Flash Mixer
A Flash Mixer (also called a Rapid Mixer) is the first unit operation in a water treatment or effluent treatment plant. Its function is to rapidly and uniformly disperse coagulants or chemicals such as PAC, alum, ferric chloride, lime, or polymers into the incoming water before it enters the flocculation tank. Efficient flash mixing ensures proper coagulation and improves the overall treatment performance.
Technical Specifications
Parameter | Typical Value |
Equipment Type | Mechanical Vertical Flash Mixer |
Application | WTP / ETP / STP |
Mixing Time (Detention Time) | 20–60 seconds |
Velocity Gradient (G) | 300–600 sec⁻¹ |
Tank Shape | Circular or Square |
Liquid Depth | 2–4 m |
Tank Material | RCC / MS Epoxy Coated / SS304 / SS316 |
Agitator Type | Vertical Shaft with Turbine or Hydrofoil Impeller |
Mixer Speed | 80–300 RPM |
Power Requirement | 0.5–15 kW (depends on flow rate) |
Drive | Geared Motor |
Motor Protection | IP55, TEFC |
Insulation Class | Class F |
Power Supply | 415 V, 3 Phase, 50 Hz |
Shaft Material | SS304 / SS316 |
Impeller Material | SS304 / SS316 |
Bearings | Heavy Duty Antifriction Bearings |
Seal | Mechanical Seal / Gland Packing |
Design Criteria
Parameter | Recommended Value |
Detention Time | 30–45 sec |
Velocity Gradient (G) | 400–600 sec⁻¹ |
Power per Volume | 20–60 W/m³ |
Impeller Diameter | 25–40% of Tank Diameter |
Tip Speed | 2–5 m/s |
Baffles | 4 Nos. (Optional) |
These values are commonly used for rapid chemical dispersion and effective coagulation prior to flocculation.
Common Materials of Construction (MOC)
Component | Material |
Tank | RCC / MS Epoxy / SS304 / SS316 |
Shaft | SS304 / SS316 |
Impeller | SS304 / SS316 |
Fasteners | SS304 |
Bridge | MS IS 2062 with Epoxy Coating |
Main Components
- RCC or fabricated MS/SS tank
- Vertical agitator assembly
- Geared electric motor
- SS shaft
- Turbine or hydrofoil impeller
- Bearing housing
- Mounting bridge or support frame
- Chemical dosing inlet
- Drain and overflow connections
- Access platform (if required)
Typical Chemicals Mixed
- PAC (Poly Aluminium Chloride)
- Alum
- Ferric Chloride
- Ferric Sulphate
- Lime
- Sodium Hydroxide
- Polyelectrolyte
- pH Correction Chemicals
Typical Applications
- Water Treatment Plants (WTP)
- Effluent Treatment Plants (ETP)
- Sewage Treatment Plants (STP)
- Drinking Water Plants
- Industrial Process Water Treatment
- Chemical Mixing Systems
Advantages
- Instant and uniform chemical dispersion
- Higher coagulation efficiency
- Reduced chemical consumption
- Better floc formation
- Improved sedimentation efficiency
- Compact design
- Low maintenance
- Energy-efficient operation