1. Working Principle of Low-Pressure Spray Guns

The core design concept of low-pressure spray guns is to achieve paint atomization by reducing air pressure and increasing air flow. Its working principle is based on the following key links:

• Compressed air: Compressed air is ejected at high speed through the annular hole of the spray gun cap, forming a negative pressure area at the front end of the nozzle, sucking the paint out of the storage tank.

• Atomization stage: After the paint is mixed with air, it is broken into fine particles by the synergistic effect of the nozzle and the cap. Low-pressure spray guns reduce paint rebound and overspray by optimizing air flow distribution.

• Spraying molding: The atomized paint forms a uniform coating on the surface of the workpiece, and its thickness and glossiness can be adjusted by air pressure, flow and spray gun distance.

Compared with high-pressure spray guns, the atomized particles of low-pressure spray guns are finer, and the paint transfer efficiency can be increased to more than 65%, reducing material waste.

2. Main types and technical features of low-pressure spray guns

Based on the paint delivery method and atomization technology, low-pressure spray guns can be divided into the following categories:

Classification by paint supply method

Gravity type (upper pot): The paint tank is located above the spray gun and relies on gravity to feed the material. Suitable for small-area operations, convenient color change, but limited capacity.

Siphon type (lower pot): The paint tank is located below the spray gun and sucks the material through the Venturi effect. Suitable for medium-viscosity paint, but cleaning is more troublesome.

Pressure delivery: The paint is delivered through an external pressure tank or pump, suitable for continuous large-scale operations, but the equipment cost is relatively high.

Classification by atomization technology

HVLP (high flow and low pressure): large air flow (10-25 CFM), pressure below 0.7 bar, paint transfer efficiency up to 80%, but the spraying speed is slow.

LVLP (low flow and low pressure): balances air consumption and atomization effect, suitable for detail repair, and lower energy consumption.

Mixed air spraying: combines high-pressure paint atomization with auxiliary air, taking into account both efficiency and quality, and is suitable for industrial production lines.

3. Advantages of low-pressure spray guns

• Environmental protection and energy saving

Reduce overspray and paint drift, reduce VOC emissions, and comply with environmental regulations.

High paint utilization rate, saving costs.

• High-quality painting

Uniform atomization particles, smooth coating surface, reducing "orange peel" or sagging phenomenon.

Suitable for coatings with high surface requirements such as metallic paint and high-gloss paint.

• Operation-friendly

Small recoil, reducing operator fatigue; low noise, improving the working environment.

4. Maintenance and troubleshooting of low-pressure spray guns

Daily maintenance points

Cleaning: Immediately flush the paint channel with solvent after each use to avoid curing blockage. Metal tools are prohibited from cleaning the nozzle. Special brushes and cleaning needles are recommended.

Lubrication: Regularly apply silicone-free lubricating oil to the gun needle and sealing ring.

Inspection: Make sure that the air holes of the hood are not blocked, otherwise it will cause the spray width to be distorted or uneven atomization.

Common faults and solutions