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Fund
amen
tals
of
Mic
rom
achi
ning
Vac
uum
Sys
tem
s
Out
line
•V
acuu
m p
rinc
iple
s
•V
acuu
m p
umps
•V
acuu
m m
ater
ials
and
com
pone
nts
•V
acuu
m in
stru
men
tati
on
•V
acuu
m s
yste
ms
Use
s of
Vac
uum
in M
icro
fabr
icat
ion
Rou
gh V
acuu
mH
igh
Vac
uum
Ult
ra-H
igh
Vac
uum
waf
er c
huck
sev
apor
atio
nsu
rfac
e an
alys
islo
ad lo
cks
ion
impl
anta
tion
mol
ecul
ar b
eam
epit
axy
(MB
E)
sput
teri
ngre
acti
ve io
n et
chin
g(R
IE)
low
pre
ssur
e ch
emic
alva
por
depo
sitio
n(L
PCV
D)
Uni
ts o
f Pr
essu
re M
easu
rem
ent
•1
atm
osph
ere
=–
760
mm
Hg
= 7
60 to
rr
–76
0,00
0 m
illit
orr
or m
icro
ns
–29
.921
3 in
. Hg
–14
.695
9 ps
i
–1.
0132
5 ba
r
–10
13.2
5 m
illi
bar
–10
1,32
5 pa
scal
s (P
a)
–40
7.18
9 in
. H2O
–33
.932
4 ft
. H2O
1 P
asca
l = 1
N/m
2
1 T
orr
= 1
mm
Hg
1 m
icro
n =
1 µ
m H
g
760
mm
Hg
33.9
3 ft
H2O
Vac
uum
Ran
ges
•L
ow o
r R
ough
Vac
uum
(L
V)
–76
0 to
10-3
torr
•H
igh
Vac
uum
(H
V)
–10
-3 to
10-8
torr
•U
ltra
-Hig
h V
acuu
m (
UH
V)
–10
-8 to
10-1
2 to
rr
Part
ial P
ress
ures
of
Gas
es in
Air
at S
TP
Gas
Sym
bol
Vol
ume
Per
cent
Par
tial
Pre
ssur
e, T
orr
Nitr
ogen
N2
7859
3O
xyge
nO
221
159
Arg
onA
r0.
937.
1C
arbo
n D
ioxi
deC
O2
0.03
0.25
Neo
nN
e0.
0018
1.4
x 10
-2
Hel
ium
He
0.00
054.
0 x
10-3
Kry
pton
Kr
0.00
018.
7 x
10-4
Hyd
roge
nH
20.
0000
54.
0 x
10-4
Xen
onX
e0.
0000
087
6.6
x 10
-5
Wat
erH
2OV
aria
ble
5 to
50,
typ
.
Idea
l Gas
Law
- 1
•V
= v
olum
e of
enc
losu
re
•N
= n
umbe
r of
mol
ecul
es
•N
m =
num
ber
of m
oles
= N
/NA
•n
= p
arti
cle
dens
ity
= N
/V
•P
= p
ress
ure
•T
= a
bsol
ute
tem
pera
ture
•k B
= B
oltz
man
n’s
cons
tant
= 1
.381
x 1
0-23
J/K
•N
A =
Avo
gadr
o’s
num
ber
= 6
.022
x 1
023 p
arti
cles
/mol
e
•R
= G
as c
onst
ant =
NAk B
= 8
.315
J/m
ole-
K
Tnk
P
TN
kP
V
RT
NP
V
BB
m
===
Idea
l Gas
Law
- 2
•H
isto
rica
l Law
s:–
Boy
le’s
Law
: P
1V1
= P
2V2
at c
onst
ant
T
–C
harl
es’
Law
: V
1/T 1
= V
2/T 2
at c
onst
ant
P
–G
ay-L
ussa
c’s
Law
: V
= V
0(1
+ T
/273
)
Kin
etic
Gas
The
ory
•V
eloc
ity
of a
mol
ecul
e is
•M
ean
squa
re v
eloc
ity
is
•Pr
essu
re e
xert
ed o
n a
wal
l in
the
x-di
rect
ion
is
•If
vel
ocit
ies
for
all d
irec
tion
s ar
e di
stri
bute
d un
ifor
mly
,
•T
hus,
•E
ach
mol
ecul
ar D
OF
has
an a
vera
ge e
xcit
atio
n of
k BT
/2.
zv
yv
xv
vz
yx
ˆˆ
ˆ+
+=
r
22
22
zy
xv
vv
v+
+=
2 xx
vnm
P=
22
3xv
v=
Tnk
vnm
PB
==
231
Tk
vm
B23
221
=
Dis
trib
utio
n Fu
ncti
ons
- 1
•B
oltz
man
n’s
post
ulat
es f
or a
n id
eal g
as:
–T
he n
umbe
r of
mol
ecul
es w
ith x
-com
pone
nts
of v
eloc
ity
in th
era
nge
of v
x to
v x +
dv x
is p
ropo
rtio
nal t
o so
me
func
tion
φ o
f v x
2
only
:
–T
he d
istr
ibut
ion
func
tion
for
spe
ed v
mus
t be
the
prod
uct o
f th
ein
divi
dual
and
iden
tica
l dist
ribu
tion
fun
ctio
ns f
or e
ach
velo
city
com
pone
nt:
zz
vzy
yvy
xx
vxdv
vN
dNdv
vN
dNdv
vN
dN)
()
()
(2
22
φφ
φ=
==
zy
xz
yx
zy
xvz
vyvx
dvdv
dvv
vv
dvdv
dvv
N
dN)
()
()
()
(2
22
2,
,φ
φφ
ψ=
=
Dis
trib
utio
n Fu
ncti
ons
- 2
•A
mat
hem
atic
al s
olut
ion
to th
e ab
ove
equa
tion
s ha
s th
efo
rm o
f (A
and
vm a
re c
onst
ants
):
•N
orm
aliz
atio
n of
the
dist
ribu
tion
fun
ctio
ns:
22
/2)
(m
xv
vx
Ae
v−
=φ
Nv
NA
dvN
Ae
dNm
xv
vvx
mx
==
=∫
∫∞ ∞−
−∞ ∞−
2/
22
π2/1
2)
(−
=mv
Aπ
m
Tk
vdv
ev
vdN
vN
vB
mv
v
m
vm
34
12
23/
03
4
0
22
22
==
==
−∞
∞
∫∫
π2/1
2
=
m
Tk
vB
mdv
vdv
dvdv
zy
x2
4π= D
istr
ibut
ion
Func
tion
s -
3
•N
orm
aliz
ed d
istr
ibut
ion
func
tion
for
a s
ingl
e ve
loci
tyco
mpo
nent
(Gau
ssia
n):
•N
orm
aliz
ed d
istr
ibut
ion
func
tion
for
vel
ocit
y m
agni
tude
(Gau
ssia
n):
•N
orm
aliz
ed d
istr
ibut
ion
func
tion
for
a r
ando
mly
dir
ecte
dve
loci
ty (M
axw
elli
an):
−
=T
kmv
Tkm
vB
x
Bx
2ex
p2
)(
22/1
2
πφ
−
=T
kmv
Tkm
vB
B2
exp
2)
(2
2/3
2
πψ
−
=Φ
Tkmv
vT
kmv
BB
2ex
p2
4)
(2
2
2/3
2
ππ
Impi
ngem
ent R
ates
•T
he n
umbe
r of
mol
ecul
es w
ith
a ve
loci
ty f
rom
v x to
vx +
dv x
is d
Nvx
= N
φ(v x
2 ) d
v x.
