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EL 31/1, Electronic Zone, MIDC, Bhosari

Pune, Maharashtra- 411 026, (India)

Level Management Solutions   Send Enquiry

Protocontrol with a vast experience of more than 25 years offers complete level management solutions. We offer solutions for measuring levels of liquid, powder, granule, solids and bulk solids. We are the first in India to develop Capacitive Proximity Switch for packaging industry. We are the first to design and prove Chute Block Switch for bulk solids.

Manufacturing Capabilities

Our factory is located in industrial area in Pune. We have full flanged set up to manufacture and test products from simple single point switches to complex level monitoring systems.

Technical Support

Level management field is complex and require detailed knowledge of materials and process. Protocontrol engineers are trained to offer you suitable but cost effective solution. We are aware of requirements of every industry and offer product considering process and operating condition of particular industry. We have solutions for your every level measurement need. Please contact us with your application and requirement, our technical team will offer you most appropriate solution.

Products Offered P/L(Point Level)

Cable Ended Float Level Switch CEFS

This is one of the most simple and economical levels switch designed for sensing level of water in large tanks and sumps. The float (PP) contains micro switch assembly and is suspended with a cable. When float tilts upwards due to rise in level, operates a micro switch inside. Adjustable stopper is supplied with the cable for adjusting the set point and on off differential.


  1. Ordering Code : CEFS 5
  2. Float Material : PP
  3. Cable length : 5 Mtrs, PVC, 3 Core
  4. Contacts : 1 C/ O rated for 10 Amp resistive at 230 V AC
  5. Max Operating Temp : 70 C
  6. Specific Gravity : 0.90 to 1.3
  7. Actuation : Internal steel roller ball and micro switch arrangement
  8. Position of stopper : Adjustable, 280 mm minimum from the end of float
  9. Optional Accessories : Cable Length : 10 Meters: Add suffix 10 in ordering code
  10. Flange with termination box: Add suffix F
  11. Terminal Box : Add suffix T

Vertically Guided / Magnetic Float Level Switch VGLS


This is most economical level switch designed for single point operation. Ideal for monitoring level of liquid in small tanks. Suitable for liquids like clear water, lubricating oil, chemicals, and coolant having density of 0.8 to 1.

Float Material Polypropylene Foam SS 316
Float 24 mm x 21 mm 28 mm x 28 mm
Lead wire 900 mm 2 Meter
Contact rating 50 VA, 240 VAC Max 50 VA, 240 V AC
Max Contact SPST SPST
Temperature Up to 80 C Up to 120 C

Note : Switches with other stem length are available. Consult factory.

Details Required:
Liquid to be sensed,Specific Gravity, Operating Temp, Operating Pressure, Switching Voltage and current

Side Mounted Miniature Liquid Level Switch SMLS M



  1. Measuring level of Liquid
  2. Use in Process, food Industry

Operating Principle :

The permanent magnet is housed inside the float rod and reed switch is housed inside the stationary stem. When the float gets lifted, the magnet is moved into the proximity of the reed switch; the reed switch contact gets actuated.


  1. Easy to install
  2. Low Hysterics and high repetition switching accuracy
  3. Economical
  4. Operation is independent of liquid characteristic

Details Required: Liquid to be sensed, Density, Operating Temp, Operating Pressure, Switching Voltage and current

Ordering Proforma :

Type                             Enclosure

SMLS P OM                   Plastic, Outside Mounting
SMLS P IM                     Plastic, Inside Mounting
SMLS SS IM                   Metallic Internal Mounting
SMLS SS OM                 Metallic Outside Mounting

Side Mounted Heavy Duty Liquid Level Switch SMLS H



  1. Ordering Code : SMLS H
  2. Mounting : Horizontal
  3. MOC of float : Stainless Steel
  4. Length of float : 130 mm
  5. Float Dia :44 mm
  6. Specific Gravity : Min 0.7
  7. Logic : 1 C/O
  8. Contact Rating : 2 Amps resistive at 240 VAC
  9. Terminal Compartment : Cast Al, IP 65
  10. Max. Temperature : Up to 120 Degree Cent
  11. Max Pressure : Up to 20 Kg/ Cm Square at 25 degree cent
  12. Mounting : Flanged, Diameter 120 mm, having four holes of 14
    mm dia. at 92 PCD (Other Flange Sizes on request)

Details Required:Liquid to be sensed, Density, Operating Temp., Operating Presssure, Switching voltage and current.

