Pressure Swings
Pressure Swings
(OP)
Guys,
I am looking into pressure swings in a manufacturing space at a particular time of the day.I believe this is due to the flow variation in the exhaust fan due to wind. The fan is installed on the roof and equipped with a side discharge.Does anyone have any good idea as to how to isolate the fan discharge from the effects of wind?
I am looking into pressure swings in a manufacturing space at a particular time of the day.I believe this is due to the flow variation in the exhaust fan due to wind. The fan is installed on the roof and equipped with a side discharge.Does anyone have any good idea as to how to isolate the fan discharge from the effects of wind?





RE: Pressure Swings
and take room readings over time to find the most efficient position
RE: Pressure Swings
RE: Pressure Swings
If pressurization not that critical, consider pressurizing the entire building & having gravity backdraft damper operated roof vents to relieve excess pressure. The dampaers bust be reqularly maintained clean.
I have seen roof exhaust vent duct that are elbows with flat metal sail on top. The elbow rotate about a vertical axis & the elbow sail rotates it to always discharge away from the wing. This would minimize wind effect on the fan performance but would not counter the wind pressure effects on the building windward versus leeward side.
RE: Pressure Swings
RE: Pressure Swings
We have kind of ruled out reasons such as control instabilities,frequent door openings due to shift changes etc.If you can think of any other reasons, do let me know.
The swing happens in the late afternoons when the wind speed around that time is about 7m/s~8m/s and it does not happen everyday.The fan is discharging into the wind.On the face of it the wind seems to create the swings.We are trying to reorient the fan discharge.Will post the results soon
RE: Pressure Swings
RE: Pressure Swings
RE: Pressure Swings
RE: Pressure Swings
Scorching summer winds choke fan output. Now, block blistering winds with new 58-inch Wind Diverter Kits! Protect your large tunnel ventilation fans and stop ventilation rates from crashing to dangerous levels!
SAK9, This may be of some help ht
RE: Pressure Swings
If you install a 'tee' discharge on the outlet, the air will flow initially straight ahead and then split left and right. If the wind blows from one side or the other,(into one end of the tee- it will have no effect on the fan discharge.
Personally, I would install a VJ vertical jet discharge fan rather than one with a single sided discharge.I would also use a BC fan which is less susceptible to external forces.
You will also get problems if the inlet and outlet louvres are on different sides. Where a wind prevails, the louvres should be on the same side of the building to cancel each others affect out.
Friar Tuck of Sherwood