Having a portable air system in your vehicle will prove to be an invaluable asset, and you will find yourself wondering why you didn't have one long ago. The obvious use for a portable air source is tire inflation. However, it may also be used for almost any inflation need, such as inflating air mattresses or toys at the beach, blowing the sand and dirt off your equipment before stowing it away, and some even use it to run air tools like impact wrenches and pneumatic nail guns. The information supporting proper tire inflation is irrefutable and has been published ad nauseam and will not be repeated in this article.
| portable Vehicle Air Systems single Purpose Kit
Given the variety of driving conditions and terrain, one pressure certainly does not work in all applications. Case in point is traversing sand: Enter a sandy area at a street tire pressure-be it 45 or 75 psi-and you will discover travel to become painfully slow with extremely high rpm. Significantly lower the tire pressure and you will quickly be on your way. Although, if you do not have an adequate inflation method for when you return to the road, it is highly unlikely you will consider airing down. A portable air system is one of those mandatory items that should be included on the don't-leave-home-without-it list. A portable air source is a worthwhile investment for people looking for a convenient, lightweight, easy-to-use air system.
Today, there are basically two families of portable air systems-they either plug in or clip onto the vehicle's battery or are a compressed cylinder filled with some sort of gas. The common air compressor has been around for more than 100 years, because air as a resource is safe, flexible, clean, and convenient. The most common type of compressors work by filling a chamber with air and reducing the chamber's volume, which is similar to an internal combustion engine-except no fuel is added. When the air is compressed, a significant amount of heat is generated, and heat kills moving parts. When the temperature of the compressor reaches the preset level, a switch will activate and shut off the motor to prevent damage. Therefore, all the portable air compressors we tested have automatic, internal thermal cut-off switches.
| Single-purpose group timed tire inflation testing-30 minutes was the maximum time allowed to perform a task
The second family of portable air systems we tested is carbon dioxide (CO2) gas cylinders. A CO2 cylinder is filled with liquid CO2 by weight-usually 10-, 15-, or 20-pound tanks. The liquid inside the tank evaporates and pressurizes the tank based on its temperature. At room temperature, the pressure inside the tank is approximately 860 psi and is directly proportional to temperature. When the gas is released, the pressure inside the tank drops and so does the temperature. This is why aerosol cans get cold when used too long. As the gas is expelled from the tank, more liquid CO2 boils off as gaseous CO2, and this process of evaporation continues until all the liquid CO2 is gone. For that reason, the CO2 tank pressure is constant until it is almost gone. Because the CO2 is stored in a liquid state, the same size cylinder has more than 50 times the volume of compressed air and 5 times the volume of nitrogen. When outfitted with a quality pressure regulator, CO2 systems can be used for numerous tasks beyond tire inflation, including pneumatic tool operation. For these reasons, CO2 systems are a popular choice for portable air sources.
We tested 12 different portable air systems and have categorized them into two groups (single- and dual-purpose) based on their ability to inflate a tire and run an air tool. We ran each one through a series of tests while monitoring parameters such as temperature, sound pressure level (SPL), and the amount of walking during use. All units were tasked to perform the following tests five times:
Inflate a single 35x12.50x17 tire mounted on a vehicle from 15 to 45 psi
Inflate all four 35x12.50x17 tires from 15 to 45 psi-within 30 minutes or thermal shutdown, whichever occurred first
Inflate a spare ST235/80R16 RV tire from 15 to 80 psi-within 30 minutes or thermal shutdown, whichever occurred first
| The portable air sources we tested included lightweight and heavy-duty 12-volt air compressors, as well as liquid CO2 systems. All of these units are designed with tire inflation in mind, and some of them may even be powerful enough to run air tools.
The second group (dual-purpose) performed the aforementioned three tasks as well as the following:
Remove eight-lug nuts tightened to 100 ft-lb with a 1/2-inch drive impact wrench
Drive three 3 1/2-inch lag bolts into a piece of 4x4 lumber
Similar to the previous testing, each task was performed five times to obtain an average time for comparison.
