BMT 964 Configuration guide

Cleaning the cuvette of the BMT 964, Rev. 07/2012
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OZONE ANALYZER BMT 964
Dismantling the Analyzer and Cleaning the Cuvette
Rev. 07/2012
Attention: The installation of the power connector (pluggable terminal block) has to be
done by a person aquainted with the problems involved. Do not connect or disconnect
the terminal block as long as mains voltage is on!
1. Opening the enclosure
Remove the four screws at the corners of the rear panel using a 2 mm Allen wrench (do not loosen any other
screws!), extract the device at its rear panel from the casing. The tubing connections or the filter may be used
for pulling the device out, but do not pull on any cables.
2. Unscrewing the inner tubing connections
Unscrew the three knurled nuts fixing the cuvette's PTFE tubing to the rear panel and the pressure sensor and
withdraw the tubing. While disconnecting the pressure sensor's tubing from the cuvette, make sure the
mechanical stress on the sensor's leads is kept to a minimum.
3. Separating the lamp housing and the cuvette block from the circuit board
The lamp housing and the cuvette block - the black "T" on the circuit board - comprise an inseparable unit.
This unit can be removed by unscrewing the four outer screws (M3 Philips) on the lower side of the circuit
board. Do not loosen the two screws fixed with varnish - this could damage the UV lamp!
The cuvette opening (on the circuit board side) must always point upwards so that the inner parts of the
cuvette do not fall out. Keep both the circuit board and the cuvette block pressed together (against the spring
inside the cuvette block). In the cabinet version BMT 964 C, there is a seperate plate holding the inner parts in
place while separating the "T" from the circuit board.
First, the two screws near the edge of the circuit board shall be unscrewed, followed by the two screws at the
centre of the circuit board. The circuit board then is lifted from the cuvette block with the bottom side
pointing upwards.
4. Dismantling the cuvette
The following parts may now be removed from the
bore in the cuvette - and in this order:
spring
black aluminium ring
white O-ring (seal)
lower cuvette window (if separate from the
spacer, ranges 50g/Nm3and lower)
spacer, bonded to lower window
(which determines the length of the cuvette)
upper cuvette window
white O-ring (though it normally remains in
the cuvette block)
The aluminum ring usually does not fall out itself.
Use two screw drivers as shown in the photo, insert them crossed over eachother into the aluminum ring in
order to bring some force onto the inner side of the aluminum ring, and lift it out of the hole.

Cleaning the cuvette of the BMT 964, Rev. 07/2012
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OUT
cuvette block
bottom view
Cleaning the cuvette
The cuvette window, spacer and seals can be cleaned with water (or with household detergent or alcohol). If
the cuvette is soiled badly, check and clean the cuvette block (you can clean the 12mm bore with a "Q-Tip" or
similar), the inner walls of the PTFE tubing, the filter holder and the fittings. Dry all the parts, and remove
dust with a paint-brush, particularly from the seals. If necessary, use new (quartz) cuvette windows and O-
rings (FFKM).
5. Re-assembling the cuvette
The assembly of the cuvette has to be done in
reverse order of its disassembly:
insert the upper O-ring (if it was removed)
insert the upper cuvette window
insert the spacer-window combination
The etched spacer is bonded to the lower cuvette
window. The assembly must make sure that the
radial opening is facing the outlet and the almost
tangential opening matches the inlet and that the
spacer is located between the
two windows.
For the 50g/Nm3range, a wire
spacer is used, which consists
of two thick rods and two thin
wires which join them. During
assembly, one of the two
thicker rods is placed
diagonally between the gas inlet and outlet (but
without blocking them!).
For special measuring ranges, where a PVC spacer is used, there is only one possible orientation - whereby the
openings of the spacer are lying adjacent to the cuvette block's holes.
Next:
insert the lower cuvette window (if not combined with the spacer)
insert the O-ring
insert the black aluminium ring with the conical face pointing towards the sealing O-ring
insert the spring
Join the circuit board with the cuvette block and fasten it with the four screws, first tightening the two screws
near the cuvette. Whilst tightening the screws, press the circuit board and the cuvette block together (against
the force of the spring) so that the spacer in the cuvette stays in its correct orientation.
6. Re-connecting the tubing
Re-connect the tubing to the fittings on the backplane and tighten the knurled nuts by hand. Now, a leak test is
obligatory! If dust is not removed from the O-rings in the cuvette, fittings and tubing, this could result in an
ozone leakage!
7. Closing the casing
Slide the circuit board into the casing's guide slots and fasten the rear panel with the four Allen screws.
8. Functional test
After thightening the screws holding the rear panel connect the instrument with power and allow warmup for
a several minutes.
Zero the instrument and check the cuvette status value as described in the manual. Factory setting (=clean
cuvette) is 0.0%.
If cleaning was unsuccessful, only a replacement of the cuvette windows will help, now.
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