•A
= a
rea
unde
r co
nsid
erat
ion.
•O
nly
thos
e m
olec
ules
with
in s
trik
ing
dist
ance
v xdt
wil
l hit
the
wal
l aft
er d
t sec
onds
.
•T
he n
umbe
r of
mol
ecul
es w
ith
velo
citie
s fr
om v
x to
v x +
dv x
impi
ngin
g up
on th
e w
all p
er ti
me
dt is
()
PT
mk
mTk
VN
Adt
dNB
Bi
2/12/1
22
−=
=π
π
2/1
0
2
2)
(
=
∫∞
mTk
dvv
vB
xx
xπ
φdt
dvv
Av
VNN
dx
xx
vx)
(2
2φ
=in
tegr
ate:
Gas
Flo
w -
1
•V
isco
us F
low
–oc
curs
for
pre
ssur
es g
reat
er th
an 1
0-2 to
rr
–ga
s m
olec
ules
con
stan
tly
coll
ide
wit
h on
e an
othe
r
–co
llis
ions
wit
h ea
ch o
ther
are
mor
e fr
eque
nt th
an w
all c
olli
sion
s
–ga
s be
have
s li
ke a
coh
eren
t, co
llec
tive
med
ium
; it a
cts
like
a f
luid
•Fr
ee M
olec
ular
Flo
w–
occu
rs f
or p
ress
ures
less
than
10-2
torr
–ga
s m
olec
ules
trav
el f
or la
rge
dist
ance
s be
twee
n co
llis
ions
–co
llis
ions
wit
h w
alls
are
mor
e fr
eque
nt th
an w
ith
each
oth
er
–ga
s m
olec
ules
fly
inde
pend
entl
y of
eac
h ot
her
Gas
Flo
w -
2
•Pi
pe o
f ra
dius
r a
nd le
ngth
l:
•V
isco
us F
low
–P
oise
uill
e’s
equa
tion:
•Fr
ee M
olec
ular
Flo
w–
Knu
dsen
’s e
quat
ion:
)(
8
32)
(1
2
2/13
12
PP
mTk
lrP
PC
QB
mol
−
=
−=
ππ
()
2 12 2
4
12
16)
(P
Pl
rP
PC
Qvi
s−
=−
=η
π
2/1
2
2
=
ππσ
ηT
mk
fB
Mea
n Fr
ee P
ath
•M
FP is
the
aver
age
dist
ance
a g
as m
olec
ule
trav
els
befo
reco
llid
ing
with
ano
ther
gas
mol
ecul
e or
the
cont
aine
r w
alls
.
•σ
is th
e di
amet
er o
f th
e pa
rtic
les
•πσ
2 is
the
cros
s-se
ctio
nal a
rea
for
hard
-sph
ere
coll
isio
ns
Mea
n F
ree
Pat
h (c
m)
=5
x 10
-3 to
rr-c
m
Pre
ssur
e (t
orr)
22
MFP
22
πσπσ
P
Tk
N
VB
==
For
com
mon
gas
es, {
H2O
, He,
CO
2, C
H4,
Ar,
O2,
N2,
H2}
, at T
= 3
00 K
:
Gas
Thr
ough
put
•Q
= P
S
•P
= g
as p
ress
ure
in to
rr
•S
= p
umpi
ng o
r le
akin
g sp
eed
in li
ters
/sec
ond
(L/s
)
•Q
= g
as th
roug
hput
in
torr
-lite
rs/s
econ
d (t
orr-
L/s
)–
Thi
s is
the
quan
tity
of
gas
mov
ing
thro
ugh
an o
rifi
ce p
er u
nit t
ime.
•Q
is d
irec
tly
rela
ted
to th
e po
wer
nee
ded
to m
ove
the
gas:
–1
Wat
t = 7
.50
torr
-L/s
ec =
100
0 Pa
-L/s
ec
•C
= g
as c
ondu
ctan
ce in
lite
rs/s
econ
d (L
/s)
•Q
= C
(P2
- P
1)
Vac
uum
Pum
p Pr
essu
re R
ange
s
-12
-10
-8-6
-4-2
0+2
Pre
ssur
e in
Tor
r (u
nits
are
exp
onen
ts o
f ten
)
Ultr
a-H
igh
Vac
uum
Hig
h V
acuu
mR
ough
Vac
uum
VE
NT
UR
I PU
MP
RO
TA
RY
PIS
TO
N M
EC
HA
NIC
AL
PU
MP
DR
Y M
EC
HA
NIC
AL
PU
MP
RO
TA
RY
VA
NE
ME
CH
AN
ICA
L P
UM
PS
OR
PT
ION
PU
MP
BLO
WE
R/B
OO
ST
ER
PU
MP
LIQ
UID
NIT
RO
GE
N T
RA
PD
IFF
US
ION
PU
MP
CR
YO
PU
MP
TU
RB
OP
UM
PIO
N P
UM
PT
I SU
BLI
MA
TIO
N P
UM
P
Vac
uum
Pum
ps
•T
wo
fund
amen
tal t
ypes
:–
Con
cent
rati
on p
umps
•G
as e
nter
ing
the
inle
t is
com
pres
sed
and
expe
lled
out
an
outl
et
•C
an r
un c
onti
nuou
sly
–E
ntra
inm
ent p
umps
•G
as e
nter
ing
the
inle
t is
trap
ped
insi
de
•M
ust b
e re
gene
rate
d to
em
pty
the
trap
ped
gas
Rot
ary
Van
e M
echa
nica
l Pum
ps -
1
Inle
tO
utle
t
Ele
ctric
Mot
or
Fra
me
Gas
Bal
last
Val
ve
Oil-
Fill
ed P
ump
Bod
y
Oil
Fill
Oil
Dra
in
Oil
Sig
htG
lass
Rot
ary
Van
e M
echa
nica
l Pum
ps -
2
Firs
t Sta
geS
econ
d S
tage
Gas
Bal
last
Val
ve
Inte
rsta
ge R
elie
f Val
veD
isch
arge
Val
ve
Rot
ary
Van
e M
echa
nica
l Pum
ps -
3
•G
ases
are
rem
oved
by
com
pres
sing
them
sli
ghtl
y ab
ove
atm
osph
eric
pre
ssur
e an
d th
en f
orci
ng th
em th
roug
h a
chec
k va
lve.
