Agilent Technologies UHV-24 User manual

Agilent UHV-24/UHV-24p Ionization Gauge
User Manual

2 Agilent UHV-24/UHV-24p Ionization Gauge User Manual
Notices
Manual Part Number
699905505
Edition G.00, February 2023
Copyright
© Agilent Technologies, Inc. 2023
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Safety Notices
A CAUTION notice denotes a hazard. It
calls attention to an operating
procedure, practice, or the like that, if
not correctly performed or adhered to,
could result in damage to the product
or loss of important data. Do not
proceed beyond a CAUTION notice
until the indicated conditions are fully
understood and met.
A WARNING notice denotes a hazard.
It calls attention to an operating
procedure, practice, or the like that, if
not correctly performed or adhered to,
could result in personal injury or death.
Do not proceed beyond a WARNING
notice until the indicated conditions
are fully understood and met.
WARNING
CAUTION

Contents
Agilent UHV-24/UHV-24p Ionization Gauge User Manual 3
Contents
1Instructions for Use 5
About this manual 6
Validity 6
Definitions and terminology 7
Definition of Caution, Warning and Note 7
Warning Symbols 8
Safety 10
Proper use 10
Improper use 11
Grounding the Gauge Controller 11
Use with Combustibles and Mixtures 12
Vacuum Equipment Cleanliness 12
Disposal 13
Service 14
2Technical Information 15
Description of the UHV-24/UHV-24p Ionization Gauge 16
Operation 16
Installation 18
Technical Specifications 19
Application Notes 21
Degas 23
Bakeout 23
Maintenance: Filament Replacement 24
Tungsten Filament Replacement 24
Yttria-coated iridium filament Replacement 25
Gas Correction Factors 26
Accessories and spare parts 29

Instructions for Use
4 Agilent UHV-24/UHV-24p Ionization Gauge User Manual

Instructions for Use
Agilent UHV-24/UHV-24p Ionization Gauge User Manual 5
1Instructions for Use
About this manual 6
Validity 6
Definitions and terminology 7
Definition of Caution, Warning and Note 7
Warning Symbols 8
Safety 10
Proper use 10
Improper use 11
Grounding the Gauge Controller 11
Use with Combustibles and Mixtures 12
Vacuum Equipment Cleanliness 12
Disposal 13
Service 14

Instructions for Use
6 Agilent UHV-24/UHV-24p Ionization Gauge User Manual
About this manual
Validity
This manual lists the instructions for the users of the UHV-24/UHV-24p Ion Gauge,
with particular reference to the notions relating to safety, operation and first level
maintenance, limited to maintenance operations for which the user is responsible.
The maintenance operations, illustrated in the specific sections, with specific
provisions relating to the higher level of maintenance (personnel specifically trained
for maintenance operations) must not be carried out by the user.
NOTE
1This manual contains useful information so that all personnel using the
UHV-24/UHV-24p Ion Gauge can operate it safely and guarantee perfect
efficiency, for its entire life span.
2Keep this manual, together with all the related publications, in an accessible
place known to all operators/maintenance personnel.

Instructions for Use
Agilent UHV-24/UHV-24p Ionization Gauge User Manual 7
Definitions and terminology
Definition of Caution, Warning and Note
Some important references of this manual are highlighted and framed in
contrasting color.
CAUTION
Caution messages are displayed before procedures which, if not observed, could
cause damage to the equipment.
WARNING
Warning messages draw the operator's attention to a specific procedure or
practice which, if not performed correctly, could result in serious personal
injury.
NOTE
Notes are intended to call attention to important information and provide more
detail regarding specific steps.

Instructions for Use
8 Agilent UHV-24/UHV-24p Ionization Gauge User Manual
Warning Symbols
The following is a list of symbols that appear in conjunction with warnings on the
UHV-24/UHV-24p Ion Gauge. The hazard they describe is also shown.
A triangular symbol indicates a warning. The meanings of the symbols that may
appear alongside warnings in the documentation are as follows:
Dangerous voltages Hot surface Generic hazard
Cutting hazard
European Declaration of Conformity
Waste Electrical and Electronic Equipment

Instructions for Use
Agilent UHV-24/UHV-24p Ionization Gauge User Manual 9
The following symbol may be used on warning labels attached to the instrument.
When you see this symbol, refer to the relevant operation or service manual for the
correct procedure referred to by that warning label.
The following symbols appear on the instrument for your information.
Production date
Dangerous voltages
Hot surfaces
Generic hazard
CE certification
Waste Electrical and Electronic Equipment

