In fuel oil applications fuel is typically stored in day tanks, the controlof the level in these tanks are handled by level switches. Typically thelevel probe will have several level switches mounted on a single rod. Typical switches are used for:
• Turning on and off a supply pump to refill a tank
• Closing the supply valve when a tank has reached the “full” level
• High level alarm
• Turn on a return pump to protect the tank from overfilling
• Low level alarm that may also turn on a backup pump
• A very low alarm that is usually used to turn off the• generator to protect the generator
• As an option a temperature sensor can be built into the• sensor to protect the generator from overly hot fuel oil
In some short tanks such as base tanks located under thegenerator these level switches may not fit on one rod, therefore multiple probes are used.
• 2″ NPT tank fitting, but others are available
• Brass Stem
• 316SS Floats
• 240V DC/AC Switch contact rating
• Cast Aluminum J-Box with terminal strip
• Individual pair of contacts for each switch
For large main tank which typically have continuous level monitoring(displayed in gallons), a simple level switch is typically used as a backup up to stop filling of the main tank. These switches are typically set at between 90 and 95% of full. So on a 12 foot diameter tank these singlelevel switch probes will go into the tank only 12 to 18 inches.
Dry.Pump Protection Switch
A level switch can be mounted in a pipe well before a pump to actas an interlock to protect the pump from running dry. With no oil inthe pipe before the pump the float will open the circuit and thepump will not be allowed to run.
Overflow Level Switches
Level switches can also be fitted into the vent of a tank, if the oil wasto raise to a level where it overflows into the vent the level sensorwill sense oil and act as an interlock to protect from the oil fromoverflowing and possible going out the vents.