At General Air Products, we get asked a lot:
“Should I use Nitrogen or Dry Air in my freezer room or cold storage dry system?”
Our answer, every single time, is Dry Air. We don’t say that lightly. We manufacture Nitrogen Generators, Dry Air Generators, and Air Compressors. That puts us in a unique position to speak plainly and honestly about where each one fits best.
When it comes to cold storage or freezer room fire protection, Dry Air is the right answer. Not sometimes. Always.
The Easy One: Never Use Standard Compressed Air in a Freezer
Let’s knock this out right away: never use a standard air compressor alone in a freezer room application. It’s asking for ice plugs.
When you compress air, you pull in water vapor. Even with aftercoolers and drains, some of that moisture heads downstream. In a freezer system, that moisture freezes where ambient meets subzero, forming ice plugs that block pipe and cripple system performance.
It doesn’t take long.
And pulling air from inside the freezer doesn’t solve this – air gets heated during compression, which condenses vapor and makes the problem worse.
So that leaves you with two real choices: Dry Air or Nitrogen.
Corrosion Isn’t the Problem Here
The main reason people choose nitrogen or other products like Vapor Corrosion Inhibitors over air is corrosion mitigation. And it makes sense in typical dry pipe systems – especially ones with poor pitch, frequent hydro testing, or standing water.
But that’s not what’s going on in cold storage. In fact, these systems rarely see water inside the pipe once commissioned. Why?
Because once installed, the system is rarely flow-tested again. Turning off a freezer to run water through the system is a logistical nightmare, so most owners avoid it entirely. And if there’s no water, there’s no corrosion.
Dry Air and Nitrogen are both dry gas sources. If corrosion isn’t a concern—which it largely isn’t in cold storage—then you shouldn’t be choosing your air supply based on corrosion. You should be choosing it based on reliability, leak tolerance, cost, and ease of maintenance.
Dry Air wins on every one of those fronts.
Dry Air is Less Expensive – Especially at Scale
When your system hits 1,000 gallons or more (which is often the case in cold storage), nitrogen generator costs skyrocket. Dry air systems – like our Dry Air Pac® – scale far more affordably.
So if corrosion isn’t your concern, why would you pay significantly more for nitrogen?
Even in edge cases where a nitrogen generator comes in cheaper on the front end (usually only in very small systems), Dry Air is still the better long-term play.
And if someone tries to pitch you on a single Nitrogen Generator for over 10 dry systems, we’ve got a bridge to sell you – because…
Most Importantly, Nitrogen Generators Can’t Keep Up with Leaks
This is the dealbreaker, and if you take nothing else away from this article, take this:
Nitrogen Generators are fundamentally limited in how much air they can push into a system. And in cold storage, where leaks are inevitable, that limitation causes real problems. Let’s break it down:
At their core, Nitrogen Generators and Dry Air Generators are both air compressors with fancy filters – but what those filters do, and how much they restrict airflow, is the key difference.
- In a Dry Air Generator like our Dry Air Pac®, the compressor pushes air through a desiccant dryer system, which removes moisture while preserving a relatively high air flow (CFM).
- In a Nitrogen Generator, that air gets pushed through a membrane or PSA filter, which is designed to strip out oxygen and concentrate nitrogen. But if you want high-purity nitrogen (like 98%, which is standard in fire protection applications), you’re going to severely throttle your airflow.
Just how severe is that restriction? Let’s look at an example:
- For a 2,000 gallon dry system, a correctly sized fire protection air compressor gives you 24 CFM.
- A correctly sized dry air generator gives you about 20 CFM.
- A correctly sized nitrogen generator set at 98% purity? You’ll get about 0.6 CFM.
That’s less than 3% of the original flow from the compressor. And that’s not just a little drop – it’s a complete chokehold on your system’s ability to respond to leaks. So why does this restricted air flow from nitrogen generators matter so much in cold storage?
Because leaks happen. Especially in cold storage systems. Think about what these systems go through:
- Constant vibration from forklifts and pallet movement
- Expansion and contraction from extreme temperature differentials
- Aging gaskets, shifting racks, valve wear
- Condensation and freezing cycles in poorly maintained or aging systems
Leaks form. And they get worse for a variety of reasons in the field.
When you have a nitrogen generator that can only push a trickle of gas into the system (because it’s filtering 98% pure nitrogen), it doesn’t take much for that flow to get outpaced by even a modest leak. Once that happens, you’re on a slippery slope:
1. System pressure starts dropping
2. Nitrogen generator runs continuously trying to keep up
3. Run-time or low-pressure alarms trip
4. System may accidentally trip, dumping water into a freezer space
You’re now facing a costly emergency, product loss, and possible system shutdown. And when that generator can’t keep up anymore, your only option is to flip it into air mode and start leak hunting. In a freezer. That means:
- Spraying soapy water on overhead pipes 30 feet up
- Using ultrasonic sensors with compromised sensitivity due to low temps
- Introducing scents into the piping network and trying to sniff the leaks out.
Meanwhile, a dry air generator – delivering 30x the flow – absorbs those minor and moderate leaks without skipping a beat. It keeps the system pressurized, keeps you compliant, and buys you time. Weeks, months, sometimes years before you need to chase leaks.
Freezer rooms need reliability. They need flow capacity. They need forgiveness. High-purity nitrogen generators don’t offer any of that.
Dry air does. And that’s why it’s the right choice.
The Best Solution: Dry Air Pac®
General Air Products’ Dry Air Pac® has been dutifully serving as the air supply in freezer room and cold storage fire sprinkler systems for over 25 years and the issues mentioned here are why it works where other technologies run into costly struggles and freezer room down-time. In addition, dry air is almost always a lower cost solution than a nitrogen generator.
As mentioned in the beginning of the article, all of these technologies have pros and cons. Standard compressed air is the least expensive but does contribute to corrosion to varying degrees. Nitrogen generators reduce corrosion best where there are large amounts of standing water in the fire sprinkler system, and dry air generators are best applied where there are small amounts of standing water, such as in freezer rooms. Both nitrogen and dry air generators are maintenance intensive – filters must be changed or the units will not perform as designed.
It is for all of these reasons that we definitively tell our customers that they should use a dry air generator on their cold storage or freezer room dry pipe sprinkler systems. Every time.
And now, we’ve made Dry Air Pac® even better.
Introducing the Dry Air Pac® Advance Series.
The new Advance Series is the most reliable, efficient, and user-friendly dry air solution we’ve ever offered. With upgraded desiccant towers for improved moisture removal, an intuitive digital control panel, and easy-access push-connect fittings for simplified maintenance, the Advance Series is purpose-built to handle the demands of freezer rooms and cold storage fire protection systems.
Learn more here.