MKS 640B - Chapter One: General Information; Introduction

Chapter One: General Information Introduction
5
Chapter One: General Information
Introduction
The 640B Series, RoHS-compliant
1
version Pressure Controllers, includes the Type 640B
absolute pressure controller and the Type 641B gage pressure controller. The 640B Series
Controllers consist of a Baratron
®
capacitance manometer (either absolute or gage pressure), a
normally closed proportional control valve, and closed-loop control electronics. The closed-loop
control circuitry enables the unit to function as a proportional-integral (PI) controller. The unit’s
compact size and small, three-inch footprint reduce space requirements.
The 640B Series offers a variety of options including the seal material, full-scale range, and
calibration. The seal material is available in an elastomer (Viton
®
or Kalrez
®
, refer to Appendix
D: Model Code Explanation, page 63, for information) or all-metal material. Available control
valve plug materials are Viton
®
, Kalrez
®
, Kel-F
®
, or metal. Full-scale ranges are available from
10 Torr to 100 psi with a flow capacity of 50 sccm (standard cubic centimeters per minute) to 50
slm (standard liters per minute).
The 640B Series Pressure Controller can be used in either upstream or downstream pressure
control applications. The transducer inlet port is identified as the “Controlled Pressure Port” to
ensure that you install the 640B Pressure Controller into your system correctly.
The 640B Series Controllers provide two user-settable alarm trip points. The trip points can be
set from 1 to 100% of full-scale. Each trip point controls an open collector transistor. An LED
light located on the top of the unit, indicates the trip point status.
Note
The proportional control valve in the 640B Pressure Controller is not a
p
ositive shutoff valve. Depending upon your application, you may need
to install a separate positive shutoff valve.
1
The RoHS, “Restriction of Hazardous Substances,” directive aims to restrict certain dangerous
substances commonly used in electronic and electronic equipment.