Groundwater Monitoring

Using our long experience and technical know-how, we will help you to monitor your groundwater resources level & quality and to ensure a minimal impact to your aquifer system.

Floating Oil Spill Alarm

Reliable monitoring of sumps and containment for oil spills

For separated Oil-on-Water applications, Sigma Hellas offers the Hydrocarbon Float Sensor. This floating sensor monitors the surface of water in sumps, tanks, and lagoons to alert when oil has separated to the water surface. This is typically used to alert of spills or control pumps.
The sensor monitors the surface dielectric and locks in on the capacitance of the water.

Oil that separates to the surface changes the capacitance field and activates the relay alarms.

This unit is typically used in sumps or containment where oil is not typically present. Normal sheens will not alarm but an upstream leak or spill that accumulates in the sump will alarm the monitor. The floating design allows the unit to track the changing water level in the sump and immediately alert operators, pumps or valves if there is an accumulation of oils.

Features & Benefits

table tri-float design follows level changes
Adjustable time delay and sensitivity to eliminate nuisance alarms
Remote electronics via standard twisted pair
Sensor available Intrinsically Safe for Hazardous Locations
Waterproof PVC and SS wetted parts allow for use in harsh environments
Unit also alarms on dry sump conditions to shut down pumps
Capacitance technology responds to all types of oils and separated liquids of similar dielectrics
Alarms at a minimum of 2 mm surface oil, can be desensitized to 25mm oil
Floating sensor follows changing water levels
Alarms on petroleum, synthetic, and vegetable oils
Potted stable sensor eliminates nuisance alarms

Technical Specifications - Control Unit

Operating Temp.: -20˚C to +55˚C
Resolution: .007% (.07 pF at 1,000 pF)
Accuracy: .04% of full scale pF
Power Input: 12 vdc or 24 vdc or 100-240 vac +/- 10%
Alarm Relay: 2 x 10 amp@240 vac, SPDT, dry
Analog Output: 4 mA normal/20 mA alarm
Communication: Modbus RS-485
Certified: UL 61010-1, 2nd Edition
CAN/CSA-22.2 61010-1-4
IEC/EN 61010-1, 2nd Edition
IEC 61326-1
CE Declared
Enclosure: Type 4/IP 66 painted steel
or Type 4X/IP 66 polycarbonate or SS
Optional Light, buzzer, beacon

Technical Specifications - Float Sensor

Operating Temp.: 0˚ to +55˚C (optional to 141˚C)
Intrinsic Safety: CSA Intrinsically Safe when ordered with Approved Barrier in Control Unit
Div 1, Class I, Groups A,B,C,D;
Class II, Groups E,F,G;
Class III, Encl.Type 4
Wetted Parts: PVC and 304SS

Typical Application of Monitoring Hydroelectric Dam Sumps for oil

Oil that has leaked from generators and transformers will typically accumulate in sumps. To protect the river environment Sigma offers the unique spill monitor that will detect any oil in the equipment. A floating sensor scans for changes in the water’s surface and signals when there is a build-up of oil present.

The device has been designed to not raise nuisance alarms from trace oil sheens. In applications where the sump is used to accumulate and hold significant amounts of oil, the sensing probe is available.

A warning is emitted if any oil has collected near the drain.




oil in water monitor
in a Hydro Station sump