GA 12.137/2.02 - 05/2002
30
Maintenance
4 Maintenance
Warning
Separate the compressor unit safely from
mains power supply before beginning any
work.
After making repairs to the electrical equipment, the
compressor unit may not be returned to service without
conducting an electrical safety test. It is for this reason
that work of this type may be carried out only by trained
and qualified personnel or by the Leybold Service
Department.
Maintenance work carried out improperly will jeopardize
the safety, longevity and availability of the equipment
and will void the warranty.
Any work which is not described in these operating
instructions may be carried out only by the Leybold Ser-
vice Department or by personnel specially trained by
Leybold for this purpose.
4.1 Helium gas pressure
adjustment
Warning
Observe all safety regulations when work-
ing with pressurized gas cylinders.
If the helium pressure in the compressor unit has fallen
below the minimum level, it will be necessary to recharge
with helium. If the helium pressure in the compressor
unit is too high release helium.
Helium filling pressures
Minimum value
Operation at 50 Hz
14 bar (203 psig; 1.4 MPa)
Operation at 60 Hz
13 bar (189 psig; 1.3 MPa)
Nominal value
Operation at 50 Hz
15 bar (218 psig; 1.5 MPa)
Operation at 60 Hz
14 bar (203 psig; 1.4 MPa)
When making measurements and when topping up or
draining helium at the compressor unit, switch the unit off
and allow it to cool down to room temperature and the
cold heads being served to warm up.
Detaching the flexlines when the cold head is at low tem-
perature can result in a loss of helium.
Warning
Detaching the flexlines with the cold head at
low temperature can, when they heat up,
result in a rise in pressure beyond the per-
missible 28 bar (406 psig; 2.8 MPa) opera-
ting pressure.
Warning
The maximum permissible operating pres-
sure for the helium filling adapter when the
self-sealing couplings are detached is 28
bar (406 psig; 2.8 MPa). Do not exceed this
pressure level when setting the pressure
reducer.
Warning
All pressure lines and components of the
helium circuit must have been joined pro-
perly, and any open couplings must be pro-
vided with protection caps.
Warning
Keep the face and bodily openings away
from the adapter discharge orifice.
Compressed gas can induce asphyxiation
effects at high concentration. Do not inhale
helium or use it to create a “squeaky voice”
effect.
Releasing helium gas
A helium filling/drain adapter is provided for this purpose
with the compressor unit. Unscrew the protective cap
from the filling/drain connection (6/3).
Slowly and carefully screw the self-sealing couplings of
the adapter onto the filling/drain connection.
Caution
Do not screw the adapter on too quickly as
there is otherwise the danger that too much
helium will escape or that oil will be swept
along with the helium out of the compres-
sor.
Once the correct helium filling pressure has been rea-
ched, remove the filling/drain adapter. Put back the pro-
tective cap on the filling/drain connection (6/3).
