TELEDYNE HASTINGS
INSTRUCTION
INSTRUMENTS
INSTRUCTION MANUAL
HASTINGS MODEL DNV-33D
VACUUM GAUGE
Table of Contents
I
GENERAL DESCRIPT ION ..................................................................... 5
OPERAT ION PRINCIPLE ....................................................................... 7
II
1.0 SPECIFICAT IONS ................................................................................... 7
2.0 INSTALLAT ION PROCEDURE ............................................................. 8
2.1 Panel Mounting .................................................................................................................. 8
2.2 Gauge Tube Connections ................................................................................................... 8
2.3 Connection of Relay Contacts and Output Terminals ....................................................... 8
2.4 Gauge Tube Installation ..................................................................................................... 8
3.0 OPERAT ION OF VACUUM GAUGE...................................................... 9
3.1 Powering of Vacuum Gauge ............................................................................................... 9
3.2 Switch Position ................................................................................................................... 9
4.0 CALIBRAT ION AND T ROUBLESHOOT ING GUIDE
9
4.1 Check of Tube Accuracy .................................................................................................... 9
4.2 DNV-33 Calibration ........................................................................................................ 10
4.2.1 Reference Check .............................................................................................................. 10
4.2.2 Recalibration for Length GaugeTube Cable.................................................................... 10
4.2.3 Optimizing Gauge Tube Accuracy ................................................................................... 10
5.0 NOT ES ON VACUUM MEASUREMENT ........................................... 10
5.1 Effects of Condensable Vapors ......................................................................................... 10
5.2 Outgassing........................................................................................................................ 11
5.3 Ingassing .......................................................................................................................... 11
5.4 Effect of T hermal Conductivity ...................................................................................... 11
5.5 Effect of System Conductance ......................................................................................... 15
6.0 WARRANT Y ........................................................................................... 12
SECTION I
General Description
T he Hastings Digital Vacuum Gauge, Model DNV-33D, incorporates proven Hastings thermo-
pile technology to produce a linear vacuum gauge that covers the range of 1-1000 mTorr. T he
digital display reads directly in mTorr. T he instrument provides an analog output signal which
may be used to drive a remote indicator for recording, data logging, etc. T he output is scale is
1 volt for 1000 mTorr.
T he DNV-33D also includes dual set points (A set and B set) with LED indicators located on
the front panel. Relay contacts are also provided for remote switching.
T he rear panel of the instrument provides access to terminal blocks for AC power cord, gauge
tube, relays and analog output connections. T he calibration adjustment potentiometers may also
be accessed through the back panelof the unit. T he instrument is factory calibrated on a stan-
dard average curve for DNV-33 vacuum gauges.
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SECTION II
Operating Principle
T he operation of Hastings vacuum gauges uses a patented noble metal thermopile circuit. T he
hot junctions of the thermopile are heated directly by an AC current while an equal number of
cold junctions are kept at ambient temperature by heavy mounting studs. T hus a DC voltage is
then generated between the hot and cold junctions. As the pressure decreases, the lowering of
the thermal conductivity of the gas surrounding the hot junction tends to increase the tempera-
ture of the hot junctions, thus increasing the output of the thermopile. T his change in output is
then amplified, linearized, and calibrated as a function of pressure.
1.0
SP ECIFICATIO NS
Indicator Model ....................................................................................................DNV-33D
Case Dimension ....................................................... Front Panel 96mm SQ. Depth 10 ¾”
Gauge Tube Type ....................................................... DV-33D-1, DV-33D-2, DV-33D-3*
Gauge Tube Shell ......................................................................Welded stainless steel shell
Overpressure .............................................................................................1500 PSIG max.
Panel Cut-out ................................................ 3-1/16” (77.5 mm) H x 3-5/8” (92mm)W
Range .............................................................................................................. 1-1000 mTorr
Readout ........................................................................................................... Digital Meter
Power ....................................................................................... 115 VAC, less than 6 watts
Outputs ................................................................. Linear 0-1 VDC analog @ 4 ma. Max.
