Safety should always be a serious concern within industrial environments. Walk through any production facility and you should see all kinds of steps taken to give a safe workplace to the operators, contractors, and other team members. Whether this is through a sign showing PPE required to enter an area, an emergency exit sign, a safe walkway, or machine guards. Safety has become a standard that should never be lowered and there is good reason for that.
EXAIR designs all of our products to be safe and they meet or exceed OSHA standards that are directed toward compressed air safety. The first is to ensure that an operator or maintenance worker will not be injured through air impinging their skin should they come into contact with an EXAIR product. This OSHA standard is 29 CFR1910.242(b) claiming that all point of use compressed air products must be regulated to have less than 30 psig of dead end pressure. This directive is critical for worker safety and the way many blowoffs skirt by is to cross drill holes in the end of the blowoff.
Cross drilled holes may satisfy the dead end pressure standard but it does not address OSHA’s next important compressed air standard about noise exposure, OSHA standard 29CFR1910.95(a). The allowable noise level standard combined with 30 psig dead end pressure will render many home made or retail nozzles near useless because few, if any, meet both standards. Again, EXAIR has engineered and designed our Super Air Nozzles to permit 80 psig inlet pressure and still meet or exceed both of these OSHA standards so that the work can still be done by the operators while remaining safe and retaining their hearing.
For a better explanation and demonstration of how our nozzles meet these standards please see the video below.
While I use nozzles and cross drilled pipes as examples within this blog these safety features are designed into every product that EXAIR offers. This is due to the fact that OSHA, NIOSH, and the CDC do not delineate between a blow gun, blow off within a machine, or even a Cabinet Cooler System. If the device is powered by compressed air then the two key OSHA standard are in effect due to the inherit dangers of compressed air.
I encourage you now to walk through your facility and try to listen or spot compressed air points of use within your facility. Then, I ask you to call, chat, e-mail, or tweet an Application Engineer here at EXAIR and let us help you determine the most efficient and safest product to get the work done.
To understand the value of a having a Pressure Regulator at every point of use we should start with identifying the two types of Pressure Regulators, Direct Acting & Pilot Operated. Direct Acting are the least expensive and most common (as shown above), however they may provide less control over the outlet pressure, especially if they are not sized properly. However when sized properly they do an outstanding job. Pilot Operated Regulators incorporate a smaller auxiliary regulator to supply the required system pressure to a large diaphragm located on the main valve that in turn regulates the pressure. The Pilot Operated Regulators are more accurate and more expensive making them less attractive to purchase. The focus of this Blog will be on the Direct Acting Pressure Regulator.
The Direct Acting Pressure Regulator is designed to maintain a constant and steady air pressure downstream to ensure whatever device is attached to it is operated at the minimum pressure required to achieve efficient operation. If the end use is operated without a regulator or at a higher pressure than required, it result’s in increased air demand and energy use. To clarify this point, if you operate your compressed air system at 102 PSI it will cost you 1% more in electric costs than if the system was set to run at 100 PSI! Also noteworthy is that unregulated air demands consume about 1% more flow for every PSI of additional pressure. Higher pressure levels can also increase equipment wear which results in higher maintenance costs and shorter equipment life.
Sizing of the Air Regulator is crucial, if it is too small to deliver the air volume required by the point of use it can cause a pressure drop in that line which is called “droop”. Droop is defined as “the drop in pressure at the outlet of a pressure regulator, when a demand for compressed air occurs”. One commonly used practice is to slightly oversize the pressure regulator to minimize droop. Fortunately we at EXAIR specify the correct sized Air Regulator required to operate our devices so you will not experience the dreaded “droop”!
Another advantage to having a Pressure Regulator at every point of use is the flexibilty of making pressure adjustments to quickly change to varying production requirements. Not every application will require a strong blast sometimes a gentle breeze will accomplish the task. As an example one user of the EXAIR Super Air Knife employs it as an air curtain to prevent product contamination (strong blast) and another to dry different size parts (gentle breeze) coming down their conveyor.
EXAIR products are highly engineered and are so efficient that they can be operated at lower pressures and still provide exceptional performance! This save’s you money considering compressed air on the average cost’s .25 cents per 1000 SCFM.
Compressed air is used to operate pneumatic systems in a facility, and it can be segregated into three sections; the supply side, the demand side, and the distribution system. The supply side is the air compressor, after-cooler, dryer, and receiver tank that produce and treat the compressed air. They are generally located in a compressor room somewhere in the corner of the plant. The demand side are the collection of end-use devices that will use the compressed air to do “work”. These pneumatic components are generally scattered throughout the facility. To connect the supply side to the demand side, a compressed air distribution system is required. Distribution systems are pipes which carry the compressed air from the compressor to the pneumatic devices. For a sound compressed air system, the three sections have to work together to make an effective and efficient system.
An analogy, I like to compare to the compressed air system, is an electrical system. The air compressor will be considered the voltage source, and the pneumatic devices will be marked as light bulbs. To connect the light bulbs to the voltage source, electrical wires are needed. The distribution system will represent the electrical wires. If the wire gauge is too small to supply the light bulbs, the wire will heat up and the voltage will drop. This heat is given off as wasted energy, and the light bulbs will dim.
