Model 6761-L-2-SPDT Top Mounted Displacer Switch
The Model 6761 Displacer Switch is designed for mounting at the top of a
tank in order to either open or close a circuit when the roofing float in the
tank rises to a level that causes the displacer to move the steel armature
into the magnetic field of the switch assembly which in turn causes the
mercury switch to tilt.
The switch assembly is supplied with dual switches for high or low level alarm service.
Standard materials of construction consist of an aluminum flange and housing, stainless steel isolation tube, stainless steel bead chain, lead roof displacers and stainless steel trim.
The wetted parts of the assembly consist of stainless steel and lead and as a result offer excellent corrosion resistance and are suitable for may types of petroleum and chemical products.
The mercury switches supplied are SPDT, mercury to metal. Resistive ratings are:
- 5 amps at 115 V.A.C.
- 2.5 amps at 220 V.A.C.
Snap action switches can be supplied to satisfy special requirements.
The standard tank mounting connection is a 4" - 125# ASA flat face flange of aluminum construction. The 4" size has been selected so that the 2-1/2" diameter displacer can readily pass through the tank nozzle. Other size connections both flanged and threaded are optionally available where existing vessel connections require other sizes. Other flange materials such as cast iron, carbon steel or stainless steel are also available.
Each switch assembly is carefully adjusted at the factory prior to shipment and the adjustment is based upon the customer providing information that consists of:
- the type of floating roof
- operating temperature
- tank pressure
- level actuation point
The level actuation point can be readily adjusted in the field by positioning the roof displacer on the stainless steel bead chain. The standard chain length is 10 FT. but longer chain is optionally available if specified.
NOTE SWITCH WILL NOT OPERATE IN LIQUID IF THE FLOATING ROOF SINKS