MKS Granville-Phillips Mini-Convectron 275... User manual

Granville-Phillips®Mini-Convectron®Module
with RS-485 and Dual Process Relays
Instruction Manual
Instruction manual part number 275545
Revision C - November 2016
Series 275

Granville-Phillips®Mini-Convectron®Module
with RS-485 and Dual Process Relays
Series 275
Instruction Manual
This Instruction Manual is for use with Granville-Phillips Series
275 Mini-Convectron Modules with RS-485 and dual process
relays. A list of applicable catalog numbers is provided on the
following page.
Customer Service / Technical Support:
MKS Pressure and Vacuum Measurement Solutions
MKS Instruments, Inc., Granville-Phillips®Division
6450 Dry Creek Parkway
Longmont, Colorado 80503 USA
Tel: [phone]
Fax: [phone]
Email: [email protected]
MKS Corporate Headquarters
MKS Instruments, Inc.
2 Tech Drive, Suite 201
Andover, MA 01810 USA
Tel: [phone]
Fax: [phone]
Email: [email protected]
© 2016 MKS Instruments, Inc. All rights reserved.
Granville-Phillips®and Convectron®are registered trademarks, and mksinstTM is a
trademark of MKS Instruments, Inc. All other trademarks and registered trademarks are the
properties of their respective owners.

Chapter 1
This manual is for use only with the following catalog numbers:
275546 - # # - #
Sensor Type:
Gold-Plated Tungsten G
Platinum P
Flange/Fitting:
1/8 NPT / 1/2 inch tubulation P
1/4 inch VCR-type female fitting Q
1/2 inch VCR-type female fitting R
NW16KF flange D
NW25KF flange E
NW40KF flange K
1.33 inch (NW16CF) ConFlat-type flange F
2.75 inch (NW35CF) ConFlat-type flange G
Measurement Units:
Torr T
mbar M
pascal P
Instruction Manual
(20)275318 (20)275507–EU 275507–EU 275527–EU
275528–EU 275529–EU 275530–EU 275531–EU
275532–EU 275533–EU 275534–EU 275535–EU
275536–EU 275546–EU 275546–EU–1 275585–EU
275546–##–#
Granville-Phillips®Mini-Convectron®Module
with RS-485 and Dual Process Relays
Catalog numbers for Series 275 Mini-Convectron Modules

Mini-Convectron Module with RS-485 5
Instruction Manual - 275545
Table of Contents
Safety Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Safety Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Damage Requiring Service . . . . . . . . . . . . . . . . . . . . . . . . . 8
Overpressure Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Warranty Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Service Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
FCC Verification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Canadian Users . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Chapter 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
1.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
1.2 Using this Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Chapter 2 Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
2.1 Receiving Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Domestic Shipments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
2.2 International Shipments . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
2.3 Damaged Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
2.4 Important Precautions for Mini-Convectron Installation . . . 18
2.5 Gauge Tube Construction . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.6 Mounting Orientation and Physical Dimensions . . . . . . . . . 20
Mounting Convectron Gauges . . . . . . . . . . . . . . . . . . . . . . 20
Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
2.7 Grounding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
2.8 Gauge Mounts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Compression Mount/Quick Connect . . . . . . . . . . . . . . . . . . 21
1/8 NPT Mount . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
NW or Flange Mount . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
ConFlat Flange . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
2.9 Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
2.10 I/O Connector Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
2.11 RS-485 Network Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Chapter 3 Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
3.1 Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
3.2 Front Panel Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
3.3 Digital Communications . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Syntax/Address Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 28
RS-485 Address Switch Settings . . . . . . . . . . . . . . . . . . . . . 28
Baud Rate, Stop Bit and Parity . . . . . . . . . . . . . . . . . . . . . . . 28
Command Set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

