Magnetrol® top mounted displacer type level measurement switches can be utilized for detection of the floating roof on hydrocarbon storage tanks.
Series A15 (single stage) and B15 (dual stage) units are furnished with a non-sparking brass weight and are ideal level switches for high and high-high alarms on a floating roof tank. Model A15 can perform dual detection, detection of the roof or the liquid, should the roof become submerged. MAGNETROL'S unique hollow brass displacer offers actuation on either the liquid or the roof with the advantage of the non-sparking brass displacer. The optional Proof-er® ground checker allows manual verification of function of the level switch without having to climb the tank.

Operating Principle

Operation is based upon simple buoyancy, whereby a spring is loaded with weighted displacers, which are heavier than the liquid. Immersion of the displacers in the liquid results in buoyancy force changing to net force acting on the spring. The spring compresses as the buoyancy force increases. A magnetic sleeve is connected to the spring and operates within a non-magnetic barrier tube. Spring movement causes the magnetic sleeve to move into the field of a pivoted magnet, actuating a switch mechanism located outside the barrier tube. Built-in limit stops prevent over stroking of the spring, under level surge conditions.


Floating Roof Detection


- Single or Dual stage units
- Displacers adjustable at any point along the suspension cable
- 10 feet (3 meters) suspension cable standard
- Anti-surge design eliminates the possibility of switch shortcycling
- Flanged or threaded mounting available
- PROOF-ER Ground Checker
- Easy installation
- Field adjustable set point and switch differential
- Choice of switch mechanism:
+ Dry contact
+ Hermetically sealed
- Choice of switch mechanism enclosure:
+ TYPE 4X/7/9 Class I, Div. 1, Groups C & D, polymer coated aluminum
+ TYPE 4X/7/9 Class I, Div. 1, Group B, polymer coated aluminum or cast iron


- Displacer cable length
- Tank connection
- PROOF-ER ground checker control


- XP=Explosion Proof
- IS=Intrinsically Safe
- NI=Non-Incendive
- NS=Non-Sparking
- ELV=EMC/Low Voltage


+ Product Catalog
+ Instruction & Operating Manual