Model 6761-M-1-SPDT Top Mounted Displacer Switch
The Model 6761-M-1-SPDT Displacer Switch is designed for mounting at the top
of a tank in order to either open or close a circuit when the floating roof
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 is also designed to operate in liquid
in the event the floating roof were to sink.
The switch assembly is supplied with a single switch for high or low level alarm service.
Standard materials of construction consist of an aluminum flange and housing, stainless stell isolation tube, stainless steel cable, PVC displacer and stainless steel trim.
The wetted parts of the assembly consist of stainless steel and PVC which as a result offer excellent corrosion resistance and are suitable for many types of petroleum and chemical products.
The mercury switch supplied is 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 3-1/2" diameter displacer can readily pass through the tank nozzle.
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
- liquid stored
- specific gravity
- operating temperature
- tank pressure
- level actuation point
The level actuation point can be readily adjusted in the field by positioning the displacer on the stainless steel cable. The standard cable length is 10 FT. but longer cable is optionally available if specified.