Ametek Land 4200, Руководство пользователя

Страница: 11 / 48

Page 5
User Guide Model 4200 Dust & Opacity Monitor
4 System Description
4.1 The System
The Land Model 4200 Continuous Opacity/Dust Monitoring System normally
requires only two major components to complete a monitoring system. The
double pass instrument is known as a transmissometer. A transmissometer
installed with a retro-reflector on the opposing side of the stack or duct operate
as a double pass cross stack opacity/dust monitor. The analogue output from the
transmissometer is normally relayed to the user's data acquisition system.
There are several other optional parts available for the system: Air purge units
which provide a stream of clean air to keep dust and stack gases away from
the optical surfaces. Without the air purge units, dust could rapidly build
up on the optical surfaces and would cause the opacity readings to be
excessively high or even result in complete failure and damage to the
instruments. Optional automatic fail safe shutters when properly installed
protect the optical surfaces from corrosive stack gases in the event of air supply
failure.
NOTE
Shutters provide temporary protection only. Additional protection
is required if there is any prolonged air purge outage.
An optional weather cover can be used to provide added protection from the
environment for the transmissometer. (See options in specification).