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Level sensor in 4 - 20 mA loop for city water supply

Hello sir, I am using SS634 level sensors from your company . Could you give me some example of connection sensor in 4-20mA loop ? I am not sure if I have to connect + of voltage supply to red or blue wire of sensor , i. e. if current goes from sensor from red or blue wire ? The sensor is protection against reverse polarity and is fully calibrated in two points, 4mA @ 0cm, and the 20mA @ the max(depended on the sensor). I am making level monitoring of drinking water in one of pools in city watter supply, would need probably sensors for water depths for 1m, 2m and 5m , 4-20mA output .

SS634 Series Submersible Pressure Sensor for level and depth applications

CE conformity
Hermetically sealed
Protective cap included
Stainless steel 316L diaphragm
All stainless steel structure, oil filled
Various power supply: 1.5mADC, 5VDC,12~36VDC
AK Fluids US silicon oil, nontoxicity, good bio-compatibility
Output signals: 4-20mA, mV and 0-10V, 0-5V voltage output
Pressure ranges in gauge or absolute from 0.05 up to 20 bar

SS122/634/634P series submersible pressure sensors use piezoresistive technology, oil filled, all stainless steel integrated structure with IP68 grade, suitable for liquid level and depth measurement. Their all stainless steel, hermetically sealed housing makes them suitable for immersion in most industrial liquids and oils, are designed to give accurate readings at pressure ranges from 50 mBar up to 20 Bar (corresponding to water column depths of 0.5 m to 200 m).

The electrical connection is a special designed PE cable with air tube and the pressure connection part is an exposed 316L stainless steel diaphragm, no pressure port and no blocking problems, easy for daily maintenance. The all-welded design eliminates the need for an O-Ring seal, thereby eliminating potential leak paths. Typical applications including water and sewage treatment plants, water level monitoring at reservoirs/dams, down-hole water wells.

Technical data

Performance (EN 60770)

Total error band(inside the compensated temperature range)


Response time

< 4 ms

Overload pressure

2 × FS

Pressure Range


Pressure type

vented gauge



Temp coefficient


Environmental conditions

Medium temperature range

-20°C → +85°C

Ambient temperature range

-20°C → +85°C

Compensated temperature range

0°C → +60°C

Mechanical characteristics



Stainless steel 316L


Stainless steel 304



Weight (depending on cable length)

4.0 kg

Cable Sealing rating