Oerlikon RUVAC WA, Installation And Operating Instructions Manual

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ATEX
15 GA03107_002_A4 - 09/2015 - © Oerlikon Leybold Vacuum
Equation (1)
(1) p
a, max. permissible
= p
const, TX
/ k
th
p
a,
max. permissible = maximum permissible operating pressure RUVAC
(intake side) for complying with TX
p
const, TX
= Table value for TX (see table), pressure at Roots pump discharge side
k
th
= Theoretical compression ratio
Table 2: Maximum forevacuum pressures pconst for complying with
TX
Generally the following T2 T3 T4
applies to the max.
pressure difference
RUVAC ∆ p
max
p
const,
T2 p
const,
T3 p
const,
T4
[mbar] [mbar] [mbar] [mbar]
WA/WAU 251 80
∆p
max
/ (k
th
-1)*
57 13
WA/WAU 501 80
∆p
max
/ (k
th
-1)*
34 11
WA/WAU 1001 80
∆p
max
/ (k
th
-1)*
23 7
WA/WAU 2001 50 25 12 3
∆ p
max
= Maximum permissible pressure difference for continuous operation: pv – pa
* The RUVAC WAU fulfils in every operating range the T2 limit. The pressure balance line limits
the pressure difference.
p
const, TX
= Table value for TX (see table), pressure at RUVAC discharge port
k
th
= Theoretical compression ratio
p
V
= Compression pressure = Pressure at the RUVAC discharge side
p
a
= Operating pressure RUVAC (intake side)
For the operating range with higher pressures p
v
from p
const, TX
the following
applies: The higher the ratio pumping speed Roots pump/pumping speed
backing pump (= k
eff
) is, the higher the gas temperatures at the discharge
side of the Roots pump will be.
ATEX operation of the RUVAC WA and WAU above p
const, TX
is only permissi-
ble after having asked Oerlikon Leybold Vacuum for a design rating.
Within this respective pressure range p
v
> p
const, TX
the installation of the
temperature sensor which has been described is mandatory.
In the following cases the installation of a temperature sensor is mandatory
independently of the operating range:
■
The gas inlet temperature at the RUVAC exceeds 40 °C.
■ Thermally critical gases at high concentrations are being pumped
(at times) like, for example, argon, helium or other noble gases.
CAUTION