Sierra Monitor Corporation 2-Wire Series User Manual

 

Although the 4501-XX Gas Sensor Module is designed and constructed for installation and operation in 
industrial applications including hostile environments, caution should be taken to insure that the installation is 
made in compliance with this instruction manual and that certain procedures and conditions are avoided.  This 
chapter discusses the necessary cautions.  Read the entire chapter prior to installation of the equipment. 

Avoid installing sensor modules where they will be unnecessarily exposed to wind, dust, water (i.e. direct hose 
down), shock, or vibration.  Observe temperature range limitations. 

Sensors may be adversely affected by prolonged exposure to certain materials.  Loss of sensitivity, or 
corrosion, may be gradual if such materials are present in low concentrations.  These materials include: 
Halides (compounds containing chlorine, fluorine, bromine, iodine), acid vapors, caustic liquids or mists. 

Care has been taken by the manufacturer to ship modules in protective packaging to avoid contamination prior 
to installation.  It is recommended that the modules remain protected during installation and that the covering 
be removed immediately prior to system start-up. 

During normal use the sensor is protected from dirt and oil contamination by a sintered metal cover.  If this 
cover becomes clogged, the response of the sensor will be reduced.  Protect the sensor from contamination 
by careful placement, or by use of rain shields and dust shields. 

Sensor modules must not be painted.  Paint may contain compounds which will contaminate the sensor.  Paint 
will cause clogging of the sintered metal cover and will cause difficulties during attachment of the calibration 
head or other maintenance activity.  It is recommended that the module be tagged 

. 

The manufacturer recommends that extra caution be taken where the installation is near any sources of 
electromagnetic or radio frequency interference.  Precautions include: 

•  Avoid running sensor module cable close to high power cables, radio transmission lines, or cables 

subject to pulses of high current.  

•  Avoid running cables near large electric motors or generators. 
•  Analog devices require shielded cable. 
•  In conduit installations and cable applications the shield should be connected to instrument ground. 
•  All splices must be via either a termination hardware system or soldered.  Improperly spliced cable can 

result in corrosion, resistance changes and system errors. 

The 4501-XX calibration frequency is six months (180 days). However, prudent gas detector maintenance 
practices normally suggest a simple recalibration following incidences of exposure to high levels of H

2

S that 

would lead to alarm activation within any system utilizing the output of the 4501-05.