measuring principle

Radar, originally used in the military field, emits electromagnetic waves and receives reflected waves to measure the distance and orientation of targets.

The radar level gauge antenna emits extremely narrow microwave pulses, which propagate at the speed of light in space. When they encounter the surface of the measured medium, some of their energy is reflected back and received by the same antenna. The time interval between transmitting and receiving pulses is proportional to the distance from the antenna to the surface of the measured medium. Due to the extremely high propagation speed of electromagnetic waves, it is difficult to confirm the time interval between the emitted pulse and the received pulse, which is very small (in the nanosecond range). The FT8161 series radar level gauge adopts a special correlation demodulation technology, which can accurately identify the time interval between the transmitted pulse and the received pulse, and further calculate the distance from the antenna to the surface of the measured medium.

　　characteristic

The radar level gauge adopts a transmission frequency of up to 26GHz, thus possessing:

Shorter wavelength, more suitable for level measurement of small particulate matter

Small beam angle, concentrated energy, stronger anti-interference ability, greatly improving measurement accuracy and reliability

The antenna size is small, making it easy to install and install antenna protection devices such as dust covers

The measurement blind spot is smaller, and it can also achieve good results for measuring small cans

Equipped with advanced microprocessors and unique Echo Discovery echo processing technology, it can be applied to various complex working conditions

Adopting pulse working mode, with extremely low transmission power, it can be installed in various metal and non-metal containers, and has no harm to human body and environment

Typical applications

Liquid, lightweight slurry, particle, interface, powder

Water, acid, dilute alkali, oil level, grain, raw coal, coal powder, cement, lime powder, flour

　　performance index

Measurement equipment level: CAT I level, transient rated voltage 1500V, cannot be used for levels other than CAT I level

Output: 4-20mA HART protocol, software adjustable current output direction

Measurement method: can be set as level/distance measurement method by software

Microwave frequency: 26G

Power supply: 15-35VDC (standard type) 21.6-26.4VDC (intrinsic safety type)

Power: less than 0.5W

Accuracy: FT8161:3mm FT8162:15mm

Resolution: 1mm

Temperature effect: 2.5mm/10 ℃ (18 ℉)

Load resistance: Output circuit load resistance capacity of 450 Ω at 24VDC

Environmental temperature: T5: -40 to+70 ℃ (-40 to 158 ℉); T6: -40 to+60 ℃ (-40 to 140 ℉) (The influence of medium temperature on ambient temperature cannot exceed the instrument's requirements for ambient temperature)

Response time:<2 seconds

Delay: 0-40 seconds (software adjustable)

Range: FT8161:0-30m; FT8162:0～70m

Blind spot: antenna end

Electrical interface: M20 × 1.5 (optional 3/4 "NPT)

Process connection: 1 1/2 "NPT thread installation (standard, BSPT optional), flange installation (optional)

Shell material: die cast aluminum with epoxy coating

Shell protection: Compliant with IP67 protection standard

Explosion proof grade: Ex ia IIC T5/T6 Ga

Certification: PCEC/NEMSI. For other certifications, please consult the manufacturer

Probe indicators

FT816X wiring diagram

The FT816X series liquid level gauge is an intrinsic safety instrument. When installed in hazardous environments, a certified safety barrier needs to be added to its power supply circuit. Both single and double barriers are acceptable, but the connection method is different. The following diagram shows the system wiring diagram, with examples of single and double barrier installation. Please consult our company or our agent for certified safety barrier products. Please refer to the instructions for the use of safety barriers for grounding requirements. The maximum impedance of cables, loads, and safety barriers under 24VDC power supply is 450 Ω. The liquid level gauge is powered by a certified safety barrier. Please refer to the instructions for using the safety barrier for grounding requirements. The requirements for safety barriers in this level gauge are:

Uo=28VDC

Io=93mA

Po=0.65W

Co=0.083uF

Lo=4.2mH

Safety parameters of this instrument:

Ui=30V

Ii=100mA

Pi=0.75W

Ci=6nF

Li=240uH

System wiring diagram

Overall wiring diagram of the sensor

Power wiring diagram

FT6002 modulation and demodulation wiring diagram

According to the communication requirements of the HART protocol, in the current loop of the instrument output signal, it should be ensured that the load on the power supply side of the instrument is greater than 250 ohms. If necessary, a 250 ohm resistor should be directly added to the power supply side.

Installation requirements for FT816X

The installation, use, and maintenance of the product should comply with the relevant provisions of the product installation, commissioning, and use instructions, GB50257 "Code for Construction and Acceptance of Electrical Equipment in Explosive and Fire Hazardous Environments", GB3836.15 "Electrical Equipment for Explosive Gas Environments Part 15: Electrical Installation in Hazardous Areas (excluding Coal Mines)", and GB3836.13 "Electrical Equipment for Explosive Gas Environments Part 13: Maintenance of Electrical Equipment for Explosive Gas Environments".

When installing instruments, they should be kept as far away as possible from vibration sources, high temperature environments, corrosive air, and any places that may cause mechanical damage. If the requirements cannot be met, please replace the instrument with a new component. The ambient temperature should be between -40 and 70 ℃ (-40 and 158 ℉).