6Mini-Convectron Module with RS-485
Instruction Manual - 275545
ReaD Convectron pressure response . . . . . . . . . . . . . . . . . . 30
Set Offset Address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Set span (typically at atmospheric pressure) . . . . . . . . . . . . 31
Set zero (at or near vacuum) . . . . . . . . . . . . . . . . . . . . . . . . 32
Set setpoint 2 trip point . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Set setpoint 1 trip point . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Read setpoint 2 trip point . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Read setpoint 1 trip point . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Read Mini-Convectron firmware version . . . . . . . . . . . . . . . 34
Set factory default . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Set baud rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Set parity to 8 bits, none . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Set parity to 7 bits, odd . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Set parity to 7 bits, even . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Set frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Reset module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Set pressure units of measure . . . . . . . . . . . . . . . . . . . . . . . 36
Read pressure units of measure . . . . . . . . . . . . . . . . . . . . . . 36
Command – Response Timing . . . . . . . . . . . . . . . . . . . . . . . 36
RX, TX Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Chapter 4 Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
4.1 Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Vacuum Adjust . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Atmosphere Adjust . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
4.2 Use with Gases Other Than N2and Air . . . . . . . . . . . . . . . . 40
Chapter 5 Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
5.1 General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
5.2 Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
5.3 Mini-Convectron Disassembly . . . . . . . . . . . . . . . . . . . . . . 47
5.4 Symptoms and Possible Causes . . . . . . . . . . . . . . . . . . . . . . 48
5.5 Returning a Mini-Convectron Module for Service . . . . . . . . 50

Mini-Convectron Module with RS-485 7
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Safety Instructions Introduction Installation Operation MaintenanceCalibration
Safety Instructions
Safety Introduction START BY READING THESE IMPORTANT SAFETY INSTRUCTIONS AND
NOTES collected here for your convenience and repeated with additional
information at appropriate points in these instructions.
In these instructions the word “product” refers to the Mini-Convectron
Module and all of its approved parts and accessories.
NOTE: 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 further assistance is required, contact MKS,
Granville-Phillips Division at the address on the title page of this manual.
This product is designed and tested to offer reasonably safe service
provided it is installed, operated, and serviced in strict accordance with
these safety instructions.
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 Instruments, Inc. disclaims all liability for the customer's failure to
comply with these requirements.
These safety alert symbols in this manual
or on the Product rear panel, mean
caution − personal safety, property
damage or danger from electric shock.
Read these instructions carefully.
Failure to comply with these instructions may result
in serious personal injury, including death, or
property damage.
The service and repair information in this manual is
for the use of Qualified Service Personnel. To avoid
shock, do not perform any procedures in this manual
or perform any servicing on this product unless you
are qualified to do so.

8Mini-Convectron Module with RS-485
Instruction Manual - 275545
•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.
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
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.
Do not substitute parts or modify 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
Granville−Phillips for service and repair to ensure
that safety features are maintained. Do not use this
product if it has unauthorized modifications.

Safety Instructions
Mini-Convectron Module with RS-485 9
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Safety Instructions Introduction Installation Operation MaintenanceCalibration
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.
Replacement Parts − When replacement parts are
required, be certain to use the replacement parts that
are specified by Granville−Phillips or that have the
same characteristics as the original parts.
Unauthorized substitutions may result in fire,
electric shock or other hazards.
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.
Finite Lifetime − After ten years of normal use or
even non−use, the electrical insulation in this product
may become less effective at preventing electrical
shock. Under certain environmental conditions
which are beyond the manufacturer’s control, some
insulation material may deteriorate sooner.
Therefore, periodically inspect all electrical
insulation for cracks, crazing, or other signs of
deterioration. Do not use if the electrical insulation
has become unsafe.
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 peculiar to this product.

10 Mini-Convectron Module with RS-485
Instruction Manual - 275545
Overpressure Conditions
Series 275 instruments are furnished calibrated for N2. They also measure
the pressure of air correctly within the accuracy of the instrument. Do not
attempt to use a Series 275 Gauge calibrated for N2to measure or control
the pressure of other gases such as argon or CO2, unless accurate
conversion data for N2to the other gas is properly used.
A pressure relief valve should be installed in the system if the possibility of
exceeding 1000 Torr (1333 mbar) exists.
Suppliers of pressure relief valves and pressure relief disks are listed in the
Thomas Register under “Valves, Relief” and “Discs, Rupture.”
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.
Install suitable devices that will limit the pressure 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 the pressure that the system
can safely withstand.
Series 275 Gauges should not be used above 1000
Torr true pressure.
If accurate conversion data is not used, or is
improperly used, a potential overpressure explosion
hazard can be created under certain conditions.

