Ideal Vacuum XactGauge XGC-321 User manual

Doc. Ref. XGC-321-100119 1 V00 (2019-11)
XactGauge™
Convection-Enhanced Pirani Gauge
Sensor
XGC-321
Operating Manual
Incl. EU Declaration of Conformity

2 Doc. Ref. XGC-321-100119 V00 (2019-11)
Product Identification
In all communications with Ideal Vacuum Products, please spe-
cify the information given on the product nameplate. For conven-
ient reference copy that information into the space provided
below.
Validity
This document applies to products with part numbers:
P1010261 (ISO-KF-16)
P1010260 (ISO-KF-25)
P1010259 (ISO-KF-40)
P1010258 (CF 1.33”)
P1010257 (CF 2.75”)
P1010256 (4 VCR female)
P1010255 (8 VCR female)
P1010245 (1/8" MNPT)
The part number (PN) can be taken from the product nameplate.
If not indicated otherwise in the legends, the illustrations in this
document correspond to the product with vacuum connection
DN 25 ISO-KF. They apply to the other products by analogy.
We reserve the right to make technical changes without prior
notice.

Doc. Ref. XGC-321-100119 3 V00 (2019-11)
Important User Information
There are operational characteristic differences between solid
state equipment and electromechanical equipment. Because of
these differences, and because there are a variety of uses for
solid state equipment, all persons that apply this equipment must
take every precaution and satisfy themselves that the intended
application of this equipment is safe and used in an acceptable
manner.
In no event will Ideal Vacuum Products be responsible or liable
for indirect or consequential damages that result from the use or
application of this equipment.
Any examples or diagrams included in this manual are provided
solely for illustrative purposes. Because of the many variables
and requirements imposed on any particular installation, Ideal
Vacuum Products cannot assume responsibility or liability for
any actual use based on the examples and diagrams.
No patent liability is assumed by Ideal Vacuum Products with
respect to use of information circuits, equipment, or software
described in this manual.
Throughout this manual we use notes, notices and apply inter-
nationally recognized symbols and safety messages to make
you aware of safety considerations.
Identifies information about practices or circumstances that can
cause electrical or physical hazards which, if precautions are not
taken, could result in death or serious injury, property damage,
or economic loss.

4 Doc. Ref. XGC-321-100119 V00 (2019-11)
CAUTION
Identifies information about practices or circumstances that can
cause electrical or physical hazards which, if precautions are not
taken, could result in minor or moderate injury, property damage,
or economic loss.
NOTICE
Identifies information that is critical for successful application and
understanding of the product.
SHOCK HAZARD
Labels may be located on or inside the device to alert people
that dangerous voltages may be present.

Doc. Ref. XGC-321-100119 5 V00 (2019-11)
General Safety Instructions
•
Adhere to the applicable regulations and take the necessary
precautions for the process media used.
Consider possible reactions with the product materials.
Consider possible reactions (e.g. explosion) of the process
media due to the heat generated by the product.
•
Adhere to the applicable regulations and take the necessary
precautions for all work you are going to do and consider the
safety instructions in this document.
•
Before beginning to work, find out whether any vacuum com-
ponents are contaminated. Adhere to the relevant regulations
and take the necessary precautions when handling contamin-
ated parts.
Communicate the safety instructions to all other users.
Liability and Warranty
Ideal Vacuum Products assumes no liability and the warranty
becomes null and void if the end-user or third parties
•
disregard the information in this document
•
use the product in a non-conforming manner
•
make any kind of interventions (modifications, alterations etc.)
on the product
•
use the product with accessories not listed in the product
documentation.
The end-user assumes the responsibility in conjunction with the
process media used.
Gauge failures due to contamination or wear and tear, as well as
expendable parts (e.g. Pirani filament), are not covered by the
warranty.

