GA 12.107/5.02 - 12/97
18
Maintenance
4. Maintenance
Warning
Separate the compressor unit 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 Topping up Helium Gas
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.
Helium filling pressure
Operation at line frequency
————————————————————————
Minimum values
50 Hz
15 bar
60 Hz
13 bar
Nominal values
50 Hz
16 bar
60 Hz
14 bar
When making measurements at the compressor unit,
switch the unit off and allow it to cool down to room tem-
perature 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) operating pres-
sure for the disconnected flexline. All the
self-sealing couplings which are not in use
shall be provided with protective caps.
Caution
Only helium of the highest purity (99.999%
or better) shall be used.
Warning
The maximum permissible operating pres-
sure for the helium filling adapter when the
self-sealing couplings are detached is 28
bar (406 psig). Do not exceed this pres-
sure level when setting the pressure redu-
cer.
Use the pressure reducer and a suitable high-flexline to
connect the helium cylinder to the helium filling adapter
supplied with the unit; do not yet tighten the Swagelock
connector.
Open the valve at the cylinder.
Open the pressure reducer and the shut-off valve slightly
so that the high flexline and the filling adapter are purged
with helium.
Tighten down the Swagelock connector after purging the
configuration several times.
Set the pressure in the supply line to correspond to the
set-point value of the compressor unit. If there is insuf-
ficient pressure in the supply line, oil can pass from the
compressor unit into the supply line.
Observe the instructions given in Section 2.6.
Use a 19 mm open-end wrench to tighten the couplings.
Connect the coupling at the helium filling adapter to the
Summary of Contents for RW 6000-1
Page 23: ...GA 12 107 5 02 12 97 Notes 23...
