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Pressure sand filter production steps: from design to final testing

July 21, 2025
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Introduction

Pressure sand filters are essential equipment for industrial water treatment systems, swimming pools, and sewage treatment plants. These filters use a layer of sand and silica to remove suspended particles from the water. In this article, we will cover the complete production steps 。 of the pressure sand filter, from initial design to final testing

1. Pressure sand filter design

The first step in production is the engineering of the filter according to the customer’s requirements:

Key design parameters:

  • Processing capacity (m³/hour).

  • Tank diameter and height (usually 400mm to 3000mm).

  • Body plate thickness (suitable for working pressure 2.5 to 10 bar).

  • Filter media type (silica, anthracite or activated particles).

  • Backwash system (manual or automatic).

Design software used:

  • AutoCAD is used for technical drafting

  • SolidWorks for 3D modeling

  • Pressure calculation software, such as PV Elite

2. Select raw materials and cut plates

The main ingredients include:

  •  The main body is made of carbon steel plate (ST37).

  •  The parts in contact with the drinking water are made of 304/316 stainless steel plates

  •  Polyethylene pipes for water supply systems

Cutting process:

  • Laser cutting of body plates with an accuracy of ± 0.5mm

  • Press brake bends the body to shape

3. Structure of the main filter body

A) Structure of cylindrical shell:

  • Roll cut the sheet using a roll forming machine

  • Longitudinal welding is performed using the SAW method (submerged arc welding) to achieve high strength

B) Structure of the upper and lower covers:

  • Use a hydraulic press to shape the cap

  • The head is welded to the body using the GTAW method (argon soldering).

c) Inlet/outlet nozzles:

  • Welded installation of inlet, outlet and discharge nozzles

4. Water distribution system (branch pipe).

The water distribution system in the filtration layer includes:

  • The main pipes are made of PVC or stainless steel

  • Cross tube with 0.3 mm groove

  • Stainless steel nozzle for even water distribution

5. Coating and anti-corrosion coating

Extend filter life:

  1.  Use alumina sand for surface blasting

  2.  Phosphating surface treatment

  3. Epoxy paint for corrosive environments (thickness 150-200 microns).

  4.  The last layer is polyurethane paint

6. Equipment assembly and installation

  •  Install manual/automatic valves (multi-way valves).

  •  Place a manometer to display the pressure

  •   Install the sight glasses

  • automatic control system in advanced models

7. Filter media charging

Steps to fill the filter with silica:

  1. Bottom layer: coarse silica sand (3-5mm).

  2. Middle layer: medium silica sand (1-2mm).

  3. Surface layer: fine silica sand (particle size 0.5-1mm).

*Standard ratio: 30% coarse + 50% medium + 20% fine*

8. Quality and performance testing

a) Hydrostatic test:

  • Pressure tested with water up to 1.5 times the operating pressure

  • Duration: At least 30 minutes

b) Performance Testing:

  • Check the water flow

  • Backwash test

  • Valve tightness test

c) Output material testing:

  • Measure the turbidity of the outlet water (must be less than 1 NTU).

9. Packaging and shipping

  • Impact-resistant polyethylene coating

  • Metal chassis for large models

  • Label technical specifications

Conclusion

The production of pressure sand filters is a specialized process that requires precise design, welding, and quality testing .  Filters manufactured according to AWWA B100-09 and EN 12255 standards have a service life of up to 15 years.

Keywords: sand filter production, sand filter design, sand filter testing, sand filter standard, sand filter price.

Contact our experts for technical advice and price inquiries on pressurized sand filters.