1. No category

VARI..\.\J 801 TI-lER\OCDUPLE GAUGE O)NTROL
I NSTALLI\TION, CALIBRATION AND OPERATI NG I NSTRUCfIONS
The Var i an 801 thennocouple gauge control is a compact, sel f -contained
ins t rument , designed primarily for panel mounting. It is supplied ~ i th
a 6 ft. line cord and a 10 ft. thermocouple gauge cable. The ins t rument
is l ine voltage regulated, and a temperature sensitive element to compen~ate
for temperature drift in thermocouple gauges i s built i nt o th e the rmocoupl e
cable socket. The indicator dial, which covers the pressure ran ge from I to
2000 mdllitorr (1 millitorr is 1/1000 of 1 mm of mercury, or 1/1 000 of
1 torr), is calibrated for a Varian 531 thermocouple gauge i n dry air. The
. mechani cal zero adjust is located on the front of the instrument. lne
pressure calibration can be reached through a hole in the rear cover (Fig. 1a
and ld). The meter voltage (0 - 11 my) is available at two sol der tennin al s
at the rear for operating remote indicators whose input res istance should
be 200 ohms or more.
Installation
A panel cutout, as shown in Fig. la, is required for the installat ion of
the Varian 801 thermocouple gauge control . The instrument is mounted
from the front and fastened with three nuts supplied (Fig. lb, Ie).
Calibration'
1.
With the line power disconnected, adjust the mechanical met er zero
until the needle reads OFF.
2.
Connect a Varian 531 thenoocouple gauge to a vacuum system capable
of maintaining a pressure of less than 1.0 micron.
3.
Pump do\Yn the system to less than 1.0 micron.
4.
Connect the thermocouple cable of the Varian 801 control to the
Varian 531 thermocouple gauge.
5.
Plug the line cord into a l15V 50/60 cycle outlet.
6.
Turn the calibration control in the rear of the instrument until the
meter registers Zero millitorr.
7.
Allow the system to stabilize for approximately 15 minutes, and
readjust the zero if necessary.
OOTE:
If so desired, the gauge can be calibrated against a
~1cLeod
gauge.
varian
!texingtoo v1.'Cuum division
121 hartwelllMlnUe/lexingtlOli / massactusetts 02173
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8888-08-000
~ Ia i n te n a n c e
Due to a ging and/or contamination of the thermocouple gauge,
recalibration may be necessary from time to time. The a bove proce dure s ho u l d then be followed. As the temperature compensation
for the TC ga uge is built into the TC cord socket, it is not advisab l e to cut the plug off the TC cord. If the cable is too lon g, it
s ho u l d be coiled.
Disassembly, of Control
The 801 should give years of trouble-free service, but if
repairs are necessary, the following procedure of dismantling
should be followed.
1.
Unplug line cord.
2.
Remove the two screws that hold the rear cover and terminals.
3.
Remo ve the plastic cover.
4.
Remove printed circuit card from meter.
NOTE:
If, after assembly, the meter reads backwards, turn
printed circuit card one-half turn.
Desc ript ion
Part Number
Transformer, Tl
Thermistor
Meter
T.C. Board
T.C. Gauge Tube
0881-6581-00-125
0881-6542-08-005
0881-6522-08-275
0881-F2737-301
053-F0472-301
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CABLE
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GAUG£
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INS T A L L A TION & O P ER A TING INSTRU C TIONS
for
MODEL 501 THERMOCOUPLE GAUGE
Typ e and L en gth of Leads
The le ad wires must be soldered to an octal tube sock e t fol l owin g t h e a p propria te connections shown on drawing M-IS95. The user m u s t t a k e
care to m ake good so lde r joints since all circuits us e d w i t h the ga ug e a r e
both low i n volta ge and re sistance.
The l ength of leads i s not critical provided the total lead r es i s t a n c e i n
either t h e heater or t he th ermocouple c i r c u it does not e x ce ed one - h a lf
ohm. The thermoco uple lead s should be kept close to g e ther to minim i ze
the effect of exter n al temperatur e variations in produ c ing str ay el ectrotrio tiv e forces.
The use of conduit is recommended where long leads a r e used ;
Installation
\
\
A suitable l/S" IPS coupling must be provided in the s y s t e m for i ns t a ll a tion of the gauge. Direct drilling and tapping is recommended only if the chamber wall is more than 1/4" thick.
.
