Introduction
General Description
The Brasch Environmental Technologies GSE Generation 2 Gas Detector is designed to
function as a dual-zone standalone gas sensor and ventilation controller. The detector
consists of a sensor (or sensors), six control relays, and digital control circuitry. The unit
monitors the signal from the sensor, compares the signal to preset values, and controls relay
contacts based upon the comparison. These relay contacts then provide signals that control
ventilation components such as exhaust fans, louvers, and dampers. A four-digit display and
indicator LEDs are mounted on the front panel to provide a visual indication of the detector’s
operational condition. A linear proportional output is also included for communication with a
building management system (BMS), direct digital controls system (DDCS), or variable-
frequency drive (VFD).
The sensors used in the detector operate on the electrochemical principle and are able to
detect Carbon Monoxide or Nitrogen Dioxide. A current is produced when the target gas
reacts chemically with an electrode inside the sensor. This small current is converted to an
analog voltage, amplified, and converted to a digital signal. This signal is proportional to the
gas concentration present at the sensor and is shown on the display. After comparing the
digital signal to preset values, the unit activates the appropriate LEDs and relays. The actual
gas concentration is sampled and updated approximately every five seconds.
The detector’s circuitry consists of three or more printed circuit boards mounted inside a
polycarbonate housing. The housing has a NEMA 3R rating and is supplied with conduit
fittings so that the detector can mount directly to a standard four inch conduit box. Short
lengths of 16 AWG wire, connected to the power and relay terminals inside the housing, extend
through the conduit fittings. These wires are color-coded so that most installations will not
require opening the front panel of the detector.
Space is available in the detector housing for mounting two sensor assemblies. This allows for
local detection of two target gases. Additionally, remote sensors can be attached via a five-
conductor shielded cable. Each detector supports up to a total of four sensors mounted either
locally, remotely, or both.
IOM01
Rev 1.0 – December 22, 2020 4
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