Just like doctors, lawyers and other engineers, the world of Commercial Kitchen Ventilation (or CKV) has its own jargon that can take simple concepts and make them feel like a complicated word salad.
“When the pressure differential of your CKV is >5 kPa, the SP resistance is too great to allow your required CFM to be removed at the optimal FPM of air flow to capture grease particles of 8 microns or smaller.”
Huh?
Nobody wants to be the person to stop a meeting to ask for clarification on items everyone else seems to understand. While not everyone will be a CKV expert, there are concepts that can help conversations make more sense to everyone.
Consider this a peek behind the CKV jargon curtain.
Air Flow
Air flow is one of the most common concepts discussed. Let’s take a look at an example:
“A hood is designed for 250 CFM PLF” or “This hood exhausts 2,500 CFM.”
PLF stands for Per Linear Foot, which is just a fancy way to say length. UL listings measure air flow based on the length of the hood. The longer the hood, the more air you remove. Makes sense, right?
In this example, for every foot of hood, 250 additional CFM is removed from the space (a 10-foot would exhaust 2,500 CFM).
I know what you’re thinking. But what’s CFM? It stands for Cubic Foot per Minute. Great! But what’s that mean exactly? CFM is a measure of how many cubic feet of air are pulled out of a hood every minute.
A simple way to think of it: a cubic foot is about the same as a basketball. A hood’s CFM rate, therefore, is about how many basketballs worth of air are pulled out of it every minute. Around 2,500 basketballs every minute? That’s a lot of air!
Static Pressure
Static pressure (or SP) is a measure of resistance, either in WC (inches of water column in imperial systems) or kPa (kilopascal in metric). These are used to measure how hard a fan has to work to move the amount of air we need. I think it’s easiest to think of these in terms of drinking straws.
If you have a wide, straight boba straw, you don’t have to try very hard to get a drink. Let’s switch that to a cocktail straw or one of the kids’ loopidy loop straws that doesn’t get clean in the dishwasher (you know the ones). You have to work two or three times as hard to get a drink. That’s because of the extra resistance – or higher static pressure. This happens in a kitchen when you aren’t bringing back as much air as you are exhausting.
Microns
Microns are a measurement of diameter, essentially measuring how big (or small) the individual grease particles are floating in the air. The diameter of a human hair is about 75 microns, so we’re talking about some tiny grease particles!
Let’s Take Another Look at That Jargon
Now that we understand some of the jargon, let’s breakdown that first example again.
“When the pressure differential of your CKV is >5 kPa, the SP resistance is too great to allow your required CFM to be removed at the optimal FPM of air flow to capture grease particles of 8 microns or smaller.”
What this is saying is that our kitchen has too much negative pressure for the air to move at the right velocity, which isn’t allowing us to capture all of the grease particles. Now that makes sense!
When you apply that to saving money, it makes even MORE cents…sense (sorry, got money on my mind). If you’re pulling out 2,500 basketballs, there needs to be 2,500 basketballs returned to the space. Every one of those basketballs needs to get heated or cooled every minute to be in line with the ambient temperature of your kitchen.
If you exhaust fewer basketballs, you won’t have as much to heat and cool. If we were to use the Eco Arch energy efficient hood, we could reduce the exhaust from 2,500 to 1,500. Think about how much money could be saved by not heating and cooling those 1,000 additional basketballs every minute. Those costs add up.
And because hoods exhaust to the outdoors, all of those heated and cooled basketballs aren’t comforting your customers. Those thousands of basketballs are floating outside…every minute!
There are many different hood styles, systems, and products to fit the different types of installations, restaurants, and equipment layouts of today’s commercial kitchens. Choosing the right one can be tricky, but we’re here to help.
Let Avtec’s Design Specialists help you select the right hood and design your system today.
Jefferson Kenney
Design & Product Specialist – Ventilation
Electrolux Professional Group – Avtec
800-621-8560 EXT 6492
