Fan stacks
The fan stack shapes the air leaving the fan and sets the tip clearance. A distorted stack wastes fan power continuously and can destroy a fan.
Understanding the component
The fan stack, or fan cylinder, is the fiberglass shroud around and above the fan. It does two jobs. It sets the tip clearance between blade and shroud, and it recovers velocity pressure as the air slows on leaving, which reduces the work the fan has to do.
Tip clearance is the item worth understanding. Air that recirculates through the gap between blade tip and stack does no cooling; it simply costs power. Precision fan assemblies are built to tolerances that allow minimum tip clearances, and that precision is wasted if the stack is out of round, out of level or has grown soft with age.
A velocity-recovery stack extends and flares above the fan to convert velocity pressure back to static pressure. It is taller and costs more, and it reduces fan power for the same air flow. Stacks are also available with access doors and view ports, which make inspecting the fan and drive considerably safer and more likely to actually happen.
We supply components for cooling towers from every manufacturer, including towers whose original makers no longer exist. If it is on your tower, we can identify it.
What actually goes wrong
These are the failures we find in the field, roughly in order of how often we find them. If you recognize one, we can usually tell you what to check next over the phone.
| Failure | What it means |
|---|---|
| Distortion and out-of-round | The stack goes oval or out of level, tip clearance becomes uneven, and the fan is unbalanced aerodynamically around every revolution. |
| Delamination and softening | Aged FRP losing resin and stiffness, particularly at the top edge and around penetrations. |
| Cracking at supports | Fatigue cracking where the stack is bolted to its supports, driven by fan-induced vibration. |
| Storm displacement | High wind shifting a stack on its mountings, a routine finding after a named storm, and one that puts tip clearance out immediately. |
| Missing hardware | Corroded or absent fixings around the base, which is how a stack starts moving in the first place. |
Manufacturers and product lines
We are independent, so the recommendation follows your tower, your water and your duty rather than a single manufacturer's catalog.
Midwest Towers
Fiberglass fan stacks in a wide range of sizes and profiles.
Polymer Fabrication
FRP fan stacks and cylinders.
BAC · Baltimore Aircoil
Replacement stacks for BAC and Pritchard towers.
Dynamic Fabricators
Fiberglass fan stacks.
US Cooling Towers & Supply
Fiberglass fan stacks.
Names you may find on the nameplate
Including lines that are no longer current. Many of the towers we work on are thirty to fifty years old, and identifying the modern equivalent of a discontinued component is part of the job rather than an obstacle to it.
- Midwest Towers
- Polymer Fabrication
- BAC Pritchard
- Dynamic Fabricators
- US Cooling Towers & Supply
What we would tell you on the phone
Fire rating.
Stacks are available in Class I, Class II and Class III fire ratings. Which you need is driven by your site's fire requirements and insurer, and it is worth confirming before ordering rather than after.
Easy field installation and tip clearance adjustment.
Current stacks are designed to be assembled and adjusted in the field, which matters because tip clearance has to be set against the fan that is actually installed, not the one on the drawing.
Replace stack and fan together where you can.
They are one aerodynamic system. Fitting a new fan inside a twenty-year-old distorted stack throws away much of the benefit you just paid for.
For towers whose makers no longer exist.
Fan stacks are one of the components we are most often asked to supply for orphaned towers. A stack can be made to suit measured dimensions.
Usually replaced or inspected at the same time
Fans
Fiberglass and aluminum fan assemblies, blades and hubs: Hudson, Amarillo Chittom, Moore and Cofimco.
View componentCasing & louvers
FRP casing in 4.2 corrugated and 5.33 V-Beam profiles, and inlet louvers. Fire rated panels available with UL flame spread of 25 or less.
View componentFRP shapes
Pultruded fiberglass angle, channel, tube, decking, grating and walkway sections for structural and safe-access work.
View componentGear reducers
Right-angle fan drives, including direct replacements for the Marley Geareducer line. Frequently rebuilt in place.
View componentSend us the nameplate and we will identify it
The fastest route to a correct quote is a photograph of the nameplate and of the component in place. Model numbers get superseded and drawings go missing; photographs do not lie.
- Phone
- (713) 643-0691
- Shop & office
-
3811 Cedar Blvd Ste A
Baytown, TX 77523