•T
he r
otar
y va
ne m
odul
es a
re im
mer
sed
in a
n oi
l bath
.
•T
he p
urpo
se o
f th
e oi
l is t
o:–
cool
the
pum
p
–lu
bric
ate
the
rota
ry v
anes
–pr
ovid
e a
lip
seal
for
the
vane
s
–op
en th
e se
cond
sta
ge e
xhau
st v
alve
at l
ow in
let p
ress
ures
•T
hey
are
pow
ered
by
an e
lect
ric
mot
or:
–B
elt d
rive
: 25
0 to
400
rpm
–D
irec
t dri
ve:
1725
rpm
(m
ost c
omm
on ty
pe)
Rot
ary
Van
e M
echa
nica
l Pum
ps -
4
•Po
tent
ial P
robl
ems:
–O
il m
ust h
ave
low
vap
or p
ress
ure
to a
chie
ve d
esir
ed p
erfo
rman
ce•
Wat
er o
r di
rt o
r im
puri
ties
in th
e oi
l wil
l rai
se th
e va
por
pres
sure
–B
acks
trea
min
g of
oil
vap
or c
an o
ccur
at l
ow p
ress
ures
•T
his
can
be tr
appe
d in
a m
olec
ular
sie
ve f
ilte
r
•M
ost o
ften
res
pons
ible
for
the
oily
sm
ell i
n a
vacu
um c
ham
ber
–L
arge
gas
load
s ca
n fr
oth
the
oil a
nd p
reve
nt s
eali
ng•
Gas
bal
last
can
be
open
ed to
all
ow f
roth
to s
ettl
e
•R
ough
ing
valv
es s
houl
d be
ope
ned
slow
ly (
feat
here
d) to
pre
vent
this
–B
elts
can
bre
ak o
n be
lt-d
rive
pum
ps•
Dir
ect d
rive
pum
ps e
lim
inat
e th
is p
robl
em
Sorp
tion
Pum
ps -
1
Sorp
tion
Pum
ps -
2
Liqu
id N
itrog
en B
ath
Sty
rofo
am L
N2
Buc
ket
Blo
w-O
ut P
lug
Alu
min
um B
ody
with
Inte
rnal
Fin
s
Mol
ecul
ar S
ieve
Nec
k F
lang
e
Sorp
tion
Pum
ps -
3
•G
ases
are
pum
ped
by–
Cry
ocon
dens
atio
n: g
ases
fre
eze
into
sol
id p
hase
on
cold
sur
face
s
–C
ryos
orpt
ion:
gas
es a
re tr
appe
d in
a p
orou
s m
olec
ular
sie
ve
•V
esse
l is
cool
ed b
y im
mer
sion
in li
quid
nit
roge
n (L
N2)
whi
ch r
each
es -
196°
C, o
r 77
° K
.
•P
umpi
ng is
com
plet
ely
oil f
ree
and
has
no m
ovin
g pa
rts.
•E
ach
sorp
tion
pum
p re
quir
es a
bout
2-3
gal
lons
of
LN
2 an
dab
out 2
0 m
inut
es to
coo
l dow
n.
•Se
vera
l sor
ptio
n pu
mps
are
oft
en c
ombi
ned
on a
man
ifol
d.
•Pu
mps
mus
t be
rege
nera
ted
by h
eati
ng to
250
° C
for
30
min
s. to
mel
t fro
st a
nd d
egas
the
mol
ecul
ar s
ieve
mat
eria
l.
Ven
turi
Pum
ps -
1
Muf
fler
Low
Pre
ssur
eV
entu
riH
igh
Pre
ssur
eS
uppl
y A
ir
Low
Vac
uum
Suc
tion
Ven
turi
Pum
ps -
2
•B
erno
ulli’
s pr
inci
ple
is u
sed
to p
ull v
acuu
m f
rom
the
pinc
hed
mid
sect
ion
of a
flo
w r
estr
icti
on.
•T
ypic
ally
dri
ven
by 6
0 psi
cle
an d
ry a
ir.
•V
entu
ri p
umps
can
usu
ally
pum
p a
cham
ber
from
760
Tor
rto
60
Tor
r.
•C
ompl
etel
y oi
l fre
e an
d ha
s no
mov
ing
part
s.
•In
stan
t on
and
off.
•V
entu
ri p
umps
can
rem
ove
abou
t 90
% o
f th
e ai
r in
ach
ambe
r, g
reat
ly r
educ
ing
the
capa
city
req
uire
men
ts o
fot
her
pum
ps.
•D
raw
back
is th
eir
nois
e; th
ey u
sual
ly n
eed
a m
uffl
er.
Roo
ts B
low
ers
/ Boo
ster
Pum
ps -
1
Inle
t
Out
let
Roo
ts B
low
erB
oost
er P
ump
Rot
ary
Van
eM
echa
nica
lP
ump
Roo
ts B
low
ers
/ Boo
ster
Pum
ps -
2
Inle
t
Out
let
Fig
ure-
Eig
htLo
bed
Rot
ors
Roo
ts B
low
ers
/ Boo
ster
Pum
ps -
3
•Pr
ecis
ion
shap
ed r
otor
s m
ate
to h
ousi
ng a
nd to
eac
h ot
her
to w
ithi
n on
ly a
few
thou
sand
ths
of a
n in
ch.
•R
otor
s sp
in a
t 250
0 to
350
0 rp
m.
•G
ears
syn
chro
nize
the
roto
rs.
•It
is a
hig
h th
roug
hput
, low
com
pres
sion
pum
p th
at is
use
dfo
r m
ovin
g la
rge
gas
volu
mes
.
•M
ust b
e be
low
10
Tor
r to
oper
ate.
•“W
indm
ills”
at a
tmos
pher
ic p
ress
ure,
cre
atin
g m
uch
heat
.
•R
equi
res
a m
echa
nica
l for
elin
e pu
mp.
Dif
fusio
n Pu
mps
- 1
Inle
t
Out
let
Oil
Fill
and
Dra
inA
ssem
bly
Ele
ctric
al P
lug
Oil
Hea
ter
Eje
ctor
Arm
Wat
erC
oolin
gLi
nes
Dif
fusio
n Pu
mps
- 2
Inle
t
Out
let
Oil
Fill
and
Dra
inA
ssem
bly
Ele
ctric
al P
lug
Oil
Hea
ter
Eje
ctor
Arm
Wat
erC
oolin
gLi
nes
Mul
tista
ge J
etA
ssem
bly
Dif
fusio
n Pu
mps
- 3
•O
il is
vap
oriz
ed a
nd p
rope
lled
dow
nwar
d by
an
inte
rnal
boil
er a
nd m
ulti
stage
jet a
ssem
bly.
