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Monitoring at the LPG tank
Harmful Gas
Propane is a heavy explosive gas with a flammable range between 2.1
- 9.5 vol. percent.
Gas gravity makes it accumulate in deep points indoors and outdoors.
Appropriate alarm levels can be determined from case to case, but
outdoors, we recommend level 1 to be set at 5% of UB (1000ppm) and
level 2 to 20% of UB (4200ppm).
Alarm level 1 should result in control measures while alarm level 2
is considered an emergency alarm.
When the alarm is connected to the local emergency services, it is
advantageous to allow 2 simultaneous sensors´ level 2 alarms to
control this.
Alarm Level 2 should also result in light-and / or sound alarms at
the cistern.
Monitoring of the LPG tank outdoors
Since the recommendations on monitoring is always dependent on the
circumstances of the particular case you must always evaluate the
effects of Gas monitoring.
One priority of the detector position is as follows:
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All depth points in connection with the
tank, pumps, valves, evaporators must be investigated.
Monotoring should take place if the risk of accumulation of gas
leakage is considered great.
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All equipment related to the cistern, which
is considered to be potential leak sources and which are housed in
buildings / sheds should be monitored.
-
Location of the detectors at large
accumulation of potential leakage points, such as tank valves
should be monitored.
Here it is important that the weather and wind impact on the gas
be considered.
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Sometimes you need to consider specially
local residents or to other factors when it is important that even
the slightest occurrence of gas is undesirable.
Coisterns are known to have been built inj
such a way that a certain accumulation of gas has occurred when not
even strong winds have have kept the area round the cistern free of
gas.
The advantage of an embankment is that the
alarm from the Gas monitoring system can be obtained earlier.
The disadvantage is that an explosive
concentration of gas can be built up. Without the embankment this
would probably not occur.
Detector choice
In order to monitor gas outdoor a semi-conductor or pellistor type
is recommended at risk points.
The detector may need to be EX-classified and
provided with splashing protection.
Instrument Choice
Given the importance of concentration-reading ability a facility
with a gas controller is recommended.
The Gas controller should be positioned so that the alarm and any
readings can be easily read and preferably in a place frequented
indoors in close proximity to the outdoor cistern.
To cope with the monitoring and management
data the gas controller should have 2 alarm levels (with associated
relays) and concentration readings.
2 pcs alarm levels 1000 and 4000ppm.
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