Vertically Guided Multipoint Level Switch VGLS M


Application :

  • Top Mounted Level switch for clear water and liquids
  • Suitable for Corrosive chemicals
  • Used in Food application

Operating Principle :

Magnet housed in float moves up and down with liquid, actuates a hermetically sealed switch within the stem. Multiple reed switches are placed at required height. Make sure that the liquid has no iron powder or magnetic interference.

Features :

  1. Rugged construction of reed switch provides long trouble free service.
  2. Installation is simple.
  3. Potential free output contact.
  4. Extremely compact, simple and easy to install.
  5. Not effected by electrical interference.
  6. High repeatability


Specifications :

  • No. of switching points : Please specify. Max up to 3. Factory set.
  • No. of Floats : Depends on the number of switching points. (Consult factory for specific application)
  • Float Dia. & MOC of float : Please specify specific gravity of liquid. Standard floats designed for water. Various floats available for the liquid having specific gravity less than 1 Minimum
  • specific gravity : 0.7. Please consult factory for special floats.
  • Contacts : 1 NO rated for 50 VA, 240 V AC Max, for each level
  • Temperature: Up to 120 Degree Cent.
  • Max Test Pressure : 10 Kg / Cm Square
  • Mounting : Flanged / Threaded
  • MOC of flange : MS / S.S.

Considering limitation of reed switch contact rating, we always recommend use of our Level Controller DLC for driving load like solenoid, contactor & motorized valve. Switches suitable for use in hazardous area (Gr IIa, IIB) are available. Consult factory.

Details Required : Liquid to be sensed, Density, Operating Temp, Operating Pressure, Switching Voltage and current, Switching Points (L1, L2, and L3) from bottom of flange, Specific Gravity of liquid


Please specify switching points(L1,L2,L3) in mm from bottom of the flange

Vertically Guided Sight Level Switch VGSLS


Applications :

  • Measuring and indication of level of liquid
  • Use in special purpose machines for measuring level of coolants, oil in a tank
  • Multiple level switching by using number of switches
  • Use of non contact magnetic / inductive proximity switch

Operating Principle :

The float assembly is provided with a rod which moves in a transparent acrylic tube. The rod carries magnet / M S flag which is sensed by switch kept outside the tube. Hence hi-low switching can be generated by using two switches. The switch assembly is to be fixed on the tank whose level is to be monitored. The float moves up and down inside the tank.

Features :

  • Easy to install
  • Economical
  • Indication of level from outside the tank
  • Switches are not coming in contact with liquid

Details Required : Liquid to be sensed, Length L (max), Switch type : Magnetic / Inductive Type , Number of switches, Max Liquid Temp, Max Operating Pressure.

Conductive Type Level Switch CLS


Application :

For sensing level of conducting non sticky clear liquids like water, Acid, Salt & various chemicals, Sugar solutions, Milk, Juice etc.


  • Simple, low cost level controller
  • Automatically controls liquid levels in any container.
  • Quick installation
  • Low current operated circuit ensures personnel safety.
  • Wide range of electrodes with different mounting configuration, constructions to suit every application.

Operating Principle :

A conductive Level switch operates on the base of conductive principle. These are equipped with two or more electrodes (one is ground and others are sensing electrodes). When a conductive fluid comes in contact with two or more of sensing electrodes, an electric circuit is completed. A very small alternating voltage is applied to two probes tips. The circuit gets closed by liquid when liquid touches the probe tip. Th voltage & current used are so small that no dangerous shock can occur. The use of alternating voltage prevents deposition and electrolysis.