•O
il v
apor
rea
ches
spe
eds
of 7
50 m
ph o
r m
ore
(sup
erso
nic)
.
•O
il va
por
stre
ams
trap
and
com
pres
s ga
ses
into
bot
tom
of
pum
p, w
hich
are
then
eje
cted
out
into
the
fore
line
arm
.
•O
il v
apor
is c
onde
nsed
on
side
s of
pum
p bo
dy w
hich
are
wat
er c
oole
d.
•C
an o
nly
oper
ate
at p
ress
ures
of
100
mT
or
less
.
•A
mec
hani
cal f
orel
ine
pum
p is
req
uire
d fo
r op
erat
ion.
•M
ulti
stag
e je
t ass
embl
y is
des
igne
d to
fra
ctio
nate
the
oil,
usin
g li
ghte
r w
eigh
t fra
ctio
ns f
or h
ighe
r va
por
velo
citi
es.
•T
ypic
ally
300
- 2
800
L/s
pum
ping
spe
eds.
Dif
fusio
n Pu
mps
- 4
•Po
tent
ial P
robl
ems:
–B
acks
trea
min
g of
oil
vap
or c
an o
ccur
if f
orep
ress
ure
beco
mes
too
larg
e.•
Bac
kstr
eam
ing
occu
rs f
or p
ress
ures
of
1 to
10
mT
orr.
•C
old
cap
on to
p of
mul
tist
age
jet a
ssem
bly
help
s to
red
uce
this
.
•L
iqui
d ni
trog
en f
ille
d cry
otra
p al
so h
elps
to r
educ
e th
is.
•M
axim
um to
lera
ble f
orel
ine
pres
sure
(cr
itic
al fo
repr
essu
re)
mus
t not
be e
xcee
ded,
or
pum
p w
ill “
dum
p”
or “
blow
-out
”, s
endi
ng o
il u
p in
toth
e ch
ambe
r.
–P
ump
can
over
heat
if c
ooli
ng w
ater
fai
ls•
Mos
t pum
ps h
ave
a th
erm
al c
utou
t sw
itch.
–Pu
mpi
ng r
equi
res
low
vap
or p
ress
ure
oil
•W
ater
, dir
t, or
oth
er im
puri
ties
wil
l rai
se v
apor
pre
ssur
e.
•O
nly
spec
ial o
ils
are
suit
able
for
dif
fusi
on p
ump
use.
Dif
fusio
n Pu
mp
Oil
s
•D
iffu
sion
pum
p oi
ls h
ave
very
low
vap
or p
ress
ure.
•T
ypes
–H
ydro
carb
on o
ils
•A
piez
on A
, B, C
, Lit
ton
Oil
, Con
voil-
20
–S
ilic
one
oils
•D
C-7
04, D
C-7
05, I
nvoi
l 940
–P
olyp
heny
l eth
ers
•Sa
ntov
ac 5
, Con
vale
x 10
–Fa
tty
este
rs•
Oct
oil,
But
yl P
htha
late
, Am
oil,
Invo
il
–Fl
uoro
ethe
r po
lym
ers
•K
ryto
x, F
ombl
in
Liq
uid
Nit
roge
n T
raps
/ B
affl
es -
1
Inle
t
Out
let
Fill
Ven
t Chi
lled
Baf
fles
Liqu
id N
itrog
enR
eser
voir
Liq
uid
Nit
roge
n T
raps
/ B
affl
es -
2
•B
affl
es a
nd tr
aps
in th
e pu
mpi
ng li
nes
can
grea
tly
help
tore
duce
bac
kstr
eam
ing:
–lo
w p
ress
ures
in m
echa
nica
l rou
gh p
umps
(0.
1 to
1.0
Tor
r)
–hi
gh p
ress
ures
in d
iffu
sion
pum
ps (
1 to
100
mT
orr)
–m
ost i
mpo
rtan
t with
in th
e “c
ross
-ove
r” r
egio
n.
•L
N2
cryo
trap
s sh
ould
not
exp
erie
nce
air
pres
sure
abo
ve10
0 m
Tor
r, o
r th
ey w
ill f
rost
com
plet
ely
over
.
•R
esid
ual w
ater
in a
cry
otra
p ca
n be
fro
zen
and
caus
e tr
apto
bre
ak, c
ausi
ng c
atas
trop
hic
fail
ure
of v
acuu
m s
yste
m.
–B
low
out
any
wat
er v
apor
wit
h dr
y N
2 be
fore
fil
ling
wit
h L
N 2.
•L
N2
cryo
trap
s re
quir
e co
nsta
nt r
efil
ling
.–
Exp
ensi
ve, b
ut a
utof
ill v
alve
s ar
e av
aila
ble.
Dif
fusio
n Pu
mpe
d H
igh
Vac
uum
Bel
l Jar
Sys
tem
Tur
bom
olec
ular
Pum
ps -
1
Inle
t
For
elin
eE
lect
rical
Con
nect
ion
to C
ontr
olle
r
Rot
ors
Sta
tors
Sha
ft
Hig
h S
peed
Mot
or
Tur
bom
olec
ular
Pum
ps -
2
•V
ery
clea
n m
echa
nica
l com
pres
sion
pum
p
•U
se h
igh
spee
d ro
tati
on b
lade
s to
impa
rt v
eloc
ity
and
dire
ctio
n to
gas
mol
ecul
es
•9,
000
to 9
0,00
0 rp
m m
otor
spe
eds!
•20
to 6
0 bl
ades
per
dis
k
•10
to 4
0 co
mpr
essi
on s
tage
s pe
r pu
mp
•R
equi
res
a m
echa
nica
l for
elin
e pu
mp
•T
ypic
ally
100
to 8
00 L
/sec
pum
ping
spe
eds
•Id
eal f
or h
ydro
carb
on f
ree
appl
icat
ions
Tur
bom
olec
ular
Pum
ps -
3
•Pu
mpi
ng s
peed
is p
ropo
rtio
nal t
o th
e ro
tor
spee
d.
•T
he c
ompr
essi
on r
atio
of
the
turb
ine
esta
blis
hes
the
base
pres
sure
.
•T
he c
ompr
essi
on r
atio
is h
ighe
r fo
r hi
gher
mol
ecul
arw
eigh
ts:
–A
ppro
xim
atel
y: l
og10
K =
1.5
(M
)1/2
–Fo
r H
2, M
= 1
, so
K =
101.
5 =
30
= v
ery
smal
l
–Fo
r hy
droc
arbo
ns, M
= 1
00, s
o K
= 1
015 =
ver
y la
rge
•B
ase
pres
sure
is u
sual
ly li
mit
ed b
y H 2
.
