MKS MODUCELL 325 Series User manual

MODUCELL®Pirani Vacuum
Sensor/Transducer
Instruction manual part number 103250029
Revision B- May 2020
Series 325
Instruction Manual

© 2020 MKS Instruments, Inc. All rights reserved.
MODUCELL®is a registered trademark and mksinstTM is a trademark of MKS Instruments,
Inc. All other trademarks and registered trademarks are the properties of their respective
owners.
Instruction Manual
Series 325
This instruction manual is for use with Series 325
MODUCELL®Pirani Vacuum Sensor/Transducer.
MODUCELL®Pirani Vacuum
Customer Service / Technical Support:
MKS Global Headquarters
2 Tech Drive, Suite 201
Andover MA, 01810 USA
Phone: [phone]
Email: [email protected]
Visit our website at www.mksinst.com

Series 325 Moducell Vacuum Sensor
Instruction Manual - #10325002
3
Chapter 1 General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.1 Receiving Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.2 International Shipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.3 Warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.4 Certification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.5 Customer Service / Technical Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.6 Typical Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Chapter 2 Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.1 Safety Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.2 Responsibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.3 Grounding Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.4 High Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2.5 Over Pressure Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.6 Damage Requiring Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Chapter 3 Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.1 General Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.2 Intended Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.2.1 Improper Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.3 Transportation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.4 Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.5 Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Chapter 4 Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
4.1 Sensor Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
4.2 Connect the Sensor to the Vacuum System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
4.3 Electrical Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
4.3.1 Input/Output Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
4.3.2 Inductive Loads and Arc Suppression . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
4.3.3 Adjust the Set Point . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Chapter 5 Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
5.1 Theory of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
5.1.1 Theory of the Thermal Conductivity Gauge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
5.1.2 Bridge Amplifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
5.1.3 Voltage Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
5.1.4 Comparator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
5.1.5 Open Filament Detector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
5.2 Measuring Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
5.3 Gas Other than Air or Nitrogen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
5.3.1 Nitrogen Equivalent Pressure and Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
5.3.2 Calibrating for Gases Not Shown in the Graph or Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
5.3.3 Detecting Leaks in the System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
5.4 Using the MODUCELL with a Computer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
5.4.1 Analog-to-Digital Converter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
5.4.2 Equations to Convert Voltage to Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
5.5 Energy Transfer and Measurement Limits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
5.5.1 The Energy Transfer Equation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
5.5.2 Measurement Limits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Chapter 6 Service & Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
6.1 Customer Service / Technical Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
6.2 Service Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
6.3 Damage Requiring Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
6.4 Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
6.5 Cleaning the MODUCELL Case and Sensor Tube . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
6.5.1 Venting to Atmosphere . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
6.6 Testing the Sensor Tube . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Table of Contents

4Series 325 Moducell Vacuum Sensor
Instruction Manual - #103250029
6.7 Replacing the Sensor Tube . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
6.7.1 Disassemble the MODUCELL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
6.7.2 Reassemble the MODUCELL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Chapter 7 Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

1 General Information
5
Series 325 Moducell Vacuum Sensor
Instruction Manual - #103250029
Chapter 1
1General Information
1.1 Receiving Inspection
On receipt of the equipment, inspect all material for damage. Confirm that the shipment includes
all items ordered. If items are missing or damaged, submit a claim as stated below for a domestic or
international shipment, whichever is applicable.
If materials are missing or damaged, the carrier that made the delivery must be notified within 15
days of delivery, or in accordance with Interstate Commerce regulations for the filing of a claim.
Any damaged material including all containers and packaging should be held for carrier inspection.
Contact MKS Instruments, Inc. Customer Support for assistance if your shipment is not correct for
reasons other than shipping damage.
1.2 International Shipment
Inspect all materials received for shipping damage and confirm that the shipment includes all items
ordered. If items are missing or damaged, the airfreight forwarder or airline making delivery to the
customs broker must be notified within 15 days of delivery. The following illustrates to whom the
claim is to be directed.
• If an airfreight forwarder handles the shipment and their agent delivers the shipment to customs,
the claim must be filed with the airfreight forwarder.
• If an airfreight forwarder delivers the shipment to a specific airline and the airline delivers the
shipment to customs, the claim must be filed with the airline.
Any damaged material including all containers and packaging should be held for carrier inspection.
Contact MKS Customer Support for assistance if your shipment is not correct for reasons other than
shipping damage.
1.3 Warranty
MKS Instruments, Inc. provides an eighteen (18) month warranty from the date of shipment for new
MKS Products. The MKS Instruments, Inc. General Terms and Conditions of Sale provides the
complete and exclusive warranty for MKS products. This document is located on our web site at
www.mksinst.com, or may be obtained by contacting an MKS Customer Service Representative.
1.4 Certification
MKS Instruments, Inc. certifies that this product met its published specifications at the time of
shipment from the factory.

