Rotary Level Indicator - Model KA
(Paddle ordered separately)



Point Level Sensor for Bins, Silos, Hoppers and Other Vessels Storing Bulk Solids
Twist On/Off Cover - No More Bolts!
Motor Shuts Off When Paddle is Impeded to Significantly Extend Motor Life and Reduce Maintenance Costs
Wiring Access: 2 Conduit Entrances
Competitive Price Makes The Monitor Bin Level Indicator Your Best Value
Three Bearing Design With Sealed Bearings Last Longer
Built-In Slip Clutch Extends Life
Hazardous Location Approvals Available (Model KAX has ATEX/IECex haz loc approvals)
Standard KA /KAX Units Rated to +300°F (+149°C)
Hi-Temp Models Rated to +750°F (+399°C)
Unique Low Voltage DC Design Available - Click to view Technical Sheet (PDF)

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Models KA / KAX Rotary Paddle Level Switches

Bulletin Button

Product Overview



Principle of Operation

Available Configurations


Available Models



Similar Item(s):

Rotary Level Indicator - Model KA
SafePoint® Fail-Safe Rotary Paddle Level Sensor



Monitor's KA / KAX 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 (sensores de nivel) 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.



Monitor’s rugged, reliable design make the paddle bin level indicator (sensor de nivel) 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.

Typical Applications include, but are not limited to:


Silica Sand




Calcium Dust











Foundry Sand

Pre-Mix Ingredients






Complete motor shutoff prevents motor burnout and extends the life of the unit

Twist on/off cover means no bolts to hold or lose - Hassle- free housing design

UL, CSA and ATEX/IECex hazardous location approvals (KAX)

1-1/4” NPT or 1-1/2” BSPT process connection

Two conduit connections provide easy wiring access (M20 cable glands provided with Model KA units with BSPT process connection)

Built-in slip clutch protects motor and drive gears from excessive rotational forces

Three bearing design with sealed bearings fully minimizes drive shaft loads and drag providing extended life.

Interchangeable paddle assemblies increase the paddle unit’s versatility

Built-in signal delay prevents false signaling

Field adjustable sensitivity

High operating temperature up to 300°F (149°C) (Hi-temp version up to 750°F (399°C))


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.

Installed Rotary Paddle Level Switch
This installed KA unit is being used
as a high-level alarm in a grain storage


Available Configurations

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).

115 V AC Rotary Paddle Level Switch 12/24 V DC Rotary Paddle Level Indicator

Model KA, 115 VAC, p/n 1-8301-1

Model KA, 12/24 VDC, p/n 1-8331-1

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.

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.

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.

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.



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.

1.) Standard Stainless Steel Three Vane Paddle: The most popular of all paddles. For use with average weight materials.
P/N 1-4146

Three Vane Level Paddle

2.) Large Stainless Steel Three Vane Paddle: Provides accurate level control for lightweight materials. P/N 1-4141

Large 3 Vane Paddle

3.) Insertable* Stainless Steel, Two Vane Collapsible Paddle: Provides low and high level control for light to average weight materials.
P/N 1-4161
Click Here For Product Sheet

2 Vane Collapsible Paddle

4.) Insertable* Stainless Steel, Scimitar Single Vane Paddle: Provides low and high level control for light to average weight materials.
P/N 1-4193

Insertable Level Paddle

5.) Insertable*, Stainless Steel Single Vane Paddle: Provides low level control for average weight materials and low to high level control for heavy materials under 1-1/2 inch (40 mm) in diameter. P/N 1-4145

Single Vane Paddle

6.) Stainless Steel, Two Vane Paddle: Provides low and high level control for heavy materials under 1-1/2 inch (40 mm) in diameter. P/N 1-4135

Two Vane Paddle

7.) Stainless Steel Four Vane Paddle: For use with average to heavy weight materials in low and high level control installations.
P/N 1-4156

Four Vane Paddle

8.) Stainless Steel Triangular Arc Single Vane Paddle: Provides low and high level control for light to average weight materials. P/N 1-4144

Triangle Arc Paddle

9.) Ex-Flex Three-Ply 20 inch (508 mm) Belt Paddle: Provides low and high level control for heavy materials over 2 inch (50 mm) in diameter. Top mount only. P/N 1-4137

Flexible Level Paddle

*Insertable paddles eliminate the need for a mounting plate. P/N 1-4161 and 1-4193 are insertable through either a half or full 1-1/4” or 1-1/2” coupling, that is welded to the bin wall. P/N 1-4145 is insertable through a half 1-1/4” or 1-1/2” coupling.

