There are many varieties of gas detection monitors and
systems on the market affording high levels of protection.

Knowing which product is suitable for a particular
application can be confusing, as Scott Safety explains

The issue of air quality is one that
workers in many industries around
the world have to face on a day-to-day
basis. The air that we breathe is made up of a
number of different gases and if the balance
of these gases is altered, or an additional,
harmful gas introduced, our safety can be
compromised. In 2009/10 there were seven
fatal injuries and 162 over-3-day injuries* as
a result of poisoning and/or exposure to
harmful gases, indicating that although there
are many forms of gas detection products
and respiratory protective equipment (RPE)
available, there are still a worrying number
of deaths and injuries to workers in
hazardous environments.

Know your gases
Hazardous gas monitoring is a danger that
many different industries face, including
petrochemical, oil and gas, pharmaceutical,
and wastewater treatment facilities. Knowing
the dangers, Scott Safety has produced a
detailed Gas Detection Reference Guide to
help others understand and identify the
properties and hazards of the gases that can
enter the workspace and how best to protect
themselves. The guide includes information
on the different types of technology used in
gas detection, the benefits and limitations of
the different sensor types and how they can
be best used to provide the safest protection.

It breaks each industry down into the
potential activities that would require the need
for gas detection and the notable gases that
could be present. Understanding the different
types of gases and the dangers that they can
pose is the first step in choosing the correct
form of gas detection. The guide lists the
different gases that could be present within a
workplace and the effect they can have, such
as suffocation, cancer or causing explosions.

Even the most common gases, such as oxygen
and nitrogen can have devastating effects if
present in dangerous levels.

Each gas has certain exposure limits (the
concentration to which workers can be
exposed continuously for a short period of
time), which are broken down into;
permissible exposure limit, short term
exposure limit and threshold limit value. The
combustible gas reference table and toxic gas
reference table within the guide, set out the
different gases, their various limits, and the
lowest airborne concentration that can be
detected by smell along with a ‘how to’
section verifying how to use the tables.

Fixed versus portable detection
The most common application in hazardous
atmosphere monitoring is the use of
mounted, fixed gas detection systems. These
are set up to provide continuous monitoring
in areas where leaks, ruptures or releases of
hazardous gases are likely to occur.

Designing a gas detection system, that
meets requirements and protects the
workers, comprises of a number of
components and can be tailored to differing
needs.When designing a fixed gas detection
system the following areas need to be
considered:
Understand the application
Identify the potential danger points
Establish the response functions
Determine gas characteristic
Profile the facility
Portable gas detection is a handheld or
body mounted system of sensors that
provide protection to an individual user,
with the use of visual, audible and vibratory
alarms. Portable gas detectors can usually be
configured in different sensor combinations
for use in multiple applications including
confined space entry, where fixed gas
detectors are not available or to verify that an
atmosphere is not hazardous when servicing
a fixed gas detection system.

Gas detection standards
As with many products that are made to
protect people, the standards and approvals
for gas detection are numerous and can be
confusing. It is important to understand the
many markings that can appear on the
products and their significance and value.

Within the Guide, Scott Safety has dedicated
a section to each different standard or
approval to clearly define what they mean
and how they should be applied to the
different gas detection products, including:
Hazardous area classifications
Protection methods and standards
NEMA classifications/Ingress protection
CE Marking
Scott Safety is offering its guide free on its
website. If you would like a copy, please visit
www.scottsafety.com/gasdetectionguide.

* www.hse.gov.uk/statistics/tables/index.htm
– Table RIDNAT – 2009/10p