As innocuous as these tests may appear, there were casualties. The failures ranged from a dead battery, tire chuck malfunction, blown fuses, and a burnt air hose to failed one-way check valves, leaking pressure gauges, and two complete air compressor motor failures.
| portable Vehicle Air Systems single Purpose Results
This comparison test is not intended to declare a winner or supremacy but to allow the reader to select the system that best suits his or her individual needs. The timed results were as widespread as the price ranges-from less than $80 to tipping the scales at almost $900 with accessories. The results reveal that these units have come a long way from the 12-volt compressor that used to plug into the cigarette lighter. The following guide represents our findings and should prove useful for determining which portable air system is right for your needs.
Single-Purpose Portable Air Source Group
The single-purpose portable air source group's primary function is tire inflation; therefore they were tested to determine how well they performed that task. The equipment in this group does not have an attached or auxiliary reservoir to store compressed air or the necessary CFM delivery rate to adequately run air tools.
| portable Vehicle Air Systems single Purpose Kit
How we tested:
For the single- and four-tire inflation test we took advantage of the tire pressure monitor system (TPMS) installed on our '07 Chevy 2500HD to determine the pressure of the 35x12.50R17 General Grabbers. We used automatic tire deflators to ensure the tire(s) was deflated to 15 psi before each test. See the sidebar about these must-have devices if you frequently change the pressure in your tires. Each test run was timed, measured for loudness, and the before and after temperature was noted.
For the single RV tire inflation test we used a ST235/80R16 Power King Towmax tire. It too was deflated using the same automatic tire deflator set to the starting point of 15 psi. Since this tire did not have a TPMS, we used each unit's own air pressure gauge to determine the stopping point, which was 80 psi. Because of pressure gauge inaccuracy, we calibrated each unit's gauge before the test and applied the necessary offset to ensure an accurate test. Incidentally, the range of gauge inaccuracy was 0 to 8 psi from 45 to 80 psi. Similar to the previous testing, each run was timed, measured for loudness, and before and after temperatures were taken.
| A testament to the high quality of the ARB CKMP12 system is the field-repairable air hose fittings. Using common handtools, simply unscrew the two halves, remove the offending area, and screw back together.
Each test was conducted five times to obtain an average time for comparison.
ARB 4x4 Accessories
Manufacturer: ARB 4x4 Accessories
Website: www.arbusa.com
Model: CKMP12 Portable Air Compressor kit
Price: $332.00
Maximum Pressure Rating: 150 psi
Airflow Rating: 2.65 cfm at 0 psi, 2.18 cfm at 29 psi
Power: 12-volt and 22.3-amp
Power cord: 7-foot cord with 4-inch< alligator clamps and a 40A Maxi-blade-type fuse
Duty cycle: 50 percent or 30 minutes per hour
Safety: Automatic thermal shutoff protection; pressure switch for 105-psi on and 150-psi cutoff, with 185-psi safety valve
Weight: 17 pounds
Warranty: 2 years
Portability: Durable plastic toolbox
Included Accessories: 20-foot, heat-resistant (290 degree) air hose with one-handed push-lock male and female U.S.-industrial standard (I/M) air fittings; I/M clip-on tire chuck; I/M to Schrader valve-style adapter for ball inflation; and generic air nozzle attachments
Features: Hose couplers are one-hand style and the air filter is serviceable
Impressions: The ARB CKMP12 air compressor is mounted inside a handy plastic toolbox, which is very convenient for storage of supplies and accessories. At 99.60 dB, it was the loudest in the single-purpose group. The coupler on the compressor gets extremely hot and should have a warning label. The unit got so hot it melted a hole in the air hose, stopping the four-tire inflation test. Fortunately, the hose has field-repairable couplers. An illuminated power switch confirms power to the unit. The clip-on air chuck malfunctioned during the four-tire inflation test. A dimple in the end would have prevented it from coming off. The power cable is sleeved from the motor up to the massive inline fuse near the battery clamps; our guess is that it protects the power cable from the heat generated by the compressor-nice touch.
