Ulvac CRYO-U12H, Instruction Manual

Page: 14 / 102

S-2 ULVAC CRYOGENICS INCORPORATED
necessary.
☆
KF25 flange is mounted on to the pressure relief valve for installing a duct.
Figure 1 Pressure Relief Valve (ULVAC CRYOGENICS products)
2. Confirm the safety of secondary-
generated gases in process
Some gases would be secondarily generated in vacuum processes. They might
ontain flammable gas, explosive gas, toxic gas, or combustion enhancing gas.
mentarily if there is a cause (refer to
“4
reaction with organic substances or any impact when it reaches in a high
co
to confirm the safety of the secondarily generated gas as well
s that of process gases.
c
For example, water in vacuum chamber, which comes from the atmosphere or the
substrate, dissociates into hydrogen and oxygen in plasma. Those gases may be also
discharged in large amounts from some evaporants or sputtering targets.
Oxygen is one of
the gases which increase the susceptibility to burn, and hydrogen is flammable and
explosive.
At atmospheric pressure, the mixed gas of hydrogen of 4% or more and oxygen
of 5% or more are sure to cause the explosion mo
.When pumping flammable or explosive gases”).
In addition, ozone might be secondarily generated when oxygen(O
２
) or carbon dioxide
（
CO
２
）
is resolved in plasma. Ozone is a toxic gas
，
and moreover the liquid ozone might
explode by the
ncentration.
Therefore, it is necessary
a
For handling flammable or explosive gases , refer to “4.When pumping flammable or
explosive gases”and“5.When pumping oxygen” in this chapter. Implement safety precaution
and preventive maintenance as necessary.