Tur
bom
olec
ular
Pum
ps -
4
•Po
tent
ial P
robl
ems:
–V
ery
high
spe
ed r
otor
bla
des
have
clo
se-m
atin
g st
ator
bla
des.
•S
ligh
t im
bala
nces
can
cau
se v
ibra
tion
and
bea
ring
wea
r pr
oble
ms.
•Su
dden
bla
st o
f at
mos
pher
ic p
ress
ure
can
bend
the
blad
es d
own,
caus
ing
cata
stro
phic
fai
lure
, “cr
ashi
ng th
e pu
mp.
”
–L
ubri
cati
on o
f th
e hi
gh s
peed
rot
or is
an
engi
neer
ing
prob
lem
.•
Cir
cula
ting
oil
is m
ost r
elia
ble,
but
pum
p m
ust b
e ri
ght-
side
-up.
•G
reas
e-lu
bric
ated
bea
ring
s ar
e le
ss r
elia
ble,
but
all
ow p
ump
to b
epl
aced
at a
ny o
rien
tati
on.
–T
oo h
igh
of a
pre
ssur
e w
ill c
ause
aer
odyn
amic
lift
and
dra
g.•
A m
echa
nica
l for
elin
e pu
mp
mus
t be
used
•A
erod
ynam
ic li
ft c
an b
end
blad
es, c
ausi
ng c
atas
trop
hic
fail
ure.
Tur
bo P
umpe
d H
igh
Vac
uum
Bel
l Jar
Sys
tem
Cry
opum
ps -
1
Cry
opum
ps -
2
Inle
t
Reg
ener
atio
nF
orel
ine
Exp
ande
rM
otor
Hyd
roge
n V
apor
Bul
b T
herm
omet
er
1st S
tage
Cry
oarr
ay
2nd
Sta
ge C
ryoa
rray
Exp
ande
r M
odul
e
Rel
ief
Val
ve
Hel
ium
Lin
e C
onne
ctio
ns
Cry
opum
ps -
3
•U
se a
clo
sed-
loop
hel
ium
cry
ogen
ic r
efri
gera
tor.
•Pr
imar
y pa
rts
are:
–C
ompr
esso
r
–E
xpan
der
–C
old
Hea
d
•G
ases
are
pum
ped
by tw
o pr
oces
ses:
–C
ryoc
onde
nsat
ion
(H2O
, CO
2, N
2, O
2, A
r, s
olve
nt v
apor
s)•
Gas
es a
re c
onde
nsed
into
a s
olid
pha
se o
n cr
yoge
nica
lly
cool
edsu
rfac
es.
(The
y be
com
e fr
ost!
)
–C
ryos
orpt
ion
(H2,
He,
Ne)
•N
on-c
onde
nsab
le g
ases
are
ads
orbe
d on
to s
urfa
ces
of c
ryog
enic
ally
cool
ed p
orou
s m
edia
, usu
ally
act
ivat
ed c
harc
oal o
r zeo
lite
s.
•T
ypic
ally
100
- 1
000
L/s
pum
ping
spe
eds.
Cry
opum
ps -
4
•F
irst
sta
ge a
rray
ope
rate
s at
50
to 8
0 K
–P
rim
aril
y us
ed f
or p
umpi
ng w
ater
vapo
r an
d ca
rbon
dio
xide
.
•Se
cond
sta
ge a
rray
ope
rate
s at
10
to 2
0 K
–P
rim
aril
y us
ed f
or p
umpi
ng o
ther
con
dens
able
gas
es.
•A
ctiv
ated
cha
rcoa
l in
the
seco
nd s
tage
pro
vide
scr
yoso
rptio
n.–
Pri
mar
ily
used
for
pum
ping
oth
er n
on-c
onde
nsab
le g
ases
.
–C
harc
oal a
nd z
eoli
tes
have
abo
ut 8
000
ft2 /
cm3
of s
urfa
ce a
rea.
•C
ompl
etel
y oi
l fre
e op
erat
ion.
•C
an o
pera
te f
rom
any
ori
enta
tion
.
•V
ery
clea
n va
cuum
with
hig
h pu
mpi
ng s
peed
.
•V
ery
high
impu
lsiv
e pu
mpi
ng c
apac
ity.
Cry
opum
ps -
5
•Po
tent
ial P
robl
ems:
–M
ust b
e re
gene
rate
d to
ext
ract
the
trap
ped
gase
s•
Allo
w to
war
m to
roo
m te
mpe
ratu
re (
slow
), o
r
•U
se a
bui
lt-in
hea
ter
to w
arm
to 2
50 C
and
out
gas
(fas
t).
•R
egen
erat
ion
take
s th
e pu
mp
off-
line
for
sev
eral
hou
rs.
–R
egen
erat
ion
proc
ess
can
prod
uce
cons
ider
able
pre
ssur
e.•
Pum
ps h
ave
a sa
fety
pre
ssur
e re
lief
val
ve o
n th
e bu
cket
.
–M
ust b
e st
arte
d fr
om b
elow
100
mT
orr
•U
se a
mec
hani
cal r
ough
ing
pum
p
Cry
opum
p C
ompr
esso
r M
odul
e
Coa
lesc
er
Pow
er S
uppl
y
Ads
orbe
r
Com
pres
sor
Sur
geV
olum
e
Cry
o Pu
mpe
d H
igh
Vac
uum
Bel
l Jar
Sys
tem
Tita
nium
Sub
lim
ation
Pum
ps -
1
Pop
pet V
alve
Sum
p
Baf
fle
Tita
nium
Bal
l
LN2
Col
d T
rap
Tita
nium
Sub
lim
ation
Pum
ps -
2
•“T
SP”;
a ty
pe o
f “g
ette
r pu
mp”
•T
itani
um, w
hich
has
bee
n fr
eshl
y ev
apor
ated
ont
o th
e si
des
of a
sum
p, w
ill c
hem
ical
ly c
ombi
ne w
ith g
as m
olec
ules
.
•T
itani
um s
ubli
mes
fro
m a
hea
ted
sour
ce a
nd e
vapo
rate
s to
coat
the
wal
ls o
f th
e su
mp.
•T
ypes
of T
i sou
rces
:–
35 g
Ti-
ball
; 750
W o
pera
ting
, 200
W s
tand
by
–15
g m
ini-T
i-ba
ll; 3
80 W
ope
rati
ng, 9
5 W
sta
ndby
–4.
5 g
Ti f
ilam
ent;
380
W o
pera
ting,
zer
o st
andb
y
Typ
ical
pum
ping
spe
eds
for
fres
hly
coat
ed T
i sur
face
s (L
/sec
-in2 )
:
H
2N
2O
2C
OC
O2
H2O
20°C
:20
3060
6050
20
-190
°C:
6565
7070
6090
Non
-Eva
pora
ble
Get
ter
Pum
ps
•“N
EG
” pu
mps
.
