Alcatel 1004 A Instruction Manual page 16

UQUID NITROGEN TRAP NW 25
1 Description
liquid nitrogen trap is mounted on the intake of a mechanical
hing pumps 4, 8, 12, 20 m
removable), it has the advantage of consuming
ogen.
Characteristics and part number
nsions : see figure 1.
nections : NW 25 Pneurop (inlet/exhaust).
·ght : 2,4 kg.
id nitrogen capacity : 1 liter.
ductance at 10- 1 mbar : 35 1/s.
o-•
<
onomy (P 1 mbar) :
ping speed (water vapor)
number : 786538.
.3 Operating principle
e liquid nitrogen trap is used for cryogenic pumping of vapors a.nd
ses with condensation temperatures above 77 K (temperature of
uid nitrogen). It therefore increases pumping speed for these
pars or gases.
protects the pump against condensable vapors that could be
t rained during pumping.
It prevents oil from migrating Into the vacuum sy_ s tem by means
of back diffusion.
8.3.4 lnstallatlon
a) Accessories whose tightness and materials are compatible with
the pumped gases and the required safety conditions must be
used upstream and downstream of the trap.
b) Read § 8.3.5 and 8.3.6 before installing liquid nitrogen trap.
c) The trap openings are provided with ISO NW 25 flanges for Pneu·
rop type quick connect clamps; a l lowing va r ious fittings to be
connected (see diagram 7).
d) See figure 2.
r-
.5 Operation
Important note : in general, the trap should not be used at pressu­
res above some mbar, because it becomes contaminated very
rapidly under these conditions.
A system with a by-pass valve should be used, or the trap should
not be filled until the pressure is sufficiently
a) Filling with liquid nitrogen
- Lower pressure in trap unlfl it is nearly 10· 1 mbar.
- Fill trap with liquid nitrogen.
- Use a funnel or filling tube less theai1 14 mm in
- Let trap coal, then top up a few minutes
b) Time between recharges
The time between recharges depends on the fallowing
- frequency of use.
- operating pressure (operation at high pressure causes more
rapid contamination),
- nature of pumped gases (quantity of condensable
For pumping on a clean chamber at ultimate vaccum, the trap can
be used for 12 to 15 hours between recharges.
8.3.6 Maintenance
IMPORTANT : each time the system Is dismantled, take all
necessary precautions to ensure safety and protection of per­
sonal against possible toxicity, corrosion, and radioactivity of
residues.
Proceed as follows :
1. Purge system with dry nitrogen before working on It.
2. Wear gloves, goggles and mask..
3. Ventilate area thoroughly and disassemble parts under a
fume hood.
1. Collect residues In appropriate containers.
;. Do not simply discard residues, and have them destroyed by
a competent organization If necessary.
3 /h. Made entirely of stainless steel
very
little liquid
15 hours.
: 4 Ifs.
low,
diameter.
later.
vapor).
Important note
Do not do the following when using a trap
- close trap under vacuum when cold, and allow to warm up : if the
pumped products are in the gase phase at room temperature,
overpressure will be created in the trap which depends of the satu­
rated pressure from pumped products.
Cleaning procedure :
- With trap cold, break vacuum with dry nitrogen.
- Isolate trap by closing isolation
- Disconnect trap from system.
- Open valves under a fume hood and allow trap to warm up. The
condensed products will liquefy.
-Tilt trap and drain impurities.
After using mineral oil, dip trap in a solvent such as 1. 1 .1. trichloroe­
thane or 1 .2. dichloroeth ane (cold
After using synthetic oils (Alcatel 113, Fomblln YL VAC 25-5
blin YL VAC 25-6*) clean parts when a solvent such as
lene or perchloroethylene.
During hot cleaning, use appropriate equipment and take necessary
precautions. If traces of oil remain after
Freon 113*"'.
Freon 113•• can also be used for ordinary cold cleaning.
- Rinse trap with alcohol and dry thoroughly.
- Replace trap In system.
- Close isolation valve abov.e the trap and pump down again to
degas trap.
• Registered Trademark Qf Montedison.
.., Registered Trademark of Du Pont de
84.5-:-i
Figure 1 : Dimensions
Isolation valve
t
Intake
Figure 2 : Assembly
:
valves.
cleaning).
♦
•
trichloroethy•
cleaning, remove them with
, r Nemours.
9321-
.J.
VJ 16.1
�114,3
84,5
'
Filling
ti
' -n
I [
'
L- _ .J
'
Fom·
32