Calibration .............................................................................. Calibrated for air or nitrogen
*Dash number Defines System Fitting Differences:
-1 Weld Fitting
-2 Cajon #SS-4 VCR Male Gland
-3 Cajon #SS-4 VCR Female Gland
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2.0
INSTALLATIO N
QUICK START
Install DV-33D gauge tube in vacuum system (see section 2.4). Ensure system
is leak free.
Connect the tube to the DNV-33D power supply/display and apply 115 VAC.
Allow 30 minutes for warm-up (see section 3.1).
Set the switch on the DNV-33D to the “OPR” position for normal operation
(factory calibration).
Set the switch on the DNV-33D to the “Set A” position. T he relay will now be
energized when the pressure is less than the set point. T he set point LED will be
on when the relay is energized. T he set point may be set by adjusting the appro-
priate potentiometer on the front panel.
Set the switch on the DNV-33D to the “Set B” position. T he relay will now be
energized when the pressure is less than the set point. T he set point LED will be
on when the relay is energized. T he set point may be set by adjusting the appro-
priate potentiometer on the front panel.
Set the switch on the DNV-33D to the “CAL” position. T his is to be used when
zeroing the gauge with the tube at a pressure less than 0.1 mTorr.
Set the switch on the DNV-33D to the “T EST ” position. Use this position to
check the DNV-33D and to set the gain for individual tubes.
2.1 Panel Mounting
T he DNV-33D instrument package can be mounted in a 3-1/16 inch high by 3-5/8 inches wide
hole. Secure the gauge with the mounting brackets provided.
2.2 Connect the Gauge Tube wire to the gauge as follows:
REAR PANEL
GAUGE T UBE
WIRE COLOR
“T UBE”
PIN
A
#
A
C
D
BLACK
WHIT E
GREEN
C
D
2.3 Connect other wires to relay contacts and output terminals.
2.4 Gauge Tube Installation
Install the gauge tube in a clean, dry vacuum system with the open end pointing down so as to
be self-draining should any vapors condense within the tube (See Sec. 5.1). For maximum
accuracy, it is recommended that the tube be outgassed in the vacuum system for a minimum of
4 hours.
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3.0
O P ERATIO N O F VACUUM GAUGE
3.1 Powering of Vacuum Gauge
Plug the 8 ft. power cable into a single phase 115 VAC (DNV-33D) or 230 VAC (ENDV-
33D)line. A line frequency of either 50 or 60 Hz is satisfactory. Allow 30-40 minutes for warm-
up.
Plug the gauge tube cable onto the gauge tube. When the tube is exposed to a pressure greater
than1000 mTorr, the analog output will be over 2 volts, and the display will read “1”.
T he relay will energize when the pressure is below the trip points. “Normal” relay position is de-
energized (AT M pressure side of set point.)
3.2 Switch Position
“OPR” Normal operating position. Display reads pressure. Output on back panel reads 0-1
volt.
“SET A; SET B” Displays the trip point of the appropriate relay. If the pressure is below the trip
point the relay is energized and the LED will be lit. T he trip points can be set from 0-950 mTorr.
T he relay trip points are set by adjusting the appropriate pot located on the front panel.
“CAL” Used when zeroing the vacuum gauge tube at hard vacuum. Adjust the Cal pot on the
rear panel for 000 on the display.
“Test” A voltage is injected into the 2nd stage AMP so that the GAIN of the gauge can be set on
the average curve. Adjust ‘GAIN’ pot on rear panel for “400” on the display. NOT E: T he
signal output will change when the switch is put in this position and the set points may trip. See
section 4.2.1 Reference Check.
4.0
CALIBRATION AND TROUBLESHOOTING GUIDE
All Hastings vacuum gauges and tubes have been carefully checked and calibrated at the factory
before shipment. If a calibration check is desired the methods in the following sections may
prove helpful.
4.1 Check of Tube Accuracy
T he simplest and quickest method of checking the operation and calibration of power supply/
display and gauge tube is to keep a new, clean gauge tube on hand as a “standard”. To check
operation, install both of the gauge tubes together in the same clean, dry vacuum system, and
pump until a steady pressure is obtained. Plug the gauge onto both tubes alternately and check
reading. Be sure to allow time for readings to settle. If the tube reads a considerably higher
pressure than the tube being used as a standard, a calibration shift in the old tube has occured.