| portable Vehicle Air Systems arb Kit
Brand-X
Manufacturer: Brand-X
Price: $79.99
Maximum Pressure Rating: 150 psi
Power: 14.5-volt and 23.9-amp
Power cord: 8-foot cord with 4-inch alligator clamps and a 30A blade-type fuse
Duty cycle: 50 percent or maximum continuous operation 40 minutes
Safety: Automatic thermal shutoff protection
Weight: 14 pounds
Warranty: 1 year
Portability: Zippered nylon bag with two pouches
Included Accessories: 1/4-inch x 16-foot coiled air hose with built-in 0-to-150-psi pressure gauge; quick-disconnect coupler to air compressor (the other end has a coupler to thread onto a Schrader-style valve stem, or what the company calls an E-Z twist brass inflator); E-Z inflator clip on tire chuck; two general-purpose inflation nozzles; and a sport-ball inflator
Impressions: Two units died during testing, the second one arrived with a broken positive battery clamp, and the rubber gasket inside the air chuck was not properly seated. The first compressor got so hot the intake air filter melted and fell off the unit.
| portable Vehicle Air Systems brand X Air Compressor
Masterflow
Manufacturer: MasterFlow (subsidiary of Q Industries)
Website: www.masterflowair.com
Model: MF-1089 Portable Air Compressor
Price: $149.99
Maximum Pressure Rating: 150 psi
Airflow Rating: 3.17 cfm at 150 psi
Power: 14.50-volt and 35.5-amp
Power cord: 9-foot cord with 3.5-inch alligator clamps, an integrated power switch, and a resettable fuse
Duty cycle: 50 percent or maximum continuous operation 40 minutes
Safety: Automatic thermal shutoff protection
Weight: 20 pounds
Warranty: 2 years
Portability: Single pouch zippered nylon carry bag
Included Accessories: A 1/4-inch x 24-foot coiled air hose with built-in 0-to-150-psi pressure gauge; quick-disconnect coupler to the air compressor (the opposite end has an E-Z twist brass inflator coupler); E-Z inflator clip on tire chuck; two general-purpose inflation nozzles; and a sport-ball inflator
Features: Storage container for air nozzle accessories built into body of the compressor
Impressions: The MasterFlow MF-1089 is a dual-motor air compressor system. It has a 20-inch leader hose to protect the primary air hose from excess heat. It is fast and consumes a bit of current, so the vehicle should be running while in operation. The unit is mounted to a tray via shock isolators to prevent it from walking. The handle rotates downward for stowage.
| portable Vehicle Air Systems masterflow Air Compressor
The MasterFlow MF-1089 was the fastest air compressor in the single-purpose group. The average time to fill the 35x12.50x17 LT tire was 3 minutes 54 seconds.
| portable Vehicle Air Systems masterflow Air Compressor
Superflow
Manufacturer: SuperFlow
(subsidiary of Q Industries)
Website: www.superflowair.com
Model: MV-50
Price: $79.99
Maximum Pressure Rating: 120 psi
Airflow Rating: 1.06 cfm at 150 psi
Power: 14.5-volt and 20.2-amp
Power cord: 8-foot 3-inch cord with 4-inch alligator clamps and a 30A blade-type fuse
Duty cycle: 50 percent or 40 minutes continuous operation
Safety: Automatic thermal shutoff protection
Weight: 12 pounds
Warranty: 2 years
Portability: Zippered nylon bag with two pouches
Included Accessories: 1/4-inch x 16-foot coiled air hose; quick-disconnect coupler to the air compressor (the opposite end has an E-Z twist brass inflator coupler); E-Z inflator clip on tire chuck; two general-purpose inflation nozzles; and a sport-ball inflator
Features: Pressure gauge is mounted to the head of the air compressor
Impressions: The SuperFlow MV-50 is a deceptively powerful air compressor given its small size. The air gauge is built into the body of the compressor and has an indicated accuracy of ± 10 percent. Operational noise level is a little above average, but not too loud. It is not mounted to a plate. Instead, the rubber shock isolators are used as the feet of the unit, and they do a decent job of keeping the compressor in one spot.