•Z
r-V
-Fe
allo
y th
at i
s fo
rmed
into
a c
artr
idge
ove
r a
cons
tant
an s
trip
hea
ter.
•P
umps
all
of
the
tim
e, u
ntil
load
ed w
ith
gas
mol
ecul
es.
•R
egen
erat
ed b
y he
atin
g to
~35
0°C
for
30
min
s. to
deg
asth
e al
loy.
•V
ery
sim
ple
in c
onst
ruct
ion
and
oper
atio
n.
Ion
Pum
ps -
1
NS
exte
rnal
per
man
ent m
agne
t
pum
pbo
dy
titan
ium
cath
odes
mul
ticel
lcy
lindr
ical
anod
ear
ray
+Vpo
wer
supp
ly
cold
cath
ode
disc
harg
e
Dio
de Io
n P
ump
Ion
Pum
ps -
2
NS
exte
rnal
per
man
ent m
agne
t
pum
pbo
dy
titan
ium
cath
ode
grid
s
mul
ticel
lcy
lindr
ical
anod
ear
ray
--V
pow
ersu
pply
cold
cath
ode
disc
harg
e
Trio
de Io
n P
ump
Ion
Pum
ps -
3
•O
pera
tion
is b
ased
upo
n a
rare
fied
gas
ele
ctri
c di
scha
rge.
–H
igh
elec
tric
fie
ld c
an io
nize
a g
as m
olec
ule,
for
min
g a
free
elec
tron
and
a g
as io
n.
–F
ree
elec
tron
is c
olle
cted
by
the
anod
e, w
hile
gas
ion
is c
olle
cted
by th
e ca
thod
e.
–F
ast e
lect
rons
, acc
eler
ated
by
the
E-f
ield
, wil
l col
lide
wit
h an
dio
nize
oth
er g
as m
olec
ules
.
–A
coa
xial
mag
neti
c an
d el
ectr
ic f
ield
wil
l pro
duce
spi
ral o
rbit
s fo
rth
e fr
ee e
lect
rons
; the
larg
er p
aths
gre
atly
incr
ease
the
ioni
zati
on.
–H
ighe
r io
niza
tion
leve
ls w
ill s
usta
in a
cold
cat
hode
dis
char
ge.
–G
as io
ns a
ccel
erat
ed in
to th
e ca
thod
e ca
n st
ick
and
ther
efor
e be
pum
ped.
Ion
Pum
ps -
4
•C
atho
de p
late
s ar
e m
ade
of ti
tani
um (T
i).
•P
umpi
ng m
echa
nism
s:–
Inci
dent
gas
ions
may
be
impl
ante
d in
to th
e T
i cat
hode
pla
tes.
–In
cide
nt g
as io
ns m
ay s
putt
er T
i fro
m th
e ca
thod
e pl
ates
into
the
cyli
ndri
cal a
node
cel
ls, th
us p
rovi
ding
add
itio
nal g
ette
r pu
mpi
ng.
–H
2 is
dir
ectl
y ab
sorb
ed b
y th
e fr
esh T
i sur
face
s.
–G
as m
olec
ules
may
be
trap
ped
and
burr
ied
by s
putt
ered
Ti.
–E
lect
ric
disc
harg
e cr
acks
larg
er m
olec
ules
into
sm
alle
r on
es th
atar
e m
ore
read
ily
pum
ped.
•Io
n pu
mps
mus
t be
star
ted
at 1
0-5
torr
or
less
.
•In
term
edia
te p
umpi
ng is
usu
ally
pro
vide
d by
a s
orpt
ion
ora
cryo
pum
p.
Ion
Pum
ps -
5
•D
iode
pum
ps u
se a
Ti p
late
as
the
cath
ode.
•T
riod
e pu
mps
use
a T
i scr
een
as a
gri
d el
ectr
ode
and
the
pum
p bo
dy a
s th
e ca
thod
e.
•T
ypic
al tr
iode
pum
ps w
ill o
pera
te f
or ~
35,0
00 h
ours
(ab
out
4 ye
ars)
at a
n in
let p
ress
ure
of 1
0-6 to
rr o
f N
2.
•T
he io
n pu
mp
curr
ent i
s pr
opor
tiona
l to
the
gas
pres
sure
inth
e pu
mp,
so
this
can
be
used
as
a pr
essu
re g
auge
.
•A
ppen
dage
ion
pum
ps a
re o
ften
use
d to
sus
tain
hig
hva
cuum
in lo
ng s
ervi
ce d
evic
es s
uch
as m
icro
wav
e tu
bes.
Ion
/ Ti-
Sub.
Pum
ped
Ult
ra-H
igh
Vac
uum
Sys
tem
Vac
uum
Gau
ge P
ress
ure
Ran
ges
-12
-10
-8-6
-4-2
0+2
Pre
ssur
e in
Tor
r (u
nits
are
exp
onen
ts o
f ten
)
Ultr
a-H
igh
Vac
uum
Hig
h V
acuu
mR
ough
Vac
uum
BO
UR
DO
N G
AU
GE
TH
ER
MO
CO
UP
LE G
AU
GE
CO
NV
EC
TIO
N T
HE
RM
OC
OU
PLE
GA
UG
EP
IRA
NI G
AU
GE
CA
PA
CIT
AN
CE
MA
NO
ME
TE
R
CO
LD C
AT
HO
DE
GA
UG
EIO
NIZ
AT
ION
GA
UG
ER
ES
. NIT
RO
GE
N A
NA
LYZ
ER
RE
SID
UA
L G
AS
AN
ALY
ZE
R
Bou
rdon
Gau
ges
- 1
Gea
rB
ox
Exp
ansi
onT
ube
Bou
rdon
Gau
ges
- 2
•M
echa
nica
l gas
pre
ssur
e fl
exes
the B
ourd
on tu
be a
ndca
uses
the
arc
to u
nwin
d, w
hich
thro
ugh
a se
ries
of
gear
san
d le
vers
mov
es a
nee
dle
on th
e ga
uge’
s fa
ce.
•It
is
com
plet
ely
inse
nsit
ive t
o th
e ch
emic
al c
ompo
sitio
n of
the
gas.
•It
can
be
used
for
mea
suri
ng p
osit
ive
pres
sure
and
vac
uum
.
•L
ower
sen
siti
vity
for
vac
uum
mea
sure
men
ts is
abo
ut 0
.1to
rr.
•G
auge
s ar
e pr
ecis
ion
inst
rum
ents
and
can
be
dam
aged
by
mec
hani
cal s
hock
.