1 General Information
6Series 325 Moducell Vacuum Sensor
Instruction Manual - #103250029
1.5 Customer Service / Technical Support
Some minor problems are readily corrected on site. If the product requires service, contact the MKS
Technical Support Department at [phone]. If the product must be returned to the factory
for service, request a Return Material Authorization (RMA) from MKS. Do not return products
without first obtaining an RMA. In some cases a hazardous materials disclosure form may be
required. The MKS Customer Service Representative will advise you if the hazardous materials
document is required.
When returning products to MKS, be sure to package the products to prevent shipping damage.
Shipping damage on returned products due to inadequate packaging is the Buyer's responsibility.
For Customer Service / Technical Support:
MKS Global Headquarters
2 Tech Drive, Suite 201
Andover MA, 01810 USA
Phone: [phone]
Email: [email protected]
Visit our website at: www.mksinst.com
1.6 Typical Applications
for the MODUCELL Pirani Vacuum Sensor/Transducer
• Measuring foreline and roughing pressures generated by mechanical vacuum pumps
• Controlling valves and pumps to automate system pump down using the relay set point
• Sensing abnormal pressure and taking appropriate security measures using the relay set
point
• Controlling system pressure using the analog output as input to an automatic pressure
controller
• Starting or stopping system processes using the relay set point
• Activating high vacuum sensors in their operating range

2 Safety
7
Series 325 Moducell Vacuum Sensor
Instruction Manual - #103250029
Chapter 2
2Safety
2.1 Safety Introduction
START BY READING THESE IMPORTANT SAFETY INSTRUCTIONS AND NOTES collected here
for your convenience and repeated with additional information at appropriate points throughout
this instruction manual.
These safety alert symbols in this manual or on the Product mean caution - personal safety, property
damage or danger from electric shock. Read these instructions carefully.
This product was designed and tested to offer reasonably safe service provided it is installed,
operated, and serviced in strict accordance with these safety instructions.
Danger indicates a hazardous situation which, if not
avoided, will result in death or serious injury.
Warning indicates a hazardous situation which, if not
avoided, could result in death or serious injury.
Caution indicates a hazardous situation or unsafe
practice which, if not avoided, may result in minor or
moderate personal injury.
Indicates a situation or unsafe practice which, if not
avoided, may result in equipment damage.
Notice
These instructions do not and cannot provide for every contingency that
may arise in connection with the installation, operation, or maintenance of
this product. If you require further assistance, contact MKS.
Safety Precautions
Failure to comply with these instructions may result in serious
personal injury, including death, or property damage.
Always observe and follow all safety notices that are
provided throughout this instruction manual and on the
product.

