3B SCIENTIFIC PHYSICS U104001 Instructions D'utilisation page 25

•
In order to connect the vacuum pump, take a
vacuum hose with 6 mm internal diameter and
connect it via a stopcock or preferably via a three-
way valve to the larger connector of the oil filling
device.
k
i
h
Fig. 8: Assembly of the oil filling device and connection of
vacuum pump (h) oil container, (i) valve nut,
(k) cover, (l) stopcock (or variable-leak valve)
Degassing:
•
Check whether the regulating valve is open and
the flush valve is shut.
•
Switch on the vacuum pump. Open the stopcock a
little and observe the formation of bubbles in the
castor oil.
Close the stopcock to interrupt the evacuation process
if the formation of bubbles is so strong that they can
reach the filter that is mounted on the cover. The
stopcock may be opened only after the bubbling has
subsided.
After at least 15 minutes (depending on the suction
capacity of the connected vacuum pump), the vaporis-
ing pressure of the castor oil is attained and the oil
begins to boil. This can be noticed when vapour bub-
bles begin to form "out of the blue" and rapidly be-
come larger in size as they move through the oil.
The oil is now is sufficiently degassed.
•
Shut the regulating valve and the stopcock.
Dismantling:
•
Pull out the vacuum hose from the stopcock (the
hose fitting with the stopcock continues to re-
main on the oil filling device).
•
To avoid any surges, slowly open the stopcock
and wait for the pressure to even out.
•
Pull out the hoses from both of the connectors on
the oil filling device.
•
Unscrew the container from the safety valve.
Since castor oil is relatively viscous, it trickles out of
the container very slowly. Thus, this step can be con-
ducted easily. A cleaning cloth (or kitchen paper)
which is held below the container immediately after
unscrewing it prevents any drops forming.
•
With a cleaning cloth, remove excess oil from the
l
11
safety valve and subsequently wind the hand-
wheel inwards very slightly till the oil level in the
valve is exactly at the same level as the edge
where the steel ball bearing sits.
•
Insert the steel ball bearing, position the hexago-
nal piston with the short bore onto the ball bear-
ing (use tweezers for this) and insert the compres-
sion spring into the longer bore.
•
Carefully screw the valve cap on in its end posi-
tion (not too tight) and loosen it by two turns.
Positioning the safety valve:
•
Set-up the equipment and place it in a way that
the safety valve does not point in the direction of
people who could get injured or objects which
could get damaged.
•
Open the regulating valve. Wind the handwheel
fully out and shut the regulating valve again.
•
Turn the handwheel in till an excess pressure of
approx. 65 bar has been attained.
•
From the front, wrap your arms around the appa-
ratus to reach the safety valve located at the back.
Slowly unscrew the valve cap of the safety valve
till the pressure drops to approx. 63 bar.
•
Tighten the counter nut (14 mm).
Rest position:
•
Wind the handwheel back till the pressure has
dropped to max. 10 bar.
•
Open the regulating valve and turn the hand-
wheel to its "rest position" at approx. 5 mm.
•
Shut the regulating valve.
After completing these steps, the equipment can
either be stored or refilled with test gas.
11. Upkeep and maintenance of threaded bush
11.1 Lubricating the threaded bush
To minimise wear, the threaded bush in the frame
should be lubricated approximately every 100 cycles
(one cycle = a pressure increase from 10 to 60 bar and
the subsequent reduction to 10 bar), or once weekly.
Lubrication only takes about 1 min and extends the
service life of the bush significantly. For lubrication, a
light-coloured multi-purpose grease with no graphite
or similar additives is recommended.
Procedure:
•
Inject one full stroke of lubricant from a conven-
tional grease gun into the threaded bush through
the nipple at the frame.
•
Wipe up any surplus lubricant emerging from the
bush.
When it emerges, the lubricant will also pick up any
traces of plastic that might have worn off during op-
eration, so that will be flushed out too.