Cap
acita
nce
Man
omet
ers
- 1
Met
alD
iaph
ragm
Sta
inle
ssS
teel
Bod
y
Cap
acito
rE
lect
rode
10 k
Hz
osci
llato
ran
d de
mod
ulat
or
Cap
acita
nce
Man
omet
ers
- 2
•M
echa
nica
l gas
pre
ssur
e de
form
s a
tens
ione
d m
etal
diap
hrag
m.
•A
n ai
r ga
p ca
paci
tor
is f
orm
ed b
etw
een
the
diap
hrag
m a
nda
set o
f fi
xed
elec
trod
es.
•T
he c
apac
itan
ce th
us v
arie
s w
ith
the
pres
sure
.
•T
he c
apac
itan
ce is
mea
sure
d by
a d
emod
ulat
ion
and
ampl
ifie
r ci
rcuit
that
mak
es a
10
kHz
osci
llat
or w
ith
the
diap
hrag
m c
apac
itor
.
•C
apac
itan
ce m
anom
eter
s ar
e ex
trem
ely
line
ar a
nd a
ccur
ate.
–T
ypic
ally
wit
hin
1% o
f fu
ll s
cale
.
•T
hey
are
inse
nsiti
ve to
the
chem
ical
com
posi
tion
of
the
gas.
Cap
acita
nce
Man
omet
ers
- 3
•C
an b
e us
ed to
mea
sure
pre
ssur
e in
all
mod
es:
–G
auge
–A
bsol
ute
–D
iffe
rent
ial
•A
sin
gle
capa
cita
nce
man
omet
er c
an o
nly
read
ove
r 3-
4de
cade
s of
pre
ssur
e.
•C
apac
itanc
e m
anom
eter
s ca
n be
con
stru
cted
to c
over
the
rang
e fr
om a
tmos
pher
ic p
ress
ure
dow
n to
~10
-5 to
rr b
yus
ing
diap
hrag
ms
of d
iffe
ring
stif
fnes
s.
•C
apac
itanc
e m
anom
eter
s ar
e of
ten
used
to a
ccur
atel
ym
easu
re p
ress
ure
in p
roce
ss r
eact
ors,
and
are
oft
en u
sed
infe
edba
ck c
ontr
ol lo
ops.
The
rmoc
oupl
e G
auge
s -
1
Chr
omel
Alu
mel
K-t
ype
4-po
int
heat
er a
ndth
erm
ocou
ple
Sta
inle
ssS
teel
Can
The
rmoc
oupl
e G
auge
s -
2
•E
lect
ric
curr
ent p
asse
d th
roug
h a
fila
men
t hea
ts u
p th
efi
lam
ent t
o a
tem
pera
ture
that
dep
ends
upo
n ho
w f
ast t
hesu
rrou
ndin
g ga
s co
nduc
ts th
e he
at a
way
.
•T
he te
mpe
ratu
re is
mea
sure
d by
a th
erm
ocou
ple,
whi
ch is
part
of
the
fila
men
t ass
embl
y, a
nd th
e te
mpe
ratu
re r
eadi
ngis
con
vert
ed in
to a
n ap
prox
imat
e pr
essu
re o
n a
met
er.
•S
ince
dif
fere
nt g
ases
hav
e di
ffer
ent t
herm
al c
ondu
ctiv
ities
,th
erm
ocou
ple
gaug
es r
ead
diff
eren
tly
for
diff
eren
t gas
es.
•R
ead
from
abo
ut 1
to 1
000
mT
orr.
•V
ery
rugg
ed, r
elia
ble,
and
inex
pens
ive.
Pir
ani G
auge
s -
1
Sta
inle
ssS
teel
Can
Tun
gste
nR
esis
tive
Hea
ters
Pir
ani G
auge
s -
2
•S
imil
ar to
a T
C g
auge
, an
elec
tric
ally
hea
ted
fila
men
t tak
eson
a te
mpe
ratu
re th
at d
epen
ds u
pon
the
rate
of
heat
loss
toth
e su
rrou
ndin
g ga
s.
•T
he te
mpe
ratu
re o
f th
e fi
lam
ent i
s se
nsed
by
mea
suri
ng th
ech
ange
in th
e re
sist
ance
of
the
fila
men
t as
it is
hea
ted.
–Fo
r m
ost m
etal
s, th
e T
CR
is a
bout
+20
0 pp
m/°
C.
•P
iran
i gau
ges
requ
ire
a m
ore
soph
istic
ated
con
trol
ler,
but
are
mor
e ac
cura
te a
nd f
aste
r re
spon
ding
than
a T
C g
auge
.
•M
ost u
se a
Whe
atst
one
brid
ge c
ircu
it to
line
ariz
e th
efi
lam
ent a
gain
st a
com
pens
atin
g fi
lam
ent t
hat i
s he
ld a
tat
mos
pher
ic p
ress
ure.
•P
iran
i gau
ges
are
also
sen
siti
ve to
the
gas
com
posi
tion
.
Hot
Fila
men
t Ion
izat
ion
Gau
ges
- 1
Gla
ssE
nvel
ope
Col
lect
or
Fila
men
tG
rid(0 V
)
(+25
V)
(+17
5 V
)
Hot
Fila
men
t Ion
izat
ion
Gau
ges
- 2
•A
lso
know
as
“Bay
erd-
Alp
ert”
gau
ges.
•E
lect
rons
are
ther
mio
nica
lly
emitt
ed f
rom
a h
ot f
ilam
ent
and
then
acc
eler
ated
by
a gr
id e
lect
rode
.
•T
he a
ccel
erat
ed e
lect
rons
wil
l ion
ize
any
gas
mol
ecul
es in
the
vici
nity
of t
he g
rid,
and
the
posi
tive
ly c
harg
ed g
as io
nw
ill c
ontr
ibut
e to
a c
urre
nt th
roug
h th
e co
llec
tor
elec
trod
e.
•I P
= I
E*S
*P, w
here
–I P
= p
ositi
ve io
n cu
rren
t thr
ough
col
lect
or e
lect
rode
–I E
= e
lect
ron
emis
sion
cur
rent
thro
ugh
fila
men
t
–S
= g
auge
sen
siti
vity
par
amet
er
–P
= g
as p
ress
ure
Hot
Fila
men
t Ion
izat
ion
Gau
ges
- 3
•T
he io
niza
tion
rat
e de
pend
s up
on th
e ga
s sp
ecie
s, s
o io
nga
uges
are
sen
sitiv
e to
the
gas
com
posi
tion.
•A
ccur
acy
is a
bout
10%
of
full
sca
le, w
hen
cali
brat
ed.
•Io
n ga
uges
can
wor
k fr
om 1
0-3 to
10-1
1 to
rr!
•L
ower
pre
ssur
e li
mit
is s
et b
y so
ft x
-ray
em
issi
on f
rom
elec
tron
s st
riki
ng th
e gr
id.
•H
ot f
ilam
ent r
equi
res
som
e pr
ecau
tions
:–
Exp
osur
e to
pre
ssur
es a
bove
10-3
torr
wil
l bur
n ou
t fil
amen
t.
