YST918S Submersible Hydrostatic Level Transmitter by Dalian YST
| Brand | Dalian YST |
|---|---|
| Origin | Liaoning, China |
| Manufacturer Type | Authorized Distributor |
| Product Category | Domestic |
| Model | YST918S (Standard Version) |
| Price | USD 132 (approx. ¥950) |
| Power Supply | 12–36 V DC |
| Accuracy | ±0.5% FS |
| Range | 0–10 m H₂O (customizable) |
| Medium Temperature | −10 to +70 °C |
| Compensation Temperature Range | −10 to +70 °C |
| Response Time | ≤100 ms (to 90% FS) |
| Enclosure Rating | IP68 |
| Output Interface | RS485 (Modbus RTU) & 4–20 mA analog |
| Wetted Materials | 316L stainless steel |
| Sensing Principle | Diffused-silicon piezoresistive hydrostatic pressure measurement with integrated temperature compensation and linearity correction |
Overview
The YST918S Submersible Hydrostatic Level Transmitter is an industrial-grade, fixed-mount level measurement instrument engineered for continuous, high-reliability monitoring of liquid levels in open or pressurized tanks, reservoirs, and water storage systems. It operates on the fundamental principle of hydrostatic pressure measurement: the pressure exerted by a column of liquid at a given depth is directly proportional to its height (P = ρ·g·h), where ρ is the fluid density, g is gravitational acceleration, and h is the liquid height. The transmitter employs a diffusion-bonded silicon piezoresistive pressure sensor housed within a fully welded 316L stainless steel diaphragm assembly. This core sensing element is thermally compensated across the full operating temperature range (−10 °C to +70 °C) and digitally linearized to ensure stable output under varying thermal and hydraulic conditions. Designed for permanent submersion, the unit meets IP68 ingress protection—fully dust-tight and rated for continuous immersion up to 10 meters—and delivers a dual-output signal: a standard 4–20 mA analog current loop compatible with legacy PLCs and SCADA I/O modules, and a digital RS485 interface compliant with Modbus RTU protocol for integration into modern distributed control systems.
Key Features
- Robust wetted construction using 316L stainless steel—resistant to corrosion from potable water, treated wastewater, glycol solutions, and mildly aggressive industrial fluids.
- Integrated temperature compensation and factory-applied nonlinearity correction—minimizes zero drift and span error across ambient and process temperature fluctuations.
- Hermetically sealed, laser-welded sensor housing—eliminates moisture ingress, condensation effects, and long-term calibration drift associated with gel-filled or vented designs.
- Dual-signal output architecture—enables simultaneous analog interfacing (4–20 mA, 2-wire) and digital communication (RS485, Modbus RTU) without external signal converters.
- Fast dynamic response (<100 ms to 90% FS)—suitable for applications requiring real-time level tracking during rapid fill/drain cycles or pump control feedback loops.
- Wide supply voltage range (12–36 V DC)—compatible with both 24 V industrial power rails and battery-backed remote telemetry installations.
Sample Compatibility & Compliance
The YST918S is validated for use with non-viscous, non-clogging liquids of known and relatively stable density—including municipal drinking water, cooling tower make-up water, fire suppression reservoirs, chemical dilution tanks, and HVAC expansion vessels. It is not intended for use with slurries, highly viscous oils, or media containing suspended solids >50 µm that may obstruct the pressure port. While not certified to ATEX, IECEx, or SIL standards, its design adheres to general-purpose industrial safety practices per IEC 61000-6-2 (EMC immunity) and IEC 61000-6-4 (EMC emissions). For regulated environments, the 4–20 mA output supports basic traceability when logged via third-party DCS/SCADA systems compliant with 21 CFR Part 11 audit trail requirements; however, the device itself does not implement electronic signature or user access control features.
Software & Data Management
The YST918S operates as a field-level sensor node without embedded firmware configuration tools. Parameter setup—including zero/span adjustment, damping factor, and Modbus slave ID—is performed externally using standard Modbus configuration utilities (e.g., QModMaster, Simply Modbus) or OEM-supplied commissioning software. All configuration changes are retained in non-volatile memory. Raw output data (pressure in mbar or level in meters, depending on scaling) is transmitted continuously over RS485 or as a proportional analog current. No onboard data logging, edge computing, or cloud connectivity is provided. Integration into centralized platforms (e.g., Ignition SCADA, Siemens Desigo CC, or custom Python-based IIoT dashboards) requires standard Modbus TCP gateways or analog input modules with 16-bit ADC resolution for optimal signal fidelity.
Applications
- Municipal water utilities: Real-time level monitoring of clearwells, elevated tanks, and ground storage reservoirs for automated pump staging and alarm generation (low/high level, dry-run prevention).
- Industrial process cooling: Continuous level verification in closed-loop recirculating cooling water sumps—critical for maintaining heat exchanger efficiency and preventing pump cavitation.
- Wastewater treatment plants: Monitoring of equalization basins, chlorine contact chambers, and sludge holding tanks where chemical exposure and intermittent submersion demand corrosion-resistant materials.
- Building management systems (BMS): Integration into HVAC central plants for chilled water expansion tank level control and boiler feedwater reservoir supervision.
- Remote infrastructure: Off-grid solar-powered telemetry stations utilizing low-power 4–20 mA output for GPRS/LoRaWAN gateway interfacing.
FAQ
Is the YST918S suitable for pressurized vessels?
Yes—it measures absolute hydrostatic pressure and can be used in sealed tanks when referenced to atmospheric pressure via a vented cable or compensated using a second gauge-pressure reference sensor.
Can the measurement range be extended beyond 10 m?
Yes—custom ranges up to 100 m H₂O are available upon request; recalibration and mechanical reinforcement of the pressure housing are required for higher ranges.
Does the device support HART protocol?
No—the YST918S provides only 4–20 mA (analog) and Modbus RTU over RS485; HART functionality is not implemented.
What is the expected service life under continuous submersion?
With proper installation and avoidance of mechanical impact or abrasive sediment accumulation, the sensor demonstrates ≥5 years of stable operation in clean water applications per field deployment data from municipal clients.
Is third-party calibration documentation available?
Factory calibration certificates (as-found/as-left) are provided with each unit; ISO/IEC 17025-accredited calibration services are available through authorized regional partners upon request.
