

MODEL BL-50
Rotary Paddle Bin Level Indicator
Our industry standard workhorse level detection sensor for powders and bulk solids – high reliability, low maintenance, and high value.
These rugged and reliable rotary paddle bin level indicators are the most universal sensor for detecting the presence and absence of bulk solids ranging in density from 5 to over 100 pounds per cubic foot (80 to 1600 kilograms per cubic meter). Model BL-50 units are equipped with fail-safe relay output, high intensity LED’s, industry-standard 1-1/4″ process connection, two conduit entrances, and food grade materials of construction. All units are available with folding or fixed paddles for easy installation from outside the bin and can be top or side mounted.
SUPER BRIGHT LED’s locally indicate Normal / Alarm status
Rugged aluminum enclosure with powder coat finish (FDA Compliant)
Improved moisture seal with a bolt-on cap
Selectable High/Low fail-safe output on power failure
Three bearing shaft assembly increases reliability and life
Internal bi-directional torque limiter protects motor
Automatic motor shut-off
DPDT relay output
Removable wiring terminals
Interchangeable with other brands accessories
Adjustable sensitivity (if needed)
Dual conduit entrances
MODEL BL-50
Rotary Paddle Bin Level Indicator


Our industry standard workhorse level detection sensor for powders and bulk solids – high reliability, low maintenance, and high value.
These rugged and reliable rotary paddle bin level indicators are the most universal sensor for detecting the presence and absence of bulk solids ranging in density from 5 to over 100 pounds per cubic foot (80 to 1600 kilograms per cubic meter). Model BL-50 units are equipped with fail-safe relay output, high intensity LED’s, industry-standard 1-1/4″ process connection, two conduit entrances, and food grade materials of construction. All units are available with folding or fixed paddles for easy installation from outside the bin and can be top or side mounted.
SUPER BRIGHT LED’s locally indicate Normal / Alarm status
Rugged aluminum enclosure with powder coat finish (FDA Compliant)
Improved moisture seal with a bolt-on cap
Selectable High/Low fail-safe output on power failure
Three bearing shaft assembly increases reliability and life
Internal bi-directional clutch protects motor
Various voltages
Automatic motor shut-off
DPDT relay output
Removable wiring terminals
Interchangeable with other brands accessories
Adjustable sensitivity (if needed)
Dual conduit entrances
Principal of Operation
For several decades rotary paddle technology has been used as a method for detecting the presence and absence of bulk solid materials. A robust synchronous motor drives a stainless-steel output shaft at approximately 2 RPM. The paddle is attached to the shaft and rotates freely in the absence of material within the bin.
Material presence surrounding the paddle in the bin will impede its rotation and cause the state of the built-in relay contacts to change, indicating material presence. The builtin LED’s will change to indicate the status of the alarm condition.
Application and Use
High (full), low (empty), intermediate (demand) level indication, and plugged chute detection, are common applications within a wide variety of industries.
Prevention of bin overfilling and material outage conditions are typical uses of these devices. The Model BL-50 rotary paddle bin level indicators can be used to detect materials with density from 5lbs/ft³ (80kg/m³) for low and intermediate level control applications and from 10lbs/ft³ (160kg/m³) for high level indication.
Example materials include plastic pellet, food stuffs, feed and their ingredients, grains, cement, aggregate materials,
nuts, flour, resins, sand, coal, chemicals, limestone, wood, sawdust and many more.
Technical Data
Housing | Die-cast aluminum, FDA compliant powder coat, NEMA Type 4X, IP65 |
Process Temp | Up to 300° F (149° C) |
Ambient Temp | -40° F to +158° F (-40° C to +70° C) |
Sensitivity | Low Level ≥ 5lbs/ft³, High Level ≥ 10lbs/ft³, Adjustable setting |
Motor Voltage | 115VAC |
Output | DPDT Relay, 8A @ 250VAC |
Process Connection | 1-1/4″ NPT powder coated |
Bearings | Three (3) sealed bearings |
Certifications | CE mark, SGS Mark UL61010-1, CSA C22.2 |
More Information
Click here to download product line PDF’s
Model BL-50 Rotary Paddle Accessories
- Insertable folding 1- and 2-vane paddles
- Std. 5” Dia. & Large 7” Dia. threaded tri-vane paddles
- Insertable threaded Banana and 1-vane heavy duty paddles
- 2 and 4-vane heavy duty threaded paddles
- Extension shafts and shaft guards
- Mounting plate kits
Principal of Operation
For several decades rotary paddle technology has been used as a method for detecting the presence and absence of bulk solid materials. A robust synchronous motor drives a stainless-steel output shaft at approximately 2 RPM. The paddle is attached to the shaft and rotates freely in the absence of material within the
bin.
Material presence surrounding the paddle in the bin will impede its rotation and cause the state of the built-in relay
contacts to change, indicating material presence. The builtin LED’s will change to indicate the status of the alarm condition.
Application and Use
High (full), low (empty), intermediate (demand) level indication, and plugged chute detection, are common applications within a wide variety of industries.
Prevention of bin overfilling and material outage conditions are typical uses of these devices. The Model BL-50 rotary paddle bin level indicators can be used to detect materials with density from 5lbs/ft³ (80kg/m³) for low and intermediate level control applications and from 10lbs/ft³ (160kg/m³) for high level indication.
Example materials include plastic pellet, food stuffs, feed and their ingredients, grains, cement, aggregate materials,
nuts, flour, resins, sand, coal, chemicals, limestone, wood, sawdust and many more.
Technical Data
Housing | Die-cast aluminum, FDA compliant powder coat, NEMA Type 4X, IP65 |
Process Temp | Up to 300° F (149° C) |
Ambient Temp | -40° F to +158° F (-40° C to +70° C) |
Sensitivity | Low Level ≥ 5lbs/ft³, High Level ≥ 10lbs/ft³, Adjustable setting |
Motor Voltage | 115VAC |
Output | DPDT Relay, 8A @ 250VAC |
Process Connection | 1-1/4″ NPT powder coated |
Bearings | Three (3) sealed bearings |
Certifications | CE mark, SGS Mark UL61010-1, CSA C22.2 |
More Information
Click here to download product line PDF’s
Model BL-50 Rotary Paddle Accessories
- Insertable folding 1- and 2-vane paddles
- Std. 5” Dia. & Large 7” Dia. threaded tri-vane paddles
- Insertable threaded Banana and 1-vane heavy duty paddles
- 2 and 4-vane heavy duty threaded paddles
- Extension shafts and shaft guards
- Mounting plate kits
Ordering Information
Sensor Final Assembly Part Number Structure

Ordering Information
Sensor Final Assembly Part Number Structure

1 – 115VAC
1- Ordinary Location
1- None
2- Standard Coupling
3- Optional Coupling
1- 1-1/4″ NPT aluminum
1- Standard
1 – 115VAC
1- Ordinary Location
1- None
2- Standard Coupling
3- Optional Coupling
1- 1-1/4″ NPT aluminum
1- Standard