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Negative Air Machine: The Complete Guide

Last Updated July 27, 2021

What is a Negative Air Machine?

Negative air machines are used to remove potentially harmful pathogens from the air. They are often used to clean the air in a room, and can often be found in hospitals, job sites, factories, commercial buildings, any confined spaces with mold, asbestos, etc, and can also be used in the home.

These machines create negative or positive air pressure. By creating negative air pressure, a room is isolated, and any potentially hazardous pathogens are isolated in the room. When positive air pressure is created, the room is protected, and outside air (and the harmful pathogens) are not let in.

The Best Negative Air Machine for Purchase

BlueDri Negative Air Machine

www.amazon.com/BlueDri-Industrial-Commercial-Purifier-Negative/dp/B01JHI66VC

This negative air machine also comes with a HEPA filter and will create negative and positive air while also filtering the air to get rid of pathogens, allergens, and other dirt and dust in the air. 

The machine measures 14” x 25” x 20”, and is large enough to clean the air in an entire house (small-medium living area). It will remove harmful airborne particles, including pollen, dust, smoke, pet dander, mold, and more.

With a 1-year part and a 5-year housing warranty, your home will be protected for a long time.

How does a Negative Air Machine Work?

Negative air machines have blowers that push air through a series of filters to clean the air. By creating negative pressure, air flows from areas of high pressure to areas of low pressure. 

This can mean taking the air from a room and expelling it or pumping air into a room to create a clean environment. Either way, the air is passed through pre-filters and primary filters (often HEPA) to remove dirt particles from the air. 

What is HEPA?

HEPA stands for High Efficiency Particulate Air. 

These filters are able to trap 99.97% of particles that are 0.3 microns. This size of particle is the one that gets through filters the most, so a standard needed to be set to create effective filters.

HEPA filters use a combination of direct impaction, sieving, intercept, and diffusion to remove these small particles.

When you are looking for a negative air machine with a HEPA filter, look for ‘True HEPA.’ True HEPA usually captures more particles than regular HEPA.


Uses for a Negative Air Machine

There are many places where a negative air machine is used, and we will highlight how they are effective by talking about their use in hospitals. From there, you will see how they can be applied to other spaces, such as factories, commercial buildings, and job sites.

Negative pressure will isolate a room, and this stops pathogens from leaving a room. So, if a patient is highly infectious, negative pressure can be used to isolate the pathogens in the room, stopping them from getting out.

With positive pressure, take the example of an immunocompromised patient. You do not want harmful pathogens getting in, and positive pressure stops them from doing so.

Basically, negative pressure protects people outside of the room, and positive pressure protects those inside the room.

Negative Air Machine vs. HEPA Air Scrubber

Negative air machines are generally used for larger areas compared to air scrubbers. At their heart, both filter the air, but it is only the negative air machine that changes the air pressure in a room by filtering the air outside or moving the air between two spaces.

Air scrubbers will take the air and recycle it, removing the airborne pathogens. They do this using negative particles and UV light (though there are other methods).

Air Purifiers vs Negative Air Machines

Generic Air purifier

An air purifier has a series of filters that trap contaminants. As air is circulated, it passes through these filters, and each one filters out different things. They are closely related to negative air machines but perform differently due to the air circulating through them.

Air constantly circulates with an air purifier, but will be drawn from one space to another with a negative air machine.

How Big a Negative Air Machine Do You Need?

The easiest way to determine the size of the negative air machine that you need is to use the size of your building and the volumetric rate of the machine. The volumetric rate will be found on the machine, but you may have to measure your space yourself.

Take the length, width, and height of your space, and multiply them together to get the volume (in feet). Divide that by the volumetric rate of the negative air machine to get the number of minutes it will take to process the air in the building. Divide that by 60 to get the number of air changes per hour. 

Finally, divide 6 by the number you got (the industry standard for the number of air changes per hour). The final number is the number of machines that you need for your space.


How to Set Up and Use a Negative Air Machine

Setting up your negative air machine is essential for it to work properly. Your machine will come with operating instructions, and we recommend following them exactly, but there are some important points to keep in mind with any negative air machine:

Monitor the air pressure in the containment area and adjust as necessary.

Ensure that the machine is expelling the air from the room and is hooked up properly.

Always keep the area enclosed when the negative air machine is operational.

How and When to Replace Filter 

The answer will depend on the type of filter that you are using and how often you are running the machine. Let us assume that you are using a HEPA filter, you are running the negative air machine constantly.

You can expect the primary filter to last a day before you need to change it, and the secondary filters can last up to seven days. For a HEPA  filter, around 800 hours is standard.

The lifespan of the filters will depend a lot on what is being filtered, the temperature, humidity, and other external factors.

Can You Rent a Negative Air Machine?

Yes, you can.

The rental rate will depend on the duration of the rental and the size and type of machine. Contact your local hardware or rental store and you should be able to find the right rental for you.


Which Air Filtration System is Right For You

What are you looking for in air filtration?

If you need standard air purification, then a regular air purifier can work well. This is perfect for an office or home that is small, and you can find ones with filters that will remove odors too.

If you want something that is part of your HVAC system, you can find air purifiers and air scrubbers that can be attached to your furnace and AC, and will filter the air as it circulates.

If you need something a little more heavy duty and are worried about pathogens, mold, or other hazardous particles, then a negative air machine will stop these from escaping into other rooms or from contaminating a clean-air area.