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EsiWelma Srl 

URS20SE - EW0826A1_en.docx 

Oxygen detectors – URS20SE 

16/06/2017 

Gas detection systems for industrial environments 

3/8

 

 

Sensors lifetime 

Sensor average lifetime (see technical characteristics) is referred to a typical usage 
in  a  pollution-free  environment.  Presence  of  a  high  concentration  of  pollutants  can 
shorten the lifetime of the sensing element. 

Once the detection system starts up, it has to be supplied with energy during all the 
lifetime of its sensors. 

Seasonal use of the detection system is not recommended. 

 

Installation 

 

Oxygen excess 

Since oxygen weighs more or less the same as air, unless there is forced or natural air 
circulation, it tends to spread at the point of the leak. 
So,  the  excess  oxygen  detectors  must  be  installed  near  any  likely  leakage  points,  in 
order to detect the excess oxygen as quickly as possible. 

 

Oxygen deficiency 

Detection  of  oxygen  deficiency  has  the  purpose  of  indirectly  detecting  the  presence  of 
other gases that deplete the oxygen in the air, therefore causing asphyxiation problems, 
for example. 
In this case, the detectors must be located at the breathing height of the occupants in the 
premises. 

 

 

Take into consideration the following specific installation guidelines, as well as the above 
instructions, for location of the detectors. 

The detectors must be installed: 

1.  where accidental gas leakages are possible 
2.  at least 1.5m away from heat sources or from vent holes 
3.  not in spaces where ventilation is poor and where gas pockets may form 
4.  away from hindrances to natural gas flow 
5.  away from equipment that may leak gas during normal operations 
6.  in  environments  with  a  temperature  range  of  -20°C  to  50°C  and  relative  humidity 

below 90% (non-condensing) 

7.  Disconnect  equipment  from  the  power  supply  when  mounting  and  dismantling 

detectors. 

 

 

Special 
recommendations 

 

CAUTION:  

safety is guaranteed only if cover is screwed on tight. 

-

  Tighten the cover clockwise, and  when it is screwed on, make sure that there is no 

more than 0.5 mm between housing and cover. This guarantees that it is screwed on 
tight.  Remember  to  tighten  the  hexagon  locking  grub  screw  that  fits into  the  end  of 
the cover. 

-

  Ensure  compliance  with  the  words  <<  DO  NOT  OPEN  WHEN  ENERGISED  >>, 

clearly indicated on the cover.  Alternatively, make the area safe before opening the 
sensor cover. 

 

Summary of Contents for Sensigas URS20SE

Page 1: ...entres and more in general where oxygen is stored Oxygen deficiency is an indirect measurement of the presence of other explosive or asphyxiant gases that deplete the oxygen in the air URS20SE sensors...

Page 2: ...default Consumption mode applications at 1 or 2 thresholds 4 20mA Output reference selection 4mA 0 O2 20mA 30 O2 0mA no alarm 10mA 1st threshold alarm 20mA 2nd threshold alarm by jumper selectable pol...

Page 3: ...n this case the detectors must be located at the breathing height of the occupants in the premises Take into consideration the following specific installation guidelines as well as the above instructi...

Page 4: ...iameter of the cable gland Default settings of the sensor are shown in the Technical Specifications chapter In order to change the default settings switch off the power supply input the new settings a...

Page 5: ...ions below Step 1 Insert the connection slot provided with the relay card into the control card making sure the flexible tab is towards the main terminal board Find CN3 connector CN3 connector Connect...

Page 6: ...factory calibrated so they normally do not require any other calibration once installed Still after installation an operational check of the sensors is recommended The detector will enter a 2 minute w...

Page 7: ...rned to the supplier installer who in turn will send it back to the manufacturer Sensors may need to be re calibrated using the TUL40 calibration kit and the TUS40 20 handheld terminal which must be c...

Page 8: ...industry 2 Equipment category 2 for use in Zone 1 G Equipment intended for use in explosive gas atmosphere caused by mixture of air and gas vapours flammable mist Ex d IIC T6 Type of protection compl...

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