6 Doc. Ref. XGC-321-100119 V00 (2019-11)
Contents
Product Identification 2
Validity 2
Important User Information 3
General Safety Instructions 5
Liability and Warranty 5
1 Introduction / General Information 7
1.1 Description 7
1.2 Specifications 8
1.3 Dimensions 9
2 Important Safety Information 10
2.1 Safety Precautions - General 10
2.2 Safety Precautions - Service and Operation 11
2.3 Electrical Conditions 12
2.3.1 Proper Equipment Grounding 12
2.3.2 Electrical Interface and Control 13
2.4 Overpressure and use with hazardous gases 13
2.5 Gases other than Nitrogen / air 14
3 Installation 15
3.1 Mechanical Installation 15
3.2 Electrical Installation 17
3.2.1 Grounding 17
4 Using the gauge with different gases 19
5 Service 23
5.1 Calibration 23
5.2 Maintenance 23
5.3 Troubleshooting 24
5.4 Contamination 26
5.5 Gauge replacement 28
6 Factory Service and Support 29
7 Returning the Product 29
8 Disposal 30
EU Declaration of Conformity 31
For cross-references within this document, the symbol (→  XY)
is used,

Doc. Ref. XGC-321-100119 7 V00 (2019-11)
1 Introduction / General Information
1.1 Description
Thermal conductivity gauges measure pressure indirectly by
sensing the loss of heat from a sensor to the surrounding gases.
The higher the pressure of the surrounding gas, the more heat is
conducted away from the sensor. Pirani thermal conductivity
gauges maintain a sensor (usually a wire) at some constant tem-
perature, and measure the current or power required to maintain
that temperature. A standard Pirani gauge has a useful measur-
ing range of about 10-4 Torr to 10 Torr. By taking advantage of
convection currents that are generated above 1 Torr, convection-
enhanced Pirani gauges increase the measuring range to just
above atmosphere.
The Ideal Vacuum Products XactGaugeTM XGC-321 Convection-
Enhanced Pirani Gauge Sensor is a convection-enhanced Pirani
vacuum gauge sensor that interfaces with external controllers
such as the Ideal Vacuum Products XactGaugeTM XGC-320
controller. The XGC-321 is also a direct drop-in replacement pin-
pin compatible gauge for the MKS Instruments / Granville-
Phillips® 275 Convectron® gauge. The sensor connector has the
same pinouts and signal as the corresponding Convectron®. It is
directly interchangeable with your existing Convectron® control-
lers and cables, so you don't need to change any wiring,
hardware, or process recipes.

8 Doc. Ref. XGC-321-100119 V00 (2019-11)
1.2 Specifications
Measurement range 1.3×10-4 … 1333 mbar
1×10-4 … 1000 Torr
1.3×10-2 Pa … 133 kPa
Accuracy - N2
(typical)
1.3×10-4 … 1.3×10-3 mbar
1.3×10-3 … 530 mbar
530 …1333 mbar
0.1 ×10-3 mbar resolution
±10% of reading
±2.5% of reading
1×10-4 … 1×10-3 Torr
1×10-3 … 400 Torr
400 … 1000 Torr
0.1 mTorr resolution
±10% of reading
±2.5% of reading
Repeatability - N
2
(typical)
±2% of reading
Materials exposed to vacuum gold-plated tungsten, 304
&
316 stainless steel, glass,
nickel, Teflon
®
Internal volume 26 cm3 (1.589 in3)
Internal surface area 59.7 cm2 (9.25 in2)
Weight 3 oz. (85 g)
Permissible temperature
Operating 0 … +50 °C
Storage –40 … +70 °C
Bakeout temperature ≤150 °C (non-operating, with
electronics cable detached)
Relative humidity 0 … 95%, non-condensing
Use
Operating
altitude up to 2500 m
(8200 ft.)
Storage altitude up to 12500 m
(41000 ft.)
Mounting orientation horizontal recommended
(orientation has no effect on
measurements below
1.3 mbar (1 Torr))

Doc. Ref. XGC-321-100119 9 V00 (2019-11)
1.3 Dimensions
Fitting Dimension A
mm (inch)
DN 16 ISO-KF
33
(1.3)
DN 25 ISO-KF
33
(1.3)
DN 40 ISO-KF
33
(1.3)
DN 16 CF 1.33 27.4 (1.08)
DN 40 CF 2.75” 37.3 (1.47)
4 VCR female 47.2 (1.86)
8 VCR female 44.5 (1.75)
1/8" NPT male 25.4
(1)

10 Doc. Ref. XGC-321-100119 V00 (2019-11)
2 Important Safety Information
Ideal Vacuum Products has designed and tested this product to
provide safe and reliable service, provided it is installed and
operated within the strict safety guidelines provided in this man-
ual. Please read and follow all warnings and instructions.
WARNING
To avoid serious injury or death, follow the safety informa-
tion in this document. Failure to comply with these safety
procedures could result in serious bodily harm, including
death, and or property damage.
Failure to comply with these warnings violates the safety stand-
ards of installation and intended use of this instrument. Ideal
Vacuum Products disclaims all liability for the customer’s failure
to comply with these instructions.
Although every attempt has been made to consider most possi-
ble installations, Ideal Vacuum Products cannot anticipate every
contingency that arises from various installations, operation, or
maintenance of the module. If you have any questions about the
safe installation and use of this product, please contact Ideal
Vacuum Products.
2.1 Safety Precautions - General
WARNING! There are no operator serviceable parts or
adjustments inside the gauge sensor.

