Gas Monitors Do?
Gas monitors have two tasks:
1. To detect the gas or vapor being monitored.
There is no perfect gas monitor. As with most engineered products, the end result is based
on a series of intelligent compromises that allow the manufacturer to achieve his most
important design goals with the minimum sacrifice in secondary design objectives.
Different manufacturers have found methods to amplify the strengths of their preferred
technology and minimize the disadvantages.
2. To give an alarm
Gas monitors are not analytical instruments and they are not process control
Their purpose is to warn of a hazardous condition so that action can be
taken to prevent personal injury or property damage.
Most popular gas monitors are point monitors.
They are only capable of measuring the concentration of a gas
at a single point in space.
Selecting the proper location for a sensor is the single
most important element in the application of a gas monitor.
How Should a Gas Monitor Be Selected?
To get the most protection per dollar invested, consider only three basic
Any feature, characteristic, benefit, attribute or capability that does not
contribute to these three qualities is unnecessary.
Is The Gas Monitor Simple? It should be
no more complicated than is necessary to do its job.
Unnecessary features increase the chance for human and instrument error and
increase the cost of repair. It should be of a simple design easily adapted to the
users requirements and backed by strong technology.
Is The Gas Monitor Reliable? Can the information
always be trusted?
Does it present information in an unambiguous
way that is immediately understood by anyone?
Does it always alarm when it should and never when it should not?
Is the Gas Monitor Easy to Maintain?
How often must it be calibrated? How long does it take to calibrate?
How often must sensors be changed?
Is trouble shooting simple, requiring no special expertise?
The Three Main Components of a Gas Monitor
Converts the presence of a gas or vapor into an electrically measurable signal.
The sensor is the heart of a gas monitor. The system can be only as good as its sensor.
Amplifies this signal and converts it into a more convenient form for transmission.
Some monitors collect sensor signals without the use of transmitters.
The Gas Monitor Control Module
Contains the operating controls such as zero, span and alarm setpoint adjustments
along with readouts, status indicators, recorder outputs and relay contacts.