2 Safety
8Series 325 Moducell Vacuum Sensor
Instruction Manual - #103250029
These safety precautions must be observed during all phases of operation, installation, and service
of this product. Failure to comply with these precautions or with specific warnings elsewhere in this
manual violates safety standards of design, manufacture, and intended use of the instrument. MKS
disclaims all liability for the customer's failure to comply with these requirements.
•Read Instructions – Read all safety and operating instructions before operating the product.
•Retain Instructions – Retain the Safety and Operating Instructions for future reference.
•Heed Warnings – Adhere to all warnings on the product and in the operating instructions.
•Follow Instructions – Follow all operating and maintenance instructions.
•Accessories – Do not use accessories not recommended in this manual as they may be
hazardous.
2.2 Responsibility
It is the responsibility of the Customer to comply with all local, state, and federal ordinances,
regulations, and laws applicable to the installation, operation and service of this equipment.
It is the responsibility of the end user to provide sufficient lighting at work to meet local regulations.
Operation and Service of this equipment in strict accordance with the methods and procedures
supplied by MKS is the responsibility of the Customer.
MKS assumes no liability, whatsoever, for any personal injuries or damages resulting from the
operation or service of this equipment in any manner inconsistent or contrary to the methods
supplied in MKS literature including, but not limited to, manuals, instructions, bulletins,
communications, and recommendations.
For emergencies and for product safety related matters, contact the MKS Customer Service
Department. See Section 1.5 or Section 6.1 for detailed information regarding how to contact MKS
Customer Service Representatives.
Electrical Shock or Personal Injury
The service and repair information in this manual is for the use
of Qualified Service Personnel. To avoid possible electrical
shock or personal injury, do not perform any procedures in
this manual or perform any servicing on this product unless
you are qualified to do so.
Electrical Shock or Fire
To reduce the risk of fire or electric shock, do not expose this
product to rain or moisture.
Objects and Liquid Entry - Never push objects of any kind into
this product through openings as they may touch dangerous
voltage points or short out parts that could result in a fire or
electric shock. Be careful not to spill liquid of any kind onto the
products.

2 Safety
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Series 325 Moducell Vacuum Sensor
Instruction Manual - #103250029
2.3 Grounding Requirements
See Grounding, Section 4.1 in the Installation chapter for more detailed requirements regarding
gauge and system grounding.
Grounding is very important! Be certain that ground circuits are correctly used on your ion gauge
power supplies, gauges, and vacuum chambers, regardless of their manufacturer. Safe operation of
vacuum equipment requires grounding of all exposed conductors of the gauges, the controller and
the vacuum system. LETHAL VOLTAGES may be established under some operating conditions
unless correct grounding is provided.
Ion producing equipment, such as ionization gauges, mass spectrometers, sputtering systems, etc.,
from many manufacturers may, under some conditions, provide sufficient electrical conduction via
a plasma to couple a high voltage electrode potential to the vacuum chamber. If exposed
conductive parts of the gauge, controller, and chamber are not properly grounded, they may attain a
potential near that of the high voltage electrode during this coupling. Potential fatal electrical shock
could then occur because of the high voltage between these exposed conductors and ground.
Proper Grounding
All components of a vacuum system used with this or any
similar high voltage product must be maintained at Earth
ground for safe operation.
Be aware that grounding this product does not guarantee that
other components of the vacuum system are maintained at
Earth ground.
Verify that the vacuum port to which the Series 342/343 Mini-
Ion Gauge Module is mounted is electrically grounded. It is
essential for personnel safety as well as proper operation that
the envelope of the gauge be connected to a facility ground.
Connect power cords only to properly grounded outlets or
sources.

2 Safety
10 Series 325 Moducell Vacuum Sensor
Instruction Manual - #103250029
2.4 High Voltage
High Voltage is present in the unit when electrical power is applied to the electronics enclosure.
Hazardous voltages may still be present for some time after disconnecting power to the electronics
enclosure. Refer to the Installation and Service chapters for more information.
High Voltage
Be aware that when high voltage is present in any vacuum
system, a life threatening electrical shock hazard may exist
unless all exposed conductors are maintained at Earth ground.
This hazard is not unique to this product.
High Voltage
All conductors in, on, or around the vacuum system that are
exposed to potential high voltage electrical discharges must
either be shielded at all times to protect personnel or must be
connected to Earth ground at all times.
High Voltage
Be aware that an electrical discharge through a gas may
couple dangerous high voltage directly to an ungrounded
conductor almost as effectively as would a copper wire
connection. A person may be seriously injured or even killed
by merely touching an exposed ungrounded conductor at high
potential.
This hazard is not unique to this product.
Do not connect or disconnect any electrical connectors while
power is applied to the equipment (hot swapping). Doing so
may cause damage to the equipment or severe electrical shock
to personnel. This hazard is not unique to this product.

