VALTRONICS MODEL 2008SDH-2AP
CARBON DIOXIDE MONITOR
INSTRUCTION MANUAL
Copyright 2017 VTI-Valtronics Inc.
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I. INTRODUCTION
The Model 2008SDH-2AP is a gas detection system designed to determine the carbon
dioxide content of the air for various monitoring applications. It senses and measures carbon
dioxide (full-scale ranges are available from 50% to 100%) and provides a linear output of 0-
1VDC and 4-20mA as a function of carbon dioxide concentration.
The electro-optics gas sensor contains an adjustable, right-
angled ⅛” hose barb to provide
gas flow into the optical path, where it is analyzed by NDIR (Non-Dispersive Infrared)
method.
II. DESCRIPTION (See Figure 1)
A. System
The Model 2008SDH-2AP consists of a printed circuit board with the electro-optics gas
sensor. The board contains all the power supply and signal-processing components.
B. Power Supply
The power supply converts the applied 12VDC into various DC voltages to operate the
instrument’s electronics. It consists of diode protection against reverse polarity of the
12VDC input power and solid-state regulators to provide constant voltages for operation
of various electronic circuits.
C. Circuit Board
All circuit components are mounted on a glass-epoxy printed circuit board. This board
includes the gas detection amplifier, electronic components, integrated circuits,
potentiometers, terminal block connector, and fuse.
1.
Two multi-turn slotted shaft potentiometers for user-adjustment are:
a)
ZERO: to adjust the instrument’s output to read zero voltage in the
absence of carbon dioxide.
b)
SPAN: to adjust the sensitivity of the instrument to the required voltage
value to produce a correct reading of a known gas sample.
2.
Two additional potentiometers on the board marked “4mA” and “20mA” are
factory set and should not require adjustment.
3.
External connections for input power and output for voltage and current are
provided at connector J1. The connector has a row of screw clamp terminals,
which will accept bare stripped wire (#18 awg or smaller).
4.
A 1-amp fuse adjacent to J1 for DC input protection.
