How to calculate centrifugal fan power for Korean BBQ restaurant

We are the supplier of Japanese and Korean BBQ exhaust fan and Korean BBQ exhaust pipe, and many restaurant owners and construction teams ask which power rating to choose for the centrifugal fan for the ducting.

It is perfectly normal for restaurant owners not to understand indoor BBQ ventilation design. However, we are surprised that many construction teams also lack this knowledge.

Many restaurant owners consistently discover after opening their Japanese & Korean BBQ restaurants that poor BBQ exhaust performance fills the dining area with choking smoke, ruins customer experience, and hurts revenue. They then approach us, requesting assistance in diagnosing the root causes and proposing corrective measures.

We find that some construction teams use undersized main ducts to cut costs, doubling resistance, increasing noise, and reducing exhaust efficiency. This noise and smoke disturb customers and ruin their dining experience.

Some construction teams install centrifugal fan with mismatched power ratings, design excessively long ductwork, or use overly long retractable Korean exhaust pipes, causing smoke and fumes to fail to exhaust entirely.

Today, let’s analyze how to choose a centrifugal fan for the Korean BBQ ventilation in Korean and Japanese BBQ restaurants.

The power of the centrifugal fan depends on the total exhaust airflow (Q), the fan efficiency, the transmission efficiency, and the total pressure loss (P) in the Korean BBQ ventilation system.

The formula for calculating the large exhaust fan ‘s power is:
The Power Of Large Exhaust Fan = Q × P / (3600 × fan efficiency × transmission efficiency).

Total airflow determines the extraction capacity for smoke; total pressure must be sufficient to overcome the system resistance.

Total exhaust airflow (Q) depends on the number of BBQ grills in the restaurant. We typically recommend 400–500 m³/h per grill.

If a Korean BBQ restaurant has 10 BBQ grills total, the total exhaust airflow (Q) = 4000–5000 m³/h.
To achieve optimal performance, we will use the value Q = 5000 m³/h in the following.

The efficiency data of a centrifugal fan is obtained from its performance curve, which the manufacturer supplies with each unit.

The curve plots airflow (Q) on the horizontal axis and pressure (P) on the vertical axis, with superimposed efficiency contours.

If you need assistance reading the curve, please forward it to us, and we will calculate the efficiency for you.

For a high-quality centrifugal fan, the efficiency is conservatively estimated at 0.75–0.85. A value of 0.75 is used in the subsequent calculations.

The transmission efficiency of the big extractor fan is governed by the coupling method between the motor and impeller. This varies with the mechanical design.

Should you require assistance in identifying the fan configuration, please forward the relevant data to us. A transmission efficiency of 0.95 is assumed in the power calculation.

Total pressure loss (P) depends on many factors, such as duct friction loss, duct length, number of outlets, elbow types and counts, reducing elbows, grease purifier pressure drop, and retractable pipe pressure drop.

Total pressure loss (P) = duct friction loss + losses through elbows (type and quantity) + tee (straightthrough) loss + reducer loss + outlet loss + grease purifier pressure drop + retractable BBQ smoker exhaust pipe pressure drop. (Add losses for any other inline equipment as applicable.)

If the BBQ exhaust system maintains an air velocity of 10–12 m/s, the friction loss per meter of straight duct approximates 0.8–1.2 Pa/m (we take the middle value, 1.0 Pa/m).

Note: The friction loss of straight ducts is taken as 1 Pa/m, provided that air velocity remains between 10 and 12 m/s. If the duct diameter changes, the air velocity changes as well, and the equivalent loss values must be recalculated.

If your main duct total length is 15 meters, then the friction loss in the duct equals 15 m × 1.0 Pa/m = 15 Pa.

If the main duct has only one outdoor outlet, the exit loss is roughly equivalent to the friction loss over 3–5 m of straight duct.

Assuming 1 Pa/m friction loss, we take the middle value as 4 Pa for design.
(For multiple outlets, the loss should be recalculated based on the actual configuration.)

