MKS HPS 947 Series User manual

HPS®Series 947
Digital
Convection Enhanced Pirani (CEP)
Vacuum Sensor System
OPERATION AND
MAINTENANCEMANUAL

HPS®ProductsSeries 947 CEP System
SensaVac®Series947
Digital
Convection Enhanced Pirani (CEP)
Vacuum Sensor System
February1999
Part # REV.A

HPS®Products Series 947 CEP System
Part # 947-X-XXX-XX
– __– __ __ __–__ __
Serial # __ __ __ __ __ __
Please fill in these numbers and have
them readily available when calling for
service or additional information.
(The part number can be found on your
packing slip, and the serial number is
located on the back panel of the controller.)
© 1996 by MKS Instruments, Inc. HPS®Division. All rights reserved.
SensaVac is a registered trademark ofMKS Instruments, Inc.
TeflonandVitonareregisteredtrademarks of DuPontCo.
VCR is a registered trademark of Cajon Co.
For more information or literature, contact:
MKS Instruments. HPS®Division, Inc.
5330Sterling Drive
Boulder,CO80301 USA
Phone: [phone]
800-345-1967
FAX: [phone]

HPS®ProductsSeries 947 CEP System
Table of Contents
Table of Contents
Package Contents..................................................................... 1
Symbols Used in this Manual.................................................... 2
Safety Precautions .................................................................... 3
Specifications............................................................................ 5
Controller.......................................................................................... 6
Sensor Tube.................................................................................. 7
Feature and Control Locations .................................................. 8
Typical Applications for the Series 947 CEP System................ 9
About the SensaVac® Series 947 CEP Vacuum Sensor System
................................................................................................ 10
Installing the Series 947 CEP System..................................... 11
CEP Sensor Installation................................................................. 11
Location....................................................................................... 11
Orientation................................................................................... 11
Contamination ............................................................................. 11
Vacuum Connection.................................................................... 11
CEP Controller Installation ....................................................... 12
ControllerMounting.......................................................................12
ConnectingtheSensortotheController .......................................13
ACPowerCord .............................................................................14
FuseReplacement........................................................................14
AccessoryConnector ...................................................................14
Relay Inductive Loads and Arc Suppression ................................15
Operating the Series 947 CEP System ................................... 16
Reading Pressure .......................................................................... 16
Sensor Adjustment...................................................................... 18
Calibrating for Zero and Atmosphere .......................................... 18
Adjusting the Set Points.............................................................. 18
Venting to Atmosphere................................................................ 19
Buffered Analog Output............................................................... 19
Use with Computers ................................................................... 19

HPS®Products Series 947 CEP System
Leak Detection............................................................................ 19
Using the Series 947 CEP System with Other Gases ............. 22
Nitrogen Equivalent Pressure ..................................................... 22
Calibrating for Other Gases ........................................................ 23
Maintaining the Series 947 CEP System ................................ 24
Troubleshooting and Service ...................................................... 24
Cleaning the Series 947 CEP Controller Front Panel ................. 24
Cleaning the CEP Sensor ........................................................... 25
Testing the CEP Sensor ............................................................. 25
Preparing for Bakeout ................................................................. 26
Accessories............................................................................. 27
ProductWarranty..................................................................... 29
Notes....................................................................................... 30
Appendix A: How the Series 947 CEP System Works ..........A.1
Theory of a Thermal Conductivity Sensor .................................A.1
Measurement Limits...................................................................A.1
The Series 947 CEP System Design Overview........................A.2
Bridge Amplifier .......................................................................A.2
Output .....................................................................................A.2
Set Point Relays .....................................................................A.2
Comparator .............................................................................A.2

