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EW0826A4_en - rev. A 

Oxygen detectors 

 URS20SS 

05/10/2020 

Gas detection systems for industrial environments 

2/8

 

 

Technical 
characteristics 

 

Type of sensor 

Electrochemical cell 

Detectable Gas 

O

excess 

O

2

 deficiency 

Power supply 

11÷28Vdc 

Max power consumption 

2.5W 

Measuring range 

0…30% O

2

 

Precision  

 2,5% of full scale range (in air) 

Repeatability 

 2,5% of full scale range 

Measurement resolution 

0.1% O

2

 

Microprocessor resolution 

1024 points (10 bit) 

Digital filter system 

Kalman Filter 

Watchdog 

Internal 

Warm-up time 

< 2m 

Stabilization time 

< 2m 

Response time 

< 10s (T20), < 45s (T90) 

Average Sensor life (in air) 

120 weeks 

Sensor type settings 
(O2 excess or deficiency) 

S1.7 DIP switch OFF 

(O

2

 excess)

 

S1.7 DIP switch ON 

(O

2

 deficiency)

 

Threshold limit settings  
(S1.8 = OFF, default): 

Pre-alarm 

1

st

 threshold alarm 

2

nd

 threshold alarm 

 
 

23% O

2

 

25% O

2

 

27% O

2

 

 
 

19% O

2

 

17% O

2

 

15% O

2

 

Threshold limit settings  
(S1.8 = ON): 

Pre-alarm 

1

st

 threshold alarm 

2

nd

 threshold alarm 

 
 

22% O

2

 

23% O

2

 

24% O

2

 

 
 

20% O

2

 

19% O

2

 

18% O

2

 

4..20mA Output 

Proportional mode 
(default) 

 

Consumption mode 
(applications at 1 or 2 
thresholds) 

4…20mA Output reference 
selection: 

 
-   4mA   =    0% O

2

 

- 20mA   = 30% O

2

 

 
-   0mA   = no alarm 
- 10mA   = 1

st

  threshold alarm 

- 20mA   = 2

nd

  threshold alarm 

 
by jumper selectable polarity

 

4…20mA output load resistor 

- up to 200

 at 12Vdc power supply 

- 200

 

 700

 at 24Vdc power supply 

Operating Temperature 
Storage Temperature 

-20 

 50 °C 

-20 

 70 °C 

Relative Humidity (without condensing) 

-

 

Operation 

-

 

Storage 

 

 

15 

 90 %RH 

45 

 75 %RH 

Operating pressure (KPa) 

80 

 110 

Air speed (m/s) 

 6 

Visual warnings 

Red LED visible with detector energized 

Dimensions and weight 

See dedicated section 

Options & Accessories 

 

Card with 4 SPDT relays 

UZR20.4

 

NO or NC contacts available, jumper 
selectable  

See threshold limit settings  

 Maximum relay capacity: 

50mA at 24Vac/dc, 100mA at 12Vac/dc 

Relay operating mode: 

-

 

direct: relay ON when an event is detected 

-

 

reverse: relay ON when no event is 
detected 

TUL40..

 Gas calibration kit 

See installation and commissioning chapter 

TUS40   

Handheld terminal   

for service and maintenance  

See installation and commissioning chapter 

CRG40

   Gas collecting cone 

See dedicated data sheet 

PAP40

   Powerful jets protection 

See dedicated data sheet 

 
ATEX markings 

 

        

 II 3G   Ex nA nC d IIC T6

 

Gb 

 
BVI 07 ATEX 0033 
-20°C 

 T

A

 

 +50°C 

 

 

Содержание EsiWelma Sensigas URS20SS

Страница 1: ...eaks in hospitals laboratories welding centres and more in general where oxygen is stored Oxygen deficiency is an indirect measurement of the presence of other explosive or asphyxiant gases that deple...

Страница 2: ...umption 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 polarity 4 20mA...

Страница 3: ...nstructions 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 v...

Страница 4: ...n order to change the default settings switch off the power supply input the new settings at the JP2 jumper circuit or at the S1 DIP switch as shown in the diagram then power up again in particular Th...

Страница 5: ...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 Connection slot fl...

Страница 6: ...on The sensors are 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...

Страница 7: ...return the sensor concerned 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 t...

Страница 8: ...gas vapours flammable mist Ex nA nC d IIC T6 Gb Types of protection complying with EN60079 0 and EN60079 15 sensor body with type of protection d in compliance with EN60079 1 BVI 07 ATEX 0033 Type exa...

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