T his is most likely resulting from tube contamination. T he tube calibration can possibley be
restored by gently rinsing the interior of the tube with a solvent such as trichlorethylene. After
cleaning, thoroughly dry the tube and degas it before reinstallation into a vacuum system. T his
is done to avoid system contamination by the solvent. If calibration cannot be restored by this
precedure, replace the old tube with a new gauge tube.
CAUT ION: Do not attempt to measure the resistance of the gauge tube element while it is
under vacuum. Some ohmmeters apply measuring voltages sufficient to burn out the thermo-
pile while under vacuum. T he resistance of the gauge tube can be measured safely at atmo-
spheric pressure. T his measurement is made between pins 3, 5 and 7 counting clockwise from
the key looking at the base of the gauge tube. A measuring device such as the Triple Model 630
Test Set with ohms switch on the “X10” range, is suitable for this purpose.
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Warranty and Repair
4.2 DNV-33 Calibration
All calibration voltages are factory set and will rarely change. T he methods for checking gauge
calibration are detailed below:
4.2.1
Reference Check
T he DNV-33D incorporates a quick reference check reading. To utilize this feature the front
panel switch must be in the T EST position. In this position the digital display should read “400”
(+3). If it does not read this the calibration GAIN pot should be adjusted to bring the reading
back to “400”. T his will bring the gauge back on the standard average calibration curve.
NOT E: T he signal output will change when the switch is put in this position and the set points
may trip.
Pump the gauge tube down to hard vacuum. Set the front panel switch to the ‘CAL’ position.
Adjust the ‘CAL’ pot in the rear of the unit for 000 on the display. If there is a midscale refer-
ence available to the system, see section 4.2.3 on recalibration. Calibration is complete for use
with the standard average curve.
4.2.2
Recalibration for Different Length Gauge Tube Cables
A maximum of 100 feet of gauge tube cable can be utilized by the DNV-33D. If the cable length
or size (18 gauge) is changed, the unit must be recalibrated. T he procedure for recalibration is
described in section 4.2.1.
4.2.3
Optimizing Gauge Tube Accuracy
Individual tubes can be trimmed for best fit upscale on the curve by performing a calibration
adjustment of the gain pot vs. tube output against an accurate reference standard, to do this:
Pump the gauge tube down to hard vacuum. Set the front panel switch to the “CAL” position.
Adjust the “CAL” potentiometer in the rear of the unit until the display reads 000.
Pump the system to a known pressure using a reference in the system. At this pressure, adjust
the gain potentiometer until the display reading matches the reference reading. T he unit should
now be calibrated. Best average fit to the curve will occur if 700 mTorr is used for this setting.
Do not use this instrument with another tube unless resetting the gain to “400” per 4.2.1 or
performing the above procedure for the specific tube.
5.0
Notes on Vacuum Measurem ents
5.1 Effects of Condensable Vapors
If the readings of Hastings gauges are to be compared with readings of other types of gauges,
consideration must be given to the possible effects of condensable vapors on other gauges. For
example, none of the many types of McLeod gauges, give correct readings if condensable
vapors such as water, alcohol, acetone, etc., are present in the gauge. T he McLeod gauge
operates by compressing residual gases and vapors to obtain a reading, and this compression will
tend to compress vapors that are present. T his usally results in pressure reading that is lower
than the actual pressure. Furthermore two different McLeod gauges could be used and both
may have different readings. Both of these readings however could be incorrect if vapors are
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present. Hastings thermopile gauges however, have the useful property of responding to the
total pressure of all gases and vapors that are present in the gauge tube.
To exclude vapors from a vacuum system, it is necessary to employ a trap of some kind that will
absorb or condense vapors. Water vapor is by far the most common source of this difficulty. A
cold trap cooled by liquid nitrogen is an effective means in removing vapors.
It may be necessary to keep McLeod gauges constently under vacuum for several hours, or days
with a trap before it will read correctly. T he use of rubber or Tygon tubing connecting the gauge
to the vacuum system can lead to gross errors due to excessive outgassing and or adsorbtion by
the tube. It is recommended that only glass or metal tubing be used. Reference should be made
to the instructions furnished by the manufacturer of the McLeod gauge to be sure that it is
provided with a suitable trap.