Instructions for Use
10 Agilent UHV-24/UHV-24p Ionization Gauge User Manual
Safety
This section contains the information, prescribed by the Low Voltage Directive
2014/35/EU, which is essential for the compliance and observance of the safety
regulations both generally and in relation to the specific use of the product.
Failure to comply with these instructions and the other instructions contained in
this manual may render the safety conditions envisaged in the design phase
inefficient and cause accidents to those operating the product.
Agilent Technologies declines all responsibility for damage to the product or for the
physical safety of the operator or third parties deriving from the non-observance of
the safety rules indicated in the technical documentation.
Proper use
This manual contains important warnings and safety instructions to be observed in
order for the unit to work safely.
The product described in this manual is intended exclusively for the area of
application specified in the instructions. The manual also provides indications
regarding the essential requirements for the application and operation of the
product as well as the safety measures that can be adopted to guarantee regular
operation. Agilent Technologies does not provide any guarantee or assume any
responsibility for applications other than those described in this manual or in which
the essential requirements and safety measures are not respected.
The product must only be used by qualified personnel who are able to take the
necessary safety measures under conditions that do not cause damage or injury.
Any accessories and equipment used with the product must be supplied or
approved by Agilent Technologies.
Any adjustment or maintenance operation must be performed by a professional
technician informed about the risks.
Repairs on the product must be carried out exclusively by Agilent authorized
personnel.

Instructions for Use
Agilent UHV-24/UHV-24p Ionization Gauge User Manual 11
Improper use
Agilent Technologies declines all responsibility, deriving from the improper use of
the UHV-24/UHV-24p Ion Gauge.
Improper use will cause all claims for liability and warranties to be forfeited.
Personnel responsible for pump operation and maintenance must be well-trained and
must be aware of the accident prevention rules. The accident prevention precautions
contained in this section must be continuously respected during operation and
maintenance of the pump to avoid damage to operators and to the pump. These
precautions are provided in the form of WARNING and CAUTION notes.
Grounding the Gauge Controller
Be certain that your UHV-24/UHV-24p Ion Gauge Controller and vacuum system are
separately grounded to a common ground.
WARNING
•Do not place a ground wire between the vacuum chamber and the controller
chassis; large continuous currents could flow through it.
•
Personnel can be killed by high voltages (160 to 900 V may be present in an
improperly grounded system).
•
Make absolutely sure that your vacuum system is grounded as shown in Figure 1.
•
Test the system ground to be sure that it is complete and capable of
supporting at least 10 A.
Note: Other power leads are not shown.
Figure 1 Ion Gauge and Vacuum System Connections
Do not make direct chassis to
vacuum system Connection!
Power Common or
Safety Ground Lead
Ion Gauge Controller
Vacuum System
Power Distribution
Breaker Box

Instructions for Use
12 Agilent UHV-24/UHV-24p Ionization Gauge User Manual
Use with Combustibles and Mixtures
WARNING
As with all Ionization gauges, this device is not intrinsically safe. Exercise
extreme care when using this vacuum gauge while pumping or backfilling a
system or in any other system condition which contains combustible gases
or mixtures. The filament, the end of a hot filament Ion gauge and the high
voltage discharge of a cold cathode gauge can be ignition sources.
When such a gas or mixture is present, do not turn on any such vacuum
gauge. Failure to follow this instruction could result in serious injury to
personnel and damage to equipment.
Vacuum Equipment Cleanliness
Cleanliness is vital when servicing any vacuum equipment.
CAUTION
Do not use silicone oil or silicone grease.
Use powder-free butyl or polycarbonate gloves to prevent skin oils from getting
on vacuum surfaces.
Do not clean any aluminum parts with Alconox®. Alconox is not compatible with
aluminum and will cause damage.
NOTE
Normally, it is unnecessary to use vacuum grease.
However, if it must be used, do not use silicone types, and use it sparingly.
Apiezon® L grease is recommended (Agilent Part Number 695400004).

Instructions for Use
Agilent UHV-24/UHV-24p Ionization Gauge User Manual 13
Disposal
Meaning of the "WEEE" logo found in labels.
The following symbol is applied in accordance with the EC WEEE (Waste Electrical
and Electronic Equipment) Directive.
This symbol (valid only in countries of the European Community) indicates that the
product it applies to must NOT be disposed of together with ordinary domestic or
industrial waste but must be sent to a differentiated waste collection system. The
end user is therefore invited to contact the supplier of the device, whether the
Parent Company or a retailer, to initiate the collection and disposal process after
checking the contractual terms and conditions of sale.
Figure 2 Logo "WEEE"
For more information refer to:
http://www.agilent.com/environment/product/index.shtml

Instructions for Use
14 Agilent UHV-24/UHV-24p Ionization Gauge User Manual
Service
Should a customer need an advanced exchange or repair service, please contact
local distributor or directly e-mail to:
[e-mail]
[e-mail]

Technical Information
Agilent UHV-24/UHV-24p Ionization Gauge User Manual 15
2Technical Information
Description of the UHV-24/UHV-24p Ionization Gauge 16
Operation 16
Installation 18
Technical Specifications 19
Application Notes 21
Degas 23
Bakeout 23
Maintenance: Filament Replacement 24
Tungsten Filament Replacement 24
Yttria-coated iridium filament Replacement 25
Gas Correction Factors 26
Accessories and spare parts 29