  • Control Supply : 230 V AC 50 Hz / 24V DC. Please Specify.
  • Output : 1 C/O Relay contact, rated for 5 Amps. Resistive at 230 V AC.
  • Max. Temp for control unit : 60 C
  • Enclosure : Din Rail mounting, IP 30 / Field mounting, IP 55.
  • Indication : LED Indication. For relay ON
  • Mounting of probe : Flange mounting / Threaded
  • Sensing : SS wire,
  • Insulation : PTFE.
  • Counter weight : SS

Details Rquired : Liquid to be sensed, Operating Temp, Operating Pressure, Switching Voltage and current, Length of reference electrode, Switching Points (L1, L2, and L3) from bottom of flange.

RF Capacitance / Admittance Type Level Switch: Rope Type, Rod Type, Disc TypeRFLS



  • Detection of levels of solids, liquids granules food grains and powders
  • Detection of top and bottom levels of coal bunkers
  • Detection of chute blockage in feeding hoppers : CHUTE BLOCK SWITCH
  • Level detection in cement silos
  • Level detection of Fly ash
  • Level detection for Stock Pile
  • Boot level detection

Operating Principle :

The RF Level switch operates on the basis of RF absorption. The electronic unit generates a sinusoidal wave, applied to the electrode creating a field around it. RF environment absorption changes (Electrical Loss) around the electrode are reflected on the changes of generator supply current. Such changes caused by increase in level is amplified and used to actuate the relay. Special Coat-guard amplifier is incorporated in the circuit, which will ignore the effect of deposition. The RF Admittance type, point level switch, designed with special sensing probe, using special shield coat-guard circuit and three element probe. The level switch is immune to the material built-up on the probe and material bridging between the probe and hopper wall.



  • Three Element coat-guards Technique: Ignores material built-up on probe
  • Fast end easy installation: Simple to calibrate
  • Suitable for highly dusty environment
  • Field selectable operation logic: Configurable high or low point switching
  • Economical

Specifications :

  1. Control Supply : 230V AC, 50 Hz (+_15%) (Standard), other voltages like 110V AC, 24V DC are also available
  2. Output : 2C/o Relay contact, 5 Amps. Resistive @ 230V AC
  3. Switching Delay : 2- 20 seconds adjustable (offered for liquid level sensing applications)
  4. Safety Operation : Field selected for minimum or maximum switching points
  5. Switch status LED : Green: Normal, Red: Alarm Yellow: Power ON
  1. Particle size : max 30 mm. Can also be used for material having higher particle sizes if contents fines
  2. Probe length : Rod probe: 300 mm to 1500 mm, Rope probe: 750 mm to 5000 mm The electronic circuit can be integral with probe housing or can be remote mounting Control unit ambient temperature: 0-60 Degree cent
  3. Sensor probe working temp : up to 150 degree cent. Up to 225 degree cent with stand off. For Fly Ash, we have special sensor probes with ceramic coating, working up to 450 degree cent
  4. Mounting Screwed : 11 ½ inch BSP / Flanged
  5. Enclosure : Cast Al, IP 65, Field Mounting. Special enclosure Available for flameproof area use

Details Requided : Supply Voltage, Material to be sensed, Particle size, Bulk Density, Probe Type, Probe Length, Mounting, Mounting position: From Top / sides, Operating Temp, Operating Pressure


Chute Block Detector / Boot Level Switch

RF Admittance Disc Probe: Series: RFLS D: Chute Block Switch for hoppers :
Suitable for sensing material jamming in a compact chute. Designed for mounting at the bottom of the hopper. As the disc probe does not come in the path of the material it does not block the passage and hence does not affect the material flow. Ideal for almost every material solid, powder, granule, dry and wet having particle size up to 30 mm


RF Admittance Rod Probe: Series RFLS R : Chute Block switches/ Boot Level Sensor / Level Switch:
The probe is to be inserted in the walls of hopper at required level point. When material level rises and touches the probe the contact is actuated. Suitable for almost every material solid, powder, granule, dry and wet having particle size up to 30 mm. As the probe is to be inserted in the hopper user has to ensure proper location for minimum abrasion. Provide proper canopy for long use.


RF Admittance Rope Probe: Series RFLS C : Chute Block / Stock Pile Level switch for Top level Mounting
The probe is to be hanged from the top in the hopper. The probe length is selected such that the bottom tip reaches at required level point. When material level rises and touches the probe the contact is actuated. Suitable for almost every material solid, contact is actuated. Suitable for almost every material solid, As the probe is to be hanged in the hopper user has to ensure that the falling material flow does not fall directly on the sensor.

