A fume hood is only as good as its installation. You can buy the best hood on the market, but if the ductwork is undersized, the room pressure is wrong, or the commissioning skips critical tests, you end up with expensive furniture that doesn't actually protect anyone. We've walked into Turkish labs where brand-new hoods failed containment testing because of installation shortcuts — and fixing those problems after the fact costs far more than doing it right the first time.

Before the Hood Arrives

Preparation starts weeks before delivery. The lab space needs to meet specific conditions that many building contractors in Turkey don't automatically provide for laboratory use.

Ceiling height above the hood location matters — you need clearance for the exhaust connection, typically at least 300mm between the top of the hood and the ceiling or duct entry point. We've seen labs in Istanbul where the hood was ordered before anyone checked the ceiling height. The result? An awkward offset duct that created turbulence and reduced containment performance.

The floor must be level. Fume hoods need to sit flat — if the hood body tilts even slightly, the sash won't track properly in its guides and the face velocity distribution becomes uneven. Turkish building standards generally ensure level floors, but in retrofitted industrial buildings, check this with a spirit level before the hood arrives.

Electrical provisions: most fume hoods need dedicated circuits — one for the hood lighting and controls, another for any integrated equipment like sash sensors or alarms. In Turkey, the standard supply is 220V/50Hz. HJSLab hoods come pre-wired for this specification, but the building electrician needs to have the outlets installed at the right position behind the hood before installation day.

The Ductwork Connection

This is where most installation problems originate. The duct connecting the hood to the exhaust fan must match the hood's collar diameter exactly. Reducing the duct size — a common shortcut when the building's existing ducts are smaller — increases pressure drop, reduces airflow, and can make the hood fail its face velocity test.

Duct material depends on the chemicals involved. For general chemistry, galvanized steel works fine. For acid work, PVC or PP ductwork is required — metal ducts will corrode from inside out. In Turkish pharmaceutical labs, HJSLab typically specifies PP ductwork because the chemical diversity in pharma R&D means the ducts see everything from solvents to concentrated acids over their lifetime.

Every duct joint must be sealed. We use silicone sealant rated for chemical exposure at joints, and all horizontal duct runs slope slightly (minimum 1%) toward a drain point to prevent condensate pooling. Pooled condensate in a steel duct is how you get pinhole corrosion that goes unnoticed until the duct fails.

The exhaust fan should be located at the discharge end of the duct system — on the roof or at the wall exit — not in the middle. This keeps the entire duct run under negative pressure, so any small leak draws room air into the duct rather than pushing contaminated air into ceiling spaces. This seems obvious, but we've encountered mis-positioned fans in several Turkish installations.

Room Pressure Balance

Here's something that trips up a lot of installations: the room the fume hood sits in needs to be at slightly negative pressure relative to the corridor. If the room is at positive pressure, contaminated air can leak out through door gaps when the hood is in use.

To achieve this, the building's HVAC system must supply slightly less air to the lab than the fume hood exhausts. A typical 1.5-meter fume hood exhausts about 1,500 m³/h — the supply air to that room should be roughly 10-15% less, creating the desired negative pressure. HJSLab measures room differential pressure during commissioning using a manometer at the door gap. The target is -10 to -25 Pa relative to the corridor.

Turkish laboratories in newer buildings — particularly those in Istanbul's and Ankara's science parks — usually have HVAC systems that can be balanced for this. Older buildings may need a supplementary supply air system installed.

Commissioning Tests

After installation, the hood needs commissioning before anyone uses it for chemical work. HJSLab's commissioning protocol follows EN 14175-4 and includes three test stages.

Face velocity measurement: using a calibrated hot-wire anemometer, we measure air velocity at a grid of points across the hood face opening at the normal working sash height (typically 500mm). Average velocity must be 0.5 m/s ± 10%. No individual measurement point should fall below 0.4 m/s.

Smoke visualization: we use a smoke generator to check airflow patterns. The smoke should flow smoothly into the hood from all positions around the face opening with no visible escape into the room. We check this at both the working sash height and with the sash fully open.

Alarm function test: if the hood has a low-airflow alarm, we deliberately reduce airflow to trigger it and verify it activates correctly. Sash height alarms get the same treatment.

All commissioning data goes into a report that HJSLab provides to the lab, including calibration certificates for the testing instruments. Turkish laboratories seeking TSE compliance or international accreditation need this documentation. For TSE EN 14175 compliance in Turkish labs, or to discuss an upcoming fume hood installation project, contact HJSLab's Turkish office.