| portable Vehicle Air Systems superflow Air Compressor Mv50
Superflow
Manufacturer: SuperFlow (subsidiary of Q Industries)
Website: www.superflowair.com
Model: MV-90 Portable Air Compressor
Price: $199.00
Maximum Pressure Rating: 150 psi
Airflow Rating: 2.54 cfm at 150 psi
Power: 14.50-volt and 35.5-amp
Power cord: 6-foot 4-inch cord with 3.5-inch alligator clamps (future units will have an 8-foot power cord)
Duty Cycle: 50 percent or 40 minutes continuous operation
Safety: Automatic thermal shutoff protection, 150-psi safety pressure relief valve, and resettable circuit breaker
Weight: 22 pounds
Warranty: 2 years
Portability: Single pouch zippered nylon carry bag
Included Accessories: 1/4-inch x 16-foot coiled air hose with built-in 0-to-150-psi pressure gauge; quick-disconnect coupler to air compressor (the opposite end has an E-Z twist brass inflator); E-Z inflator clip on tire chuck; two general-purpose inflation nozzles; and a sport-ball inflator
Features: Air compressor is mounted to tray via shock isolators to prevent compressor walking. However, it walked to most of the single-purpose compressors.
Impressions: The SuperFlow MV-90 is fast and big. It's a great compressor, but the power cord is too short-fortunately, it will be lengthened for future units. The air hose should be longer, too. The rubber leader hose is intended to prevent the plastic hose from heat failure, but it still allowed the hose to get hot enough to deform. It is quiet while running like the units from Viair. The handle is a metal sleeve, which is drilled for air cooling, but it still gets hot.
| portable Vehicle Air Systems superflow Mv90
VIAIR
Manufacturer: Viair
Website: www.viaircorp.com
Model: 400P-A Automatic Portable Air Compressor
Price: $250.00
Maximum Pressure Rating: 150 psi
Airflow Rating: 2.45 cfm at 0 psi
Battery Requirements: N/A
Power: 14.50-volt and 17.3-amp
Power cord: 8-foot 5-inch cord with 4-inch alligator clamps and a 40A blade-type fuse
Duty cycle: 33 percent (15/30 on/off) or 40 minutes continuous operation
Safety: Automatic thermal shutoff protection; 120-psi
on and 145-psi cutoff pressure switch
Weight: 17 pounds
Warranty: 1 year
Portability: Nylon bag with two zippered pouches and two side pockets (one with a Velcro flap and one without a flap)
Included Accessories: 1/4-inch x 25-foot coiled air hose with rubber-insulated 3/8-inch I/M female quick-disconnects, tire inflation gun with 200-psi gauge, and two extra replacement air intake filters
Features: Gearless direct-drive motor with a high-performance PTFE piston ring
Impressions: The 400P-A is lightweight and compact and ultra-quiet during operation. The air compressor is mounted to a diamond-plate tray via shock isolators to prevent compressor walking. It is one of the quietest air compressors of the bunch. The hose requires an I/M air chuck, whereas others have a threaded air chuck. The air gauge has a big-dial face (3 1/4 inch) that shows 0 to 200 psi and may also be used to deflate air from the tire. The hose has insulated boots to protect the user from heat generated while filling tires.
| portable Vehicle Air Systems viair 400p
Manufacturer: Warn
Website: www.warn.com
Model: SPC Air Compressor
Price: $162.49
Maximum Pressure Rating: 150 psi
Airflow Rating: 1.5 cfm at 0 psi, 1.0 cfm at 90 psi
Battery Requirements: 12-volt 650 cold cranking amps
Power: 14.50-volt and 20.3-amp
Power cord: 10-foot 8-inch cord with 4.25-inch alligator clamps and a 50A inline blade-type fuse
Duty cycle: Run for 10 minutes or less
Safety: Automatic thermal shutoff protection
Weight: 14 pounds
Warranty: 1 year limited warranty
Portability: Zippered nylon bag with two pouches
Included Accessories: 1/4-inch x 25-foot coiled air hose with built-in 0-to-150-psi pressure gauge, quick-disconnect coupler to air compressor (the other end has a coupler to thread onto a Schrader-style valve stem), two tips for inflation of air toys, and a sport-ball-inflating needle valve
Impressions: The Warn SPC is a dependable compressor. It is a bit slower than the others but gets the job done. It has a nice, long power cord (10 feet, 6 inches) that makes filling tires easy without the worry of accidentally disconnecting the battery clamps. The pressure gauge dial reads out 0 to 150 psi (with 5-psi divisions) with a redline at 115 psi. An insulated, cushioned handle provides a soft grip and protects user's hands from heat. It is mounted to the tray via shock isolators to prevent compressor walking.
| portable Vehicle Air Systems warn Spc
