase, which occurs when there is no longer a significant concentration of water vapour, is indicated by the gradual approach of the two pressure curves to each other during the process.
LyoBalance weighing system
The LyoBalance weighing system facilitates the determination of the drying speed and drying end point during the freeze drying processes when flasks or vials are used.
Thanks to virtually continuous measurement, the drying speed can be determined in any desired process phase under varying drying conditions.
The drying end point can be determined easily and reliably from the weight loss.
The sample retains its place next to the other vials directly on the shelf to ensure that the results are representative.
Technical data
| Measuring principle: | electromagnetic force compensation |
| Measuring range: | 0,001 to 30,0 g |
| Measurement accuracy of measurement: | ± 0,005 g |
| Flask size: | 2R to 20R (in accordance with DIN 58366) |
| Usable temperature range: | –40 °C to + 40 °C |
| Dimensions (W x H x D): | 125 x 55 x 45 mm |
| Cable pass-through: | NW 40 small flange or other on request |
| Software: | integrates in LSCplus controller |
Sample extraction system
The sample extraction system allows individual sample containers to be removed under vacuum during the drying process without interrupting the drying process. This is done by using a gripper arm to pick up the sample container, close it, and remove it through a vacuum lock. This allows individual sample containers or vials to be removed from the freeze dryer at defined intervals. The samples removed through the vacuum lock can be investigated and analysed in parallel with the ongoing process. This allows the progress of the process to be measured and documented in detail.
Technical data
| Sample containers/vials: | 6R to 30R Max. 50H |
| Coupling flange: | DN 160 clamp |
| Gripper working range: | 200 mm |
| Stoppering device: | Teflon-coated plunger |
| Vacuum lock: | DN50 |
| Materials: | Stainless stell 1.4404 and 1.4435, Teflon, Borosilicate glass |
| Visualisation: | Direct or with a digital camera, lighting fixture and monitor |
Glove box connection
High safety requirements are often imposed on unit operation in practice. For example, combinations of freeze dryers and glove boxes are used when freeze drying is necessary to protect products against harmful environmental factors or because the products concerned are highly active and possibly toxic. A special docking frame is used to connect the freeze dryer directly to the glove box. This isolates the entire drying chamber and the working area for product preparation from the technical surroundings.
Implementation using standard docking frames. Special versions are possible on request.
Manual and hydraulic stoppering devices
A manual or automatic stoppering device, depending on the unit type, is used to close drying containers or vials by pressing in stoppers. Electrohydraulic stoppering devices with stainless steel bellow seals are used in particular in pharmaceutical applications.
H2O2 disinfection
Sterilisation with vaporised hydrogen peroxide (VHP; H2O2) is an economical and effective alternative to pure manual disinfection using isopropanol or similar substances and steam sterilisation, which is common practice in production processes.
VHP is especially worthwhile in situations where the capital cost of installing steam sterilisation equipment is too high, but the benefits of using a reproducible process are necessary. With the VHP method, the freeze dryer is connected to a suitable VHP generator in a closed loop, usually by means of hoses and quick-release couplings, so that the VHP generator can also be as needed with other equipment.
Solvent-resistant version
Along with freeze-drying of aqueous media, freeze drying of substances containing aggressive solvents is necessary in some areas such as pharmaceutical research. All of the solvents in this connection have freezing points within the technically manageable range, such as DMSO (eutectic point +15 °C), tertiary butanol (+25.5 °C), dioxane (+12 °C) or acetonitrile (–45 °C). Freeze dryers for this application scenario are designed to be chemical resistant, which means they have modified valves and door seals, special vacuum pumps, and modified cooling systems. The particular advantages of lyophilisation compared to liquid removal by evaporation are the better structure of freeze-dried products (powdery or sponge-like, rather than a viscous mass), lower final solvent content and gentler handling.
Inertisation
Drying and ice condenser chambers are inertised by flushing them with an inert gas, such as nitrogen or argon. The air in the chambers at the start of the process, including the oxygen present in the air, is displaced by the inflowing inert gas. This method is used in particular for the drying of products containing solvents for which an inert atmosphere is required in the process chamber.
Nitrogen cooling
Liquid nitrogen (LN2) can be used an alternative cooling medium. The advantages of this mode of operation are very high freezing rates, very low ice condenser temperatures (below –100 °C) and low noise emissions.
Possible options:
cooling the shelves and the ice condenser exclusively with liquid nitrogen.
Emergency cooling (shelves and ice condenser) by liquid nitrogen in the event of failure of the conventional cooling system. Nitrogen booster for conventional cooling. Other advantages of Christ freeze dryers chilled with liquid nitrogen are:
- Low shelf temperatures
- High control accuracy
- Fully adjustable ice condenser temperature; constant temperature even under full load (superior performance margins)
- Low power consumption
- Minimal maintenance cost
- Environmentally friendly, future- operation without refrigerants
Drying manifold
The scope of use of pilot freeze dryers can be extended substantially by using drying manifolds mounted directly on the unit or separately. The drying manifolds are connected to the freeze dryer unit by flanges on the unit provided for this purpose, or by vacuum hoses or vacuum pipes. Containers such as ampoules, vials, bottles, wide-neck flasks, round-bottom flasks, etc. can be fitted on the drying manifolds, depending to their construction. Continuous operation is enabled by three-way rubber valves between the single containers and the drying manifold.
