Tank Level Switch vs Level Transmitter: Float, Fork, Conductive, Ultrasonic and Radar Specs Compared (Q&A)
Short answer: use a level switch when you only need to know “is the liquid above or below this point?” (start/stop a pump, high or low alarm). Use a level transmitter when you need the actual level as a number (4-20 mA or RS485) for a PLC, a display or remote monitoring. Below, every value comes from the product listing in our catalog; if a value is not listed, we do not state it.
Level switch or level transmitter: which one do I need?
- Switch (point level): one on/off contact at one height. Good for pump control, overflow and dry-run protection. Examples below: float switch, tuning-fork switch, conductive level relay.
- Transmitter (continuous level): an analog or digital value over the whole range. Good for inventory, trend charts and alarms at any setpoint. Examples below: submersible hydrostatic, ultrasonic and 80 GHz radar.
Specs at a glance: level switches
| Product | Principle | Output | Supply | Key listed specs | Price |
|---|---|---|---|---|---|
| 304 SS float level switch | Float (contact changes when the float passes the switch point) | Contact (rating not listed) | Not listed | 304 stainless steel; stem lengths 45, 75, 100, 150, 200, 300, 400 mm | $5.99–$10.99 |
| CG568 tuning-fork level switch | Vibrating fork | DPDT relay, AC 220 V 3 A / DC 30 V 3 A | 24 VDC, <1 W | G1 thread; 316 SS fork; <1 MPa; fork -30 to 150 °C; min. density 0.6 g/cm³; delay 1–20 s; IP66 (supplier listing) | $180.99 |
| VENGIM conductive level relay | Conductive (electrode probes, not included) | SPDT 5 A 240 VAC / 24 VDC resistive | 220 VAC (VG6112) or 24–240 VAC/DC (VG6012) | DIN rail; VG6012: 5–100 kΩ sensitivity, 0.5–10 s delay, pump up/down | $15.99–$19.99 |
| GEYA GRL8 level control relay | Conductive | SPDT, 10 A | AC/DC 24–240 V or 240 V | Adjustable delay 0.5–10 s | $36.85–$57.44 |
| ManHua SSRC-04 level controller | Conductive | 1 C/O, 8 A, 2000 VA | 220/230 VAC, 50/60 Hz | Sensitivity adjustable 5–50 kΩ; DIN rail or surface; IP20 | $40.31 |
Specs at a glance: level transmitters
| Product | Principle | Output | Supply | Ranges offered | Price |
|---|---|---|---|---|---|
| TL-136 submersible level transmitter | Hydrostatic pressure (probe sits at the bottom) | 4-20 mA | 24 VDC | 0-1, 0-2, 0-3, 0-4, 0-5 m | $78.99–$96.99 |
| Ultrasonic tank level transmitter | Ultrasonic, non-contact | 4-20 mA or RS485 | 24 VDC | 0-5, 0-10, 0-15, 0-20 m | $202.99–$239.99 |
| 80 GHz radar level transmitter | 80 GHz radar, non-contact | 4-20 mA with HART, plus RS485 | See listing | 0-5 up to 0-65 m; G1.5 thread | $451.99–$529.99 |
Questions and answers
Which switch works with oil, diesel or other non-conductive liquids?
Not the conductive relays: they need a liquid that conducts between the electrodes (their sensitivity is set in kΩ). For non-conductive liquids use a float switch or the CG568 tuning fork, which lists a minimum liquid density of 0.6 g/cm³. Check density and viscosity against the listing before you order.
How does a conductive level relay control a pump?
Two or three electrode probes hang in the tank. When the liquid touches the high probe the relay changes state; when it drops below the low probe it changes back. The VENGIM VG6012 lists a pump-up / pump-down selector, 5–100 kΩ sensitivity and a 0.5–10 s delay. Probes are not included with the VENGIM relay.
Can I wire a level switch to a PLC input?
Yes, through its dry contact. The CG568 has a DPDT relay (DC 30 V 3 A), so one pole can go to a 24 VDC PLC input and the other to a pump contactor or alarm. The float switch rating is not listed, so use it on a low-current PLC input or through an interposing relay.
Submersible, ultrasonic or radar: which transmitter?
Submersible (TL-136) is the lowest cost and reads level as pressure from the bottom of the tank, so it touches the liquid. Ultrasonic and 80 GHz radar mount on top and never touch the liquid. The radar listing covers ranges up to 65 m and adds HART; the ultrasonic covers 0-5 to 0-20 m with 4-20 mA or RS485.
Can these be used in a hazardous (classified) area?
None of these listings states a hazardous-area approval. Do not install them in a classified area unless you have the documentation that your site requires.
Can I watch the tank level on my phone? (free)
Yes, with a transmitter. The 4-20 mA or RS485 output of the TL-136, the ultrasonic or the radar can go through a Modbus I/O module or gateway to AutomationBotX Cloud: live level, trend chart and alarm rules in the app, plus a notice when the device stops reporting. It is read-only monitoring (it never sends commands) and it is not an overfill-protection or safety system. The first 10 machines are free, no card needed. How the signal gets from the tank to your phone.
Need several units?
Ask for a written volume quote on our wholesale page.
Free US shipping on every order. Specs above come from the product listings; if a value you need is not listed, it is not stated by the supplier. Prices checked on November 9, 2026 and may change; the product page shows the current price.