Safety Instructions
Mini-Convectron Module with RS-485 11
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Safety Instructions Introduction Installation Operation MaintenanceCalibration
Confirm that these safety devices are properly installed before installing the
product. In addition, check that:
a. The proper gas cylinders are installed,
b. Gas cylinder valve positions are correct on manual systems, and
c. The automation is correct on automated gas delivery systems.
Vacuum gauges with compression fittings may be forcefully ejected if the
vacuum system is pressurized.
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. The power cord
of this product shall be connected only to a properly
grounded outlet. Be aware, however, that grounding
this product does not guarantee that other
components of the vacuum system are maintained at
Earth ground.
Complying with the usual warning to connect the
power cable only to a properly grounded outlet is
necessary but not sufficient for safe operation of a
vacuum system with this or any similar high voltage
producing product.
Verify that the vacuum port to which the
Mini−Convectron Gauge 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. Use a ground lug on a
flange bolt if necessary.
Using the N2calibration to pressurize a vacuum
system above about 1 Torr with certain other gases
can cause dangerously high pressures which may
cause explosion of the system. See Chapter 4 before
using with other gases.
Warning − If used improperly, Mini−Convectron
Gauges can supply misleading pressure indications
that can result in dangerous overpressure conditions
within the system.

12 Mini-Convectron Module with RS-485
Instruction Manual - 275545
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
manual operation of the system and the set point programming before
switching to automatic operation.
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.
Warranty Information MKS Instruments, Inc. provides an eighteen (18) month warranty from the
date of shipment for new Granville-Phillips Products. The
MKS/Granville-Phillips Division General Terms and Conditions of Sale
provides the complete and exclusive warranty for Brooks Automation
products. This document may be located on our web site at
www.mksinst.com, or may be obtained by contacting an MKS,
Granville-Phillips Customer Service Representative.
Do not operate in an explosive atmosphere.
Do not operate the product in the presence of
flammable gases or fumes.
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 or combustible gases or gas mixtures. The
sensor wire of the Mini−Convectron Gauge normally
operates at only 125 ˚C, but it is possible that
Controller malfunction can raise the sensor
temperature above the ignition temperature of
combustible mixtures.
Danger of explosion or inadvertent venting to
atmosphere exists on all vacuum systems which
incorporate gas sources or involve processes capable
of pressurizing the system above safe limits.
The fumes from solvents such as trichloroethylene,
perchloroethylene, toluene, and acetone can be
dangerous to health if inhaled. Use only in well
ventilated areas exhausted to the outdoors. Acetone
and toluene are highly flammable and should not be
used near an open flame or energized electrical
equipment.

Safety Instructions
Mini-Convectron Module with RS-485 13
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Safety Instructions Introduction Installation Operation MaintenanceCalibration
Service Guidelines Some minor problems are readily corrected on site. If the product requires
service, contact the MKS, Granville-Phillips Division Technical Support
Department at 1-303-652-4400 or 1-800-776-6543 for troubleshooting
help over the phone.
If the product must be returned to the factory for service, request a Return
Material Authorization (RMA) from Granville-Phillips. Do not return
products without first obtaining an RMA. In some cases a hazardous
materials disclosure form may be required. The MKS/Granville-Phillips
Customer Service Representative will advise you if the hazardous materials
document is required.
When returning products to Granville-Phillips, be sure to package the
products to prevent shipping damage. Shipping damage on returned
products as a result of inadequate packaging is the Buyer's responsibility.
For Customer Service / Technical Support:
MKS Pressure and Vacuum Measurement Solutions
MKS Instruments, Inc., Granville-Phillips®Division
6450 Dry Creek Parkway
Longmont, Colorado 80503 USA
Tel: [phone]
Fax: [phone]
Email: [email protected]
MKS Corporate Headquarters
MKS Instruments, Inc.
2 Tech Drive, Suite 201
Andover, MA 01810 USA
Tel: [phone]
Fax: [phone]
Email: [email protected]

14 Mini-Convectron Module with RS-485
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FCC Verification This equipment has been tested and found to comply with the limits for a
Class A digital device, pursuant to Part 15 of the FCC Rules. These limits are
designed to provide reasonable protection against harmful interference
when the equipment is operated in a commercial environment. This
equipment generates, uses, and can radiate radio frequency energy and, if
not installed and used in accordance with this instruction manual, may
cause harmful interference to radio communications. However, there is no
guarantee that interference will not occur in a particular installation.
Operation of this equipment in a residential area is likely to cause harmful
interference in which case the user will be required to correct the
interference at his own expense. If this equipment does cause harmful
interference to radio or television reception, which can be determined by
turning the equipment off and on, the user is encouraged to try to correct
the interference by one or more of the following measures:
• Reorient or relocate the receiving antenna.
• Increase the separation between the equipment and the receiver.
• Connect the equipment into an outlet on a circuit different from that to
which the receiver is connected.
• Consult the dealer or an experienced radio or television technician for
help.
Canadian Users This Class B digital apparatus meets all requirements of the Canadian
Interference-Causing Equipment Regulations.
Cet appareil numerique de la classe B respecte toutes les exigences du
Reglement sur le material broilleur du Canada.