Diaphragm Type Level SwitchDLS



  • Sensing clogging of material on screw conveyor
  • Boot level detection of bucket elevator
  • Detect level of food grain in hopper

Operating Principle :

The pressure of the product on the membrane operates a limit switch inside the switch compartment.The contact of limit switch is used for control action.


  • Low cost but Reliable
  • No power supply required
  • Installation is simple


  1. Enclosure : Cast Al, IP 40
  2. O/L : 1 C/O relay contact rated for 15 Amp resistive at 230 V AC
  3. Mounting : Flanged
  4. Pressure for detection : Approx 2 N min. Normal Sensitivity: 60 gm
  5. Operating Temp : 10 - 80 C
  6. Diaphragm Material : SS / Neoprene Rubber
  7. Particle Size : up to 30 mm and a density of 0.3 to 2.5 g/cm3

Details Requided :Material to be sensed, Particle size, Bulk Density, Mounting position (Dimensions and diagramhopper), Operating Temp, Operating Pressure

Vibrating Fork Type Level SwitchVFLS



Find application in food , packaging , Cement, steel & power generation industries for monitoring level of free flowing products like ore, fertilizer, food grains, coal, sand, chips, granules etc. Ideal for products that do not have heavy build-up on fork. Can sense dense materials like cement. It also senses extremely light products like styrene. Not recommended for mud, slurry, sticky material or water with high turbidity.

Operating Principle :

Vibrating Fork Level switch contain Piezo-electric crystal in the probe, which causes the fork to vibrate at a frequency of 125 Hz. It detects the presence or absence of material and actuates a relay. It gives point output, indicating high & low level alarm. It is having compact and robust design, suitable for side & top mounting. The constant vibration of the fork provides self-cleaning characteristics. The change in vibration is detected by circuit which causes the relay to change state after few seconds delay ( about 2-3 seconds). When fork is free from material relay reverts to its normal condition

Features :

  • No calibration required, simple to install.
  • Performance independent of material characteristics i.e. change in conductivity, di-electric constant.
  • No moving parts, hence no wares and tears.
  • Weatherproof enclosure, SS 316 for food industry
  • Field selectable operation logic: configurable high or low point switching.

Specifications :

  • Material Siz : Up to 10 mm
  • Material bulk density : 0.05 Kg/dm3 minimum
  • Fork Length : Min 200, Max up to 2500 mm
  • Control supply : 230 V AC (standard) Other supply voltages on request
  • Output : 2 C/O relay contact, rated for 5 Amp. Resistive at 230 V AC
  • Ambient Temp : 60 degree cent max
  • Temp in vessel : 150 degree cent max
  • Enclosure : Cast Al, IP 65, integral with probe / Flameproof
  • Max pressure in vessel : 10 Kg/cm2 max
  • Mounting : Screwed : 11 ½ inch BSP / Flanged

Details Requided : Supply Voltage, Material to be sensed, Particle size, Bulk Density, Fork Length, Mounting, Mounting position: From Top / sides, Operating Temp, Operating Pressure,MOC of flange and extension pipe ( Food application )

Odering Proforma : Refer ordering profoma of Vibrating Fork / Vibrating Rod Type Level Switch given below


Vibrating Rod Level SwitchVRLS



Vibration rod type level switch is a latest addition of in the vibrating type level instruments manufactured by Protocontrol. This switch detects the minimum or maximum level in bins, silos and hoppers filled with any kind of easy flowing solids, e.g. granules or pellets like grains, granular plastics, foods, etc. The VRLS is good for detecting level of liquids with bulk densities of 20 grams per litre and higher

Operating Principle :

The electronic circuit when powered excites the stainless steel rod of the probe to vibrate on its resonance frequency. When material covers the rod of the probe the vibration stops. This is sensed by the electronic circuit which forces its relay to switch. When the rod gets uncovered, the vibration restarts and the relay switches back

Features :

