Propane, is a three-carbon alkane with the molecular formula
C3H8a gas at standard temperature and pressure, but compressible to a
transportable liquid.
A by-product of natural gas processing and
petroleum refining, it is commonly used as a fuel for engines,
oxy-gas torches, portable stoves, and residential central heating.
Basics on gas monotoring
Harmful Gas
Gas monitoring of combustible gases serve to obtain alarm in case of
gas leakage.
Propane is a heavy explosive gas
with a flammable range from 2.0 to 9.5 vol%.
The density of the gas is 1.56. (Air = 1,0)
The detector should be mounted appr.
0.2 m above the floor.
The weight of the gas allows it to accumulate in deep points both
indoors and outdoors.
Appropriate alarm levels
can be determined from case to case, but outdoors, we recommend level 1 to 10% of LEL and level 2 to 20% of LEL.
Alarm level 1 should result in control measures while alarm level 2 should be regarded as an emergency alarm.
When forwarding alarms to local emergency services, we recommend
using two detectors at alarm level 2 in order to avoid false alarms.
Alarm level 2 should result in visual and/or audible alarm/gas alarm
plate.
Flashlight should be used for alarm level 1.
Outdoor Gas Monitoring
Since recommendations on monitoring always depend on the
circumstances in the various specific cases, one must always
evaluate the effects of gas monitoring.
For
detector placement consider the following:
All pieces of equipment connected to the
object that are considered to be potential leak sources inside
buildings/sheds should be monitored.
Sometimes special consideration must be
taken to local residents or other factors where the slightest
prescence of gas is undesirable.
Plants have sometimes been built so that not
even strong winds could have prevented a certain accumulation of
flammable gas around the alarm object.
The advantage of creating a special alarm area is that alarms
from the gas monitoring unit can be obtained at a very early stage.
The disadvantage of creating a special
alarm area is that explosive gas concentrations can build up in here.
With no special alarm area, explosive gas concentrations might not
develop.
Choice of Equipment
The Stand-alone detector Combi is a detector
where power supply, alarm and control functions are integrated in
the detector housing. This detector is used where very simple
systems are sought and only few monitoring points are desired
Analog detector APRO,
Wall
CE
Environm.
APRO
declaration
declaration
Datasheet
Analog detector APRO,
Duct
Duct
IP
Calibr.
Kit
Protection
Manual
Certificate
Gas alarm plate for gas detector
Datasheet
OAW 24
Combined warning horn/flashlight
for
gas detectors
Datasheet
OA 24
Flashlight
Datasheet
Meticulous (infrared) detection This detector is very selective measuring a selected gas at a
specific absorbtionsband in the infrared wavelength area - no false
alarms.
Simply put, an infrared detector can measure tgases whose molecules
contain more than one atom.
This means that gases such as carbon dioxide, carbon monoxide,
methane, sulfur dioxide, etc. can be measured with an infrared
detector while the gases like oxygen, hydrogen and chlorine can not
be measured with an infrared detector.
Various gases absorb infrared radiation at different frequencies and
it is by measuring how much infrared radiation at a specific
frequency that is absorbed by the gas in question that you can
determine the gas concentration.
A major use for this testing method is when you want accurate
readings at low values without false alarms from other gases.
The multipoint system equipped with an
instrument for gas monitoring is based on detectors providing a
gas leak unit with a signal related to the gas concentration.
The signal is then processed in the gas leak unit where measurements,
alarms and control functions are obtained.
The
most common gas leak unit is of this type and the CGD model is used
for several measuring points.
Preferred system functions
Regardless of the type of gas leak unit you choose, we suggest a
study of the following features:
ALarm:
Should the
facility have one or two alarm levels per detector?
Control signals:
Should the facility have
one relay per alarm level and sensor?
Should the relay have a function for time delay?
Should the facility have computer output?
Measurem.
values:
Should it be possible to
read alarm values?
Should it be a digital, an analog or a flashing sign for
gas alarm?
Diagnostics:
Should the facility itself
be able to identify sensor errors, open circuits and
instrument errors?
Safety:
Should the plant be
equipped with a battery backup?
The exchangeable sensor X-CHANGE turns the
recalibration into a home game:
Delivery of recalibrated sensor
cartridges
Easy exchange, no specialized company
needs to come to you
Available for every gas type
At guaranteed exchange prices
Increased reliability (SIL2-software)
Important time and cost savings
The X-Change support guarantees a price based
on the consumption of the sensor capacitance.
For each uncalibrated sensor returned to AP,
you will receive a credit for the unused capacity of the sensor.
Disconnect the sensor cable and unscrew
the disused sensor head.
Exchange the sensor cartridge (3) and
connect the cable of the new sensor head to the PCB.
Close cover of the housing with the
screws (1). The recalibrated sensor is ready for use at once.
Electrical products in an explosive environment
A small amount of energy - a flame, spark, high surface temperature
or similar is required to ignite an explosive gas mixture.
Products installed in an area with a potential explosion hazard must
of course in themselves not be a potential explosion hazard.
For this reason, the products are manufactured in such a way that
this cannot occur.
The equipment must also be labeled and tested - ATEX classified - by
the approved testing authority.
The Ex-class information is available in "Swedish Standard" The choice of which Ex-classification is required is determined
by factors such as type of gas, permissible maximum surface
temperature and potential explosive hazards in the area where the
products are to be installed.
The potential explosion hazard in the different areas is determined
by the zone classification according to "Swedish Standard".
More about ATEX-products can be found in the following link
