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FT8620 series Smart Turning Fork level switch

publish time:2017-12-23 11:25:03



The FT8620 serial smart tuning fork level switch is a general-purpose ultrasonic fork point control. It is consist of a electronic unit and a furcated sensing element, used for level limitation or alarm. Sensing element  material are 304SS or 316SS stainless steel without or with PTFE cover for slight/mid-level corrosion.


》》》》Operation Principle

 Smart tuning fork switch stimulates the fork sensor through electrical circuit, make it vibrating and then send the signal back to the circuit, bring out resonance.  When there is some material touch the mechanical transducer part, the vibration frequency and amplitude will change till the sensor suffering over-boundary drag, the whole electro-mechanical loop will stop vibration. While the electrical part will send a output signal indicate there is material on the sensor. After the material leaves the sensor, the vibration of the electro-mechanical loop will come back to work automatically, until the amplitude and frequency above the limitation value, the circuit will send another signal indicate there is no material on the sensor.  




Ø  Patent Universal power supply21~35VDC & 30~265VAC automatic adoption

Ø  Wide applications: suitable for most kinds of liquidgranular or powder etc field applications

Ø  Reliable measurement: intelligent judgment, regardless of conductivity/dielectric constant change, measurement only related to material position in the vessel

Ø  High sensitivity:  Minimum density0.01g/cm 3, could be used for most industry materials

Ø  Quick electrical connectiondouble electrical connections make the wiring more safe and convenient

Ø  Convenient utilityNo calibration needed, instrument will work properly just after power on

Ø  Sensing element ground connection: sensing element could be connected to ground directly, by this way it will avoid material property change which may cause by the EMI or the reaction between the conductive part of instrument and the vessel/material  

Ø  SmartData process software increase the resolution incredibly, instrument has built-in self-diagnosis.

Ø  Filed re-calibrationRe-calibration function help customer to set the instrument in the field again.



》》》》Typical Applications

Ø  Liquidconductive and insulating liquid(include liquefied gas) 

Ø  Slurryconductive and insulating slurry

Ø  Granularfoodplastic chipscoal etc  

Ø  Interfaceliquid interface between two different dielectric constants

Ø  Powderplastic powdercement or fly ash etc.






》》》》 Specifications

Ø  Measuring rate of facility: CAT II, transient over voltage 2500V, only use the equipment for measurements within measurement category I and II

Ø  OutputDPDT reply (double pole double throw); LED indication

Ø  Contact Rating250VAC1A inductive3A non-inductive 

Ø  Power SupplyUniversal power supply, 30~265VAC,50/60Hz or 21~35VDC automatic adoption

Ø  Dissipation power:  2W

Ø  Resolution:    1Hz

Ø  Set point Accuracy:  ±2mm(under standard condition)

Ø  Fail safeHigh (HLFS) or low (LLFS) field adjustable

Ø  LED IndicationsRed- level alarm Green-system normal

Ø  Auto-vibration2~3 seconds

Ø  Response time<1second

Ø  Time delay0~60seconds (adjustable)

Ø  Maximum process material viscosity: 10000mm 2 /S

Ø  Minimum process material density: solid: 0.01g/cm 3 ; liquid: 0.5g/cm 3

Ø  Ambient Temp.T5:-40­+70(-40158)T6:-40­+60(-40140)

(Effect of the process temperature on the environment temperature should not exceed the environment

temperature requirements of the instrument.)

Ø  Max. process pressure: 4.0MPa(580psi) (for details please see probe specifications)

Ø  Max. process temperature: -40200(-40392) (for details please see probe specifications)

Ø  Spark protection (for electronic unit ) anti-static 4KV/8KV

Ø  Radio protection(Built-in filter) Meet IEC 61326:1998+Al standard EMC requirements   

Ø  Probe length58~5000mm(2.28”~196.8”)( for details please see probe specifications)

Ø  Electrical connectiondouble M20×1.5 (3/4” NPT optional ) 

Ø  Process connectionSolid: 1 1/2”NPT Thread(standard, BSPT optional) , Flanges (optional)  

                      Liquid: 3/4” or 1” NPT Thread(standard, BSPT optional) , Flanges (optional)

Ø  Housing Material:  Die casting aluminum epoxy coating

Ø  Ingress protectionIP67 

Ø  Explosion-proof ratingEx d IIC T5/T6 Gb


Ø  ApprovalPCEC/NEPSI, for other approval please consult factory

》》》》FT8620 Installation Requirements

l For installationapplication & maintenance of the product should comply with relative requirements in the instruction manualGB50257-96Construction & Verification Standard of Electrical apparatus mounting in explosion or flaming dangerous area GB3836.15-2000Part 15: Electrical installations in dangerous location(except coal mine)& GB3836.13 -1997Part 13: The examination of Electrical equipments in the explosion gas field.

l The mounting location of the instrument should free of vibration, high temperature, corrosive atmospheres, or any possibility of mechanical damage for maximum service life. If this is not possible, consider a remote system installation. Ambient temperature should be between -40 ~70oC (-40 ~158oF ).

l Instruments installed outdoors in areas of lightning strikes should be installed with lightning protection.

l DO NOT ADOPT MONO-COMPOSITION ENCAPSULAION SEALING inside of instrument housing since most of that kind of encapsulation will contain acetic acid. (Acetic acid could decay the electrical component.) Please consider to use SPECIAL DOUBLE-COMPOSITION ENCAPSULATION (non-erosive).

l The instrument has ground terminal on its housing. Please connect the terminals to the field ground properly during installation. For non-metallic vessel/tank installation, the filed should provide a standard ground. CONNECT TO DYNAMIC GROUND IS FORBIDDEN!

l Cable inlet should meet GB4208 standard requirements reach IP65 code to ensure reliable electrical connections. It will avoid water or other corrosive gas destroys the electronic unit. 

l Do not install the sensing element directly under a flow stream or feed line. If this is the only position available, use a baffle or shield above the probe to keep it out of the flow stream.

l Only the mounting screw or flange part of the sensing element need be well connected to the vessel, reliable sealed and electrical connected properly. Any other parts of the sensing element should not touch the vessel to ensure the fork works properly.

l The turning fork could be vertical or horizontal mounting in the field. For horizontal mounting, sensing element should be pointed downward to the vessel, angle around 10~20o. Also make sure that the two vibration forks are in vertical direction. For easy remark, please refer to the mark point on the six surfaces of the sensing element. Make the mark point upwards or downwards during the installation.

l Consider the mounting area of the sensing element while install it in the vessel. Keep the probe at least 100mm away from the vessel wall.

l For explosion-proof instrument installation, cable inlet should come with approved cable accessory such as XP fittings or XP steel conduit sealing according to GB3836.1 & GB3836.2 explosion-proof standard requirements.

l Power wire should meet IEC60245/60227 standard requirements Recommended as 3 terminal armature cable, cable O.D. should less than 12mm, conductor material of the cable is copper, section area should between 0.13 –2.1 mm2(AWG14-26), insulating capability 1500V. And associated switch should meet IEC60947 requirements. Do not make the unshielded cable parallel with power supply cable for long distance.


l Strict follow “STOP OEPN THE LID WHILE POWER ON” during field operation or maintain, recommended operate 10 minutes after power off.



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