Doc. Ref. XGC-321-100119 11 V00 (2019-11)
Do not modify this product or substitute any parts without au-
thorization of qualified Ideal Vacuum Products service trained
personnel. Return the product to an Ideal Vacuum Products
qualified service and repair center to ensure that all safety
features are maintained. Do not use this product if unauthorized
modifications have been made.
WARNING! Source power must be removed from the
product prior to performing any servicing.
Prior to installing the XGC-321, ensure that all safety checks are
made by a qualified service person. When a replacement gauge
is required, ensure that the gauge is specified by Ideal Vacuum
Products Substitutions of non-qualified parts may result in fire,
electric shock or other hazards. Use of unauthorized parts or
modifications made to this product will void the warranty.
To reduce the risk of fire or electric shock, do not expose this
product to rain or moisture. These products are not waterproof
and careful attention must be paid to not spill any type of liquid
onto these products. Do not use these products if they have
been damaged. Immediately contact Ideal Vacuum Products to
arrange return of the product if it is damaged.
Due to the possibility of corrosion when used in certain environ-
mental conditions, it is possible that the product’s safety could be
compromised over time. It is important that the product be peri-
odically inspected for sound electrical connections and equip-
ment grounding. Do not use if the equipment grounding or elec-
trical insulation has been compromised.
2.2 Safety Precautions - Service and Operation
Ensure that the vacuum port on which the XGC-321 vacuum
gauge is mounted is electrically grounded.
Remove cable to the unit before attempting to service the gauge.
Remove cable to the unit if a cable or plug is damaged or the
product is not operating normally according to this Operating
Manual. Contact qualified Ideal Vacuum Products service
personnel for any service or troubleshooting condition that may
not be covered by this Operating Manual.

12 Doc. Ref. XGC-321-100119 V00 (2019-11)
It is important that the product be periodically inspected for
sound electrical connections and equipment grounding. Do not
use if the equipment grounding or electrical insulation has been
compromised.
Do not use if the unit has been dropped. Contact Ideal Vacuum
Products for further instructions regarding evaluation of the
damaged sensor.
2.3 Electrical Conditions
WARNING! When high voltage is present in any vacuum
system, a life threatening electrical shock hazard may exist un-
less all exposed electrical conductors are maintained at earth
ground potential. This applies to all products that come in con-
tact with the gas contained in vacuum chambers. An electrical
discharge within a gaseous environment may couple dangerous
high voltage directly to any ungrounded conductor of electricity.
A person could be seriously injured or killed by coming in contact
with an exposed, ungrounded electrical conductor at high volt-
age potential. This condition applies to all products that
may
come
in contact with the gas inside the vacuum
chamber (vacuum
/ pressure containment vessel).
2.3.1 Proper Equipment Grounding
WARNING! Hazardous voltages that could seriously in-
jure
or
cause death are present in many vacuum processes.
Verify that the vacuum port on which the XGC-321 vacuum
gauge module is mounted is electrically grounded. Consult a
qualified Electrician if you are in doubt about your equipment
grounding. Proper grounding of your equipment is essential for
safety as well as intended operation of the equipment. The
XGC-321 module vacuum gauge must be connected directly to a
good quality earth ground. Use a ground lug on the XGC-321
gauge vacuum connection / flange if necessary.

