Overview - Siemens QGO21 Series Basic Documentation

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Building Technologies Division
2

Overview

The QGO21 is an oxygen sensor that is used to acquire the residual oxygen content of
flue gases in heat generating plants that heavy oil. The oxygen sensor works as a
diffusion sensor with a sintered filter for the flue gas inlet. In connection with the control
unit (LMV52 with PLL52), QGO21 monitors and controls the combustion process. For
mounting the QGO21, AGO21 mounting flange are available. They can be welded
directly into the chimney.
The QGO21 in connection with the AGO21 is suited for use on all types of heat
generating plant which burn heavy oil with flue gas temperatures up to 300 °C at the
test point.
When used in connection with burner controls type LMV52... for residual oxygen
control, the efficiency of combustion will be improved and oxygen emissions minimized.
Supply air
temperature
sensor
LMV52...
Figure 1: Example General overview
QGO21 consists of
- a stainless steel sensor tube with mounting flange
- retaining ring screwed on the front with sintered filter
- a connecting head made from die-cast aluminum
Sensor tube surrounds and protects
- the measuring cell,
- the cell heating
The connecting head contains a circuit board with terminals for electrical connections.
The cables are fed in via replaceable glands with
Pg9 screw connection. These glands can be left on the cable, making installation and
servicing easier.
The mounting flange AGO21 is an accessory for the QGO21.
- which is welded on to the point of measurement and
- acts as a mounting flange
Oxygen Sensor QGO21...
2 Overview
CAN
QGO21...
Flue gas
temperature sensor
O2 module
PLL52...
CC1P7845en
06.12.2017