The motorsports industry is one of the most highly competitive in the world today. Racing teams are always on the look for even the slightest advantage over other teams. With this highly competitive market, comes a tremendous opportunity for gas distributors and equipment manufacturers to aid in the development of new products and/or processes to make cars go faster and pit stops go smoother.
For many years, NASCAR, IRL, CART and other racing leagues have given little thought to enhancing the performance of gas pressure and flow control equipment. Recently, however, teams have begun to realize that this is an area that can yield significant improvements in reducing pit stop times and saving costs on equipment.
All teams use welding gases (Ar, CO2) to build and customize the frames. In addition to these traditional welding gases, a tremendous amount of nitrogen is used to power pneumatic tools and to suspend the cars during pit stops. Most teams have large portable carts that house from three to six nitrogen cylinders and teams almost always have more than one cart, so, if problems arise during a competition, a duplicate setup is readily available. Considering that there are hundreds of professional racing teams and thousands of amateur teams in the U.S. alone, this is a huge gas and equipment market. And worldwide, professional racing is even more popular than in the U.S.
Aside from welding gases, there are primarily two areas of gas usage in motorsports; tire removal and on-board suspension systems. Tire removal guns are usually custom-made for the particular tire configuration. NASCAR and IRL, for instance, may not secure the wheels the same way. The nuts that secure the wheels are very high torque and require high flow impact guns to remove. Typical working pressures are in the range of 150-350 psig for these guns. To avoid restrictions and to insure adequate flow, engineers must be careful to correctly size their compressed gas regulator feeding these guns. The flow rate of the supply regulator as well as the downstream hoses and fittings will directly affect how quickly wheel nuts can be removed. A regulator which has a small flow coefficient (Cv) will be restrictive and not deliver the necessary volume of gas to the gun, or, may require excessive pressures (more than the gun is rated for) to reach the flow rates needed to quickly remove the nut.
On-board suspension systems are primarily used in IRL, CART and Formula 1 racing. NASCAR, ARCA and Busch racing leagues use manual car jacks during stops. These on-board suspension systems use nitrogen or compressed air along with pneumatic cylinders or pumps to lift the car. The primary goal is to jack the car up in the least amount of time during a stop. Properly sized, a nitrogen flow control system can accomplish this in about 0.9 – 1.2 seconds. Typical working pressures are 400-600 psig. Many teams are trying to use off the shelf welding regulators for this application. Standard welding regulators are much too flow restrictive to work optimally for this operation and will result in increased pit times.
When designing a pressure and flow control system it is imperative that each individual component be carefully evaluated for its suitability based on the intended flow requirements. For motorsports, engineers should look at the compressed gas regulator, the quick-connect fittings and the flexible hose or pipe used. The following give some general guidelines for choosing these components.
Compressed Gas Regulators
Many engineers in the racing field fail to properly size a nitrogen regulator for its intended use. For instance, standard welding regulators have flow coefficients in the 0.1 to 0.3 range.
The flow through these regulators would be adequate if working pressures were in excess of 500 psig, but most pneumatic tools are not rated for pressures this high. In fact, most teams use no more than 250 psig for wheel guns. In this case, regulators with a 400-500 psig output range should be used. This will allow for adjustments due to pressure drops through fittings and hoses.
Engineers should use compressed gas regulators with a Cv of no less than 0.5. Most regulator manufacturers publish the Cv information in their product catalogs or, if not, this information would be readily available by contacting the manufacturer. Also, look for regulators with outlet ports larger than ¼” NPT.
Many times a regulator may have adequate flow capacity, but the outlet fitting is too restrictive. Outlet pipe fittings of at least 3/8” NPT, Schedule 80 should be used. Schedule 40 fittings can be used if the working pressures of the fitting are not exceeded.
Do not make the mistake of using piston-type regulators for motorsports applications. Engineers should always use diaphragm regulators for pressures less than 1000 psig, particularly in applications where high flow rates are needed at relatively low pressures. Piston regulators have low Cv’s, and very poor flow regulation. This commonly results in large changes in the flow rate if small changes in regulator outlet pressure occurs. Also, flow decreases, as cylinder pressure decays, more rapidly than diaphragm regulators.
It only takes one weak link to break down performance in a flow control system. Your regulator may be able to part the Red Sea, but if the quick-connect fitting is not sized properly, you will not have an adequate flow rate. Quick-connect fittings are very important to racing teams because of the need to quickly change from one setup to another. There are literally thousands of these fitting in the market. It is extremely important to choose a quick-connect with a larger Cv than the regulator to insure that it will not restrict regulator flow. Most teams use connectors with a Cv of at least 1.0. Fittings this size will typically have 3/8” or ½” pipe fittings.
Likewise, the hose used needs to be oversized to insure it is not flow restrictive. Some consideration needs to be given to the length of the hose or pipe. A minimum ½” I.D. hose should be used if the length is 12 feet or less. If hoses need to be longer, a 1” I.D. hose would be advisable. Also, a pressure drop will normally occur through a given length of hose, so this may need to be accounted for in setting working pressures.
If these general guidelines are followed, racing teams can realize optimal performance with their pressure and flow control equipment. Several Cart, IRL and NASCAR racing teams have already redesigned their equipment and are reaping the benefits of a properly designed nitrogen system in shorter pit stop times. This is no small victory because, in this industry, 1 second at 200 mph will put you 293 feet closer to that checkered flag.
David Gailey is the manager for Specialty Products for The Harris Products Group, A Lincoln Electric Co. He has been with Harris for 27 years and served as past chairman of the CGA Industrial Gas Apparatus Committee.