Technical Information
16 Agilent UHV-24/UHV-24p Ionization Gauge User Manual
Description of the UHV-24/UHV-24p Ionization Gauge
The UHV-24 Nude Ionization Gauge, with an x-ray limit of 2x10-11 Torr, provides
reliable pressure measurement from 1 mTorr down to 2x10-10 Torr, with reduced
performance at pressures lower than 2x10-10 Torr.
The UHV-24p Nude Ionization Gauge utilizes an extremely thin collector which lowers
its x-ray limit to 5x10-12 Torr. As a result, it can measure pressure from 1m Torr down to
5x10-11Torr, with reduced performance at pressures lower than 5x10-11 Torr.
Properly mounted nude gauges, where the grid structure protrudes into the vacuum
chamber, offer the lowest error in terms of the local vacuum pressure being the
same as the chamber pressure. Both gauges are available with either dual tungsten
or yttria-coated iridium filament, which are field replaceable.
Nude gauges are recommended for bakeable, all-metal, ultra-high vacuum systems
where maximum exposure to the vacuum gives the highest possible accuracy.
The gauges are designed with replaceable dual filament assemblies.
The UHV-24/UHV-24p Ionization Gauge models are the following:
X3004-64401 UHV-24 gauge, dual yttria-iridium filaments,
2.75 in DN 40 ConFlat flange.
X3004-64402 UHV-24p extended range Ion gauge, dual thoria-iridium
filaments, 2.75 in DN 40 ConFlat flange.
Operation
The UHV-24/UHV-24p Nude Ionization Gauge contains three elements:
Filament – The filament serves as a source of electrons.
Grid – The grid functions as the electron collector operating at a positive
potential (typically +150 V) with respect to the filament.
Collector wire – Along the center of the cylindrical grid structure is a very small
diameter ion collector wire operating at a negative potential (typically 28 V) with
respect to the filament.

Technical Information
Agilent UHV-24/UHV-24p Ionization Gauge User Manual 17
The process is as follows:
1Electrons from the filament pass through the grid several times, on average,
before being collected at the grid. While passing through the interior of the grid
structure, the electrons ionize gas molecules at a rate which is proportional to
the gas density.
2The positive ions produced on the inside of the grid structure are accelerated
toward and are neutralized at the collector by electrons from the external
circuit. The number of ions produced per electron is proportional to gas density,
and the positive ion current to the ion collector is used as an indication of
pressure. Thus, for a constant value of accelerating voltage in excess of the
ionization potential of the gas, the number of positive ions formed should vary
linearly with pressure and with electron current. This is described by the relation
Ic= S P Ie
where:
Icis the Ion current in amperes to the collector,
Ieis the electron current in amperes to the grid, and
P is the pressure in Torr.
The sensitivity, S, of a given Ion gauge is the proportionality constant in the basic
ionization gauge equation above. Thus,
S = 1 Ic
P Ie
For UHV-24 gauges, S for air (nitrogen) is 25 (Torr)-1. For the UHV-24p, S for air
(Nitrogen) is 20 (Torr)-1. The normal operating electron current is 4 mA. For the
UHV-24, the ion current at a pressure of 10-9 Torr is 10-10 A.

Technical Information
18 Agilent UHV-24/UHV-24p Ionization Gauge User Manual
Installation
The UHV-24 and UHV24p Nude Ionization Gauges can be operated with any ion
gauge control unit capable of supplying the necessary operating voltages and
currents. Degassing of this gauge is by electron bombardment of the grid.
To install the gauge:
1Remove the metal sleeve protecting the collector wire.
2Mount the nude Ionization gauges in any position.
NOTE
Install the gauge in a relatively open space to reduce wall outgassing due to
localized heating by the filament.
When the gauges are mounted horizontally, position the filaments to the side of the
grid rather than below or above it so that a slight vertical movement of the grid or
filament does not change their relative spacing.

Technical Information
Agilent UHV-24/UHV-24p Ionization Gauge User Manual 19
Technical Specifications
Table 1 Technical Specifications
Filament Voltage
3 to 4.5 V (AC or DC) - Varies with pressure and emission current
Filament Current
2.5 to 3.5 A - Varies with pressure and emission current
Element Voltages
Collector voltage: V
c
= 0
Filament voltage: Vfil = 28 VDC
Grid voltage, Vg= +180 VDC
Degas Power Requirements (40 W)
Grid Voltage: +600 VDC max
Emission Current (total): 67 mA DC
Filament Voltage: 7 V
Measurement Specifications
Sensitivity:
•
25/Torr (UHV-24), nominal
•
20/Torr (UHV-24p), nominal Emission Current:
•
4 mA for widest measurement range 5x10-10 Torr
to 1x10-4 Torr
•
10 mA for pressures lower than 5x10-10 Torr ≤0.1 mA for
pressure over 1x10
-4
Torr
Materials
Filament: Tungsten or yttria-coated iridium filaments
Filament Supports: SST
Collector - tungsten:
•
0.007" diameter for UHV-24
•
0.002" for UHV-24p
Grid: SST
Feedthrough: SST, Alumina, Nickel Alloy

Technical Information
20 Agilent UHV-24/UHV-24p Ionization Gauge User Manual
Figure 3 Typical Gauge Characteristics Graphs