MKS Micro-Baratron 870B, Инструкция по эксплуатации, Страница: 29 / 68

Chapter One: General Information Introduction
19
Chapter One: General Information
Introduction
The MKS Type 870B and 872B Micro-Baratron
®
Absolute Pressure Transducers are part of the
MKS family of general purpose pressure transducers designed to provide accurate, reliable, and
repeatable pressure measurements from 1000 Torr (
≈
20 psia) to 3000 psia. The 870 unit has a
“single-ended” design (refer to Figure 1, page 25), and the 872 unit has a “flow-through” design
(refer to Figure 3, page 27).
The 870/872 unit, designed for ultraclean gas delivery applications, offers the proven technology of
the Baratron transducers in a considerably smaller package. The sensor exposes only Inconel
®
and Incoloy
®
to the process permitting use with corrosive, hazardous, or dirty gases and
eliminating contamination of the process with transducer materials. Measurements are
independent of gas composition. Using the latest single-sided, dual-electrode sensor design,
coupled with a low impedance, fixed-frequency bridge signal conditioner, these instruments are
capable of withstanding high overpressure conditions with minimal or no shifts in output over their
range. The advanced bridge signal conditioning technology provides high accuracy and operation
which is extremely temperature-stable at operating pressure.
The transducer provides an output signal that is proportional to pressure. The output, provided
through a fixed cable with flying leads (with an optional attached connector) located on top of the
unit, is either a DC voltage (0 to 10 V, 0 to 5 V) or mA current (4 to 20 mA). For a direct readout
of the pressure measurement, a meter (analog or digital) is required.
The 870/872 transducer requires a power supply of 12 VDC (minimum) to 36 VDC (maximum),
regulated to ±5%. The specific power supply required depends on the output configuration of the
transducer (refer to
Power Requirements , page 22, for more information). The unit is available
with a variety of fittings, is capable of measuring pressure at ambient temperatures of 0° to 50° C
(32° to 122° F), and has an uncertainty of 1% of reading. There are two environmental options
available: as a standard unit for indoor use, or as a weather resistant NEMA 4/4x compliant unit
for outdoor use. The 870/872 transducer can be mounted in any position; it is fully functional
regardless of its orientation.
Protection from RF interference and noisy electrical environments is increased by the use of a
metal case, by internal design elements, and by the use of surge and ESD suppression networks
and RFI filtering on all inputs and outputs. The 870/872 transducer meets the electromagnetic
testing required for the European CE Mark when used with an overall metal braided shielded
cable, properly grounded at both ends. The 870/872 transducer offers additional manufacturing
advances that meet the requirements of ultraclean processing. Each transducer is manufactured
in a Class 100 clean room environment and packaged in double sealed bags backfilled with clean,
dry nitrogen gas. All wetted surfaces have less than a 5
µ
inch Ra finish.