Mini-Convectron Module with RS-485 15
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Safety Instructions Introduction Installation Operation MaintenanceCalibration
Chapter 1 Introduction
1.1 Introduction Unlike traditional thermocouple and Pirani gauges, Convectron gauges take
advantage of heat loss due to convection cooling at higher pressures. This
extends the range of accurate, repeatable vacuum measurements to
atmosphere.
The Mini-Convectron module is a self-contained measurement device
incorporating Convectron gauge technology and electronics in a compact
modular design. The electronics and gauge are packaged in an all-metal
package that provides a rugged enclosure and a high level of immunity to
electrical noise. The Convectron gauge used in the module is
field-replaceable.
The Mini-Convectron module is available in a variety of output
configurations. This instruction manual is for use with a Mini-Convectron
module with RS-485 output and dual process control relays. These
adjustable setpoints allow control of valves, switches, alarm signals, or
other controls.
Figure 1-1 Series 275 Mini-Convectron Module with RS-485 and Dual Process Relays

Chapter 1
16 Mini-Convectron Module with RS-485
Instruction Manual - 275545
1.2 Using this Manual This manual contains information on installation, operation, and
trouble-shooting the Mini-Convectron module with RS-485
communications and dual process control relays. Following the instructions
contained in the manual will ensure that this device will operate to
specifications.
Within this manual:
• The term “module” refers to the entire Mini-Convectron module.
• The term “gauge” refers to the replaceable Convectron gauge.
Table 1-1 Specifications for the Mini-Convectron Module
Function Description
Measuring range for N2•1x0
-4 to 1000 Torr
Operation in the range of 1x10–4 to 1x10-3 Torr will require periodic
verification of the zero by reducing system pressure to below
1x10
–5 Torr
•1x10
–4 to 1.300 mBar
•1.0
–2 to 130 KPa
Ambient operating temperature range +4 to +40 °C
Bakeout temperature range (non-operating) 85 °C max.
IP Rating IP20
Digital interface RS–485, (2 wire)
Baud rate 300, 1200, 2400, 4800, 9600, 19200 (default), 38400
Data format 7 bits, even parity, 1 stop bit or 7 bits, odd parity, 1 stop bit or 8 bits,
no parity, 1 stop bit.
Power required • +11 Vdc to 26.5 Vdc at 0.12 A
• Protected against reversals, transients or over-voltages
• 2 watts maximum
Gauge tube internal volume 40 cc (2.5 cu in.)
Sensor wire Gold plated tungsten
Setpoints (two) • Single pole, double throw relay, silver alloy - gold clad contacts
• UL rating: 1 A at 30 Vdc
Setpoint factory default Disabled - set at 999 Torr
Connector Input power, computer interface, and setpoints - 15 pin D male
Package • Aluminum extrusion design with aluminum end plates
• 4.5” long x 1.7” wide x 2.5” high plus gauge port and fitting

Mini-Convectron Module with RS-485 17
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Safety Instructions Introduction Installation Operation MaintenanceCalibration
Chapter 2 Installation
2.1 Receiving Inspection
Domestic Shipments Inspect all material received for shipping damage.
Confirm that your shipment includes all material and options ordered. If
materials are missing or damaged, the carrier that made the delivery must
be notified within 15 days of delivery in accordance with Interstate
Commerce regulations in order to file a valid claim with the carrier. Any
damaged material including all containers and packing should be held for
carrier inspection. Contact our Customer Service Department, 6450 Dry
Creek Parkway, Longmont, Colorado 80503, 303-652-4400 if your
shipment is not correct for reasons other than shipping damage.
2.2 International Shipments Inspect all material received for shipping damage. Confirm that your
shipment includes all material and options ordered. If items are missing or
damaged the carrier making delivery to the customs broker must be notified
within 15 days of delivery.
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, not the freight forwarder.
2.3 Damaged Material Any damaged material, including all containers and packaging, should be
held for carrier inspection. Contact our Customer Service Department,
6450 Dry Creek Parkway, Longmont, Colorado 80503, U.S.A. Telephone
303-652-4400 if your shipment is not correct for reasons other than
shipping damage.