2 Safety
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Series 325 Moducell Vacuum Sensor
Instruction Manual - #103250029
2.5 Over Pressure Conditions
Danger of injury to personnel and damage to equipment exists on all vacuum systems that
incorporate gas sources or involve processes capable of pressuring the system above the limits it
can safely withstand.
For example, danger of explosion in a vacuum system exists during backfilling from pressurized gas
cylinders because many vacuum devices such as ionization gauge tubes, glass windows, glass
belljars, etc., are not designed to be pressurized.
Install suitable devices that will limit the pressure from external gas sources to the level that the
vacuum system can safely withstand. In addition, install suitable pressure relief valves or rupture
disks that will release pressure at a level considerably below that pressure which the system can
safely withstand.
Suppliers of pressure relief valves and pressure relief disks can be located via an online search.
Confirm that these safety devices are properly installed before installing and operating the
product.
Ensure the following precautions are complied with at all times:
(1) the proper gas cylinders are installed,
(2) the gas cylinder valve positions are correct on manual systems,
(3) and the automation is correct on automated gas delivery systems.
Explosive Environment
Do not use the Series 325 Sensor in an environment of
explosive or combustible gases or gas mixtures. Operation of
any electrical instrument in such an environment constitutes a
definite safety hazard. Do not use the product to measure the
pressure of explosive gases or gas mixtures.
Potential Automatic Operation
It is the installer's responsibility to ensure that the automatic
signals provided by the product are always used in a safe
manner. Carefully check the system programming before
switching to automatic operation.
Vacuum Chamber High Pressures
Where an equipment malfunction could cause a hazardous
situation, always provide for fail-safe operation. As an
example, in an automatic backfill operation where a
malfunction might cause high internal pressures, provide an
appropriate pressure relief device.

2 Safety
12 Series 325 Moducell Vacuum Sensor
Instruction Manual - #103250029
2.6 Damage Requiring Service
Disconnect the product from all power sources and refer servicing to Qualified Service Personnel
under the following conditions:
a. When any cable or plug is damaged.
b. If any liquid has been spilled onto, or objects have fallen into the product.
c. If the product has been exposed to rain or water.
d. If the product does not operate normally even if you follow the operating instructions.
Adjust only those controls that are covered by the operation instructions. Improper
adjustment of other controls may result in damage and will often require extensive work
by a qualified technician to restore the product to its normal operation.
e. If the product has been dropped or the enclosure has been damaged.
f. When the product exhibits a distinct change in performance. This indicates a need for
service.
See Service Guidelines, Section 1.5 for detailed information regarding how to contact MKS
Customer Service Representatives.
Vacuum gauges with compression fittings may be forcefully
ejected if the vacuum system is pressurized.
Notice
Do not substitute parts or modify the instrument.
Because of the danger of introducing additional hazards, do not install
substitute parts or perform any unauthorized modification to the product.
Return the product to a service facility designated by MKS for service and
repair to ensure that safety features are maintained. Do not use this
product if it has unauthorized modifications.
Notice
Safety Check - Upon completion of any service or repairs to this product,
ask the Qualified Service Person to perform safety checks to determine that
the product is in safe operating order.

