Metal block thermostats , evaporators and test panels
Köhler VLM evaporators are a cost-effective alternative to rotary evaporators and other concentrators when a large number of samples need to be processed. The evaporation of the solvent is accelerated by gassing with nitrogen, a method that is particularly gentle on samples that are sensitive to oxidation. The metal block thermostats serve to compensate for the evaporative cooling, thereby maintaining the temperature of the system.
A complete evaporator system consists of the evaporator unit with motor-driven lift or a manually height-adjustable stand, the gas dosing unit and the metal block thermostat QS, EC, LS or VIS. In the lift version, this stands on a base plate that can be pulled out to the front, which makes changing the heating blocks or samples very convenient.
After turning the EVA lift's gas dosing unit by 180°, the stainless steel cannulas or Pasteur pipettes (adapter plate required) can be easily inserted into the silicone holders from above. In the tripod version, the gas dosing unit can be removed and also fitted from above after turning it over.
As an accessory, we supply cabinets that can be connected to a laboratory ventilation system if there is no space in the fume hood. It is also possible to pulse the nitrogen flow and switch it off after a preselected time.
The EVA-EC complete systems for 48, 24 or 16 samples consist of:
Evaporator with gas dosing unit and motor-driven lift or tripod unit
EC thermostat with heating pan for exchangeable heating blocks, working temperature up to 130°C or 210°C
1 heating block for 48, 24 or 16 standard test tubes Ø16 mm, drilling depth 65 mm
48, 24 or 16 stainless steel cannulas optionally coated with PVDF (extra charge) Microtiter plates: 96 cannulas
PU connection hose with adapter for connection to gas fittings
Optional: Adapter plate for the use of paste pipettes or pipette tips (extra charge)
Optional: Gas pressure reducer with pressure gauge
The Köhler-VLM Evaporator-VIS
The figure on the left shows the standard version of the device for the use of 3 heating blocks for 72 standard test tubes Ø 16 mm.
The heating blocks are provided with longitudinal slots so that the falling liquid level in the front block can be observed. A fluorescent lamp provides better lighting conditions. Under these conditions, it is possible to concentrate the samples to a residual volume. The nitrogen supply for the rear heating blocks can be opened at different times. Most of the solvent has already evaporated, because it is not necessary to observe the liquid level in this phase. After the front block has been removed, the blocks behind it are pulled forward to stop evaporation in the final phase. Thanks to this time-saving procedure, the Köhler-VLM Evaporator-VIS enables a high sample throughput.
We supply heating blocks for test tubes, Eppendorf reaction vessels, chromatography vials, round and pointed flasks. The gas dosing unit is divided into three chambers, into each of which nitrogen is fed separately. The flow rate for each of the up to 72 samples is set individually using the valve screws. Outlets that are not required remain closed. Instead of the stainless steel capillaries, glass Pasteur pipettes can be used after attaching the adapter plate.
The Köhler VLM thermostat is equipped with a JUMO microprocessor PID controller and ensures precise temperature control of the samples and compensation for evaporative cooling.
