DESIGNED & OPTIMISED
MODERN F-T INFRARED &
PRECISION HEATED CELLS
- SERIES HNIR
The Ventacon system comprises of a cell to fit any near infrared
spectrometer with 2"x3" industry standard sample holding
rails in the sample chamber. The cell has a rectangular sample holding
zone and will accept cuvettes up to 20mm in path length. To hold the
cuvettes and to maximise the transfer of heat two metal spacers are
provided. The cell is closed with a precisely fitted lid. The cell
oven is drilled with passageways through which compressed air or water
can be passed.
Temperature control is made using low voltage
heaters and platinum resistance thermometry. The single output cable
will plug into a Ventacon D2 Universal Power Supply. Monitoring and
power control connections are made through the cable. No separate
thermocouple is required in this system.
The cell is supplied with its Power Supply and the latter has
been configured for the cell. However, we advise that you proceed
- Fit the cell into the instrument and connect its cable to the
power supply using the HOT socket. Fit the cuvette and the longest
spacer that will go into the cell.
- Check the voltage setting for the power supply and adjust is appropriate.
- Turn on the supply. After a few seconds the temperature controller
will read the temperature of the cell. Switch the power supply to
- Press and hold the * key on the CAL controller and you will see
the 'set' temperature. Adjust using the UP and DOWN keys, to your
- The temperature will now rise. You can use high power to hurry
the process but you must lower the energy as you approach the set
- Leave the cell for 5 minutes to allow the temperature of the sample
to rise. Remember, the cuvettes are made of silica, a material with
poor thermal conductivity. Set the power to MEDIUM above 50º or
LOW for set temperatures below this.
- Activate the Autotune routine.
A facility that uses the CAL controllers brain
to set the unit up for optimal control of the accessory connected
to a set temperature.
The CAL unit is supplied ready for use with standard Hot and
Cold cells and will control them adequately. It has however
been found that the default settings are not appropriate for the
accurate and steady control of the catalysis cell for one. In
this configuration it is recommended that Autotune should be used
and that it would be beneficial to use it for each and every change
of setpoint with all cells.
For successful operation of the system using Autotune carry out
the following procedure:-
|NOTE: When Autotune is in use the Hot and Cold
cell power switches must not be disturbed at all.
We recommend that the Hot power switch be set to med
and the Cold power switch be set to low before
- Set the required temperature by holding down the *
button whilst using UP or DOWN, as appropriate.
- Press and hold UP and DOWN
until tunE is displayed. Release the buttons.
- Press DOWN repeatedly until CyC.t.
- Hold * and hold UP until
A - -. Release the buttons.
- Press UP repeatedly until tunE.
- Hold * and press DOWN once
briefly to on. Release *.
- Press and hold UP and DOWN
until tunE disappears and a figure is displayed.
Release the buttons.
- Plug the required cell in to its appropriate socket.
- Set the Output Select switch to point to the output
supplying the accessory in use.
- Leave the unit to calculate all necessary settings for optimal
control of the cell, to your setpoint.
The setpoint should be reached within approximately 5 minutes
with insignificant overshoot and will hold the value very accurately.
If you change the set temperature by more than 10º OR change
the sample size (path length or depth) you should autotune
again to maintain best performance.
COOLING THE CELL
It is possible to pass water through the cell using the two
connections on the end. We prefer that you use compressed air for
cooling. There is little point in cooling very rapidly, as the sample
will not follow the temperature of the cell. It is permissible, of
course, to pass thermostatted water. If the power supply is tuned
on, the controller will read the cell temperature but the output knob
must be switched to COLD or the power supply will try to heat the
cell. In a sense passing thermostatted water is not to be recommended
because the cell itself can be controlled more precisely than the
After the use of water the internal passages in the cell MUST
be blown out with compressed air. If drops of water are left inside
the cell, the temperature control will be poor especially above 100º
The cell is not designed to be dismantled routinely. The two
windows can, however, be replaced. The front window is accessed by
removing the small screws in the 3"x2" plate. DO
NOT OVER TIGHTEN THEM. Removing the rear window is much more
difficult. Please request help before attempting removal.
The windows are best cleaned using petroleum ether on a cotton
[Heated NIR Cell]
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