Thermal flow sensor-3220 principle and structure

The 3220 type thermal flow sensor, based on the thermal principle, contains two resistors inside a closed probe. One is heated as the detection resistor, and the other is not heated as the reference resistor. When the medium flows, the heat on the heating resistor is taken away, and the resistance value is changed. The difference between the two resistors is used as the basis for judging the flow rate. The probe adopts an anti scaling coating, which can effectively prevent the adhesion of scale, rust and other dirt in the pipeline, with stronger anti fouling ability and more stable operation.

Thermal flow sensor-3220 product features

Unique conical probe design can effectively prevent entanglement of objects in the medium.

● Fully waterproof shell design, unique waterproof adjustment knob, can be adjusted freely without disassembling the sealing thread, convenient and more reliable.

● Suitable for a wide range of pipe diameters, adjustable set points, optional anti-corrosion type, pressure resistance up to 100Bar, indicator light directly displays flow rate, optional

Relay, analog output or analog switch integrated output.

Real time monitoring of liquid flow in pipelines, with no moving parts, maintenance free, and easy installation,

One model is suitable for various pipe diameter requirements, simulates switch output, and uses 6 LEDs to display fluid flow rate status in real time, achieving the following monitoring functions:

Medium flow, reduce/increase flow rate; Existence/non existence of medium; Medium flow/static; Monitor the fluid flow velocity inside the pipeline, monitor flow interruption, or prevent pump idling.

Application of Thermal Flow Sensor-3220 Product

Widely used in industries such as petrochemicals, electricity, metallurgy, steel mills, papermaking, food processing, water treatment, battery factories, etc.

● Gas liquid dual-use type, can be used for pneumatic and hydraulic systems, can be used for flow monitoring of circulating water, cutting fluid, and lubricating oil, as well as pump idle protection.

Thermal flow sensor-3220 performance parameters

Setting range:						25 CM/S (water)
						3... 7500 CM/S (oil)
						20... 50000 CM/S (air)
Signal output:						PNP、NPN、 Relay, analog quantity (4... 20mA)
						Normally open+normally closed (SPDT)
Power supply:						DC 24V±20%
Connect the power supply:						Maximum 400mA (PNP or NPN type)
						maximum 1A@48VAC /DC (relay type)
No load current:						Maximum 80mA
Traffic indication:						LED row (6 pieces)
Setting method:						Potentiometer setting
Voltage endurance range:						100bar
Temperature variation of the medium:						≦4℃/s
Response time:						1…13s, Typical value 2s
Initialization time:						About 8 seconds
Electrical protection:						Reverse/short circuit/overload protection
Protection level:						IP67
Medium temperature:						-20…100℃
Environmental temperature:						-20…80℃
Storage temperature:						-20…100℃
Wiring method:						M12 connector
texture of material:						304 stainless steel
Shell:						304 stainless steel
Repetition accuracy:						±2%

Wiring diagram

Dimensional drawing

LED function and settings (switch type)

Install the flow switch so that the medium flows at the desired flow rate, adjust the potentiometer so that the first green LED lights up exactly. Afterwards, when the flow rate is lower than the current value, the switch will be released. To make the switch point smaller than the current flow rate, adjust the potentiometer to make the green LED brighter.

LED function and settings (analog type)

Analog output type flow sensor, with an output of 4... 20mA, proportional to the flow rate, and a non-linear output. Each sensor has two knobs, one for "upper limit (20mA)" and one for "lower limit (4mA)", used for output settings.

Install the flow sensor so that the medium flows at the low limit flow rate that needs to be monitored. Adjust the lower limit knob so that the fourth green LED lights up (20mA). After that, the output will be proportional to the flow rate between the static and upper limits, that is, 4mA corresponds to the static flow rate, and 20mA corresponds to the upper limit flow rate.

Working principle

The 3220 digital thermal flow switch is designed based on the principle of heat exchange. The probe is equipped with a built-in heating module and a sensing module. The heat conduction of the flow switch is closely related to the flow rate of the medium. During measurement, the heating module emits heat. If there is no medium flow in the pipeline, the heat received by the sensing module is a fixed value,

When a medium flows, the heat received by the thermal module will vary with the flow rate of the medium. The thermal module converts this temperature difference signal into an electrical signal, which is then converted into a corresponding standard analog signal or contact signal output by the processor. The flow switch displays and controls the flow rate of the medium through this signal.

Installation instructions

　　1. Horizontal installation:When the medium in the pipeline is full, this installation method can be used, but when the liquid in the pipeline is not full, this installation method cannot be used because it may cause the probe of the flow switch to not contact the medium and not work properly.

2. Side installation:

This installation method can be used when the medium inside the pipeline is full or not full.

3. Vertical installation:

When installing vertical pipelines, they should be installed under the flow pipe section of the medium from bottom to top.

4. Inverted:

This installation method is prohibited as it may cause sediment at the bottom of the pipeline to cover the head, resulting in the flow switch not working properly. If the seal is not tight during installation, it may cause leakage water to soak the flow switch for a long time, causing damage to the flow switch. Additionally, this installation method is not conducive to setting the parameters of the flow switch.

Selection code

	1		2		3		4		5		6
3220-		-		-		-		-		-		-

			Style type
			1		2-lamp thermal flow sensor (flow switch)
			2		4-Lamp Thermal Flow Sensor (Flow Switch)
			3		6 lamp type thermal flow sensor (flow switch)
			4		6 Lamp Type Thermal Flow Sensor (Flow Switch) Plastic Shell Economy Type
			5		7-lamp thermal flow sensor (flow switch)
			6		Digital thermal flow sensor (flow switch)
1			7		Explosion proof function of digital thermal flow sensor (flow switch)
			Interface thread
			G12		Interface external thread G1/2
2			G14		Interface external thread G1/4
			Power supply mode
			D		DC 24V ± 20% power supply
3			W		AC 220V ± 20% power supply
			output signal
			P		PNP output
			N		NPN output
			C		Relay
4			A		4... 20mA output (DC power supply optional)
			Output
			R		Normally open+normally closed output (SPDT)
5			N		4... 20mA output
			Connection
6			Q		Plug in type
			OEM customization
			/		Regular shipment without customized content
			A		Nameless light plate customized product
7			B		Designated nameplate, designated trademark product