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Syntron Hopper Level
Controls & Flow Switches


Syntron Paddle Type Hopper Level Controls

Syntron Paddle Type Hopper Level Controls employ a revolving paddle to detect the level of materials in bins and hoppers. They can be used to control the flow of fine or granular materials. When the rotating paddle senses a lack of material it immediately sends a "supply" signal to feeder equipment. As the material rises to the desired level and impedes paddle rotation, the unit acts to stop the flow of material.

Our Paddle Type Hopper Level Controls offer several distinct advantages over other available models. Adjustable sensitivity is one of them. These units can be field adjusted to meet the specific density of your particular materials.

Additional special features include complete motor cut-off. When the paddle stalls, the motor continues to rotate until the micro-switch shuts off current. Hence unit can be stalled indefinitely. A built-in signal delay prevents false starts due to vibration or material shift.

All units are completely interchangeable in mounting dimensions with most commonly used units. A slip clutch allows paddle to be turned manually in either direction.

We also offer a choice of several different paddle assemblies so the correct one can be matched to your operation.

Standard Model SLC is a very versatile unit. It mounts easily in any position on either flat or curved surfaces and is ideal for high or low-level applications. Standard construction consists of a cast aluminum housing, flexible stainless steel shaft and couplings, a stainless steel paddle, a 110-volt a.c. motor and two SPDT switches. The unit carries U/L and CSA listing.

Explosion-proof Model SXLC offers the same features and operating advantages as Model SLC, but also meets critical machining specifications, tolerances, clearances and insulation requirements. It is labeled by the U/L and CSA for Class I groups C and D, and Class U, for groups E, F and G for explosion-proof applications.

The unit can be used in hazardous atmospheres charged with explosive dusts or volatile vapors, Construction is similar to Model SLC. A stainless steel mounting plate can also be provided when required.

Download a 4-page brochure on this product

Principle of Operation

The operation of FMC's paddle type hopper level control products 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 firs 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 the 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 activated.

Features & Benefits

Motor shut-off feature

Economical, versatile point level indicator

Simple electromechanical operation

Built-in slip clutch protects internal components from external forces

Rugged cast aluminum construction

Dust tight and watertight cast aluminum housing

Dependable design reduces component wear

UL, CSA approved

Two SPDT 15 amp. switches

Operating temperatures: -57 F to +200 F external (+300 F internal bin)

3/4 NPT conduit connection

Most units are actuated by 115 volt (50/60 Hz) 2.7 Watt motor
230 volt (50/60 Hz) motor available upon request

Unit sealed, including bearings, against maximum pressure: 30 PSI

Sensitivity adjustable from 10 lb/ft3, based on paddle selection

Top mounting units can extend down a maximum of 20 ft from control

Complete motor shut-off prevents motor burnout and extends the life of the unit

Interchangeable paddle assemblies increase the paddle unit's versatility

A. Complete Motor Cut-Off When paddle stalls, motor continues to rotate until microswitch is actuated. Microswitch shuts off current flowing through motor windings. Eliminates all possibility of wear, adds years to service.

B. Adjustable Sensitivity Dual purpose return spring starts motor when material drops away from paddle. Can be field adjusted to meet material sensitivity /density. Provides built-in actuation response from 4- to 12-inch ounces as standard.

C. Built-in Signal Delay Allows for small amounts of paddle motion in stalled position without initiating a signal. Prevents false starts due to vibration or material shift.

D. Stainless Steel Flexible Coupling Standard equipment on all models. Absorbs shock loading best. Need only be shielded when required by good engineering practice. 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 shaft extension is used.

E. A choice of paddle assemblies can be made to best suit the application. See paddle selection data for a choice of paddles.

F. Mounting Interchangeability All units 100% interchangeable in mounting dimensions and diameters, bolt holes, etc., with most commonly used units.

G. Slip Clutch Slip clutch inside casing allows paddle to be turned manually in either direction.

H. Shaft Seal Stainless steel shaft seal works on bin pressures up to 30 PSI.

I. Shaft Extension Many top mount installations require that the paddle extends into the vessel to a predetermined level. Remove paddle from coupling and screw in standard 1/4" pipe with standard pipe threads. Up to 21 feet can be added without interfering with sensitivity of unit.

Shaft Guards Shaft guards are recommended for use with 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" in length.

J. Lower Switch Actuating Pressure (Field adjustable). Six-ounce pressure at tip of standard paddle actuates switch mechanism (leaving eight ounces of reserve torque in unit). On materials that tend to stick in the seal area the reserve power enables unit to break loose and actuate itself.


Typical applications include, but are not limited to:

Coal Metals
Limestone Regrind
Sandstone Pellets
Limestone Dust Wood
Sand & Gravel Sawdust
Foundry Sand Clays
Silica Sand Rocks

Syntron Flow Switches

Control part levels in rotary or vibratory feeders

Syntron Flow Switches are designed to detect and correct the lack of materials at critical points in bulk material handling systems. When the flow of materials past the device is interrupted, the unit's sensor arm swings into the operating position and activates feeding equipment or alarms. A number of switches can be used in one system -- each located at a critical point. Operation is from 115, 230 or 460 volt. The actuation switch has a rating of 15 amps.

Flow Switch features include:

Low cost

Low torque:1 inch - ounce or less

Long life

High cyclic - electronic versions

Broad range of styles and sizes

FMC's wide variety of Flow Switches assure that the proper style is available for your application.

Standard Flow Switches

Rod type mechanical limit switch, suitable for most applications. Various column heights and paddle lengths are available

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The light-duty Model FS-4 Flow Switch detects and corrects the lack of bulk materials flow and can also control the depth of small parts flow in feeder bowls.Generally mounted in a vertical position, the flow switch can be installed by bolting or welding the base to any flat surface. The sensor arm may be easily adjusted radially as required up to 45 from vertical as shown. The actuation switch and sensor arm are fitted on a support column and support are which are available in various lengths. Standard construction includes a dust-tight switch housing. A special switch is available to meet J.I.C. requirements.

Rod type electronic limit switch conforming to JIC electronic specifications. Offers low torque (less than one inch - ounce) and high cyclic capabilities.

Standard flow switches are offered in stand-alone column mounts with a choice of actuator rod lengths and rotary feeder mounts which are adjustable to fit all FMC Rotary Feeders.

Special models are available upon request.

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