The SiloPatrol� SMU SE is a durable weight and cable (plumb bob) based continuous level measurement sensor that is unaffected by application factors such as humidity, dust, spurious reflections, dielectric constant and conductivity.

Q...Just wondering what you would suggest for a sensor in a 27 ft. (8.2m) silo that holds ground plastic that is under 3/8 inch (1cm) in size? The silo is made of steel and it has a cone on the bottom. We would also like to bring in a signal to our control system.

	SafePoint� Fail-Safe Level Indicator

A...For a high or low point level indicator, our first recommendation would be the TrueCap RF Capacitance level sensor. This is a fully electronic unit with no moving parts and superior sensitivity of material detection. There are also a variety of probe configurations to fit a specific application (See below article for more details). Another recommendation would be a rotary paddle level sensor like Monitor's Model KA/KAX. This type of sensor has a history of being a reliable and affordable solution in plastic materials and other materials as light as 5 lbs/ft3 (80kg/m3). For added safety, Monitor's SafePoint� self-validating, fail-safe rotary paddle level sensor detects power loss and internal failure. It also includes an external status LED. Both the Model KA/KAX and the SafePoint have outputs that can be used to provide signals to your system. 

If continuous level measurement is desired, we would recommend the SiloPatrol� weight and cable level sensor. The SiloPatrol is a durable, yet economical, continuous level sensor that is not affected by material characteristics like dielectric constant, conductivity, dust and humidity. It works well with plastic materials in vessels up to 150 ft (46m). An additional benefit is that this unit is easy to install. The 4-20mA analog version provides a signal that can communicate with existing PLCs. The smart RS-485 version includes Modbus connectivity to communicate with existing control systems that use Modbus. The RS-485 version can also be used with SiloTrack� inventory management software or HMI2 local operator interface. Since there is a cone at the bottom of the silo, having an accurate measuring / cable length is critical to ensure proper measurement and to prevent the plumb bob from going through the discharge opening and possibly damaging a rotary lock, slide gate, auger, etc.