3 Specifications
13
Series 325 Moducell Vacuum Sensor
Instruction Manual - #103250029
Chapter 3
3Specifications
3.1 General Description
The Series 325 MODUCELL®Pirani Vacuum Sensors are a heat-loss manometer which infers the
pressure of a gas by measuring thermal loss from a heated wire. Pirani sensors use the pressure-
dependent thermal energy transport from a hot wire to measure pressure.
3.2 Intended Use
The 325 Sensors are for vacuum system pressure measurement. These instruments are to be used
only in accordance with the instructions in this operation manual.
3.2.1 Improper Use
• Removal of any factory installed components.
• Modifying any factory installed components.
• Removal of any labeling or warranty seals.
• Operation of this device in any condensing vapor or liquid, or explosive environment.
3.3 Transportation
• Reuse the original shipping container.
• Replace all of the dust caps on all ports prior to shipping.
3.4 Storage
• Store the Sensor indoors between -40 oC to +70 oC (-40 0F to 158 0F).
• Bag the assembly in a sealed or shrink wrapped bag with desiccant.
• All of the components should be bagged and boxed together along with the instructions for
future reference.
Figure 3-1: Series 325 MODUCELL Sensor

3 Specifications
14 Series 325 Moducell Vacuum Sensor
Instruction Manual - #103250029
3.5 Specifications
(1) Do NOT use this product with flammable or explosive gases.
(2) The fast response (15 msec) is for a quick pressure rise to atmosphere, and the slower response
(150 msec) is for smaller pressure changes. Special circuitry allows for this dual response.
Table 3-1 Specifications for the Series 423 I-Mag Sensor
Parameter Specification
Performance
Measurement Range for N2/ Air (1) Torr: 1.0 x 10-3 to 100
mbar: 1.3 x 10-3 to 1.3 x 10+2
Pascal:1.3 x 10-1to 1.3 x 10+4
Useful Setpoint Range Torr: 5.0 x 10-3 to 30
mbar: 6.6 x 10-3 to 4.0 x 10+1
Pascal: 6.6 x 10-1 to 4.0 x 10+3
Accuracy +/- 5% operating
Calibration Gas Air/nitrogen
Operating Power 15 Vdc, 0.175 A or 24 Vdc, 0.175 A
Output Voltage 0.2 to 3.25 VDC,
1 kW (max) impedance
Physical
Vacuum Connection NW40 ISO-KF, .75 in. OD CF, 1 in. OD Tube, or NW25 ISO-KF
Electrical Connection 9 pin sub-miniature “D” type
Relay Contact Rating 2A @ 28 VDC
2A @ 50 VAC, SPDT
Relay Response(2) 15 to 150 msec
Case Material Aluminum,
Materials exposed to vacuum SS 304, platinum, alumina ceramic, silverbrazing alloy, nickel200
Weight 0.23 kg (0.5 lb)
Dimensions 60.3 mm x 31.8 mm x 111.1 mm
(2.37" x 1.25" x 4.37")
Internal volume less than 8 cm3(0.49 in3)
Mounting Orientation Any. However, avoid mounting the gauge directly below the
chamber to prevent sputtered material or other debris falling into
the gauge.
Operating Temperature 0 oC to +70 oC (32 0F to 158 0F) ambient, indoor use only,
ordinary protection from moisture
Operation Humidity 0 to 90%
Bake out Temperature 85 oC (185 oF)
Specifications and dimensions are subject to change without notice.