Each time the airflow turns a corner or changes crosssectional area, it impinges on the duct walls, creating substantial pressure loss. Thus, every elbow contributes to the total pressure drop.

Thus, minimize the number of elbows in the duct design, and use 45° elbows or long-radius 90° elbows to reduce pressure losses.

The calculation of elbow pressure loss is complex and is therefore not detailed here for simplicity.

Common elbow types include 90° round elbows, 45° round elbows, tee (straight-through) fittings, pipe reducers, and elbow reducers.

Typically, the pressure drop for a 90° round elbow is approximately 5–8 Pa (we take the design value as 7 Pa), assuming only 90° round elbows are used.

Equipment pressure drops in the BBQ ventilation often account for over 70% of the total pressure loss. The grease purifier is the largest contributor to this loss.

A typical plate type electrostatic purifier has a pressure drop of about 150–250 Pa. For simplicity, we use 250 Pa as the design value.

If the BBQ restaurant uses a high-efficiency, low-emission grease purifier, the pressure drop may exceed 300 Pa.

If the retractable Korean grill exhaust pipes used in the restaurant are equipped with grease filter boxes and Korean BBQ exhaust hoods, their total pressure drop is approximately 97–182 Pa. We adopt 150 Pa as the design value.

Assume your Korean BBQ restaurant has a main duct 15 m long (along the path), with three 90° elbows, one outdoor exhaust outlet, and one grease purifier in the duct. And there are 10 BBQ grills and 10 retractable Korean exhaust pipe.

The total pressure drop for this system in Korean BBQ restaurant:
Total pressure drop (P) = Main duct friction loss + loss through elbow types + loss through elbow quantity + loss from reducers (size changes) + outdoor outlet loss + pressure drop from duct equipment + pressure drop from retractable Korean exhaust pipes.

Total pressure drop (P) = main duct friction loss (15 Pa) + elbow loss (21 Pa) + outlet loss (4 Pa) + grease filter loss (250 Pa) + total pressure drop of retractable Korean exhaust pipes (150 Pa) = 440 Pa

Main duct centrifugal fan power calculation formula:
Power of Centrifugal Fan = Q × P / (3600 × fan efficiency × fan transmission efficiency).

Therefore, the power of the centrifugal fan for the main duct in this Korean BBQ restaurant = 5000 m³/h × 440 Pa / (3600 × 0.75 × 0.95) ≈ 858 W (this is the theoretical value).

Over time, the grease accumulate on the inner surfaces of the retractable Korean BBQ exhaust pipes, grease filters, main duct, and purifier, gradually increasing the system resistance.

Fan motor manufacturing tolerances and voltage fluctuations also contribute to resistance variations.

Finally, select a 1.1 kW or 1.5 kW centrifugal fan for the main duct.

The 1.5 kW centrifugal fan with a VFD is strongly recommended. Operating at a low frequency during normal conditions saves energy and reduces noise. If duct blockage increases the pressure drop, increase the VFD frequency to compensate, ensuring stable exhaust performance.

1.We will verify the optimal BBQ ventilation fan power to prevent poor exhaust. And the proper fan can significantly reduce your monthly electricity costs.
2.Based on your floor plan, we will calculate airflow, duct diameters, and recommend main duct height and retractable BBQ pipe lengths.
3.We will assess your main duct sizing and routing for correctness and efficiency.
4.We will suggest BBQ exhaust pipes, barbecue grills, and BBQ table that suit your restaurant.

We manufacture Japanese and Korean BBQ smoke extractors, barbeque grills, BBQ tables, and smokeless hot pot tables. With over 10 years of experience spanning production, design, sales, and after-sales service, we go beyond equipment supply—we deliver complete, custom-tailored exhaust solutions to our customers.

Email: [email protected]
WhatsApp: +8618138505729
Website: www.medabbqconcept.com