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LM600
MDP Hydraulics
The industrial hydraulic ultrasonic liquid level meter is a non-contact, high-precision liquid level monitoring instrument specially designed for hydraulic system oil tanks, storage tanks, and containers. It employs advanced ultrasonic echo ranging technology, measuring the time it takes for ultrasonic waves to be emitted from the probe and reflected back from the liquid surface, to accurately calculate the liquid level height. This product has perfectly addressed the problems such as oil contamination adhesion, mechanical wear, and seal leakage that traditional contact-type liquid level meters encounter in hydraulic oil applications. It provides reliable data support for the stable operation of hydraulic systems, oil management, leakage warning, and preventive maintenance.
The core working principle is based on the Time-of-Flight method for measuring ultrasonic pulse echo time.
1. Emission: The piezoelectric ceramic transducer (probe) inside the instrument, driven by the electronic unit, emits a high-frequency ultrasonic pulse (with a frequency typically ranging from 20 kHz to 200 kHz) towards the liquid surface of the hydraulic oil being measured.
2. Propagation and Reflection: The ultrasonic wave propagates in the air (or nitrogen) above the oil tank. When it encounters the oil surface, due to the significant difference in density between air and oil, the vast majority of the sound wave energy is reflected back.
3. Reception and Calculation: The same transducer receives the reflected echo and converts it into an electrical signal. The high-performance microprocessor built into the instrument precisely measures the round-trip time (t) of the ultrasonic wave from emission to reception.
4. Liquid Level Output: According to the formula Distance (L) = (Sound Speed v × Time t) / 2, the distance (L) from the probe to the liquid surface is calculated. Given the installation height of the probe (TH, which is the distance from the probe to the bottom of the tank), the current liquid level height can be determined: Liquid Level Height (H) = TH - L. The instrument is equipped with a built-in temperature sensor, which can real-time compensate for the influence of environmental temperature on the propagation speed of ultrasonic waves in the air, ensuring measurement accuracy.
• Contactless measurement, maintenance-free: The probe does not come into direct contact with the hydraulic oil, completely avoiding problems such as oil contamination, corrosion, crystallization, which cause probe blockage, damage or inaccurate readings. This significantly reduces maintenance costs and downtime.
• High precision and high reliability: By employing advanced digital signal processing (DSP) technology and intelligent echo processing algorithms, it can effectively identify and filter out interference echoes caused by the internal structure of the oil tank (such as supports, pipes), foam or stirring. The measurement accuracy can reach ±0.2% to ±0.5% FS (full scale), with high repeatability and stable, reliable data.
• Compatibility with media: Suitable for various mineral-based hydraulic oils, water ethylene glycol (HFC), phosphate esters, etc. There are no requirements for the color, transparency or conductivity of the media.
• Environmentally robust: The probe is usually made of materials such as PVDF (polyvinylidene fluoride) or Nylon (polyamide) that are resistant to oil and chemical corrosion. The housing has a protection level of IP67/IP68, capable of withstanding the common oil mist, humidity and dust conditions found in hydraulic stations.
• Wide temperature range: The instrument and probe can operate stably within an environment temperature range of -20℃ to +80℃ (even wider), capable of adapting to various working conditions from cold workshops to hot equipment areas.
• Abundant output and communication interfaces: It offers 4-20mA analog signal, relay switch quantity alarm output, as well as RS485 (Modbus RTU) digital communication interface. These features enable easy integration with PLC, DCS, SCADA or IoT (Internet of Things) platforms, facilitating remote monitoring, data recording, and automatic refueling/alarm linkage.
• Installation is simple and flexible: It offers threaded (such as G1½" and NPT1½") or flange installation methods. Just make a hole on the top of the oil tank for installation, without the need to modify the interior of the tank. The instrument is usually equipped with a backlit LCD display locally, allowing for direct reading of liquid level, percentage, temperature, etc. on-site, and parameter settings can be made through buttons.
Measurement principle: Ultrasonic pulse echo ranging method
Measurement range: 0 - 3m, 0 - 5m, 0 - 10m, 0 - 15m, 0 - 20m (optional)
Measurement accuracy: ±0.3% of FS (typical value), with a maximum of ±0.2% of FS
Resolution: 1mm or 0.1% FS (take the larger value)
Blind zone: 0.25m ~ 0.6m (depending on the range; the liquid level must be above this area during installation)
Operating frequency: 20 kHz ~ 200 kHz (wide range for low frequencies, narrow range with high precision for high frequencies)
Output signal: 4-20mA (two-wire system / four-wire system), RS485 (Modbus), relay contacts (normally open / normally closed)
Power supply: DC 24V (±10%) or AC 220V (optional)
Medium temperature: -20℃ to +80℃ (probe part)
Environmental temperature: -20℃ to +60℃ (for the electronic unit part)
Protection level: Probe: IP68; Instrument housing: IP65/IP67
Probe material: PVDF (resistant to strong corrosion), Nylon/PP (general oil resistance), Stainless steel (threaded part)
Process connection: G1½" thread, flange DN50/80/100 (optional)
To ensure optimal performance, please select the equipment based on the following key factors:
1. Determine the range: Range = probe installation height (TH). Ensure that the highest liquid level is below the blind zone and the lowest liquid level is within the range. It is recommended to leave a 10%-20% margin.