  • Easy installation, no calibration required
  • No readjustment required: unaffected by environmental changes e.g. temperature, pressure, humidity
  • No maintenance required: the vibration has a self cleaning effect
  • High durability: no moving parts, no wear-out
  • Reliable function due to unique patented single rod design : this eliminates bridging problem, where material builds a bridge from one rod to the other ( in Vibrating Fork )
  • Rod Length: min 150 max 3000 mm
  • Fail-safe design : if power supply fails, the relay drops

Specification TLS 602 :

  • Mounting : Screwed : 1 inch BSP Flanged, Standard 204 mm dia,8 mm thick, 6 holes of 10 mm dia on 178 mm pcd (Other flange size available, please specify )
  • Supply : 240 V AC, 50 Hz / 110 V AC (Pleases specify)
  • Output : 1 C/O Relay contact rated for 5 Amp resistive at 230 V AC
  • Enclosure : Cast Al, Field mounting type, IP 65
  • Shaft extension : Min 75 mm, Max: 1500mm with protection pipe extension
  • Bulk Density : Min 700 gm to 1 Kg. Please specify bulk density to offer suitable paddle


Rotating Paddle Type Level SwitchPLS


Application :

Used in almost any dry bulk material application in hoppers, silo, bins & tanks. Durable rugged design, that is compatible with many bulk solids, pelletized and granule applications.

Operating Principle :

Paddle type switches consist of motor, which drives a paddle through a planetary gearbox arrangement. The absence of material allows motor to turn the paddle uninterrupted. When the unit senses the presence of material via the restricted rotation of the paddle, the reversing torque actuates the internal micro-switches and alarms the unit, to give corresponding output signal.


  • Simple but reliable switch for level control
  • Specially designed motor, which does not burn under lock rotor condition
  • Specially designed PTFE seal to prevent ingress of dust particles into main enclosure
  • Field replaceable paddle assembly to suit various applications

Specification TLS 602 :

  • Mounting : Screwed 1 inch BSP Flanged, Standard 204 mm dia,8 mm thick, 6 holes of 10 mm dia on 178 mm pcd (Other flange size available, please specify )
  • Supply : 240 V AC, 50 Hz / 110 V AC (Pleases specify)
  • Output : 1 C/O Relay contact rated for 5 Amp resistive at 230 V AC
  • Enclosure : Cast Al, Field mounting type, IP 65
  • Shaft extension : Min 75 mm, Max: 1500mm with protection pipe extension
  • Bulk Density : Min 700 gm to 1 Kg. Please specify bulk density to offer suitable paddle


Tilt SwitchTLS 602


Application :

Tilt switch is an electronic device specially developed for sensing the level of an approaching stockpile on stacker-reclaimed or material in hopper in a silo and to provide an output signal which can be used to initiate control action. It is used for measuring level of solids & granules.

Operating Principle :

The Tilt switch comprises of two parts : Sensor Probe & Monitoring Unit. The sensor probe is of tubular structure & is hanged by means of a chain link arrangement. When tilt probe gets tilted by material, the output relay gets actuated. The sensor probe unit has omni-directional sensing pattern and hence on whichever side its tilts, it provides output signal. It has built-in adjustable ON & OFF delays to take care of nuisance tripping due to wind flow or momentary jerks at the start and stop of the machine.

Features :

  1. Adjustable ON & OFF delay, to prevent nuisance tripping
  2. Omni-directional sensor probe. The switch operates when tilts to any direction
  3. Less maintenance

Specification TLS 602 :

  • Supply voltage : 110/240 V AC,50 Hz.
  • OFF Delay : 1 to 10 secs (Continuously Adjustable)
  • ON Delay : 1 to 10 secs (Continuously Adjustable)
  • Output contacts : 2 C/O relay contact
  • Contact rating : 5 Amp. resistive at 240 V AC
  • Sensor probe : 38 mm diameter x 250 mm long. Enclosure
  • For Control circuit : Cast Al, IP 65 / DIN Rail / Flameproof

Details Requided :
Supply Voltage, Material to be sensed, Particle size, Bulk Density, Chain Extension if required , Operating Temp, Operating Pressure

Miniature Capacitive Type Point Level Switch

Application :

