Optical Level Switches

Optical level Switches

Operational principle
An optical level switch works by emitting a beam of infrared light within a prism and measuring the amount of light received. When the measured fluid reaches the sensor the amount of emitted light received drops thus triggering the contacts. As the sensor is detecting the state between material covering or not covering the prism it can be used to detect the presence or absence of fluid thus preventing damage to pumps.

The compact unit houses the infrared transmitter, the prism, the receiver and the electronics, there is also an external LED indicator to show the condition of the switch. The sensor requires a power supply of between 10-28 Volts Dc. The benefit of the modern optical sensor is that there are no moving parts that can retain material and get clogged up or damaged, simply fit and forget.

Product Feature
• High quality sealed unit with 2m lead

• NPN, PNP open collector output to energise relay or PLC.

• Enclosure material of P (Polycarbonate), PS (Polysulfone), 304 or 316 Grade Stainless Steel for acidity and alkaline; applicable in waste water, Wine, Vinegar solutions, liquor, alcohol .... etc.

• Over current and reverse polarity protected

• LED Status indication

• Not recommended for use where fluids may leave residue.

Typical Product Specification
I. Ingress Protection: IP68

2. Operational temperature : -10°C- 125°C

3. Power Supply: 10-28 Volts DC

4. Ambient light: 5000 Lux (Visible light)

5. Load Current: Max Load 100mA

6. Overload Current Protection: 100mA

1. Connection Thread : M12x1, 3/8" BSP or 3/8" NPT

8. Body Material: P (Polycarbonate), PS (Polysulfone), 304 (S4) or 316 (S6) Grade Stainless Steel

9. Operational Pressure: Max 10Kg/cm2 (Polycarbonate, Polysulfone) Max 40Kg/cm2 (304 S/S, 3 I b SOS) 10. Ambient Temperature: -10°C- 80°C

11. Lead Wire: 2m cable (dip 3.8) Score PVC 22 AWG

Liquid Level Control
In fig 4a two optical switches are installed individually in the upper and lower level of the tank. When liquid rises to cover the upper optical switch it will trigger the solenoid valve to close. When the liquid level drops to the lower level the optical switch reopens the solenoid to refill the tank

Motor protection
In Fig 4b an optical switch is installed in the lower level of the tank which will cut the power to the pump thus protecting it from damage

This information has been kindly supplied by:

Assemtech Europe Ltd.

March 2011


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