The instrument installation area requires lightning protection devices to prevent lightning strikes.

It is prohibited to use single component ambient temperature sulfurized sealant inside the instrument casing. This substance often contains acetic acid, which will corrode electronic components. Special two-component sealant (non corrosive) should be used.

The instrument casing is equipped with grounding terminals, and users should ensure reliable grounding during installation and use. When used for non-metallic cans, a standard ground should be provided on site and cannot be connected to the power ground.

The electrical interface should be equipped with cable sealing joints with a protection level of IP65 or above that meet the requirements of GB4208 standard, to ensure reliable sealing and prevent damage to the instrument electronic unit caused by water ingress or other corrosive gases.

Do not disassemble the sensor or loosen the sealing nut to avoid probe leakage.

The installation of sensors should avoid material flow or inlet/outlet ports. If there are no other installation locations, protective covers or partitions should be installed. Microwave beams should not intersect with the feeding material flow.

The installation of threads or flanges should be firmly connected to the container, reliably sealed, and have good electrical contact. Except for the connection, other parts of the sensor should not come into contact with the container to ensure good insulation.

When an antenna emits microwave pulses, there is a certain emission angle. There shall be no obstacles in the area radiated by the emitted microwave beam from the lower edge of the antenna to the surface of the measured medium. Therefore, during installation, it is advisable to avoid facilities inside the tank as much as possible, such as ladders, limit switches, heating equipment, brackets, etc. If necessary, 'false echo learning' must be performed.

The highest material level shall not enter the measurement blind zone.

The instrument must be kept at a certain distance from the tank wall, and the installation of the instrument should be as perpendicular as possible to the transmission direction of the antenna and the surface of the measured medium.

Instruments installed according to explosion-proof standards must be equipped with explosion-proof stuffing boxes or explosion-proof steel pipe sealing joints certified by GB3836.1 and GB3836.2 explosion-proof standards for electrical interfaces.

The instrument circuit installed according to intrinsic safety standards must be equipped with safety barriers certified by GB3836.1 and GB3836.4 explosion-proof standards.

The ripple of 24VDC power supply shall not exceed 100mV.

The instrument connection cable shall comply with the requirements of IEC60245/60227 standard. It is recommended to use armored shielded 3-core cables with an outer diameter of no more than 12mm. The cable conductor material is copper, and the cross-sectional area of the conductor is 0.13-2.1mm2 (AWG14-26). The insulation strength of the cable is 1500V. Long distance unshielded cables cannot be used in parallel with AC power cables.

When using and maintaining on site, the principle of "no opening with power on" must be followed, and it is recommended to shut off the power for 10 minutes before operation.

FT816X Typical Installation

1: Blind spot, once the target enters the blind spot, the instrument will not work properly;

2: Upper range (URV);

3: Lower Range Vehicle (LRV); Attention: The upper and lower ranges are set according to the distance method;

4: Maximum measurement range.

The reference surface for measurement is the sealing surface of the thread or flange. It is important to maintain a distance of at least 200mm between the instrument and the container wall. When using a radar level gauge, it is necessary to ensure that the highest level does not enter the measurement blind zone (as shown in the area above).

For conical containers with flat tank tops, the optimal installation position for instruments is in the center of the top of the container, which ensures measurement to the bottom of the container.

Installation with universal joint

Moisture proof

For instruments installed outdoors or in damp indoor environments, as well as on cooling or heating tanks, in order to prevent moisture, the cable sealing sleeve should be tightened, and the cable should be bent downwards at the inlet.

Container takeover

The length of the container connector must ensure that the probe extends at least 10mm beyond the connector

Common Installation Location Diagram

1. Correct; 2. Error: Installing the instrument on an arched or circular tank top can cause multiple reflections and echoes, which should be avoided as much as possible during installation.

1. Correct; 2. Error: Do not install the instrument above the feed stream to ensure that the measurement is on the surface of the medium rather than the feed stream.

Special Installation Diagram

Installation of reflector plate

When there are obstacles in the tank that affect the measurement, a reflector can be installed to reflect the reflected waves of the obstacles elsewhere. If necessary, "false echo learning" can be performed.

Mixing and waveguide installation

When there is agitation in the tank, the instrument should be kept as far away from the agitator as possible if necessary. After installation, "false echo learning" should be carried out in the stirring state to eliminate the influence of false echoes generated by the stirring blades. If foam is generated or waves are turned up due to mixing, wave guide tube installation shall be used.

The use of waveguide tube installation (waveguide tube or bypass tube) can avoid the influence of obstacles in the container and foam on the measurement.

Note: The diameter of the pressure equalization hole is (5-10) mm.

1. Due to feeding, stirring or other processes in the container, foam will be formed on the surface of some liquid media to attenuate the signal. If the foam causes measurement error, you should install the sensor in the guided wave tube or use the guided wave radar level meter.

If the FS0 X or FS1X series is installed inside a waveguide for measurement, the minimum diameter of the waveguide is 50 mm.

3. When connecting the waveguide, prevent large cracks and welds. Additionally, if necessary, perform 'false echo learning'.

4. Attention: When measuring adhesive media, do not use waveguide installation.