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Both male a n d fe m ale threads shoul d b e cleaned of a ll d i r t or gre as e b y
rinsing with acetone or ether a n d allowing the threads to dry. Do n ot
touch threads' with fingers after cleaning. j
Apply a thin c oati n g of glyptal lacquer to the male th r e ad s o t h at t he fir st
on e or two thread s remain dry, insert and make up t o a b o ut the same t i ghtnes s as r equired for a standard water pipe connection. On comple tion of
th e j oi nt , retouch lightly with more g l y ptal.
C a libr a t ion
,.
A cali br a tion cur ve fo r dr y a i r is s ho w n on dr a w i n g MG - 8 0 44 . Since t he
cali b r a t io n of the gauge d epends on the t y pe of gas, s p e c i a l c a l ibr ati on s
are required when the ga ug e is u s ed w ith g a ses o t h e r t han d r y ai r. T h e
gauge will,how ever, indi cate rel a tive pre ssu r e c h a ng e s .
E a c h ga uge h as a num b er stamp ed on the shor t h exa gonal t u be w h i ch co n ne c t s t he g a ug e en v e l op e to th e v ac uu m sy stem. Th i s number re prese n ts
h u n d re d th s o f a n a rnp e r e , T h e r equired he a t er i np u t c u r r e n t i s obtain e d
by ad di ng 0.6 to the number sta mped o n th e g a ug e con sidered a s h undr ed th s.
T h u s , if t he n urn b o r s t a m p e d i s 3 thi s r e p r e s e n t s 0. 0 3 a m p e r es , and th e
h e a t er input curre nt th us be com e s 0 . 63 a mpe re s .
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PHYSICAL SPECIFICATIONS
'
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OPERATING CHARACTERISTICS
for
MODEL 501 THERMOCOUPLE GA UGE
Physical Specifications
Dimensions:
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"
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"
6-1/16" long.x 1-1/4" diameter envelope
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Electrical Cable Connections: Standard octal a-prong tube base.
Mating plug not furnished, may be had on s pe c i al order
as Part 5-0001.
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Weight:
,
6 ounces.
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Shipping weight:
".
1 pound .
') ? p e r a t i n g Characteristics
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Heater current: 0.6 amperes plus hundredths of an ampere, corresponding to calibration number stamped on hexagonal
nipple
of gauge. --.......
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'-. -: -...
Maximum Heater Current:
1.0 amperes.
,H e a t e r 'r e s i s t a n c e : 0.2 ohms (approximate).
The r-rnocoupl e output:
Range:
0 to 14 millivolts.
1 - 1000 microns mercury absolute in dry air, scale nonlinear.
NATIONAL RESEARCH CORPORATION
C ,ambridge 42, M assachusetts ,.. ~~_., ~
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KMB:mw,mrq,pb
1 June, 1950
Issue No.3, supersedes all issues prior to 1 June, 1950
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,
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:0 - 1 B
L e ak Hunting
For l e ak huntin g use an acetone or ether spr ay. Increase t h e i n p ut
current to about 1.0 amper e for greater sen sitivity. When a leak is
hit, the thermocouple output will drop, due to the change in vap o r in
the gauge.
Pr ec aution
, T h e gauge should be protected against v ibration, shock a n d r- xc e s s i ve
heating and cooling from outside sources. The gauge can be op erated
' a t atrrios phe r ic pressure, without damaging the filament.
'.
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NA TIONAL RESEARCH CORPORATION
Cambridge 42, Massachusetts
KMB:pb
Is s u e No.3, supersedes all issues pr ior to 1 June, 1 950
\,
NA T1 ()NA .i-, R ESE.ARCH C.ORl--C :.;A ' '- H) '\:
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5
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HEATER
BOTTOM VIEW
PRONG ARRANGEMENT
SUPPORT
THERMOCOU~Lt !
JUNCTION
5
7
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PRONGSI85-HEATERINPUT
PRONGS 387-THERMOCOUPLE
OUTPUT
SECTIONAL VI EW
MODEL 501 THERMOCOUPLE GAUGE
TYPE 05- 0100
SCALE: FULL
'MO- 18 9 5
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CALIBRATION CURVE- DRY AIR
MODEL 501 THERMOCOUPLE GAUGE
70 OHM IMPEDANCE METER CIRCUIT
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180
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PRESSURE IN MICRONS OF MERCURY
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MG- 8044