5.2 Outgassing
Hastings gauge tubes are fabricated from materials which have been proven by years of usage to
be relatively free from outgassing. However; all surfaces of glass and metal that are exposed to
the vacuum system may liberate gases and vapors that were previously adsorbed during expo-
sure to the atmosphere. If the surfaces are contaminated with foreign matter, this outgassing
may be much more persistent than if the surfaces are clean. T he possibility of outgassing must
be considered in checking the accuracy of Hastings gauges or in checking for leaks. T his is
especially important when working with pressures of less than 10 mTorr where atmospheric
gases are likely to flood the enclosure due to leaks.
Also, if the system is being pumped continuously, gauges spaced at different distances from the
pump will register different pressures. For a reliable comparison of different vacuum gauges, it
is necessary then to insure that the vacuum system be free of any outgasses or other sources of
apparent leaks. T his can best be determined by closing off the system from the pumps and
observing if there is any rise in pressure within the range of interest.
5.3 Ingassing
Ingassing is an effect opposite to outgassing and may also lead to erroneous readings. Ionization
gauges exhibit a kind of pumping action that tends to clean up residual gasses in certain ranges
of pressure and thereby lower the pressure. Also, if a cold trap is in a closed system, the total
pressure may change considerable while condenseble vapors such as water, carbon dioxide and
mercury and being condensed.
5.4 Effects of T hermal Conductivity
All Hastings vacuum gauges are originally calibrated in dry air. Since this calibration is a
function of thermal conductivity, any gas having a thermal conductivity different from that of air
will also have a different calibration. Contact factory for calibration in gases other than air.
5.5 Effects of System Conductance
Each element that makes up a vacuum system has associated with it a certain conductance (that
is the opposite of resistance). For example, baffles, connecting tubing, and sharp turns may
cause pressure drops throughout the system during pumping and during the time in which the
system is reaching static equilibrium. It is not an uncommen occurence to measure different
pressures at different locations in a vacuum system. In checking the calibration of a vacuum
gauge, care must be taken to insure that the gauge and the reference are at the same pressure.
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SECTION 6
Warranty
6.1 War ranty Repair Policy
Hastings Instruments warrants this product for a period of one year from the date of shipment to be free
from defects in material and workmanship. T his warranty does not apply to defects or failures resulting
from unauthorized modification, misuse or mishandling of the product. T his warranty does not apply to
batteries or other expendable parts, nor to damage caused by leaking batteries or any similar occurrence.
T his warranty does not apply to any instrument which has had a tamper seal removed or broken.
T his warranty is in lieu of all other warranties, expressed or implied, including any implied warranty as to
fitness for a particular use. Hastings Instruments shall not be liable for any indirect or consequential
damages.
Hastings Instruments, will, at its option, repair, replace or refund the selling price of the product if
Hastings Instruments determines, in good faith, that it is defective in materials or workmanship during the
warranty period. Defective instruments should be returned to Hastings Instruments, shipm ent pr epaid,
together with a written statement of the problem and a Return Material Authorization (RMA) number.
Please consult the factory for your RMA number before returning any product for repair. Collect freight
will not be accepted.
.2 Non-War ranty Repair Policy
Any product returned for a non-warranty repair must be accompanied by a purchase order, RMA form
and a written description of the problem with the instrument. If the repair cost is higher, you will be
contacted for authorization before we proceed with any repairs. If you then choose not to have the
product repaired, a minimum will be charged to cover the processing and inspection. Please consult the
factory for your RMA number before returning any product repair.
TELEDYNE HASTINGS INSTRUMENTS
804 NEWCOMBE AVENUE
HAMPTON, VIRGINIA 23669 U.S.A.
ATTENTION: REPAIR DEPARTMENT
TELEPHONE
(757) 723-6531
1-800-950-2468
FAX
(757) 723-3925
E MAIL
hastings_instruments@teledyne.com
INTERNET ADDRESS http:/ / www.teledyne-hi.com/
Repair Forms may be obtained from the “Information Request” section of the
Hastings Instruments web site.
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