MKS 640A User manual

116669-P1
Rev B, 12/97
MKS Type 640A/641A
Pressure Controller

Copyright © 1997 by MKS Instruments, Inc.
All rights reserved. No part of this work may be reproduced or transmitted in any form or
by any means, electronic or mechanical, including photocopying and recording, or by any
information storage or retrieval system, except as may be expressly permitted in writing by
MKS Instruments, Inc.
Baratron®is a registered trademark of MKS Instruments, Inc., Andover, MA
Cajon®is a registered trademark of Cajon Company, Macedonia, OH
Kalrez®and Viton®are registered trademarks of E. I. DuPont de Nemours and Co. Inc.,
Wilmington, DE
NUPRO®is a registered trademark of Crawford Fitting Company, Solon, OH
Swagelok®, VCR®, and VCO®are registered trademarks of Swagelok Marketing Co., Solon,
OH
Inconel®is a registered trademark of Inco Alloys International, Inc., Huntington, WV
Chemraz®is a registered trademark of Greene, Tweed, & Co., Inc., Kulpsville, PA

Kel-F®is a registered trademark of 3M Company, Minneapolis, MN

Table of Contents
v
Table of Contents
Pressure Transducer Safety Information..............................................................................1
Symbols Used in This Instruction Manual.................................................................1
Symbols Found on the Unit......................................................................................2
Safety Procedures and Precautions..........................................................................3
Chapter One: General Information......................................................................................5
Introduction............................................................................................................5
How This Manual is Organized................................................................................6
Manual Conventions ...................................................................................6
Customer Support...................................................................................................7
Chapter Two: Installation ...................................................................................................9
How To Unpack the 640 Series Controller ...............................................................9
Unpacking Checklist...................................................................................9
Product Location and Requirements.........................................................................10
Interface Cables.....................................................................................................11
Generic Shielded Cable Description .............................................................12
Dimensions ............................................................................................................13
Front and Back Views................................................................................13
Side View..................................................................................................14
Setup.....................................................................................................................15
Fittings.......................................................................................................15
Mounting Hardware....................................................................................15
Gas Pressure..............................................................................................15
Installing the Unit........................................................................................16
The I/O Connector .....................................................................................18
Initial Configuration.................................................................................................20
Chapter Three: Overview...................................................................................................21
General Information................................................................................................21
Pressure Control Range ..............................................................................21

Table of Contents
vi
A Typical Control System...........................................................................22
How The 640 Series Pressure Controller Works.......................................................23
Tuning the 640 Series Pressure Controller................................................................24
Proportional Term.......................................................................................24
Integral Term.............................................................................................25
Tuning the 640 Controller............................................................................27
Priority of Commands .............................................................................................29
Trip Points .............................................................................................................30
Action of the Trip Points.............................................................................30
Applications with a Large Differential Pressure........................................................31
Labels....................................................................................................................31
Chapter Four: Operation.....................................................................................................33
How To Check the Zero.........................................................................................33
How To Zero a Type 640 (Absolute) Unit....................................................33
How To Zero a Type 641 (Gage) Unit .........................................................34
How To Adjust the Span.........................................................................................35
How To Tune the 640 Series Controller ...................................................................35
How To Adjust the Trip Point Values ......................................................................36
How To Select the Trip Point Action .......................................................................37
How To Use Trip Points as Error Indicators.............................................................39
How To Change the Pressure Output Signal Range ..................................................40
How To Select Upstream Control............................................................................42
Appendix A: Product Specifications ....................................................................................45
Performance Specifications.....................................................................................45
Environmental Specifications ...................................................................................46
Trip Point Specifications..........................................................................................46
Physical Specifications............................................................................................47
Appendix B: Valve Orifice Selection...................................................................................49
General Information................................................................................................49
Checking the Orifice Size............................................................................49
How To Verify the Orifice Selection........................................................................51

Table of Contents
vii
Using Different Gases ................................................................................54
Appendix C: Gas Density Table ..........................................................................................57
Appendix D: Model Code Explanation.................................................................................61
Model Code Description..........................................................................................61
Index.................................................................................................................................65

Table of Contents
viii

List of Figures
ix
List of Figures
Figure 1: Front and Back Views of the 640 Series Controller................................................13
Figure 2: Side View of the 640 Series Controller..................................................................14
Figure 3: Bottom View of the 640 Series Controller..............................................................15
Figure 4: Downstream Pressure Control..............................................................................16
Figure 5: Upstream Pressure Control..................................................................................17
Figure 6: Top View of the 640 Series Controller...................................................................21
Figure 7: Sample Pressure Control System..........................................................................23
Figure 8: Effects of the Proportional Control........................................................................24
Figure 9: Effects of the Integral Control..............................................................................25
Figure 10: Controller Response with Initial P Term and I Term Values..................................27
Figure 11: Controller Response with Increased P Term........................................................28
Figure 12: Controller Response with Increased I Term.........................................................28
Figure 13: Serial Number Label..........................................................................................31
Figure 14: Jumper Positions on the Transducer Board..........................................................37
Figure 15: Jumper Positions on the Control Board................................................................42
Figure 16: Model Code Explanation.....................................................................................49
Figure 17: Flow Range Selection.........................................................................................53

List of Figures
x