1. Before Operation (Preparation Stage)
🔧 Equipment Inspection
Check hydraulic oil, engine oil, coolant, and fuel levels
Inspect delivery hoses, clamps, and flanges for wear, cracks, or leaks
Confirm spray arm, rotation joints, and cylinders move smoothly
Test emergency stop, remote control, and limit switches
Ensure air compressor pressure and water supply are stable
🧱 Material & Mix Design
Use qualified wet-mix concrete (proper slump, usually 120–180 mm)
Ensure aggregates are clean and within size limits (commonly ≤10–15 mm)
Verify accelerator compatibility with cement and temperature
Calibrate accelerator dosing system before spraying
👷 Safety Preparation
Operators must wear helmet, goggles, dust mask, gloves
Clear non-essential personnel from the spraying area
Ensure adequate ventilation in tunnels
2. During Spraying (Operation Stage)
🎯 Spraying Technique
Keep nozzle perpendicular (≈90°) to the rock surface
Maintain spraying distance of about 0.8–1.2 m
Spray from bottom to top to avoid sloughing
Use circular or "S-shaped" motion for uniform thickness
⚙️ Equipment Operation
Start spraying with water and air first, then concrete
Adjust air pressure to ensure dense compaction (not excessive rebound)
Monitor pump pressure and hose vibration
Keep accelerator dosage stable and uniform
🪨 Rebound & Quality Control
Control rebound rate (typically ≤15% for walls, ≤25% for crown)
Remove loose rock and previous rebound before spraying
Avoid spraying onto running water or muddy surfaces
Check layer thickness-single layer usually 5–10 cm, multi-layer if thicker
3. After Operation (Shutdown & Cleaning)
🧼 Cleaning
Pump clean water or cleaning balls through pipelines immediately
Thoroughly clean nozzle, accelerator lines, and mixing chamber
Remove residual concrete before it sets
🔍 Inspection & Maintenance
Check hoses, seals, and wear parts for damage
Inspect spray arm pins and joints for looseness
Lubricate moving parts as required
Record operating parameters and any faults
4. Common Problems to Watch For
| Issue | Likely Cause | Attention Point |
|---|---|---|
| Pipe blockage | Low slump, delayed spraying | Keep mix fresh, continuous spraying |
| Excess rebound | Wrong angle or air pressure | Adjust nozzle position |
| Uneven thickness | Poor nozzle control | Maintain steady movement |
| Accelerator failure | Blocked dosing line | Clean daily |
5. Special Notes for Tunnel & Slope Work
In tunnels: prioritize ventilation and lighting
On slopes: ensure machine stability and anchoring
For high-boom wet spraying machines: watch boom envelope limits to avoid collision
If you want, we can also provide:
Standard operating procedures (SOP) for tunnel wet spraying
Typical spraying parameters (pressure, output, accelerator ratio)
Troubleshooting guide specific to high-boom or truck-mounted wet spraying machines
Just tell us your construction scenario
