In spray paint booths, baking paint rooms, air supply/exhaust systems, and negative-pressure ventilation equipment, Fiberglass Filter Media is the most commonly used first line of defense for capturing paint mist and large dust particles.

However, in many on-site operations, improper installation direction or poor sealing of the filter often leads to restricted airflow, reduced ventilation efficiency, or even fan damage. This article, prepared by a professional filtration engineering team, provides a complete breakdown of the standard installation procedures and core filtration principles of green-and-white fiberglass filter media.

Why Does Green-and-White Fiberglass Filter Media Have a Specific Direction?

The Science Behind “Green Side In, White Side Out”

Green-and-white fiberglass filter media is designed with a Progressive Density Structure, meaning each side has a different density and filtration function:

• Green Side (Air Intake Side / Upstream Side):
  The structure is looser with larger fiber gaps. Its function is to capture large dust particles and paint mist first while allowing smaller particles to penetrate deeper into the filter media, preventing premature surface clogging.
• White Side (Air Outlet Side / Downstream Side):
  The structure is denser with smaller fiber gaps. Its role is fine filtration — trapping smaller particles and providing overall structural support.

⚠️ Important Warning:
If the white side is accidentally installed facing the incoming airflow (reversed installation), large particles will quickly clog the dense white surface. This causes a rapid increase in filter resistance (pressure drop), significantly higher power consumption, and can reduce the filter’s service life by more than 50%.

Green-and-White Fiberglass Filter Installation SOP

Step 1: Cleaning & Inspection

Key Operation Points:

After removing the old filter, thoroughly clean the inside of the holding frame and guide rails. Ensure there is no remaining paint residue, dust, or foreign debris.

Core Purpose:

A clean frame ensures the new filter media fits flat and tightly, preventing gaps caused by uneven debris buildup.

Step 2: Sizing & Direction Check

Key Operation Points:

Measure the frame dimensions and accurately cut the fiberglass filter roll to size (typically leaving an extra 1–2 cm for tight fitting). Double-check the installation direction:

• Green Side: Must face the incoming airflow direction (upstream side).
• White Side: Must face the outgoing airflow direction (downstream side / fan side).

Step 3: Alignment & Tight Fitting

Key Operation Points:

Carefully place the filter media into the frame. Smooth the edges by hand to ensure all four sides fit tightly against the frame. The filter surface must remain flat without wrinkles, curling, or lifted corners.

Step 4: Final Seal Verification

Key Operation Points:

Inspect the entire installation carefully to confirm there are absolutely no visible gaps between the filter media and the frame. Re-tighten retaining strips or grilles to ensure the filter remains secure under airflow pressure.

Core Purpose:

Prevent unfiltered bypass airflow from carrying dust particles through the system and ensure optimal performance of the negative-pressure ventilation system.

Frequently Asked Questions (FAQ)

Q1: How can I quickly determine the airflow direction in a factory system?

A:

• For ceiling intake filtration in a paint booth:
  Airflow moves from top to bottom (fresh air entering the room). Therefore, the green side should face upward (toward incoming fresh air), while the white side should face downward (toward the interior workspace).
• For floor or side exhaust filtration in a paint booth:
  Airflow moves from inside to outside (exhaust air toward the fan). Therefore, the green side should face inward (toward the working area), while the white side should face outward (toward the exhaust fan).

Q2: How often should green-and-white fiberglass filters be replaced?

A:

Replacement intervals depend on operating frequency and dust load. Under normal operating conditions, filters should be replaced immediately if:

• The green surface is heavily covered with paint residue,
• The filter color becomes significantly darker,
• Airflow volume noticeably decreases,
• Or exhaust performance becomes poor.

Routine inspections are generally recommended every 60–100 operating hours.

Q3: What happens if fiberglass filters are not replaced regularly?

A:

When the filter media becomes saturated and is not replaced:

• System resistance increases significantly,
• Indoor ventilation performance deteriorates,
• Odors and dust backflow may affect coating quality,
• Exhaust fans may become overloaded and burn out,
• And dust leakage could potentially violate environmental regulations.

Filtration System Optimization & Bulk Purchase Consultation

To learn more about fiberglass filter roll specifications and high-capacity paint mist filtration solutions, feel free to contact our professional technical team. We provide customized air purification solutions tailored to your operational requirements.