  • Sensing level of dry and free flowing solids and powder like cement, milk powder, food grains,
  • Clear liquid like water, diesel, oil
  • Plastic granules

Operating Principle :

The change in dielectric is sensed by switch. Due to presence of material, the dielectric will change which is detected by switch to produce O/P

Features :

  • Low cost
  • Installation is simple
  • Extremely compact


  • Size Of Switch : Tubular threaded enclosure: M 18 or M 30 size, Probe length: 70 mm
  • Supply Voltage : 230 V AC (Two wire switch) / 24 V Dc (Three wire switches)
  • O/P : AC switch will drive size 0 contactor, while DC switches drive relay or PLC gate
  • Contact : Solid state NO contact rated for 250 m Amp
  • Mounting : Top / Side
  • Temperatur : Up to 70 Degree Cent
  • Optional : Flange, Products for high pressure application

Details Requided : Supply Voltage, O/P , Material to be sensed, Particle size, Bulk Density, Special Probe Length, Mounting, Mounting position: From Top / sides, Operating Temp, Operating Pressure, Optional Flange.

Note: We always recommend use of our level controller DLC for driving loads like solonoid, contactor and motorised valve.

RF Capacitance Type Continuous Level TransmitterRFLT


Application :

  • Level measurement of liquids and solids in tank and vessels with analogue O/P
  • Level transmitter for water, diesel and oils, Acids, Acetone, Ammonia Benzine, Feed water, fruit juice, milk, wine,

Operating Principle :

The probe forms an electrical capacitor with the surrounding metal contained wall, or with auxiliary reference probe . With the vessel empty, initial capacitances exists between the electrode and the metal well or the auxiliary reference probe. When the probe become covered with material to be measured the capacitances will increase and the change will be measured and covered into an analogue (4-20 mA) output signal proportional to the change. Rod or flexible cable can be used for various conductive or non conductive Liquids

Features :

  • Compact, Low cost
  • Analogue 4-20 mA/ 0-5 V O/P


  • Supply : b24 V DC
  • O / P : 4-20 mA
  • Measuring Range : 0.2 to 3 Mtrs for liquid
  • Probe material : SS / Part or full insulation (for conducting liquids) by PTFE as per requirement
  • Mounting : Vertical, ½ inch process connection

Details Requid :Liquid to be sensed, Density, Conducting / Non conducting, Probe Length, Insulation , Operating length, Operating Temp, Operating Pressure, Tank material

Ultrasonic Type Level Transmitter


Application :

It is low cost, non contact type level measurement technique. The analogue O/P (4-20 mA, 20-4 mA) is used for indication and control purpose. The sensor is to be mounted on tank or hopper, the O/P signal can be processed at field or in control room for control action. Various models are offered for sensing range up to 50 Meters for liquid application. For solids application the range is approx 25 Mtrs.

This product finds application in:

  • Food and Beverages
  • Water / Wastewater without foam
  • Chemicals without fumes
  • Oils

Features :

  • Simple push-button calibration
  • Output 4-20 mA , 20-4 mA
  • Built-in temperature compensation
  • Compact Size for Easy Mounting
  • Easy to install

Principle Of Operation :

An ultrasonic pulse is transmitted from the sensor face. The pulse travels to the surface being monitored and is reflected off this surface back to the sensor. The time of flight is divided by 2 and converted to an output signal directly proportional to the material level

Radar Level Transmitter



  • For level monitoring of liquids and free flowing solids
  • Suitable for highly dusty environments such as cement industry
  • Less affected by environment effects like vapors, wind, rain, foam, fumes etc.

Operating Principle :

Level Transmitters operates on Time Domain Reflectometry principle. A wave is emitted by the antenna. As soon as the pulses reach the surface of the medium, it is reflected back to the electronic module. Level / distance is directly proportional to the flight time of the pulse. The measured Level data is converted into 4-20 mA DC analog, isolated output (4 wire models). Optionally information about level measurement is sent via RS232 or RS 485 to a PC for processing such as diagnostics, programmable set-up and data logging.


  • Minimizes signal loss
  • Eliminates false echoes
  • No moving parts
  • High accuracy
  • Solid, Flexible & co-axial probes
  • Non-contact type Level Transmitters