User guide

Application Guide | Gas detection in refrigeration systems
8 DKRCI.PA.S00.A1.02 | 520H12772 © Danfoss | DCS (MWA) | 2018.05
The need for gas detection
There are several reasons why gas detection
is required. Two obvious reasons are to protect
people, production and equipment from the
impact of potential gas leakages and to comply
with regulations. Other good reasons include:
• Reduced service cost (cost of replacement gas
and the service call).
• Reduced energy consumption cost due to lack
of refrigerant.
• Risk for damaging stock products due to a
substantial leak.
• Possibility to reduce insurance costs.
• Taxes or quota on non-environmentally
friendly refrigerants
The various refrigeration applications require gas
detection for different reasons.
Ammonia is classified as a toxic substance with
a very unique smell, as such it is “self alarming”.
However, gas detectors are required to guarantee
early warnings, and to monitor areas where
people are not always present, such as machinery
rooms. It is important to be aware that ammonia
is the only common refrigerant lighter than air.
In many cases, this will lead to ammonia rising
above the breathing zone making it impossible
for people to early detect ammonia leakages. The
use of gas detectors in the right zones ensures
early warnings in case of ammonia leakages.
Hydrocarbons are classified as flammable. Thus,
it’s critical to verify that the concentration around
the refrigeration system does not exceed the
flammability limit.
Fluorinated refrigerants all have a certain
negative impact on the environment, for which
reason it’s very important to avoid any leaks.
CO
2
(Carbon Dioxide) is directly involved in
the respiration process and should be treated
accordingly. Approximately 0.04% CO
2
is
present in the air. With higher concentration,
some adverse reactions are reported starting
with increase in breath rate (~100% at 3%
CO
2
concentration) and leading to loss of
consciousness and death at CO
2
concentrations
above 10%.
Legislation and standards The requirements for gas detection are different
across countries worldwide. An overview of the
most common rules and regulation can be found
on the following pages.
Europe:
The present safety standard for refrigeration
systems in Europe is EN 378:2016.
The specified alarm levels in EN 378:2016 are set
at levels to allow evacuation of an area. The levels
do not reflect the effects of long term exposure
to leaked refrigerants. In other words, in EN 378
a gas detector is to warn when a sudden large
release occurs, while machine room ventilation
and system quality measures are to ensure that
small leaks are too small to cause adverse health
effects.
Note!
Requirements for gas detection
equipment in Europe are covered by
national legislation in the different
countries, and consequently may differ
from the requirements specified in EN
378.