The quality of radar level transmitter installation directly determines its measurement accuracy and operational stability. Especially in complex operating conditions such as those found in the chemical, petroleum, and metallurgical industries, scientific and standardized installation is a prerequisite for the equipment to perform optimally. The following sections detail key considerations from four perspectives: pre-installation preparation, core installation points, handling of special operating conditions, and post-installation calibration.
I. Pre-Installation Preparation Considerations
Verification of Compatibility with Operating Conditions: Prior to installation, it is essential to reconfirm that the radar level transmitter model matches the actual operating conditions. Key verification points include the dielectric constant of the medium (e.g., for light oil, a focused antenna type must be selected; when the dielectric constant is ≤1.8, a waveguide must be used), temperature range (for high-temperature media, verify the compatibility of cooling components), pressure rating (for high-pressure vessels, verify the flange pressure-resistant parameters), and explosion-proof rating (for flammable and explosive environments, ensure compliance with Ex d IIB T4 or higher), to prevent operational failures caused by model mismatches after installation.
Site Survey: Conduct a preliminary survey of the installation area on the vessel top to identify the locations of obstacles such as feed ports, agitators, and supports, and mark installation points where the radar beam is unobstructed. Simultaneously verify the spatial dimensions of the installation area to ensure sufficient working space for flange connections or threaded fastening. If working at heights, a safety platform must be erected in advance.
Preparation of Tools and Accessories: Prepare appropriate tools based on the installation method. For flange connections, prepare a torque wrench (adjust according to the torque values specified in the equipment manual) and gaskets (PTFE or graphite material, suitable for the corrosiveness of the medium). For threaded connections, prepare pipe wrenches and Teflon tape (for non-corrosive conditions only). Also prepare auxiliary accessories such as grounding cables (copper core, cross-sectional area ≥ 2.5 mm²) and explosion-proof junction boxes (for flammable and explosive environments).
II. Key Installation and Operation Precautions
1. Installation Location and Beam Path Control
Prioritize installation directly above the vertical axis of the vessel to ensure the antenna beam points vertically toward the medium surface, as this minimizes measurement error. If centered installation is not possible, the deviation from the center must not exceed one-third of the vessel’s diameter, and the distance between the beam edge and the vessel wall must be no less than 200 mm or three times the antenna diameter (whichever is greater).
Installation directly below the inlet or outlet is strictly prohibited to prevent level fluctuations caused by material impact or beam obstruction by splashing material; the horizontal distance from the agitator must be greater than 10% of the measurement range. If the agitator speed is high (＞150 r/min), an anti-interference baffle must be installed between the beam path and the agitator.
If the vessel has a conical or domed roof, the installation point must be located 100–200 mm below the highest point of the roof to ensure the beam covers the entire liquid level range and to prevent abnormal beam reflection caused by the roof’s curvature.
2. Installation Angle and Connection Sealing Requirements
For standard operating conditions (no foam, low-viscosity media), install vertically, with the antenna’s perpendicularity to the media surface not exceeding ±1°; If the medium is prone to forming dense foam (e.g., black liquor in papermaking) or is highly viscous (e.g., asphalt), the sensor may be installed at a 10°–15° angle to utilize surface reflection and improve signal reception efficiency. However, after tilting, ensure that the reflected wave can return stably to the antenna without signal loss.
For flange connections, clean the flange sealing surfaces thoroughly, place the gasket, and tighten the bolts evenly using a “diagonal alternating” sequence to ensure the flanges are tightly sealed and there is no risk of medium leakage. In high-pressure applications, use a torque wrench to tighten the bolts to the torque specified in the manual to avoid damaging the flange due to over-tightening or causing seal failure due to under-tightening.
For threaded connections, apply high-temperature or corrosion-resistant sealant to the threads (select based on the medium’s properties). Avoid excessive force when tightening to prevent thread damage. After installation, check the coaxiality between the sensor and the mounting bracket; the deviation must not exceed 0.5 mm.
3. Explosion-Proof and Grounding Guidelines
In flammable or explosive environments, the installation process must not compromise the sensor’s explosion-proof structure (e.g., removing the explosion-proof housing or damaging the sealing gasket). Wiring must be routed through an explosion-proof junction box, and the cable entry point must be sealed with an explosion-proof cable gland to ensure no flammable gases enter the device.
The equipment must be reliably grounded separately. Use copper-core insulated wire with a cross-sectional area of at least 2.5 mm² for the grounding conductor, and ensure the grounding resistance is ≤4 Ω. The grounding electrode should be located away from the grounding circuits of other equipment and no more than 5 m from the sensor to prevent signal interference.
When wiring, distinguish between power and signal lines to ensure correct polarity connections; reverse connections are strictly prohibited. Cable routing must be kept away from strong sources of electromagnetic interference, such as high-power inverters and motors. Signal cables must use shielded twisted-pair wiring, and the distance from power cables must be no less than 300 mm.
III. Installation Precautions for Special Operating Conditions
High-Temperature/Low-Temperature Conditions: When measuring media with temperatures exceeding 200°C, installation components with cooling jackets must be used. The flow rate of the cooling medium (typically water or compressed air) must meet equipment requirements to ensure the sensor body remains within the normal operating range of -40°C to 80°C. For low-temperature conditions (< -40°C), specialized low-temperature sensors must be selected. During installation, avoid direct contact between the sensor housing and the walls of low-temperature vessels to prevent frost formation from affecting antenna performance.
Highly Corrosive Conditions: The parts of the sensor in contact with the medium must be made of corrosion-resistant materials (such as 316L stainless steel or PTFE). Avoid using ordinary carbon steel fittings during installation, and prioritize PTFE gaskets for flange seals. If the medium is a highly corrosive gas, install a corrosion-resistant protective cover over the sensor antenna; the cover must be made of a wave-transparent material (such as PTFE) and must not interfere with radar wave transmission.
High Dust Concentration Conditions: The installation location must avoid areas where dust accumulates. When installing the antenna facing downward, the tilt angle may be appropriately increased to reduce dust adhesion. An anti-adhesive coating may be applied to the antenna surface, and dust should be regularly cleaned from the surface. If necessary, install a dust cover, ensuring a clearance of at least 50 mm between the dust cover and the antenna to avoid obstructing the beam.
IV. Post-Installation Calibration and Maintenance Precautions
Post-Installation Inspection: After installation, first clean the antenna surface of any residual installation debris such as oil or dust. Check that the sensor is securely mounted and that the wiring is correct. Before powering on, use a multimeter to verify that the power supply voltage is stable and meets the equipment’s input requirements (typically 24 V DC).
Signal Calibration: After powering on, observe the device display panel to confirm there are no fault alarms. Verify measurement accuracy through on-site calibration using the “known level comparison method,” which involves filling the container with a known height of medium and comparing the radar level transmitter’s display value with the actual value. The error must be controlled within ±0.1% FS. If the error exceeds this range, perform calibration using the device buttons or the accompanying software.
Basic Maintenance Plan: Establish maintenance intervals based on the severity of operating conditions. In environments with dust or viscous media, inspect the antenna for cleanliness once a month; in standard operating conditions, inspect it once every three months. Regularly check for loose grounding wires and leaks at sealing points. Conduct a comprehensive accuracy calibration once a year to ensure long-term, stable operation of the equipment.