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Series 325 Moducell Vacuum Sensor
Instruction Manual - #103250029
Chapter 4
4Installation
4.1 Sensor Location
Locate the MODUCELL Sensor where it can measure process chamber or manifold pressure. Install
it away from pumps, other vibration sources, and gas sources to give the most representative values.
Locate and orient the Sensor where contamination is least likely. If it is installed directly above a
diffusion pump, for example, oil vapor could contaminate the cathode, anode, or other vacuum
exposed components, causing the calibration to shift.
The Sensor can be installed with the body set in any direction. Operating position does not affect
accuracy. Installing it with the vacuum port facing down is optimal as this helps prevent
contaminants falling into it. If particulates in the system are common, it is necessary to keep them
from entering the Sensor using a screen or porous filter at the port. A centering ring with a screen,
MKS p/n 100318601 is useful.
4.2 Connect the Sensor to the Vacuum System
Mount the Sensor to a grounded vacuum system.
Connect the MODUCELL to the vacuum system flange using the appropriate gasket and mounting
hardware.
Notice
Install the gauge on the vacuum chamber where it is protected from
physical damage and high heat.
See Section 2.5, Over Pressure Conditions, for important safety information
before mounting the gauge.
Proper Grounding
Improper grounding could cause product failure or personal
injury.
• Follow ground network requirements for the facility.
• Maintain all exposed conductors at Earth ground.
• Make sure the vacuum port to which the gauge is mounted is
properly grounded.
• See the grounding cautions in Section 2.3.

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Instruction Manual - #103250029
Orient the MODUCELL to prevent condensation of process vapors on the internal surfaces through
line-of-sight access to its interior. If vapor condensation is likely, orient the port downward to help
liquids drain out.
For an NW16KF, NW25KF or NW40KF flange:
The NW##KF style flange requires a self-centering O-ring between mating flanges. Use a metal
clamp and tighten the clamp to compress the mating flanges together. Do Not use a plastic clamp.
See the Grounding Requirements.
Attach the MODUCELL to the mating NW-style connector on the vacuum chamber. Use a new seal
and the appropriate tools to tighten the metal clamp.
For an NW16CF (1.33 inch) or NW35CF (2.75 inch) flange:
Attach the MODUCELL to the mating flange on the vacuum chamber. Use a new copper seal
between the flanges - do not use a previously used seal. If the flanges have leak test grooves, be sure
they are properly aligned.
Finger tighten all 6 bolts. Use the appropriate tools to tighten the 6 bolts. Tighten the bolts in a
circular pattern (such as 1, 3, 5, 2, 6, 4, 1, 3, 5, 2, 6, 4) until the flanges are in contact. After contact,
torque each bolt to 12 lb ft.
For a VCR-type fitting:
Remove the bead protector cap from the fitting.
Place the gasket into the female nut.
Assemble the components and tighten them to finger-tight.
While holding a back-up wrench stationary, tighten the female nut 1/8 turn past finger-tight on 316
stainless steel or nickel gaskets, or 1/4 turn past finger-tight on copper or aluminum gaskets. Do not
twist the gauge to tighten the fitting.
For a NPT-type fitting:
When fitting the MODUCELL with the 1/8" NPT-M thread, do not use the case for tightening; the
Sensor's tube has 9/16" hex flats for tightening. A single wrap of thread-sealant tape should be used
on the threads of the tube to ensure a leak-free seal.
Notice
A solid electrical connection between the sensor tube and the grounded
vacuum system must be used to shield the tube element from external
power sources. In applications where the system may be exposed to large
voltage fluctuations, a centering ring (HPSTM part # 100318601) with a
screen should be installed, and the screen and tube then grounded.
Do not use a compression mount/quick connect fitting for
positive pressure applications.

