Case Study — Helping BelarusLift Choose the Right Spray Booth Airflow Type

How CoatTech turned a simple question — “which airflow type fits which application?” — into a documented selection guide that a distributor can hand straight to their end customer.

1. The Enquiry

BelarusLift, a Belarusian manufacturer of lifts and lifting equipment, approached CoatTech with a request for a coating system for their end customer. After an initial round of discussion, the question that came back was deceptively simple:

“Could you explain the application scenarios of the different airflow types?”

It is the question we hear most often, and it is the right question to ask. Airflow type is not a minor specification line — it is the decision that determines finish quality, operator environment, civil works, capital cost and energy consumption for the entire life of the booth.

2. Why Airflow Type Is the First Decision

The airflow type describes the path filtered supply air takes as it enters the booth, travels across the workpiece, and carries overspray and solvent vapour to the extraction system. It governs four things at once:

· Overspray removal — whether paint mist is lifted off the surface or dragged across it, which decides dirt nibs, orange peel and rework.

· Operator environment — whether contaminants travel away from or through the painter's breathing zone.

· Pressure control — a slight positive pressure (supply slightly above extract) keeps unfiltered workshop air out.

· Safety — continuous dilution of solvent vapour below the safe limit (NFPA 33 requires below 25% of the Lower Explosive Limit).

Critically, the airflow type is locked in by booth structure, duct layout and civil works. It cannot be changed later without major reconstruction. That is why we never quote a booth before this question is settled.

3. CoatTech's Response

Rather than sending a one-line recommendation, CoatTech's engineering team produced a dedicated “Spray Booth Airflow Type — Selection Guide”. The document sets out the four conventional airflow types, each illustrated with a schematic of the actual air path, and maps each type to the application it suits. This gives a distributor or end customer everything needed to make an informed decision before a single machine is specified.

The guide covers: the four airflow types and their application scenarios, a side-by-side comparison table, key design and acceptance parameters, six questions to confirm before quoting, civil-work notes, and a FAQ.

4. The Four Airflow Types and Where Each One Fits

4.1 Crossdraft — the budget-first workhorse

Figure 1 — Crossdraft airflow: fresh air enters at the front and travels horizontally to the rear wall

Filtered air enters at the front of the booth, travels horizontally along the full length of the workpiece and is exhausted through filters in the rear wall. No pit is required.

Where it fits:

· Low-volume bays where budget is the primary constraint.

· Commercial vehicles, construction machinery, structural steel and general industrial components.

· Primer, surfacer and pre-spray preparation work where finish grade is not critical.

· Leased premises and temporary installations that cannot accept civil works.

The trade-off: overspray is dragged along the entire workpiece before it is captured, so the rear sees the most contamination and front-to-rear consistency is the weakest of the four types.

4.2 Semi-Downdraft — the balanced middle ground

Figure 2 — Semi-downdraft airflow: ceiling supply at the front, extraction at the base of the rear wall

Air is supplied through a ceiling plenum over the front portion of the booth and flows diagonally down and back to exhaust filters at the base of the rear wall. Still no pit required.

Where it fits:

· Mid-size operations that want a clear step up from crossdraft without paying for civil works.

· Mixed workloads — general industrial parts plus occasional higher-grade components.

· Sites where the floor cannot be cut but the finish requirement has moved beyond entry level.

The trade-off: airflow uniformity is lower than a full downdraft, and consistency at the rear of the booth and over horizontal surfaces is weaker.

4.3 Side Downdraft — premium finish without a pit

Figure 3 — Side-downdraft airflow: full ceiling plenum with extraction at the base of both side walls

A full-length ceiling plenum delivers air uniformly downward; it is then drawn into exhaust plenums at the base of both side walls. Gravity does the work — no pit needed.

Where it fits:

· Passenger-car refinishing and high-appearance industrial components where a near-top finish grade is required.

· Sites where the floor cannot be excavated: leased buildings, high water tables, structurally constrained foundations.

· Dealerships and chain body shops wanting premium results without pit construction.

The trade-off: more side-wall filters to maintain, and the exhaust plenums reduce usable interior width — both must be checked at the selection stage.

4.4 Full Downdraft — the recognised top grade

Figure 4 — Full-downdraft airflow: full ceiling plenum with extraction through a floor pit or raised basement

Air is delivered through a full ceiling plenum, travels straight down over the workpiece and passes through a floor grate into an exhaust pit or a raised steel basement. This is the cleanest configuration available.

Where it fits:

· Premium passenger-car refinishing and OEM-certified body shops.

· High-throughput operations where rework and polishing hours are the dominant cost.

· Waterborne, metallic and pearl finishes that demand uniform airflow and consistent flash-off.

· Sites that can accept a recessed pit or a raised-floor platform.

The trade-off: the highest capital cost and longest programme because of the civil works, plus higher fan power and heating demand.

5. Comparison at a Glance

6. What CoatTech Recommended for This Application

BelarusLift's workload is lifting equipment and fabricated steel components, not passenger-car refinishing. That distinction matters: the workpiece is a structural steel part, not a Class-A automotive surface. On that basis CoatTech proposed the following selection logic rather than defaulting to the most expensive option:

The final configuration depends on the customer's site conditions — above all whether a pit can be excavated, the available headroom, the daily throughput and the local VOC and fire-safety requirements. CoatTech supplied the guide so those six parameters can be confirmed before the booth is specified, which is exactly what prevents costly changes later.