40
BÜCHI
Fat Determination
B-820/B-821
1. In order to check the
hydrogen flow rate
, the cursor is
positioned on <Press. system: H2> and the air pressure is
switched off internally (p air: 0 kPa). Connect the soap
bubble meter, containing approx. 2 ml soap solution, to
the FID (see figure 19) and wait until the Ready LED lights
up.
2. Press the bulb to release a soap bubble. Use a stopwatch
to time how long the bubble takes from marker 1 to marker
2 (see figure 20).
When using the
short column
, the time should be 7 ±
0.1 sec (flow rate: 10 ml/7 ± 0.1 sec).
When using the
long column
, the time should be 10 ±
0.1 sec (flow rate: 10 ml/10 ± 0.1 sec).
3. If the stopped time deviates from the set time, the
hydrogen pressure must be adjusted accordingly, Position
the cursor on H2 pressure and enter new value. Once the
ready LED lights up, the flow rate can be remeasured.
This procedure should be repeated until the set value has
been achieved.
4. Reposition cursor on <Press. system: H2> and press <Op-
tion>. The display now reads <Press. system: Air>.
The pressure values “55 kPa” and “250 kPa” are standard
values, for total fat and fatty acid modes respectively, and
can vary depending on the unit.
Press. system: H2
p H2
55kPa
H2-pressure: 55kPa
p air
0kPa
Main menu
T oven
130°C
T inj.
220°C
Wait until ready
T FID
260°C
Req. flow H2:
10 ml/7 s
Figure 19: Installing the soap bubble meter
5 Operation
Determination "Total Fat" (
short column
)
Press. system: H2
p H2
280kPa
H2-pressure: 280kPa
p air
0kPa
Main menu
T oven
150°C
T inj.
220°C
Wait until ready
T FID
260°C
Req. flow H2:
10 ml/10 s
Determination "Fatty Acid" (
long column
)