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Series 325 Moducell Vacuum Sensor
Instruction Manual - #103250029
For an O-ring Compression Seal fitting:
The MODUCELL can also use a ½" O-ring compression seal acting on the tubing above the thread,
but the O-ring seal cannot be used for positive pressure applications.
4.3 Electrical Connections
Connect a user-supplied cable to the MODUCELL using a mating 9-pin D-sub connector with strain
reliefs to ensure proper electrical connection and to reduce stress on the connectors.
Connect the cable to the Sensor and to the Controller before turning ON the system. Tighten the
thumb screw on top of the cable to make sure it is securely in place.
4.3.1 Input/Output Wiring
The following chart and the figure at the right identify the pins in the MODUCELL 9-pin D-sub
connector. The user can make a cable using the information from this chart.
The power supply input may range from 12 to 15 Vdc (or 22 to 26 Vdc). The positive side (+) of the
power supply is connected to pin 3 and the minus side (-) is connected to pin 4 of the D-sub
connector. Damage will occur if the polarity of the power supply input is reversed.
The ground connection to the set point relay in the MODUCELL® is pin 7 of the D-sub connector. If
pin 7 is left open, then the MODUCELL®'s set point relay is disabled. The set point relay may also
be disabled by setting the set point voltage below 200 mV. Any switching mechanism used to
control this line must be capable of handling 50 mA at 15 V (or 30 mA at 24 V).
Do not connect or disconnect any electrical connectors while
power is applied to the equipment (hot swapping). Doing so
may cause damage to the equipment or severe electrical shock
to personnel. This hazard is not unique to this product.
Table 4-1: Power Connections / 9-pin D-sub Connector
Pin # Description
1 Set point relay - normally open contact
2 Set point relay – normally closed contact
3Power supply input (+)
4 Power supply input (-)
5 Analog output voltage (+)
6 Set point relay – common
7 Set point relay – disable
8Analog output voltage (-)
9 Set point relay output voltage

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Instruction Manual - #103250029
Do not ground pin 7 to pin 4. Doing this will cause a sudden voltage drop on the ground wire,
resulting in a large transient in the analog output voltage. Pin 7 must be grounded at the power
supply.
The differential analog outputs are pin 5 (+) and pin 8 (-). They can be connected to a differential
input voltmeter or an A/D converter in a system controller.
Note: Do not connect the (-) side of the analog output (pin 8) to the power supply ground (pin 4).
This will cause half of the power supply current to flow through this wire. The voltage drop caused
by this current will produce very large errors in the measured output voltage. The longer the cable,
the worse the error.
The set point voltage (relay trip point) is available on pin 9. This voltage can be measured during a
start-up check to be sure that it is adjusted correctly.
4.3.2 Inductive Loads and Arc Suppression
If the set point relay is used to switch inductive loads, e.g., solenoids, relays, transformers, etc., the
arcing of the relay contacts might interfere with controller operation or reduce relay contact life.
Therefore an arc suppression network, shown in figure 1, is recommended. The values of the
capacitance C and the resistance R can be calculated by the equations,
C = I2/(1 x 107) and R= E/(Ix),
where,
Cis in farads
Ris in ohms
Iis DC or ACpeak load current in amperes
Eis DC or ACpeak source voltage in volts
x= 1 + (50/E)
Note that:
Rmin = 0.5 W and Cmin = 1.0 x 10-9 F.
Figure 4-1: Relay Arc Suppression Network
Do not short circuit the set point relay terminals to the analog
output.

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Series 325 Moducell Vacuum Sensor
Instruction Manual - #103250029
4.3.3 Adjust the Set Point
The set point relay can be adjusted to actuate at a particular pressure, using the MODUCELL's built-
in potentiometer.
To adjust the set point relay to a particular pressure, use the data in Figure 5-1 and Figure 5-2 to find
the corresponding voltage. Connect a digital voltmeter to the tip jacks on the side of the
MODUCELL shown in Figure 4-2. While monitoring the voltage at the tip jacks, adjust the
potentiometer next to the tip jacks until the indicated voltage matches that of the graph (Figure 5-1)
or Figure 5-2 for the relay activation pressure.
Figure 4-2: MODUCELL Set Point Adjustments
As the measured pressure falls below the set point value, the relay contacts labeled normally open
will close, the contacts labeled normally closed will open, and the LED, shown in Figure 4- 3, will
turn ON.
As the measured pressure rises above the set point value, the relay contacts labeled normally open
will open, the contacts labeled normally closed will close, and the LED will turn OFF.
Power or sensor failure causes the relay to de-energize, creating the same condition as when the
pressure is above the set point.
Figure 4-3: Set Point LED on the MODUCELL

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Instruction Manual - #103250029
Notes: