MKS Baratron 631D, Инструкция по эксплуатации, Страница: 25 / 64

Chapter One: General Information
17
Chapter One: General Information
Introduction
Note
Some Baratron
®
products may not be exported to many end user countries
without both US and local government export licenses under ECCN
2B230.
The MKS Baratron
®
Type 631D Absolute Pressure Transducer 1 is part of the MKS family of
RoHS (Restriction of Hazardous Substances)-compliant, general purpose pressure transducers
designed to provide accurate, reliable and repeatable pressure measurements from 1000 Torr
down to 1 Torr, Full Scale (F.S.). The 631D is temperature-controlled to prevent contamination
build-up and is available in either of two operating temperatures: 150

C and 200

C. These
instruments have a small footprint and self-contained signal conditioning electronics mounted
directly above the sensor. The precision pressure transducer operates on a variable capacitance
technique
2 and requires

15 VDC input to provide a 0 to 10 VDC output linear with pressure over
the sensor’s measurement range.
The 631D transducer is available with an optional trip point relay system. The relay system
provides two (2) internally-mounted solid-state trip point relays with user adjustable pressure
conditions that will turn ON or OFF each solid state relay. The trip point relay system includes a
status LED, trip point value adjustment, direction selection and signal access for each of the two
trip points.
The 631D pressure transducer is comprised of a sensor and signal conditioner. An MKS or
compatible power supply is required to complete the pressure-to-electronic output conversion. A
power supply/readout can also be used to provide a direct pressure display; the necessary Y-type
cables are available from MKS.
The 631D transducer measures absolute pressure, so only the measurement port has a connector.
During production, the reference port (P
R
) is pumped down to a pressure less than 10
-7
Torr, and
outgassed thoroughly. A chemical getter is added to maintain the low pressure, and the port is
permanently sealed.
Temperature control of the transducer minimizes the effects of ambient or process temperature
variations typically encountered in process line environments. The sensor temperature is
continually monitored; two status LEDs provide visual indication of the unit’s temperature
control status. The LED labeled “Htr Fail Status” is normally off. If the sensor heater fails, the
LED becomes red and the associated relay becomes de-energized. The LED labeled “At Temp
Status” is yellow while the unit heats up and green when the unit is at the correct temperature.
(The unit requires a warm up time of two hours before any pressure data should be taken.)
Using the latest single sided, dual-electrode Inconel
®
sensor design, coupled with low impedance,
fixed-frequency bridge signal conditioner, these instruments are capable of withstanding high
1
U.S. Patent No. 5625152.
2
U.S. Patent No. 4785669.