The flexible coupling works to absorb heavy loads, side loads and loads caused by product surges, thus protecting the internal workings and extending the life of the paddle unit. A flexible coupling should be used with heavy materials and in top mount installations where a solid shaft extension is used. Monitor offers the following coupling option:
Spring-Flex: P/N 1-3335

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.
Mounting Plate

SHAFT EXTENSIONSFlexible Cable Extension
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 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.




Power Requirements:

115 VAC (+/- 10%), 50/60 Hz;
230 VAC (+/- 10%), 50/60 Hz;
24 VAC (+/- 10%), 48 VAC (+/- 10%), 50/60 Hz;
12/24 VDC (10.2-27.6 VDC)

Power Consumption:

4W max.

Operating Temperature:

-40°F (-40°C) to +200°F (+93°C) ext. amb.; to +300°F (+149°C) internal bin temperature. High Temp Unit to +750°F (+399°C) internal bin temperature

Conduit Connection:

Two (2) 3/4" NPT; M20 cable glands (Model KA units with 1-1/2” BSPT process connection only;Not on KAX units)

Outputs Contacts:



2-Circuit Configuration

Two SPDT 15A @ 250 VAC ea. max


3-Circuit Configuration

One SPDT 15A @ 250 VAC max
One DPDT 10A @ 250 VAC max

Maximum Pressure:

30 PSI (2 bar) maximum


5 lb/ft³ (80 kg/m³) minimum material density (when using large 3-vane paddle)


Die cast aluminum, NEMA 4 / ENCLOSURE TYPE 4, IP66

Housing Finish:

Powder coating

Mounting Connection:

1-1/4" NPT or R 1-1/2 (BSPT 1-1/2)

Shipping Weight:

Approx. 7 lbs (3.2 kg)

Materials of construction/accessories:

Flexible Couplings: 304 stainless steel

Mounting Plates: Carbon steel or 304 stainless steel

All Paddles except Ex-Flex: 304 stainless steel

Ex-Flex Belt: 304 stainless steel coupling, rubber/fabric blend belt

Flexible Cable Extension: 304 stainless steel

Solid Shaft Extension/Guards: Galvanized or 304 stainless steel

Shaft Seal: Nitrile



UL and CSA: Ordinary Locations


UL and CSA:
Class I, Div. 1 & 2, Groups C, D;
Class II, Div. 1 & 2, Groups E, F, G

(Ex) II 1/2 D c T 100°C
ExtD A20/A21 T 100°C
(Ta -40°C to +93°C)

DIP A21 IP6X TA 100°C
-40°C to +93°C

All Models:

CE Mark



Monitor Technologies LLC warrants each rotary paddle bin indicator it manufactures to be free from defects in material and workmanship under normal use and service within two (2) years from the date of purchase. The purchaser must give notice of any defect to Monitor within the warranty period, return the product intact and prepay transportation charges. The obligation of Monitor Technologies LLC under this warranty is limited to repair or replacement at its factory. This warranty shall not apply to any product which is repaired or altered outside of the Monitor Technologies LLC factory, or which has been subject to misuse, negligence, accident, incorrect wiring by others or improper installation. Monitor Technologies LLC reserves the right to change the design and/or specifications without prior notice.

