Table of Contents：

• 1. Overview
• 2. Flow switch
  • 2.1 How it works
  • 2.2 Advantage & Disadvantage
• 3. Ultrasonic Sensor
  • 3.1 How it works?
  • 3.2 Advantage & Disadvantage
• 4. Pressure Sensor
  • 4.1 How it works?
  • 4.2 Advantage & Disadvantage

1. Overview

This URL introduce different methods to detect the water / liquid level.

2. Flow switch

2.1 How it works

Below is an example of flow switch. and product link:

https://www.amazon.com/Float-Switch-Septic-System-Sump/dp/B0064BHEVM/ref=sr_1_5?crid=2PCMSD63FBP42&keywords=float%2Bswitch&qid=1671230997&refinements=p_72%3A1248909011&rnid=1248907011&s=hi&sprefix=float%2Bswitch%2Caps%2C155&sr=1-5&th=1 

The switch will switch on/off to show if the water / liquid has dedicate level.

To use such switch with Dragino Products, use can connect it to LSN50v2 use the same way as a door switch. See reference link:

http://wiki.dragino.com/xwiki/bin/view/Main/User%20Manual%20for%20LoRaWAN%20End%20Nodes/LSN50%20%26%20LSN50-V2%20-%20LoRaWAN%20Sensor%20Node%20User%20Manual/#H2.4.5DigitalInterrupt 

2.2 Advantage & Disadvantage

Advantage : Reliable , Easy to install & Immue to different environment.

Disadvantage: Only be able to detect one speicify level. Not able to detect full range of water. 

3. Ultrasonic Sensor

3.1 How it works?

Such as LDDS75 / LDDS45. They are using ultrasonic technologic to detect the distance between the probe and a flat object such as water level.

Below is photo and URL shows how Ultrasonic Sensor works to detect Water Level

https://www.electricalvolt.com/2022/06/ultrasonic-level-transmitter-working/ 

When choose the ultrasonic sensor, we need to check the measure range , blind spot and angel to fit the tank.

An important notice, if there are moisture accumulated in the sense area of Ultrasonic Probe of LDDS75/LDDS45. the reading will become invalid.

3.2 Advantage & Disadvantage

Advantage :   Able to detect the level. Good Accurancy.

Disadvanage: Wrong reading when probe is block by moisture or other stuff. Affect by temperature.

4. Pressure Sensor

4.1 How it works?

Pressure Sensor such as PS-LB measures the pressure of the air / gas / liquid so can calcualte the liquid level.

there are two types , Thread type and Immersion type. as below:

4.2 Advantage & Disadvantage

Advantage :  Able to detect air / gas / liquid pressure level. Immue to factors such as moisture / blocking. etc. Flexible for installation for

Disadvanage :