2. Specify the medium and environment:
Medium type: Confirm the type of hydraulic oil (mineral oil, HFC, phosphate ester, etc.). For highly corrosive media, it is essential to choose a probe made of PVDF material.
Environmental temperature: Select products that are suitable for the extreme temperatures of the site.
Explosion-proof requirements: If it is to be used in environments where there is potential for explosive gases (such as certain mines and chemical areas), the model must have the corresponding explosion-proof certification (such as Exd IICT6).
3. Challenges in identifying working conditions:
Foam: If the liquid surface may form foam (such as due to oil return impact), it is necessary to select a model equipped with intelligent echo processing and foam compensation algorithms to penetrate the foam layer and identify the actual liquid surface.
Mixing or turbulence: Intense fluctuations in the liquid surface can affect the stability of the echoes. Therefore, an instrument with functions of dynamic signal averaging and filtering should be selected.
Steam or oil mist: A large amount of steam or thick oil mist will attenuate the ultrasonic signal. Therefore, it is necessary to consider using a probe with higher power (lower frequency) or a product with automatic signal gain adjustment function.
4. Select output and power supply: Based on the requirements of the control system, choose the output signal (4-20mA for analog data acquisition, RS485 for digital communication). Determine whether the on-site power supply is DC24V or AC220V.
• Installation location: The probe should be installed vertically and directly facing the liquid surface. Avoid positions such as the oil inlet and oil return ports where turbulent flow, bubbles or oil mist may occur. Ensure that there are no obstacles (such as beams or heating tubes) along the ultrasonic wave propagation path.
• Safety zone guarantee: During installation, it is essential to ensure that the highest liquid level (including possible surges) is below the measurement blind zone of the instrument; otherwise, measurement will not be possible.
• Wiring and Grounding: Follow the instructions strictly for wiring. Signal cables are recommended to use shielded cables and be routed separately, away from power cables. The instruments should be properly grounded to suppress electromagnetic interference.
• Regular maintenance: Periodically inspect the surface of the probe for any accumulation of dust, oil stains or condensation water, and clean it with a soft cloth to prevent interference with ultrasonic transmission and reception. In extremely dusty or oily environments, it may be advisable to install protective baffles.
• Initialization and Calibration: After installation, two-point calibration should be conducted in both empty and full tank conditions (or at known liquid levels) to input the accurate installation height and range, ensuring measurement accuracy.
Non-Contact Ultrasonic Measurement
Eliminates direct contact with liquids, reducing sensor wear and maintenance while ensuring reliable operation in corrosive or contaminated environments.
Flexible Power & Output Configuration
Supports 12–24V DC power supply with adjustable analog outputs and digital communication, making system integration simple and cost-effective.
Advanced Communication & Data Integration
RS485 Modbus and customizable serial data formats allow seamless connection to PLCs, SCADA systems, and industrial control networks.
Multi-Level Control & Alarm Functions
Equipped with NPN and relay outputs for level control, alarms, and automated material handling, improving operational safety and efficiency.
Explosion-Proof & Industrial-Grade Design
Optional explosion-proof construction ensures safe operation in hazardous areas such as chemical plants and oil storage facilities.
User-Friendly OLED Interface
Clear OLED display with English and Chinese menus enables quick setup, calibration, and parameter adjustment on-site.
Water & Wastewater Treatment: Continuous level monitoring in tanks, reservoirs, and pumping stations
Chemical & Petrochemical Plants: Safe liquid level measurement in corrosive or explosive environments
Oil & Fuel Storage Tanks: Non-contact level control for fuel, oil, and chemical storage
Industrial Automation Systems: Integrated level sensing for smart factories and automated processes
Material Handling & Storage: Level control for silos, containers, and process vessels
Yes. Explosion-proof versions are available, suitable for hazardous industrial applications.
It supports analog outputs (4–20mA / 0–10V), RS485 Modbus, and customizable serial communication formats.
Absolutely. The RS485 Modbus protocol allows easy integration with most PLC and SCADA platforms.
Yes. Users can freely set start and end points, alarm levels, and control outputs based on application requirements.
| Range:5,8,10,12,15,20, 25,30,35, 40m (optional on order) |
| Blind areas: < 0.4-2m (different from the range) |
| Eror. +0.3% f.S. |
| Display: OLED Menu in English and Chinese (with self-illumination) |
| Minimum display resolution: 1mm |
| Keyboardt three light patch keys |
| Working frequency: 20 ~ 350KHz (depending on the type and specification) |
| Power supply mode (optional) : 12-24VDC or 220VA |
| Cardiac output (optional) :4- 20 ma RL> 600 Ω (standard) |
| 1-5V\ 1-10V |
| RS485 (Optional Bluetooth corersion accessory) |
| GPRS |
| 3-channel NPN(configurable as pp pulse output) |
| 2-channel relay (Ac:5A 250V DC:10A 24V) |
| Instrument material: ABs engineering plastics |
| Cardiac dimensions: φ 92 mm *198 mm * M60, 92 mm * 270 mm * Ф DN80 |
| Electrical interface: M20x1.5 (two groups) |
| installation interface: M60X2 or c61MM round hole (with large nut) |
| DN80 non-standard |
| incoming cable: There are teminal teminals at the user's discretione |
| Working environment: room temperature and pressure |
| protection level can be customized) |
| Explosion-proof grade: Exia llB T4 Ga(optional) |
