FW Murphy, 15700037, DF Series Hydrostatic Head Level Switch, Adjustable Trip Point
This is diaphragm-operated hydrostatic head pressure level switches. A pressure sensitive diaphragm operates a snap-switch that can be wired directly to electric pilot circuits to control pumps at predetermined levels. Typical application is to start and stop electric driven pump(s) to maintain tank levels. It is also applicable to engine-driven pumps.
The nitrile sensing diaphragm is impervious to most liquids and is sensitive enough to control levels with 1/4 in. (6 mm) repeatability. Materials include aluminum body, glass-filled nylon bottom plate and a special alloy leaf snap switch.
This simple level switch is highly reliable and can be worked into almost any system without major modification or special tools.
It is suitable for atmospheric tanks in a non-hazardous area.
For more information, please see 
Data Sheet