The same thing happens within a compressed air system. If the piping size is too small, a pressure drop will occur. This is also wasted energy. In both types of systems, wasted energy is wasted money. One of the largest systematic problems with compressed air systems is pressure drop. If too large of a pressure loss occurs, the pneumatic equipment will not have enough power to operate effectively. As shown in the illustration below, you can see how the pressure decreases from the supply side to the demand side. With a properly designed distribution system, energy can be saved, and in reference to my analogy, it will keep the lights on.
To optimize the compressed air system, we need to reduce the amount of wasted energy; pressure drop. Pressure drop is based on restrictions, obstructions, and piping surface. If we evaluate each one, a properly designed distribution system can limit the unnecessary problems that can rob the “power” from your pneumatic equipment.
Restriction: This is the most common type of pressure drop. The air flow is forced into small areas, causing high velocities. The high velocity creates turbulent flow which increases the losses in air pressure. Flow within the pipe is directly related to the velocity times the square of the diameter. So, if you cut the I.D. of the pipe by one-half, the flow rating will be reduced to 25% of the original rating; or the velocity will increase by four times. Restriction can come in different forms like small diameter pipes or tubing; restrictive fittings like quick disconnects and needle valves, and undersized filters and regulators.
Obstruction: This is generally caused by the type of fittings that are used. To help reduce additional pressure drops use sweeping elbows and 45-degree fittings instead of 90 deg. elbows. Another option is to use full flow ball valves and butterfly valves instead of seated valves and needle valves. If a blocking valve or cap is used for future expansion, try and extend the pipe an additional 10 times the diameter of the pipe to help remove any turbulence caused from air flow disruptions. Removing sharp turns and abrupt stops will keep the velocity in a more laminar state.
Roughness: With long runs of pipe, the piping surface can affect the compressed air stream. As an example, carbon steel piping has a relative rough texture. But, over time, the surface will start to rust creating even a rougher surface. This roughness will restrain the flow, creating the pressure to drop. Aluminum and stainless steel tubing have much smoother surfaces and are not as susceptible to pressure drops caused by roughness or corrosion.
As a rule, air velocities will determine the correct pipe size. It is beneficial to oversize the pipe to accommodate for any expansions in the future. For header pipes, the velocities should not be more than 20 feet/min (6 meter/min). For the distribution lines, the velocities should not exceed 30 feet/min (9 meter/min). In following these simple rules, the distribution system can effectively supply the necessary compressed air from the supply side to the demand side.
To have a properly designed distribution system, the pressure drop should be less than 10% from the reservoir tank to the point-of-use. By following the tips above, you can reach that goal and have the supply side, demand side, and distribution system working at peak efficiency. If you would like to reduce waste even more, EXAIR offers a variety of efficient, safe, and effective compressed air products to fit within the demand side. This would be the pneumatic equivalent of changing those light bulbs at the point-of-use into LEDs.
Many times, when discussing product selection with a customer, we commonly reference supplying as clean and dry air as possible to promote peak performance. In iron piping systems for example, when moisture is present, rust can develop which can reduce the performance of end use compressed air operated devices like air tools or cause issues on the exhaust side as you could exhaust unwanted mist onto a surface, like in a painting operation.
Typically, an efficient and properly installed industrial compressed air system will include some type of dryer to remove any moisture that may be present in the supply.
Let’s take a look at the various types of dryers available.
Refrigerant and desiccant dryers are two of the more commonly used types of dryers.
Refrigerant based systems have several stages. The compressed air first passes through an air to air heat exchanger which initially cools the air. The air is then delivered to an air to refrigerant exchanger where an external source of liquid refrigerant further cools the air and sends it to a separator, where the water vapors condensate and are removed through a drain trap. Now that the air is dry, it is then cycled back to the air to air exchanger where it is heated back to ambient temperature and exits the system.
Desiccant dryers typically incorporate 2 tanks containing a porous desiccant which causes the moisture to sort of “cling” to the surface. In these systems, compressed air flows through one tank, while, using it’s own regeneration cycle, heated or unheated air is blown through the desiccant in the other tank to remove the moisture and dry the air.
Membrane Dryers are typically used at the end use product. These types of systems utilize membranes to dissipate water vapor as it passes through the material, while allowing a small amount of the dry air to travel the length of the membrane to sort of “wipe” the condensate and remove it from the system.
Deliquescent Dryers use a drying agent which absorbs any moisture in the air. As the vapors react with the desiccant, like salt, the desiccant liquefies and is able to be drained at the bottom of a tank. These are the least expensive dryers to purchase and maintain because they have no moving parts and require no power to run.
When a dryer is being considered for a particular setup, there are 3 common reference points used when determining the dryers rating – an inlet air temperature of 100°F, supply pressure of 100 PSIG and an ambient air temperature of 100°F. Changes in supply pressure or temperature could change the performance of a particular dryer. You want to follow the manufacturer’s recommendations when dealing with variances as they will typically provide some type of conversion.
For help with this or any other topics relating to the efficient use of compressed air, please give us a call, we’d be happy to help.