Chapter 2
18 Mini-Convectron Module with RS-485
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2.4 Important Precautions for
Mini-Convectron
Installation
The following precautions in the use and installation of the
Mini-Convectron must be observed.
• It is recommended that the Mini-Convectron be installed with the port
oriented vertically downward to ensure that no system condensates or
other liquids collect in the gauge tube. The gauge tube axis must be
horizontal if it is to be used at pressures above 1 Torr. Although the gauge
tube will read correctly below 1 Torr when mounted in any position,
erroneous readings will result at pressures above 1 Torr if the tube axis is
not horizontal.
• Do not use a compression mount (quick connect) for attaching the
Mini-Convectron to the system in applications resulting in positive
pressures in the gauge tube, Positive pressures might blow the tube out of
a compression fitting and damage equipment and injure personnel. Pipe
thread or flange mounting systems should be used for positive pressure
applications. In any case, the absolute pressure in the tube should not
exceed 1000 Torr.
• Do not perform electrical continuity tests on the Mini-Convectron tube
with instruments applying voltages in excess of 1 volt when the tube is at
vacuum, or 5 volts when at atmospheric pressure. Exceeding these
voltages will damage the sensing element.
• Keep the tube clean. Do not remove the mounting port cover until you
are ready to install the tube.
• Do not mount the Mini-Convectron in a manner such that deposition of
process vapors, upon the internal surfaces of the gauge tube, may occur
through line-of-sight access to the interior of the gauge tube.
• Do not install the Mini-Convectron where high amplitudes of vibration
are present. Excessive vibration will cause forced convection at high
pressure giving erroneous readings.
• Do not bake the Mini-Convectron at temperatures exceeding 85 °C.
• Do not install the gauge tubes where they will be subject to corrosive
gases such as mercury vapor or fluorine which will attack the gold plated
sensor.
• For greatest accuracy and repeatability the Mini-Convectron tube should
be located in a stable room temperature environment.
• All connections to the unit are to be made with shielded cable or cables.
The shield or shields are to be connected to the connector shell.

Installation
Mini-Convectron Module with RS-485 19
Instruction Manual - 275545
Safety Instructions Introduction Installation Operation MaintenanceCalibration
2.5 Gauge Tube Construction The transducer is a convection enhanced Pirani gauge providing rapid
response, six-decades of pressure transduction, stable calibration, and good
accuracy. The Pirani sensing element, R1 of the schematic of Figure 2-1, is
one leg of a Wheatstone Bridge. A temperature compensating network, R2,
forms the second leg of the bridge. The temperature sensitive component of
this network is mounted inside the gauge tube envelope with the sensor. All
other resistors of the bridge are mounted upon the exterior electrical
feedthrough pins of the gauge tube. Pin 4 serves as an electrical terminal for
construction of the compensating network, R2, but no connection is made
therefrom to the controller.
All materials have been chosen for ultra high vacuum service, corrosion
resistance and bakeability to 150 °C. The gauge tube envelope is type 304
stainless steel. All metallic joints in the envelope are welded. No solder is
used within the envelope. The following materials are exposed to the
vacuum: Type 304 stainless steel, Carpenter Alloy 52, Kovar, Kapton®, gold
plated tungsten and borosilicate glass.
Figure 2-1 Gauge Tube Schematic
PIN 1
PIN 5
PIN 3
PIN 2
R1
R2
R3
R4

Chapter 2
20 Mini-Convectron Module with RS-485
Instruction Manual - 275545
2.6 Mounting Orientation and
Physical Dimensions
Mounting Convectron
Gauges
• Cleanliness pays. Keep the port cover in place until moments before
installation.
• For proper operation above about 1 Torr, install Mini-Convectron
Modules with the gauge axis horizontal (see Figure 2-2). Although the
gauge will read correctly below 1 Torr when mounted in any position,
erroneous readings will result at pressures above 1 Torr if the gauge axis
is not horizontal.
• Vibration causes convection cooling of the sensor and will result in high
pressure readings. Mount Mini-Convectron Modules where they will not
vibrate excessively.
• Orient the gauge 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
(see Figure 2-2).
Figure 2-2 Mini-Convectron Module Installation
Environment To minimize temperature effects, locate pressure gauges away from internal
and external heat sources, in an area where the ambient temperature is
reasonably constant.