3/4" Digital Water Flow Switch, 5-40L/min, NPN/ PNP

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SKU: SUCH-FLS-NPF3W74006

$395.59

● 3/4 inch connection diameter ● 5-40 L/min rated flow range ● NPN/ PNP/ 4-20mA/1~5V ● Karman vortex street type

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🕒 Delivery date: 6-12 days

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Overview
Specs
Application
FAQ
Reviews

Overview

The high-precision 3-4 inch digital water flow switch is suitable for measuring low-viscosity liquids such as water and ethylene glycol solutions. It supports flow detection and setting ranges from 1.7 to 22.0 L/min, featuring LED digital display for real-time monitoring of instantaneous and cumulative flow rates. With multiple output options including NPN/PNP, 4–20mA, and 1–5V, it is ideal for cooling equipment, water treatment systems, and industrial pipeline monitoring.

Feature

3-4 inch digital air flow switch feature

This flow switch employs the Karman vortex street detection principle to stably measure flow rates within the 5–40 L/min range. It is suitable for cooling water systems, circulating water equipment, and industrial automation flow control applications.
SUCH water flow switches achieve measurement accuracy of ±3% F.S. with repeatability of ±2% F.S. The minimum setting unit is 0.1 L/min, enabling precise flow control.
Constructed from corrosion-resistant materials like PPS and SS304, it meets IP65 protection rating. Operates reliably in liquid environments from 0–90°C and ambient temperatures up to 50°C, suitable for various industrial fluids including water and ethylene glycol solutions.

Dimension (unit: mm)

Body Dimension

Digital water flow switch dimension

Basic Dimensions	A	AA	B	D	E	F	G	H
	98	71	38	68	48.6	19.2	32	28
	J	K	L	N	P	/	/	/
	49	35	28	16.8	Ø2.7 deep 12	/	/	/
Bracket Dimensions	S	T	U	V	W	WX	Y	Z
Bracket Dimensions	34	30	42	48	58	4.5	5	1.5

M8 Lead Wire Dimension

Digital water flow switch lead wire dimension

Detail

Digital water flow switch details

Function Panel: Enables switching between functions and rapid application response.
Water Sensor: Specifically designed to detect water flow and transmit data to the main board.
Main Board: Stores memory data, records data, and provides real-time display.

Pin Number & Wire Color

Digital water flow switch wire color

Pin Number	Content	Wire Colors
1	DC (+)	Brown
2	OUT 2	White
3	DC (-)	Blue
4	OUT 1	Black

Flow Rate Diagram

Digital water flow switch flow rate diagram

Output Type	A	B	C
Voltage Output	1 V	1.5 V	5 V
Current Output	4 mA	6 mA	20 mA

Specs

Connection Diameter Rc(PT)	3/4 inch
Measured Fluid	Water and ethylene glycol water solutions (viscosity ≤3 mPa·s / 3 cP)
Detection Method	Karman vortex street type
Rated Flow Range	5–40 L/min
Display Flow Range	3.5–55.0 L/min
Set Flow Range	3.5–55.0 L/min
Minimum Setting Unit	0.1 L/min
Cumulative Pulse Conversion Value	0.5 L/pulse
Operating Fluid Temperature	0–90°C (non-condensing)
Display Unit	Instantaneous flow L/min, cumulative flow L
Accuracy	Display value ±3% F.S., analog output ±3% F.S.
Repeatability	±2% F.S.
Temperature Characteristics	±5% F.S. (at 25°C reference)
Operating Pressure Range	0–1 MPa
Pressure Loss	45 kPa at max. flow (without flow control valve)
Cumulative Flow Range	99999999.9 L / per 1 L
Output Type	NPN or PNP open-collector output
Voltage Output	1–5 V (output impedance 1 kΩ)
Current Output	4–20 mA
Maximum Load Current	80 mA
Maximum Applied Voltage	DC 28 V
Internal Voltage Drop	NPN: ≤1 V (80 mA load) / PNP: ≤1.5 V (80mA load)
Response Time	0.5s / 1s / 2s
Output Protection	Short-circuit protection
Output Mode	Hysteresis mode, upper/lower limit comparison mode, cumulative output mode, cumulative pulse output mode
Load Impedance	DC12V: 300Ω
Load Impedance	DC24V: 600Ω
Hysteresis	Adjustable
External Input	No voltage input: ≤0.4V (with or without contact), input ≥30ms
Display Method	Dual-sided display
Display Screen	4-digit 7-segment 2-color LED
Operation Indicator	Output 1 / Output 2: Orange
Power Supply Voltage	DC12–24V ±10%
Current Consumption	≤50mA
Protection Rating	IP65
Operating Temperature Range	0–50°C (non-condensing)
Operating Humidity Range	35–85%RH (non-condensing)
Withstand Voltage	AC1000V 1 minute
Insulation Resistance	≥50MΩ (DC500V)
Wetted Parts Material	PPS / SUS304 / FKM / SCS13
Standards and Regulations	CE, UL(CSA), RoHS
Lubrication	Grease-free specification
Weight	1kg

Application

Central Air Conditioning System

Boiler Equipment

Water Purification Equipment

FAQ

Q1: What liquids can digital water flow switches be used with? ❯

Most digital water flow switches are primarily designed for clean water or low-viscosity liquids, such as cooling water, circulating water, or purified water. In certain industrial applications, they may also be used with chemical liquids or other fluids, provided the liquid does not corrode the sensor materials and its viscosity and impurity content remain within permissible limits.

Q2: Does the digital water flow switch require regular maintenance? ❯

Although the digital water flow switch has a relatively simple structure, regular inspections are still recommended during long-term use. This includes checking for impurity blockages in the pipeline, sensor scaling, and loose electrical connections. For systems with poor water quality, filters should be cleaned periodically or sensors undergo simple rinsing. These maintenance measures help maintain detection accuracy and extend the device's service life.

Q3: What should be done if the digital water flow switch malfunctions? ❯

If false triggering or unstable signals occur, first inspect the pipeline for air bubbles or excessive flow fluctuations. Next, check for interference in the power supply or signal lines. Additionally, verify that the installation location meets requirements—for instance, avoid proximity to pumps or valves that generate strong vortices. If the issue persists, recalibrate the set flow value or inspect the internal sensor for damage.

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3/4" Digital Water Flow Switch, 5-40L/min, NPN/ PNP

Feature

Dimension (unit: mm)

Detail

Pin Number & Wire Color

Flow Rate Diagram

Central Air Conditioning System

Boiler Equipment

Water Purification Equipment

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