How to Select a Suitable Submersible Level Transmitter

2. Medium Temperature

• Normal temperature: Standard model 0～60°C (for most water pools and water tanks)
• Deep well or hot liquid: Special sealed model for -50～300°C

3, Medium Density

Step 2: Measuring Range 

1. Measuring range = maximum actual liquid level height 
2. Two Taboos:
   • Too small range: Sudden water level rise exceeding upper limit will directly rupture the diaphragm and scrap the sensor
   • Excessively large range: The signal variation corresponding to the same liquid level change shrinks, failing to detect tiny level fluctuations
3. Cable Length: Cable length must be ≥ pool depth plus 1~2m wiring allowance; armored tensile cable is optional for deep wells and river channels to resist abrasion and pulling.

Step 3: Accuracy & Sensing Core 

1. Accuracy Class (%FS Full Scale Error)

• ±0.5%FS: Standard industrial control (sewage stations, circulating water, chemical storage tanks, mainstream model on market)
• ±0.2%~0.1%FS: High-precision batching, metering, environmental online monitoring (water plants, precision chemical industry)

2. Comparison of Two Mainstream Sensing Cores

1. Diffused Silicon Core: Fast response, high sensitivity, economical price; suitable for clean water and mild sewage with stable temperature compensation
2. Ceramic Capacitive Core: Wear-resistant, corrosion-resistant, strong overload resistance; suitable for strong corrosive liquid acid and alkali

Step 4: Output Signal Matching Existing Control System

1. 4~20mA Two-wire System (First Universal Choice)
    

   Compatible with PLC and acquisition modules, long transmission distance, strong anti-interference performance, most widely used in industrial water pools and sewage stations; 

2. 0~5V/0~10V Three-wire System
    

   Only for short-distance short cables, susceptible to interference over long distances, only adopted for small simple control cabinets

3. RS485 Modbus RTU Digital Signal
    

   Suitable for multi-sensor networking, remote IoT and centralized upper computer monitoring; can read liquid level, temperature and fault codes, preferred for smart water services, greenhouses and reservoirs

4. Wireless WiFi LORA/4G: For wire-free deep wells, field river channels and remote reservoirs without cable laying

Step 5: Environmental Protection, Explosion-proof and Temperature Adaptation

1. Protection Rating
    

   Probe must reach IP68 (long-term full underwater immersion); external junction box above IP65/IP67 for outdoor rain and dust resistance

2. Outdoor & Field Application
    

   Select UV-resistant polyurethane cable sheath; install lightning protection modules for open-air exposure and lightning-prone areas

3. Explosion-prone Working Conditions (Petroleum, Chemical Industry, Biogas, Hazardous Chemical Storage Tanks)
    

   Must select intrinsically safe ExiaⅡCT6 certified submersible level transmitters matched with safety barriers; ordinary models are strictly prohibited

4. Ambient Operating Temperature
    

   Standard model operates at 0~60°C; low-temperature compensated model is recommended for outdoor use in northern winters to avoid temperature drift

Step 6: Installation Structure & Cable Selection

1. Probe Structure

• Standard straight rod submersible type: Directly put into water tanks and open tanks
• Split 2088 junction box: Convenient on-site wiring, optional digital display head
• Extended probe rod / sleeve type: For deep wells and deep sewage pools to prevent cable winding around mixing equipment

2. Cable Types

• PVC/PE Cable: Indoor clean water, non-corrosive environment
• PU Polyurethane Cable: Outdoor, anti-aging, mild oil resistance
• Stainless Steel Armored Cable: Diesel oil, sanitary liquid, environments with sharp debris, anti-rat bite and anti-pulling

3. Vented vs Sealed Type

• Open water tanks/ponds: Vented cable (automatically compensates atmospheric pressure for optimal measurement accuracy)
• Sealed pressure-bearing tanks: Sealed non-vented model with built-in pressure compensation

Step 7: Quick Selection Checklist for Pre-purchase Verification

1. Medium: Clean water / sewage /oil / acid /alkali / mud? Medium temperature and density?
2. Maximum liquid level height? Confirm measuring range and cable length
3. Does on-site PLC/acquisition instrument support 4-20mA or RS485?
4. Accuracy requirement: General monitoring 0.5%FS/ High precision 0.25%, 0.1%?
5. Outdoor deployment, low winter temperature, flammable & explosive environment (explosion-proof required)?
6. Anti-clogging structure needed for sediment or crystallization in medium?
7. Installation scenario: Water tank, oil tank, deep well, sealed tank, river channel? Armored cable or stilling well required?

Recommended Schemes for Common Scenarios

1. Tap Water Tank: Accuracy:0.5%, 0~3m range, 4~20mA,  SS304 probe, 5m PU cable
2. Sewage Treatment: 316L with anti-clog filter, 0~10m, RS485, 11m PU cable
3. Chemical Acid & Alkali Storage Tank: PTFE anti-corrosion probe, vented type, Exia explosion-proof, 4~20mA
4. Field River & Reservoir: IP68, armored cable, LORA wireless output, wide temperature low-temperature compensation
5. Sea water: ceramic core, titanium probe, PTFE cable