MODELS KA and KAX
ROTARY PADDLE BIN LEVEL INDICATORS

Models KA / KAX Rotary Paddle Level Switches

Monitor's KA / KAX line of rotary paddle bin level indicators consist of the most reliable, rugged and economical point level control sensors available for detection of dry bulk materials. These easy to install switches are proven performers in a wide variety of bulk materials. Monitor's paddle switches can be used to eliminate bin overflow, maintain a predetermined material level, indicate plugging of conveyors and pneumatic lines or provide any of a number of level control functions. Unlike many other available paddle units for bins and silos, Monitor's paddle level indicators incorporate a feature that automatically shuts off the motor of the unit when the paddle is in a stalled position, which both extends the life of the motor and minimizes maintenance.

Principle of Operation

The operation of Monitor's rotary paddle bin level switch is quite simple. The unit is installed through the wall of the vessel, so that the paddle protrudes inside the vessel. A small electric motor drives a paddle which rotates freely in the absence of material.

When the paddle is impeded by material, the motor rotates within the housing which triggers two switches. The first switch is a “dry” electrical contact closure that is available to control a process function or alarm circuit. The second switch cuts the power to the motor, preventing a locked rotor condition, thus extending motor life. This also activates the signaling device which is wired through that same motor switch. When the material level drops, the loaded stretched tension spring returns the motor to its original running position and the unit is reactivated.

Applications

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Monitor’s rugged, reliable design make the paddle bin level indicator compatible with many granular, pelletized and powder bulk applications. Monitor paddle switches can be used for high level indication of materials over 10 lb/ft³ (160 kg/m³ ) and for low and intermediate level indication for materials over 5 lb/ft³ (80 kg/m³). Monitor paddle units can be installed almost anywhere dry bulk materials are stored, including bins, hoppers, silos and tanks. Monitor’s KA unit is the most popular of our paddle bin monitors. This model is ideal for use in standard applications with a wide variety of materials. The KAX incorporates all the features of the KA model, but is specially designed to meet explosion-proof standards.

Features

Available Models

Monitor’s KA unit is the most popular of our paddle bin monitors. This model is ideal for use in standard applications with a wide variety of materials. The KAX incorporates all the features of the KA model, but is specially designed to meet hazardous location standards.

This installed KA unit is being used 
as a high-level alarm in a grain storage 
application.

Available Configurations

MOTOR VOLTAGES
Monitor offers several motor voltages to serve most power requirements. Available AC motors include 115 VAC, 230 VAC, 24 VAC and 48 VAC. Superior 12/24 VDC design available uses low voltage AC motor for longer life in all applications. View DC Powered Technical Sheet (PDF).

OUTPUT CIRCUITS
Monitor paddle units are available with 1, 2 or 3 output contacts. The cost effective 1-circuit model utilizes the motor switch (SPDT) as the output contact, as long as the alarm device operates on the same voltage as the motor. The most popular 2-circuit design contains the motor SPDT switch and a second SPDT isolated switch for control outputs (See wiring diagram for illustration). The 3-circuit configuration provides the user with the SPDT motor switch and an isolated DPDT switch for control outputs.

PROCESS CONNECTIONS
Monitor offers a choice of either a 1-1/4” NPT or 1-1/2” BSPT process connection. Model KA units with the 1-1/2” BSPT connection also include M20 cable glands.

APPROVALS/LABELING
Monitor paddle units are available approved to UL, CSA and ATEX/IECex requirements. Various models are approved for either general purpose, dust/ignition-proof and/or explosion-proof applications. In addition, all models carry the CE mark. See “Specifications” section for more details.

HIGH TEMPERATURE UNITS
Monitor’s high temperature models incorporate all the standard features of the KA or KAX models, but can be used in applications where temperatures reach as high as 750°F (399°C). The hi-temp models incorporate a specially designed mounting plate, pipe extension with air purge connection, shaft extension, couplings and bushings. The high-temp assembly is available in either a carbon steel or stainless steel version. See “Ordering Information” for applicable part numbers.

Accessories

PADDLE ASSEMBLIES
Monitor offers a variety of interchangeable paddle assemblies to meet the needs of a wide variety of applications. Different material densities, particle sizes and flow characteristics require specific paddles to provide optimum performance. View Paddle Assembly Selection Guide (PDF).

Dimensions are shown in inches with millimeter equivalent in brackets.

MOUNTING PLATES 
Mounting plates allow the paddle units to be mounted from the outside of a vessel to curved or flat surfaces. All mounting plates featured below mount via six bolts.

1.) Half Coupling Mounting Plate: For use in side mount installations. Available in powder coated carbon steel for general purpose applications and stainless steel for use in corrosive environments. Stainless Steel Plate: P/N 1-0112. Carbon Steel Plate: P/N 1-0101 for 1-1/4” NPT connection and P/N 1-0100 for 1-1/2” BSPT connection.

2.) Full Coupling Mounting Plate: For use in top mount installations where a shaft extension and shaft guards are required. Available in powder coated carbon steel for general purpose applications and stainless steel for use in corrosive environments. Stainless Steel Plate: P/N 1-0113. Carbon Steel Plate: P/N 1-0102 for 1-1/4" NPT connection and P/N 1-0115 for 1-1/2" BSPT connection.

3.) K-Flange Aluminum Mounting Plate: For flat surfaces or thin walled vessels where extra strength is required. Ideal for semi-corrosive environments, including out doors. P/N 1-3316.

Dimensions are shown in inches with millimeter equivalent in brackets.

SHAFT EXTENSIONS
Many top mount installations require that the paddle extends into the vessel to a predetermined level. Solid shaft extensions are available in a variety of lengths up to 144 inches (3.6 m) to meet these demands. A flexible cable extension is also available. This 6.5 foot (2.0 m) flexible extension can be easily shortened in the field by the user. The use of the flexible cable extension for lengths greater than 3 feet (0.9m) requires the use of a guard to ensure proper activation of the rotary paddle bin monitor.

SHAFT GUARDS
Shaft guards are recommended for use with solid shaft extensions to limit the movement caused by side loading that would otherwise damage the working components of the paddle unit. Shaft guards should be the same length as the extension and should always be used when the extension meets or exceeds 18 inches (460 mm) in length.

Specifications