Part Numbers / Product Configurations

Part # > Product Configuration


1-8301-1 KA,115VAC,2-CT,1-1/4,UL/CSA/CE
1-8301-11 > KA,115VAC,2-CT,UL/CSA/CE,HT-CS
1-8301-12 > KA,115VAC,2-CT,UL/CSA/CE,HT-SS
1-8302-1 > KA,115VAC,3-CT,1-1/4,UL/CSA/CE
1-8302-11 > KA,115VAC,3-CT,UL/CSA/CE,HT-CS
1-8302-12 > KA,115VAC,3-CT,UL/CSA/CE,HT-SS
1-8306-1 > KA,115VAC,2-CT,1-1/2,UL/CSA/CE
1-8307-1 > KA,115VAC,3-CT,1-1/2,UL/CSA/CE
1-8311-1 > KA,230VAC,2-CT,1-1/4,UL/CSA/CE
1-8311-11 > KA,230VAC,2-CT,UL/CSA/CE,HT-CS
1-8311-12 > KA,230VAC,2-CT,UL/CSA/CE,HT-SS
1-8312-1 > KA,230VAC,3-CT,1-1/4,UL/CSA/CE
1-8312-11 > KA,230VAC,3-CT,UL/CSA/CE,HT-CS
1-8312-12 > KA,230VAC,3-CT,UL/CSA/CE,HT-SS
1-8316-1 > KA,230VAC,2-CT,1-1/2,UL/CSA/CE
1-8317-1 > KA,230VAC,3-CT,1-1/2,UL/CSA/CE
1-8331-1 > KA,12-24VDC,2-CT,1-1/4,UL/CSA/CE
1-8331-11 > KA,12-24VDC,2-CT,UL/CSA/CE,HT-CS
1-8331-12 > KA,12-24VDC,2-CT,UL/CSA/CE,HT-SS
1-8332-1 > KA,12-24VDC,3-CT,1-1/4,UL/CSA/CE
1-8332-11 > KA,12-24VDC,3-CT,UL/CSA/CE,HT-CS
1-8332-12 > KA,12-24VDC,3-CT,UL/CSA/CE,HT-SS
1-8336-1 > KA,12-24VDC,2-CT,1-1/2,UL/CSA/CE
1-8337-1 > KA,12-24VDC,3-CT,1-1/2,UL/CSA/CE
1-8381-1 > KA,24VAC,2-CT,1-1/4,UL/CSA/CE
1-8381-11 > KA,24VAC,2-CT,UL/CSA/CE,HT-CS
1-8381-12 > KA,24VAC,2-CT,UL/CSA/CE,HT-SS
1-8382-1 > KA,24VAC,3-CT,1-1/4,UL/CSA/CE
1-8382-11 > KA,24VAC,3-CT,UL/CSA/CE,HT-CS
1-8382-12 > KA,24VAC,3-CT,UL/CSA/CE,HT-SS
1-8386-1 > KA,24VAC,2-CT,1-1/2,UL/CSA/CE
1-8387-1 > KA,24VAC,3-CT,1-1/2,UL/CSA/CE
1-8391-1 > KA,48VAC,2-CT,1-1/4,UL/CSA/CE
1-8391-11 > KA,48VAC,2-CT,UL/CSA/CE,HT-CS
1-8391-12 > KA,48VAC,2-CT,UL/CSA/CE,HT-SS
1-8392-1 > KA,48VAC,3-CT,1-1/4,UL/CSA/CE
1-8392-11 > KA,48VAC,3-CT,UL/CSA/CE,HT-CS
1-8392-12 > KA,48VAC,3-CT,UL/CSA/CE,HT-SS
1-8396-1 > KA,48VAC,2-CT,1-1/2,UL/CSA/CE
1-8397-1 > KA,48VAC,3-CT,1-1/2,UL/CSA/CE
1-8401-1 > KAX,115VAC,2-CT,1-1/4,UL/CSA
1-8401-11 > KAX,115VAC,2-CT,UL/CSA,HT-CS
1-8401-12 > KAX,115VAC,2-CT,UL/CSA,HT-SS
1-8401-2 > KAX,115VAC,2-CT,1-1/4,ATEX/IECex
1-8401-21 > KAX,115VAC,2-CT,ATEX/IECEX,HT-CS
1-8401-22 > KAX,115VAC,2-CT,ATEX/IECEX,HT-SS
1-8402-1 > KAX,115VAC,3-CT,1-1/4,UL/CSA
1-8402-11 > KAX,115VAC,3-CT,UL/CSA,HT-CS
1-8402-12 > KAX,115VAC,3-CT,UL/CSA,HT-SS
1-8402-2 > KAX,115VAC,3-CT,1-1/4,ATEX/IECex
1-8402-21 > KAX,115VAC,3-CT,ATEX/IECEX,HT-CS
1-8402-22 > KAX,115VAC,3-CT,ATEX/IECEX,HT-SS
1-8406-1 > KAX,115VAC,2-CT,1-1/2,UL/CSA
1-8406-2 > KAX,115VAC,2-CT,1-1/2,ATEX/IECex
1-8407-1 > KAX,115VAC,3-CT,1-1/2,UL/CSA
1-8407-2 > KAX,115VAC,3-CT,1-1/2,ATEX/IECex
1-8411-1 > KAX,230VAC,2-CT,1-1/4,UL/CSA
1-8411-11 > KAX,230VAC,2-CT,UL/CSA,HT-CS
1-8411-12 > KAX,230VAC,2-CT,UL/CSA,HT-SS
1-8411-2 > KAX,230VAC,2-CT,1-1/4,ATEX/IECex
