ST-15-WX Overfill Prevention and Liquid Detection Monitor

Safe, reliable, high- and low-level warning and spill prevention system for storage tanks

  • The system incorporates Dynamic Self-Checking® circuitry which monitors the controller, wiring, connections, and sensors for faults 30 times per second for maximum safety
  • Sounds an audible alarm and/or controls pumps and valves for automatic shutdown when the sensors detect liquid or a fault in the system
  • As a high level warning and emergency shut-down system, it operates independently from your gauging system to ensure that inventory inaccuracies do not compromise the safety of your operation.
  • The sensors wired to a control unit provide high level detection for a wide variety of petroleum and chemical products



The Scully WX System is certified by exida® as SIL2

  • The WX System provides for the capability of alarms as well as controlling pumps and valves for immediate, automatic shutdown of product flow
  • Monitors from 3 –12 sensing points depending on model. Well suited for multiple fixed storage tank applications where individual display and/or output control is required.
  • Uses output sensors approved as intrinsically safe for use in Class I, Division 1, Group C, and D hazardous locations
  • Features NEMA 4 style watertight housings
  • Works in conjunction with either Scully field-proven thermistor or two-wire optic sensors

Watch Demo:

The ordering information below is for FM and FMC approved units. For International ATEX and SIL approved models see:


Control Units

Part NumberDescriptionDIM XDIM YDepth
07851 ST-15-WX3Three-Channel Sensing Point Control Unit16″24″7.25″
07852 ST-15-WX4Four-Channel Sensing Point Control Unit16″24″7.25″
07853 ST-15-WX5Five-Channel Sensing Point Control Unit24″30″7.25″
07854 ST-15-WX6Six-Channel Sensing Point Control Unit24″30″7.25″
07855 ST-15-WX7Seven-Channel Sensing Point Control Unit24″30″7.25″
07856 ST-15-WX8Eight-Channel Sensing Point Control Unit24″30″7.25″
07857 ST-15-WX9Nine-Channel Sensing Point Control Unit30″36″7.25″
07858 ST-15-WX10Ten-Channel Sensing Point Control Unit30″36″7.25″
07859 ST-15-WX11Eleven-Channel Sensing Point Control Unit30″36″7.25″
07860 ST-15-WX12Twelve-Channel Sensing Point Control Unit30″36″7.25″

Product Range:Gasoline through #6 oil, waste oil, chemicals, water, etc. Consult Scully for specific application questions.
Controls:Alarm test push button; alarm silence circuit with push button and automatic reset
Indicator Lights:Green = Power On; Red = Alarm Condition
Response Time:High-level: .05 seconds maximum
Low-level: 3-7 seconds
Enclosure:NEMA 4 style for indoor/outdoor use
Power Requirements:115 VAC, +/- 15%, 50–60HZ, 20 watts maximum. Also available in 240 VAC models; consult Scully for details
Electrical Connections:Internal Terminal Strips
Output Provisions:External Alarm, 115VAC, 3 A max. Individual channel SPDT contacts, rated 5A- 250 VAC
Compatible Sensors:Refer to technical data sheets; 60635, 60715
Intrinsic Safety Information:The ST-15-WX control units can be mounted in any non-hazardous area and utilize oil tight controls and indicators. Internal circuitry provides intrinsically safe (I.S.) output, for probe connections. This output is rated for Class I, Div 1, Group D hazardous areas.
SIL Certification:IEC 61508 Certified SIL2 HFT=0 SIL3 HFT=1
Chemical Applications:Refer to technical data sheet 67100

Scully Signal