–H
ot f
ilam
ent i
s an
igni
tion
sou
rce
whi
ch c
an tr
igge
r ex
plos
ions
inth
e pr
oces
s ch
ambe
r w
ith
com
bust
ible
gas
es.
Col
d C
atho
de I
oniz
atio
n G
auge
s -
1
NS
NS
Per
man
ent
Mag
net
Cat
hode
(-20
00 V
)
Sta
inle
ssS
teel
Bod
y(0
V)
Col
dC
atho
deD
isch
arge
Col
d C
atho
de I
oniz
atio
n G
auge
s -
2
•A
col
d ca
thod
e di
scha
rge
repl
aces
the
hot f
ilam
ent f
orpr
oduc
ing
ioni
zing
ele
ctro
ns.
•Io
nize
d ga
s m
olec
ules
are
col
lect
ed b
y th
e ne
gati
vely
char
ged
cath
ode,
and
the
elec
tric
cur
rent
is p
ropo
rtio
nal t
oth
e ga
s pr
essu
re.
•C
an o
pera
te f
rom
10-2
to 1
0-8 to
rr.
•M
ore
rugg
ed th
an a
hot
fil
amen
t ion
gau
ge, b
ut le
ssac
cura
te, t
ypic
ally
only
abo
ut 5
0% o
f fu
ll s
cale
.
•C
old
cath
ode
disc
harg
e is
sti
ll a
pot
enti
al s
ourc
e of
igni
tion
for
com
bust
ible
pro
cess
gas
es.
Cle
anli
ness
Ins
ide
a V
acuu
m C
ham
ber
•A
t 10-6
torr
:–
ther
e ar
e 4
x 10
4 m
olec
ules
/cm
3
–th
e m
ean
free
pat
h is
abo
ut 5
x 1
03 cm
–th
e im
ping
emen
t rat
e is
abo
ut 1
015 m
olec
ules
/cm
2 /se
c
•T
hus,
at 1
0-6 to
rr, a
mon
olay
er o
f m
olec
ules
wil
l dep
osit
on
any
surf
ace
in a
bout
1 s
econ
d.
•10
-6 to
rr i
s eq
uiva
lent
to a
pur
ity
of 1
ppb
!–
(Rel
ativ
e to
atm
osph
eric
pre
ssur
e at
~10
3 to
rr)
•T
he m
atte
r in
one
fin
gerp
rint
(1
cm x
1 c
m x
20 µ
m),
whe
nva
pori
zed,
wil
l pro
duce
a p
ress
ure
of 1
0-4 to
rr i
nsid
e a
10ft
3 va
cuum
cha
mbe
r!
•T
hus:
AL
WA
YS
WE
AR
GL
OV
ES!
!!
Vac
uum
Mat
eria
ls -
1
•St
ainl
ess
Stee
l–
Typ
e 30
4 SS
is m
ost c
omm
on.
•E
asy
to m
achi
ne.
•E
asy
to f
usio
n w
eld.
•C
oppe
r–
Use
Oxy
gen-
Fre
e H
igh-
Con
duct
ivit
y (O
FH
C)
allo
y.•
Use
d fo
r el
ectr
ical
con
duct
ors.
•C
eram
ics
–A
lum
ina (
Al 2
O3)
is v
ery
com
mon
.•
Use
d fo
r el
ectr
ical
insu
lato
rs.
•K
ovar
–(5
4% F
e, 2
9% N
i, 17
% C
o); u
sed
for
glas
s-to
-met
al s
eals
.
Vac
uum
Mat
eria
ls -
2
•E
last
omer
s–
Bun
a-N
•In
expe
nsiv
e, g
ood
to 8
0°C
, rat
her
impe
rmea
ble
to H
e.
–V
iton
•O
utga
sses
ver
y lit
tle,
goo
d to
150
°C.
–P
olyi
mid
e•
Goo
d to
200
°C, s
tiffe
r th
an o
ther
ela
stom
ers,
per
mea
ble
to H
2O v
apor
.
–S
ilic
ones
•C
an h
andl
e hi
gher
tem
pera
ture
s, b
ut v
ery
perm
eabl
e to
H2O
and
He.
–T
eflo
n•
Ver
y in
ert,
but e
xhib
its
cold
flo
w p
last
icit
y, m
akin
g it
a p
oor
seal
.
•V
ery
perm
eabl
e to
He,
goo
d to
150
°C.
Vac
uum
Joi
ning
Tec
hniq
ues
- 1
Inte
rnal
con
tinuo
us fu
sion
wel
ds a
re m
ost c
omm
only
use
d fo
r jo
inin
g tu
bing
,pi
pes,
and
cha
mbe
r po
rts.
For
sm
all b
ore
tubi
ng, e
xter
nal o
rbita
l wel
ding
mus
t pro
duce
com
plet
epe
netr
atio
n w
elds
.
Vac
uum
Joi
ning
Tec
hniq
ues
- 2
AS
A fl
ange
s ar
e a
com
mon
sta
ndar
d th
at u
ses
a ca
ptur
ed O
-rin
g to
pro
vide
sea
ling.
Vac
uum
Joi
ning
Tec
hniq
ues
- 3
KF
or
“Qui
ck-F
lang
es”
are
a co
mm
on s
tand
ard
for
roug
h or
hig
h va
cuum
plu
mbi
ng.
The
y ut
ilize
an
O-r
ing
supp
orte
d ag
ains
t fla
t fla
nges
with
an
inte
rnal
cen
terin
g rin
g.
Com
pres
sion
is s
uppl
ied
by a
tape
red
clam
p an
d w
ingn
ut.
No
tool
s ar
e ne
eded
.
Vac
uum
Joi
ning
Tec
hniq
ues
- 4
Met
al-s
eale
d, o
r “C
on-F
lat”
flang
es a
re u
sed
for
ultr
a-hi
gh v
acuu
m a
pplic
atio
ns w
here
elas
tom
er s
eale
d fla
nges
wou
ld b
e to
o le
aky.
A k
nife
edg
e on
eac
h fla
nge
bite
s in
to a
nd c
ompr
esse
s a
copp
er g
aske
t. T
he e
xtre
mel
yhi
gh p
ress
ure
of th
e kn
ife e
dge
caus
es th
e co
pper
to d
efor
m to
mat
ch th
e su
rfac
es o
f bot
hfla
nges
. T
hese
flan
ges
are
bake
able
up
to 3
50°C
.
Thi
ngs
to W
atch
for
in V
acuu
m S
yste
ms
•R
eal L
eaks
•V
irtu
al L
eaks
•W
ater
Lea
ks
•O
il C
onta
min
atio
n
•F
inge
r P
rint
s
•O
rgan
ic M
ater
ials
that
Out
gas