1-8411-21 > KAX,230VAC,2-CT,ATEX/IECEX,HT-CS
1-8411-22 > KAX,230VAC,2-CT,ATEX/IECEX,HT-SS
1-8412-1 > KAX,230VAC,3-CT,1-1/4,UL/CSA
1-8412-11 > KAX,230VAC,3-CT,UL/CSA,HT-CS
1-8412-12 > KAX,230VAC,3-CT,UL/CSA,HT-SS
1-8412-2 > KAX,230VAC,3-CT,1-1/4,ATEX/IECex
1-8412-21 > KAX,230VAC,3-CT,ATEX/IECEX,HT-CS
1-8412-22 > KAX,230VAC,3-CT,ATEX/IECEX,HT-SS
1-8416-1 > KAX,230VAC,2-CT,1-1/2,UL/CSA
1-8416-2 > KAX,230VAC,2-CT,1-1/2,ATEX/IECex
1-8417-1 > KAX,230VAC,3-CT,1-1/2,UL/CSA
1-8417-2 > KAX,230VAC,3-CT,1-1/2,ATEX/IECEX
1-8431-1 > KAX,12-24VDC,2-CT,1-1/4,UL/CSA
1-8431-11 > KAX,12-24VDC,2-CT,UL/CSA,HT-CS
1-8431-12 > KAX,12-24VDC,2-CT,UL/CSA,HT-SS
1-8431-2 > KAX,12-24VDC,2-CT,1-1/4,ATEX/IECEX
1-8431-21 > KAX,12-24VDC,2-CT,ATEX/IECEX,HT-CS
1-8431-22 > KAX,12-24VDC,2-CT,ATEX/IECEX,HT-SS
1-8432-1 > KAX,12-24VDC,3-CT,1-1/4,UL/CSA
1-8432-11 > KAX,12-24VDC,3-CT,UL/CSA,HT-CS
1-8432-12 > KAX,12-24VDC,3-CT,UL/CSA,HT-SS
1-8432-2 > KAX,12-24VDC,3-CT,1-1/4,ATEX/IECEX
1-8432-21 > KAX,12-24VDC,3-CT,ATEX/IECEX,HT-CS
1-8432-22 > KAX,12-24VDC,3-CT,ATEX/IECEX,HT-SS
1-8436-1 > KAX,12-24VDC,2-CT,1-1/2,UL/CSA
1-8436-2 > KAX,12-24VDC,2-CT,1-1/2,ATEX/IECEX
1-8437-1 > KAX,12-24VDC,3-CT,1-1/2,UL/CSA
1-8437-2 > KAX,12-24VDC,3-CT,1-1/2,ATEX/IECEX
1-8481-1 > KAX,24VAC,2-CT,1-1/4,UL/CSA
1-8481-11 > KAX,24VAC,2-CT,UL/CSA,HT-CS
1-8481-12 > KAX,24VAC,2-CT,UL/CSA,HT-SS
1-8481-2 > KAX,24VAC,2-CT,1-1/4,ATEX/IECex
1-8481-21 > KAX,24VAC,2-CT,ATEX/IECEX,HT-CS
1-8481-22 > KAX,24VAC,2-CT,ATEX/IECEX,HT-SS
1-8482-1 > KAX,24VAC,3-CT,1-1/4,UL/CSA
1-8482-11 > KAX,24VAC,3-CT,UL/CSA,HT-CS
1-8482-12 > KAX,24VAC,3-CT,UL/CSA,HT-SS
1-8482-2 > KAX,24VAC,3-CT,1-1/4,ATEX/IECex
1-8482-21 > KAX,24VAC,3-CT,ATEX/IECEX,HT-CS
1-8482-22 > KAX,24VAC,3-CT,ATEX/IECEX,HT-SS
1-8486-1 > KAX,24VAC,2-CT,1-1/2,UL/CSA
1-8486-2 > KAX,24VAC,2-CT,1-1/2,ATEX/IECex
1-8487-1 > KAX,24VAC,3-CT,1-1/2,UL/CSA
1-8487-2 > KAX,24VAC,3-CT,1-1/2,ATEX/IECex
1-8491-1 > KAX,48VAC,2-CT,1-1/4,UL/CSA
1-8491-11 > KAX,48VAC,2-CT,UL/CSA,HT-CS
1-8491-12 > KAX,48VAC,2-CT,UL/CSA,HT-SS
1-8491-2 > KAX,48VAC,2-CT,1-1/4,ATEX/IECex
1-8491-21 > KAX,48VAC,2-CT,ATEX/IECEX,HT-CS
1-8491-22 > KAX,48VAC,2-CT,ATEX/IECEX,HT-SS
1-8492-1 > KAX,48VAC,3-CT,1-1/4,UL/CSA
1-8492-11 > KAX,48VAC,3-CT,UL/CSA,HT-CS
1-8492-12 > KAX,48VAC,3-CT,UL/CSA,HT-SS
1-8492-2 > KAX,48VAC,3-CT,1-1/4,ATEX/IECex
1-8492-21 > KAX,48VAC,3-CT,ATEX/IECEX,HT-CS
1-8492-22 > KAX,48VAC,3-CT,ATEX/IECEX,HT-SS
1-8496-1 > KAX,48VAC,2-CT,1-1/2,UL/CSA
1-8496-2 > KAX,48VAC,2-CT,1-1/2,ATEX/IECex
1-8497-1 > KAX,48VAC,3-CT,1-1/2,UL/CSA
1-8497-2 > KAX,48VAC,3-CT,1-1/2,ATEX/IECex


Last Rev.: May 21, 2021