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difference in level from the specific gravity of the liquid to be used, and set the tank pressure
higher.
9.8 Moisture contents (dew points) of carrier gas and purging gas
When a material that reacts strongly with water and the dew point of the carrier gas is high,
the material reacts in the mixing unit (mixing valve) of MV, and the reaction product is
generated in the carrier gas passage, thereby clogging the passage. Therefore, when a
material that reacts strongly with water is used, use carrier gas and purging gas whose dew
points are
80
C or less.
9.9 Carrier gas and liquid supply pressure
If the secondary shutoff valve malfunctions or a nozzle in the main unit is clogged, the
supplied carrier gas and liquid are not fed to the secondary side and flow from a side where
the supply pressure is higher to a side where the supply pressure is lower. Therefore,
monitor the clogging state on the secondary side referring to Item (1) of 9.2 “Clogging by
vaporization,” and stop the vaporization before the secondary side is completely blocked.
If the passage is clogged to stop the flow, the values output from the mass flow controller for
gas and the mass flow meter for liquid decrease, and you can find the abnormality.
However, if the liquid material enters the mass flow controller for gas, the controller may be
damaged so heavily that it cannot be restored. In addition, the piping may be contaminated
to cause particles. Set the carrier gas supply pressure higher than the liquid supply
pressure. When the carrier gas supply pressure is set higher, the carrier gas may flow back
into the liquid supply line. In this case, the line can be restored by removing the clog and
supplying the liquid.
10. Example of Preparation of Secondary Heating Piping
Insulate the secondary piping and pneumatic valve with temperature sensors, tape heaters
and insulating materials. To heat them as uniformly as possible, examine the sensor
positions, tape heater density and insulating material overlap.
Tape heater
Insulating material
Temperature
sensor
Temperature
sensor
