Selecting the size of the air diffuser (Air Diffuser) for the operating room (Operating Room)

very important Because cleanliness, pressure, temperature, and air distribution must be controlled.

efficiently They usually refer to standards such as , , or .


✅ 1. Basic criteria for designing air systems for operating rooms.

Standard value factor
Air exchange rate (ACH) 20–25 times/hour.
Air velocity through the nozzle (FPM) 20–50 fpm at the operating table area
Positive room pressure (Positive Pressure)
Temperature 18–24 °C
Relative humidity 30–60%
Cleanliness ISO Class 7 or better (in some cases ISO 5 for laminar flow)


✅ 2. Steps for calculating the size of the air supply head.

✳️ Step 1: Calculate the amount of air required (CFM)

\text{CFM} = \frac{\text{ACH} \times \text{Volume}_{\text{Room}}}{60}

Example
Operating room size 6 m × 6 m × 3 m = 108 m³
ACH = 25

\text{CMM} = \frac{25 \times 108}{60} = 45 CMM
\Rightarrow \text{CFM} = 45 × 35.3 ≈ 1,589 CFM


✳️ Step 2: Select air outlet type.

For operating rooms, use a Laminar Flow Diffuser or a HEPA Box with Diffuser.
To control the wind direction down the operating table area. and prevent back contamination

✳️ Step 3: Select the number of air nozzles.
 • If using a Laminar Diffuser that releases air 500 CFM per channel.
\frac{1589}{500} ≈ 3.18 \Rightarrow uses 4 field.
 • The air supply head should be installed. Covers the entire operating table area By allowing air to flow vertically (vertical flow) and air to flow out of the room through the return hole below.

✅ 3. Location and installation format

Position Details
Air supply head above the operating table (laminar type, large plate or multiple channels combined)
The Return channel is installed near the floor of the room wall. 2 points up.
HEPA Filter should be installed before air is released into the Diffuser or inside the Diffuser.

✅ 4. Precautions
 • Check that the noise (NC) does not exceed NC-30.
 • Avoid creating turbulence on the operating table.
 • The dispenser head should be washable. and use materials that do not accumulate germs


✅ 5. Summary

For general operating rooms, room size ~100–120 m³
Need wind 1,400–2,000 CFM
Use Laminar dispenser head size 2'x4', quantity 3–4, with HEPA filter.
Control the wind direction from top to bottom evenly and use the Return Grille close to the ground.