See the AirDog®'s Fuel Preporator® remove air from the fuel in a model of a typical diesel fuel system. Charles Ekstam, the inventor, walks you through the demonstration.  



The entrained air/vapor is removed from the fuel flow before the fuel passes through the filter media. The separated air and vapor is then returned to the fuel tank.


The Industrial AirDog®, with the 4G-HD pump and Microprocessor fuel filter monitor, is our most advanced system to date.

The 4G-HD (4th generation heavy duty) pump!

Where as the older pump design integrated the motor with the pump, the 4G pump has the motor and pump assembly as two separate units that mate together. The motor face matches the pump face with the shafts connecting through a “Butterfly” socket. This allows the motor to be removed and replaced in literally, a matter of minutes. A bushing in the "Butterfly Socket" prevents metal on metal contact of the two shafts and extremely quiet operation.

“Vacu” Seal Technology!

All AirDog® pump system's shaft seals operate under vacuum instead of pressure. This  eliminates pressure in the seal bore and extends the useful life of the seal, which also increases  the life of the pump.


Microprocessor For Commercial Trucks

The Microprocessor Fuel Filter Monitor!

In the past, a pressure switch would sense low pressure to the engine and would turn the orange low pressure indicator light on when the flow to the engine dropped below minimum. That monitored both the water separator and the fuel filter condition and left a little to be desired.


The NEW Microprocessor fuel filter monitor LED indicator light, which turns GREEN when the engine is started, turns to FLASHING GREEN when the flow to the engine drops below minimum. This will happen when the water separator becomes plugged and restricts the fuel flow to the AirDog®. As the fuel filter plugs with use, the pressure between the pump and the filter increases. When the pressure reaches the point that the filter should be changed, the indicator light will go from GREEN to RED.  Should the RED light be ignored and the filter is not changed and becomes more restricted, the light will soon start FLASHING RED.


PureFlow® Technologies, Inc.

5508 Business 50 West

Jefferson City, MO 65109

Toll Free:1.877.GO DIESEL


Direct: 1.573.635.0555

Fax:     1.573.635.0778


Hours of Operation


8:00 AM-4:30 PM

Saturday & Sunday



8 PG AirDog Commercial Brochure 2013.pdf
Adobe Acrobat document [1.0 MB]
12 PG AirDog Marine Brochure 2012 with [...]
Adobe Acrobat document [1.3 MB]


How Does Air Become Entrained In Diesel Fuel?


As in all liquids, air becomes entrained in diesel fuel from sloshing and agitation! Air can be on the surface of the fuel in the form of foam or it can be in the bulk fluid in the form of tiny bubbles. Entrained Air is an issue of an "in use" engine in operating equipment!


What is Pump Cavitation?


Pump cavitation, simply put, is the pump not having enough pressure flow, or "Net Positive Pressure Head" of fuel coming into the inlet to completely fill the vacuum chamber of the pump.


Diesel fuel, as is true with all petroleum base liquids, will give off vapor when subjected to a vacuum. The amount of vapor depends upon the level of vacuum and temperature.


How Does Fuel Filter "Restriction" Effect Cavitation?

In the diesel engine industry, "fuel filter restriction" is a term that refers to the vacuum level at the inlet to the transfer or lift pump. It is measured in inches of mercury (in hg).


As the filter plugs with use, it further restricts the flow and increases the vacuum level in the pump.


The amount of vapor produced depends upon the level of vacuum.


What Else Increases Cavitation and Vapor? 


As the fuel levels in the tank(s) goes down as the fuel is burned, the "Dry Suction Lift" increases. This reduces the flow, increasing the vacuum.  


Operating at higher altitudes, where atmospheric pressure is less, reduces the fuel flow and increases vacuum. For example, at Denver,  atmospheric pressure  is about 17% less than at sea level and at Eisenhower Tunnel, it is approximately 32% less. Having less pressure to drive the fuel from the tank to the transfer pump, reduces the flow and increases the vacuum levels.


Higher fuel temperatures cause more vapor to form than cooler fuel under the same vacuum!