MKS Baratron 127A, Инструкция по эксплуатации, Страница: 13 / 38

Chapter One: General Information Introduction
5
Chapter One: General Information
Introduction
The MKS Type 127A heated Baratron

Absolute Pressure Transducer and the Type 128A High
Temperature Absolute Pressure Transducer are capacitance manometers designed to provide
accurate, reliable, and repeatable pressure measurements in the range from 1000 Torr (1000
mmHg) to less than 0.1 Torr or micron (10
-5
mmHg). These transducers utilize the latest
balanced bridge signal conditioning technology to provide accuracy and stability previously
unavailable in low cost capacitance manometers.
The Type 127 and Type 128 transducers are specifically designed to meet the needs of vacuum
process systems, where environmental and process conditions are particularly demanding. Both
units expose only Inconel

to the process, which permits use with corrosive or dirty gases, and
eliminates contamination of the process with gauge materials. Measurements are independent of
gas composition; the 127 and 128 transducers measure true total pressure, regardless of the gas
species or whether it is a pure gas or a gas mixture. Temperature control of the sensor minimizes
the effects of ambient or process temperature variations typically encountered in process line
environments. The 127 transducer has the sensor temperature controlled at 45
°
C; the 128
transducer has the sensor temperature controlled at 100
°
C.
RFI shielding is standard to prevent interference from RF or noisy electrical environments. Both
units comply with the European EMC Directive 89/336/EEC which governs electromagnetic
compatibility. The units are protected against damage due to overpressure such as when the unit
is venting to atmosphere between process cycles. The overpressure limit is 35 psia, maximum,
for all ranges except 0.1 Torr range which is 20 psia, maximum. (However, MKS recommends
that you install an isolation valve to achieve the best zero stability.)
Both the 127 and 128 transducers are compatible with the Type PDR-C power supply/readout
units and closed-loop pressure/flow control systems such as the MKS Type 250 Pressure/Flow
Ratio Controller or the Type 152/252 Exhaust Valve Controller. In addition, the 127 and 128
transducers work with many commercial
±
15 VDC power supplies, and standard digital volt
meters (DVMs).
The 127 and 128 transducers utilize the same construction and operation procedures and are
discussed interchangeably in this manual. The 127 unit is controlled at 45
°
C and has a black
case. The 128 unit is controlled at 100
°
C and has a gray case.