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Pressure sand filter inspection

July 21, 2025
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Introduction

Pressure sand filters are critical equipment in water and wastewater treatment systems, responsible for removing suspended particles and improving water quality. Regular inspection of these filters is essential to ensure optimal performance, avoid costly breakdowns, and extend the lifespan of your equipment. This article will provide a comprehensive overview of the inspection methods、 , standards   , and maintenance of these systems.

Check the importance of pressure sand filters

Regular inspection of pressure sand filters is crucial for several reasons:

  1. Prevent the deterioration of effluent quality

  2. Reduces energy and water consumption during backwashing

  3. Prevent sudden breakdowns and repair costs

  4. Ensures the safety of the pressurized system

  5. Compliance with environmental and health standards

Types of pressure sand filter checks

1. Visual inspection

  • Filter Body: Check for signs of corrosion, cracks, or leaks.

  • Piping system: control of connections, valves and welding joints

  • Silica Substrate: Observe the state and surface uniformity of silica particles.

  • Water Distribution System: Check the nozzle and distribution plate

2. Run the check

  • Pressure drop measurement: Comparison with the original design value

  • Check effluent quality: turbidity and TSS test

  • Backwash Evaluation: Control flow rate and backwash time

  • Control system testing: Automatic valve and sensor operation

3. Technical inspection

  • Non-destructive testing (NDT).：

    • Ultrasonic (UT) detects internal cracks

    • Radiography (RT) to check for boils

    • Penetrant Detection (PT) identifies surface cracks

  • Hydrostatic pressure test: 1.5 times the working pressure is applied to ensure the health of the tank.

  • Body thickness measurement (UT thickness test): Prevents wall thickness from becoming thinner

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Pressure sand filter inspection standard

  • ASME Section VIII: Pressure Vessels

  • AWWA B100-09: American Water Association Sand Filter Standard

  • API 570: Pipeline Inspection

  • ISO 9001: Quality Management System Requirements

Check the steps regularly

1. Daily inspection

  • Record inlet and outlet pressures

  • Check the quality of the purified water

  • Check the operation of the air valve and drain valve

2. Monthly inspections

  • Check the condition of the silica bed (compression or groove flow).

  • Calibration of pressure and flow sensors

  • Backwash system check

3. Annual inspection

  • Empty the fuel tank thoroughly and perform an internal inspection

  • Silica particle size analysis (according to EN 12904).

  • Hydrostatic testing and corrosion inspection

Identify common problems and solutions

Question Possible causes Solution
Pressure drop increases Silicous bed compaction Backwash or silica replacement
The turbidity of the water outlet Nozzle breakage or silica erosion Nozzle change and particle size analysis
Body leakage Corrosion or weld cracking Weld or replace damaged parts
The valve is not functioning properly Control or precipitation system failure Valve repair and system calibration

Conclusion

Regular inspections of pressure sand filters not only prevent unexpected failures but also improve the quality of treated water and reduce operating costs. By implementing regular inspection programs based on international standards and employing advanced non-destructive testing methods, the safety and efficiency of these critical systems can be ensured.