Doc. Ref. XGC-321-100119 13 V00 (2019-11)
WARNING! In order to protect personnel from electric
shock and bodily harm, shield all conductors which are subject to
potential high voltage electrical discharges in or around the
vacuum system.
2.3.2 Electrical Interface and Control
It is the user’s responsibility to ensure that the electrical signals
from this product and any connections made to external devices,
for example, relays and solenoids, are used in a safe manner.
Always double check the system set-up before using any signals
to automate your process. Perform a hazardous operation analy-
sis of your system design and ensure safeguards and personnel
safety measures are taken to prevent injury and property dam-
age.
2.4 Overpressure and use with hazardous gases
WARNING! Install suitable protective devices that will limit
the level of pressure inside your vacuum chamber to less than
what the vacuum chamber system components are capable of
withstanding. Ideal Vacuum Products gauges should not be used
at pressures exceeding 1000 Torr absolute pressure.
In cases where an equipment failure could cause a hazardous
condition, always implement fail-safe system operation. For ex-
ample, use a pressure relief device in an automatic backfill op-
eration where a malfunction could result in high internal pres-
sures if the pressure relief device was not installed on the cham-
ber.

14 Doc. Ref. XGC-321-100119 V00 (2019-11)
The XGC-321 vacuum gauge module is not intended for use at
pressures above 20 psia (1000 Torr); DO NOT exceed 35 psig
(<2½ bars) pressure inside the sensor. If your chamber goes to
higher pressures, you should install an isolation valve or pres-
sure relief device to protect the gauge tube from overpressure
conditions. With some fittings, actual safe overpressure condi-
tions may be lower; for example, a quick-connect, O-ring com-
pression fitting may forcibly release the gauge tube from the
vacuum chamber fitting with only a few psi over local uncor-
rected barometric (atmospheric) pressure.
CAUTION! If the internal pressure of a vacuum gauge
device is allowed to increase above local uncorrected baro-
metric pressure (atmospheric pressure side), vacuum fit-
tings may release and possible overpressure conditions
may cause leaks that would allow the gas inside the gauge
tube to release into the atmosphere of the surrounding en-
vironment. Toxic, pyrophoric and flammable gases are ex-
amples of hazardous gases that if allowed to leak out of the
vacuum/pressure containment vessel into the atmospheric
environment, could cause bodily injury and possible dam-
age to equipment. Never expose the gauge tube internal
volume to pressure above local atmospheric pressure when
using hazardous gases.
2.5 Gases other than Nitrogen / air
WARNING! Do not attempt to use with gases other than
nitrogen (N2) or air without referring to correction factor data
tables.

Doc. Ref. XGC-321-100119 15 V00 (2019-11)
Ideal Vacuum Products gauges are calibrated for direct
readout of
nitrogen or air. Do not attempt to use with other gases such as
argon (Ar) or carbon dioxide (CO2) unless accurate conversion
data for N2 to other gas is properly used. Refer to the correction
factor data listed in the controller Operating Manual operating
this device. The Ideal Vacuum Products XGC-320 controller
Operating Manual provides a more complete discussion of
using correction factors when using the gauge on gases other
than Nitrogen.
WARNING! Do not use this device in an explosive
atmos-
phere
or in the presence of flammable gases, vapors or fumes.
Do not use this device to measure the pressure of explosive or
combustible gases or gas mixtures. The sensor wire in the
gauge normally operates at 125 °C, but if malfunction should
occur, the wire temperature could exceed the ignition tempera-
ture of certain combustible gases and gas mixture. This could
cause an explosion which could result in serious injury or death.
3 Installation
3.1 Mechanical Installation
Mount the XGC-321 as close as possible to the pressure you
want to measure. Long or restricted, small diameter tubing will
create a pressure difference between your process chamber and
the gauge. This may cause a delay in response to pressure
changes.
Mounting the XGC-321 too close to a gas source inlet may also
cause measurement and control instability. Do not mount the
XGC-321 near a source of heating or cooling, such as heaters or
air conditioning vents.

16 Doc. Ref. XGC-321-100119 V00 (2019-11)
Mount the XGC-321 with its main (long) axis horizontal (see dia-
gram below). Pressure reading errors may occur above 1 Torr if
the unit is not mounted horizontally. Below 1 Torr, mounting po-
sition has little to no effect.
For accurate measurements above 1 Torr, mount the gauge axis
horizontally as shown below:
Vacuum
chamber
Incorrect Orientation:
Vacuum chamber

