In the May 2016 issue a very good article appeared on the use of Air Pressure Boosters, by Mark Quasius. As a pneumatic specialist in fluid power and having worked with this and other industrial components a couple of clarifications:
The statement on a booster functioning as a transformer is slightly off. While it does increase the pressure, it does consume compressed air to do so. Typically at this pressure increase ratio 1/2 of the incoming flow will be used in work and exhausted to atmosphere. A transformer changes the voltage at reduced output amperage but the work to do so (efficiency) is expressed as 97%-99% so only 1%-3% of the energy (heat) is used to transform the voltage. In the air booster it is only 50% efficient hence a big difference in energy consumed.
On the size rating, the VBA20A is good for filling large amount of tires, small tanks that start at lower pressures, but is overkill for single tires where you are topping off the pressure to 120psi where you have a supply of 100 psi. Looking at his coach's supply of 18.7 SCFM the larger booster will use that and more if the vessels being pressurized are numerous and nearly empty. The smaller booster VBA10A-N02GN will work just as well in this environment at a typical cost of $278.75 net each, prices may vary. Only the amount of time it takes to get from and to a given pressure changes, the smaller booster will take longer but we are talking a few seconds difference more not minutes.
An advantage of the smaller booster is the use of 1/4" NPT pipe fittings instead of 3/8", most hose whips you buy locally are of the 1/4" NPT size for filling tires, then you don't need adapters to hook it up. And the VBA10A is half the length of the VBA20A, easier to find a hole to tuck it into.
Word of caution with this smaller booster, it has the capability of a true 2X supply pressure so can produce 240psi from a supply of 120psi and this must be avoided. The VBA20A is maximum of 150psi output. Setting the output pressure to 140psi is within the range of most available hoses, components but don't try filling the tires to this at all! The author's recommended hookup is on the mark, but I would add one statement. When you don't need the booster disconnect it using the quick connect from supply, or install a on/off (ball valve) prior to the booster to shut it off when not needed. The booster will always try to generate pressure to the outlet set point and if even a small leak occurs you could be using a lot of coach or compressor air and not even know it!
While you can purchase them from SMCPNEUMATICS.com, they are the California distributor of SMC products. See www.smcusa.com for a complete list of local distributors in the USA and Canada. Here is the NE it is www.airlinehyd.com for this product, see; http://www.airlinehyd.com/Webpages/Orderonline/P21Manufacturersearch.aspx?item_number=VBA10A-N02gn-Z for more info.
'09 Monaco Monarch with wife and dog. Still working.