1
HPS®Products Series 947 CEP System
BeforeunpackingyourSeries947Digital Convection Enhanced Pirani (CEP)
Vacuum Sensor System, check all surfaces of the packing material for
shippingdamage.
Please be sure that your Series 947 CEP System package contains
these items:
1Series 947 CEPController
1 female, 9-pin, subminiature D (D-sub) Accessory connector
1powercord
1 SensaVac®Series 947 Digital Convection Enhanced Pirani (CEP)
Vacuum Sensor System User's Manual.
The Series 947 System's CEP Sensor and its connecting cable are sold
separately.Please refer to page 26for necessaryordering information.
If any items are missing from the package, call HPS®Customer
Serviceat1-303-449-9861or1-800-345-1967.
Inspect the Series 947 CEP System for visible evidence of damage. If it
has been damaged in shipping, notify the carrier immediately. Keep all
shipping materials and packaging for claim verification. Do not return the
product to HPS®.
Package Contents

2HPS®ProductsSeries947 CEPSystem
The first two symbols below, located on your Series 947 Controller and/or
Sensor, identify critical safety concerns. They are used throughout this
manual to further define the safety concerns associated with the product.
The last two symbols identify other information in this manual that is
essential to highlight or useful in achieving optimal performance from your
Series 947 CEP System.
CAUTION: Risk of electrical shock.
CAUTION: Refertomanual.
Failure to heed message could result in personal injury or
serious damage to the equipment or both.
Failure to heed message could result in damage to the
equipment.
Informationcallingattentiontoimportantprocedures,
practices, or conditions.
Symbols Used in this Manual

3
HPS®Products Series 947 CEP System
Safety Precautions
Do not use the Series 947 CEP System's Sensor with explosive
gas mixtures or gases that are combustible in air.
If the control circuit fails or an exothermic catalytic reaction occurs at the
sensor platinum wire, the wire could ignite the gas mixture.
When using the Series 947 CEP System with gases other than air
or nitrogen, avoid overpressure to prevent any possibility of
explosion.
Since the Sensor is calibrated for air/nitrogen, the measured pressure of
another gas will differ from its true pressure. Calibrations diverge widely at
higher pressures. Since the different gases are not linearly related, a gas
correctionfactorcouldleadtohazardousoverpressure.Capacitance
manometersand mechanical dialgauges are best suited forhigher pressures.
Refer to page 21 for use with other gases.
In a system which is filled from a pressurized source, install a safety relief
valve or burst disc to safely limit pressure.
The Series 947 CEP Controller contains lethal voltages within the
casing.
Avoid danger of electrical shock. Unplug the power cord before opening the
casing.
Turn off power to the Controller before connecting or
disconnecting a cable to the Sensor.
Connecting or disconnecting cables while the Controller is on may damage
the Sensor.
ProperlygroundtheController.
TheControllerisgroundedthroughtheconductorofthepowercord.Ifthe
protective ground connection is lost, all accessible conductive parts may pose a
risk of electrical shock. Plug the cord into a properly grounded outlet only.
When applying a voltage or current to the ports on the rear of the panel, do
not exceed manufacturer's specifications. Electrical shock may result.
Allow only qualified technicians to service the Series 947 CEP
System.
Users should not remove covers, casings, or plug-in components. Injury may
result. Any part replacement or internal adjustments must be performed by a
qualified technician only.

4HPS®ProductsSeries947 CEPSystem
To prevent damage to the Series 947 CEP Controller, use the
correctlinevoltage.
Use the Controller with the specified line voltage only. Use a fuse of the
correct type, voltage, and current rating. Only qualified personnel should
change line voltage or fuse ratings if required.
Outside of the U.S., use only a detachable cord set having conductors with a
cross-sectionalarea equalto or greater than 0.75 mm2. Powercables should
have agency approval, for example, VDE, Semko, or SEV.
The Series 947 CEP System and all its accessories must be used as
instructed by MKS Instruments, Inc., HPS®Division, to ensure safe
operation. Use or modification of the equipment in a manner not
consistentwithspecificationsmayrendertheproduct'sinherent
protectionuseless.