What is Soft Water & Why Measure Its Flow?
Soft water refers to water treated through ion exchange or reverse osmosis to remove hardness ions like calcium and magnesium, typically exhibiting conductivity below 50 μS/cm. Its industrial significance includes:
1. Anti-scaling Protection: Extends equipment lifespan (boilers, heat exchangers)
2. Process Stability: Ensures formulation accuracy in pharma & food industries
3. Environmental Compliance: Meets ion concentration standards for wastewater discharge
Key Industries Requiring Precise Soft Water Flow Measurement:
Pharmaceutical (purified water systems)
Food & Beverage (ingredient mixing)
Microelectronics (wafer cleaning)
Chemical Processing (reactor cooling)
HVAC Circulation Systems
Comparative Analysis of Four Soft Water Flow Meter Technologies
# 1. Turbine Flow Meter for soft water
Operating Principle: soft water kinetic energy rotates a turbine, with flow rate calculated via magnetic/optical sensors detecting rotation speed.
Advantages for Soft Water flow measurement:
✅0.5% accuracy
✅Full pipe size coverage (DN4-DN200) to cover different pipelines and flow range, normal request is 1/2” RO flow meter, 1” water flow meter, 2 inch OR water, 3 inch water flow meter and so on.
✅Measures 0.3-10 m/s flow velocities
✅Stainless steel material for soft water measurement
✅
Low price cost water flow meter
✅Digital soft water flow meter with digital display, 4-20mA ,pulse output, option with MODBUS RTU.
Limitations:
-Sensitive to particulates (requires 100μm filter), liquid turbine flow meter can only measure clean liquid without particles.
-Mechanical wear affects long-term stability, because it has moving parts inside the turbine flow sensor.
# 2. Vortex Flow Meter
Working Principle: Utilizes Kármán vortex street effect, calculating flow via detected vortex shedding frequency.
Vortex flow meter for soft water measurement Performance:
✅No moving parts (low maintenance)
✅Can make into high pressure water flow meter, for example withstands 6.3MPa pressure
✅Broad temperature range (-40°C~350°C) for vortex flow sensor
✅All
stainless steel flow sensor made material of stainless steel 304 ,316 or 316L
✅Can be made into 24V DC or battery operated flow meter.
✅Can make into different process connection, such as flange, tri-clamp sanitary flow meter, screw connection and so on.
Tri-clamp connection soft water flow meter
Constraints:
-Reduced accuracy below 0.5 m/s ,and normal accuracy for water measurement is 1.0%
-Requires 10D upstream & 5D downstream straight pipes
# 3. Rotameter
Mechanism: Float position in tapered tube corresponds to flow rate, enabling visual reading.
Benefits for Soft Water rotameter flow meter:
✅Visual monitoring for water flow rate.
✅Cost-effective flow meter for RO water (40%-60% savings)
✅Rotameters have a long history and stable working performance
✅Local monitoring capability no external power
Local monitoring rotameter without power supply
Drawbacks:
-2%-5% accuracy (unsuitable for custody transfer)
-Vertical installation normal , and horizontal mounting will cost a lot money
-Suitable for low flow soft water flow measurement
# 4. Coriolis Mass Flow Meter
Core Technology: Measures phase shift from Coriolis forces in vibrating tubes to determine mass flow.
Advantages using Coriolis flow meter to measure soft water mass flow
✅±0.1% ultra-high precision, it is high accuracy flow meter
✅Multi-parameter output,beside measure software mass flow rate and total flow , it can also measure RO water density/temperature .
✅Immune to conductivity variations
✅Various flow range options, for example from 40 g/h , to 1 t/h, to 10 t/h, Silver Automation Instruments all have solutions for different flow range and pipeline sizes.
Mass water Flow Range corresponding to different size mass flow meter:
|
Inch
|
3/8”
|
1/2”
|
3/4”
|
1”
|
1.5”
|
2”
|
2.5”
|
3”
|
4”
|
5”
|
6”
|
8”
|
8”
|
10”
|
12”
|
|
DN(mm)
|
10
|
15
|
20
|
25
|
40
|
50
|
65
|
80
|
100
|
125
|
150
|
200A
|
200B
|
250
|
300
|
|
Flow Range
|
0~1.5 T/h
|
0~3 T/h
|
0~7 T/h
|
0~13 T/h
|
0~22 T/h
|
0~33 T/h
|
0~60 T/h
|
0~100 T/h
|
0~160 T/h
|
0~230 T/h
|
0~300 T/h
|
0~400 T/h
|
0~500 T/h
|
0~800 T/h
|
0~1500 T/h
|
Notes:
Coriolis is a High cost flow meter, comparing to the cost of turbine flow meters (TUF), vortex flow meter and rotameters. Water mass flow sensor is sensitive to vibrations .
When discussing water flow measurement, electromagnetic flow meters (magmeters) instinctively come to mind as the go-to solution. These
full-bore flow meter devices offer non-intrusive operation with zero flow obstruction and cost-effective pricing. However, their application proves fundamentally problematic for soft water measurement due to inherent technical constraints.
Electromagnetic flow meters (magmeters) operate via Faraday’s Law, requiring conductive fluids (>5 μS/cm). Soft water’s low conductivity (<50 μS/cm) causes:
1. Signal Attenuation: Reduced electromotive force degrades SNR
2. Zero-point Drift: Electrode polarization in low-conductivity media
3. Measurement Errors: ±5%+ deviations vs. turbine meters’ ±0.5%
Market Trends for soft water flow meter.
The global soft water flow meter market reached $1.2B in 2023, with Coriolis flow meter multi-parameter devices growing at 8.7% CAGR (Flow Research). IIoT-enabled smart flow transmitters featuring Modbus/Profibus PA protocols now dominate, offering predictive maintenance for bearing wear (turbine flow meter) or vibration anomalies (vortex flow transmitter).