Doc. Ref. XGC-321-100119 17 V00 (2019-11)
Mount the XGC-321 with port down, if possible, to help minimize
the effect of any particles or condensation from collecting in the
gauge.
Do not mount the XGC-321 where it will be subjected to exces-
sive vibration. Vibrations may cause unstable readings, measu-
rement errors and possible mechanical stress to components in
the XGC-321.
Flanges/ Fittings - follow the manufacturer's recommendations
and note the following:
- NPT fittings: When connecting the device using a NPT fitting,
apply a thread sealant compound or wrap the threaded portion
of the tubing with one-and-a-half to two wraps of pipe thread seal
tape such as PTFE (Teflon®) tape and hand tighten the
gauge into
the gauge port. Do not use a wrench or other tool which may
damage the gauge.
3.2 Electrical Installation
3.2.1 Grounding
Be sure the vacuum gauge and the rest of your vacuum
system are properly grounded for safety as well as intended
operation of the equipment. When using KF flanges, metal
clamps must be used to ensure proper grounding. Be aware that
some vacuum fittings such as NPT connections installed using
Teflon tape may not allow for metal-to-metal contact between the
vacuum gauge and the vacuum chamber. If such is the case,
use a 12 gauge or larger copper wire to connect the vacuum
gauge to a ground lug on your vacuum chamber as shown be-
low.

18 Doc. Ref. XGC-321-100119 V00 (2019-11)
Metal clamp or
metal hose clamp
Vacuum
chamber
Gauge tube
Use 12 gauge or
larger ground wire
Vacuum gauge fitting

Doc. Ref. XGC-321-100119 19 V00 (2019-11)
4 Using the gauge with different gases
A thermal conductivity gauge senses heat loss which
depends on
the thermal conductivity of the gas surrounding the sensor. Since
different gases, and mixtures, have different thermal con-
ductivities, the indicated pressure readings and outputs will also
be different. Ideal Vacuum Products convection gauges (and
most other thermal conductivity gauges) are calibrated using
nitrogen (N2). When a gas other than N2 / air is used, correction
must be made for the difference in thermal conductivity between
nitrogen (N2) and the gas in use. The gas correction data, charts
and tables listed in your controller (such as the Ideal Vacuum
Products XGC-320 controller) Operating Manual indicates how
different gases affect the display and output from an Ideal
Vacuum Products convection gauge.
WARNING! Using a thermal conductivity gauge with
gases
other
than that for which it is calibrated could result in
death or serious injury. Be sure to use the correction factor data
listed in the controller Operating Manual operating this device.
For N2 the calibration shows excellent agreement between indi-
cated and true pressure throughout the range from 1×10-4 to
1000 Torr. At pressures below 1 Torr, the calibration curves for
the different gases are similar. The difference in readings at
these low pressures is a constant, a function of the difference
between thermal conductivities of the gases.
At pressures above 1 Torr, indicated pressure readings may
diverge significantly. At these higher pressures convection
currents in the gauge become the predominant cause of heat
loss from the sensor and calibration depends on gauge tube
geometry and mounting position as well as gas properties.

20 Doc. Ref. XGC-321-100119 V00 (2019-11)
Generally, air and N2 are considered the same with respect to
thermal conductivity, but even N2 and air will exhibit slight diffe-
rences in readings at higher pressures. For example, when
venting a system to atmosphere using N2, you may see readings
change by 40 to 55 Torr after the chamber is opened and air
gradually displaces the N2 in the gauge. For most other gases
the effect is much more significant and may result in a ha-
zardous condition as described below.
Other considerations when using gases other than N2 / air
Flammable or explosive gases
WARNING! Ideal Vacuum Products convection gauges
are neither intrinsically safe nor explosion proof and are not
intended for use in the presence of flammable or explosive
gases or vapors.
Under normal conditions the voltages and currents in Ideal
Vacuum Products convection gauges are too low to cause igni-
tion of flammable gases. However, under certain failure condi-
tions, sufficient energy could be generated to cause flammable
vapors or gases to ignite or explode. Thermal conductivity
gauges like the Ideal Vacuum Products convection gauges are
not recommended for use with flammable or explosive gases.
Moisture / water vapor
In some processes (lyophilization, for example) the gas composi-
tion may not change significantly, except for moisture content.
Water vapor can significantly change the response of a thermal
gauge and correction should be made, as you would for any
other gas.
Other contaminants
If your gases condense, coat, or corrode the sensor, the gauge
calibration and response to different gases will change. Gener-
ally, if the gauge can be "calibrated" ("zero" and "span" settings),
these changes are small enough to be ignored. If you can’t set
zero and span, the gauge should be replaced or return to factory
for evaluation and possible cleaning.