Browse previously asked/answered questions below.
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I know my flowmeter tells me that I have a certain gas flow rate, but how can I be sure?
|Flowmeters must be sized properly for each particular application, type of gas, gas pressure, and operating range. First, make sure that your flowmeter is calibrated for the specific gravity of the gas that you are metering. Check the label or the glass tube of the flowmeter or call the manufacturer to be sure. Second, operate the flowmeter only at the pressure for which it was calibrated. As an example, a variable-area flowmeter calibrated for 80 psi and reading 1000 scfh will really only be delivering 760 scfh if it is operated at 40 psi. This is a 24% error! Third, for best accuracy and to allow room for adjustment, size the flowmeter so that your normal flow rate falls within 30%–70% of full scale. These three steps will help ensure that you have good control over your gas flows and, ultimately, your process. |
For a free copy of Gas Atmosphere Analysis Guidelines, please call 800-654-4567.
How can I lower the carbon monoxide levels in my steelmaking furnace off-gas?
||Greg Buragino |
Senior Principal Applications Engineer – Steel
It’s a great idea to measure carbon monoxide (CO) and other combustion products such as carbon dioxide (CO2), oxygen (O2) and hydrogen (H2) in your off-gas system. High CO levels in your ductwork indicate incomplete combustion in your furnace, which means you’re losing usable energy!
Usually, introducing dilution air to the ductwork will complete combustion when the CO combines with the oxygen in the air to form CO2. However, this exothermic reaction (post-combustion) may raise temperatures in the ductwork and off-gas handling system, which can lead to shorter life or higher maintenance costs.
Improperly calibrated flow controls, poorly mixed fuel and oxygen/air in the furnace, or other factors may cause incomplete combustion. Thankfully, by better utilizing oxygen in your furnace, you can use that lost energy to improve efficiencies and production rates and reduce emissions.
Air Products can help identify the problem and determine the most cost-effective solution for you! Call 800-654-4567.
Is it true that NFPA 86C has changed?
||Mark Lanham |
Yes, it's true. In fact, NFPA 86C no longer exists. The requirements for "Industrial Furnaces Using a Special Processing Atmosphere," formally defined in the 1999 version of NFPA 86C, have been incorporated into NFPA 86 as of July 18, 2003. Now, NFPA 86 combines the furnace safety requirements for all types of industrial furnaces, including Class A – Food and Baking Ovens, Class B – Melting Furnaces, Class C – Furnaces Using Special Processing Atmospheres, and Class D – Vacuum Furnaces.
The previous contents of NFPA 86C are now primarily found in Chapter 11 of NFPA 86. A notable change is that NFPA 86 recommends that users of Class C furnaces include a low temperature alarm panel to indicate an overdraw condition on the ambient air vaporizers used for emergency purging. Previously, NFPA 86C required the use of a low temperature flow-restricting device that could potentially limit available purging capacity. Air Products' PURIFIRE® nitrogen supply monitoring system is designed to help you comply with this new recommendation.
Users of furnaces with special processing and flammable atmospheres should fully understand the requirements and recommendations of NFPA 86 and determine how the changes from the old NFPA 86C may affect their furnace operations. For help in understanding these specifications or for more information about our PURIFIRE nitrogen supply monitoring system, contact us at 800-654-4567.
When does on-site nitrogen generation make sense versus liquid nitrogen delivery?
||Steve Ruoff |
Metals Processing Segment Manager
The amenability of on-site gas generation involves many factors—nitrogen flow and purity are the most important ones. Flows with a steady or sufficient baseline rate can be great fits for on-sites. Periodic or erratic flow patterns can be amenable if the volumes, pressure and purity are sufficient to allow gas storage that covers peak flows. Also, the lower the purity requirement, the greater the amenability—although high purity is amenable at higher volumes. Other factors include local power cost and pressure required. There are no firm rules defining when to switch from delivery to an on-site. Different on-site options are available to meet your nitrogen requirements, including pressure swing adsorption, membranes or cryogenics. Count on Air Products’ extensive experience in on-site technologies to help you determine your optimal supply mode. Call 800-654-4567 for an assessment.
How can I optimize melting of contaminated metal scrap?
||Jin Cao |
Principal Development Engineer
Metal scrap that’s contaminated with combustibles like oil, paint or plastic is difficult to melt with conventional methods. Thermal delacquering systems are often used to pretreat the scrap before it’s melted, but these systems increase operational costs. Processing contaminated scrap in air-fuel furnaces has drawbacks like high combustion gas volumes and fumes. The temperature and particles of the combustible material can overwhelm the baghouse. Often, particle load and contamination of the furnace gases do not allow the operation of regenerative burner systems, making energy-efficient melting hard to achieve. Plus, unburned combustibles can reduce furnace efficiency. Oxy-fuel and air-oxy-fuel combustion technologies can enable in situ burnout of combustible fumes, lowering combustion gas volumes and increasing temperatures. Also, utilizing the energy released by burning the contaminants can help reduce energy costs. Call us to learn more about optimizing your scrap melting, 800-654-4567.
Can I remotely monitor what’s happening in my furnaces and other process equipment while I’m away from my plant?
||Chris Ward |
With the proper instrumentation and controls, you can securely monitor and control your heat treating or thermal process from nearly anywhere in the world! This is possible using a variety of hardware and communication methods, including Internet, dial-up, and cell phones. Alarm and warning notifications can also be proactively delivered to you so you can react to upsets, trends, and events before it’s “too late.” It’s important to identify the key parameters, equipment and instrumentation you want to monitor, and then select the hardware and software that best match your needs. Contact Air Products’ team of remote process monitoring and control specialists at 800-654-4567 for an assessment and recommendations as to how to get started.
How do I know if I’m wasting gas due to leaks in my gas piping?
Gas piping leaks can result from various conditions, including improper thread sealing, missed brazed joints, defective piping, over pressurization, or even vibration and shocks. A pinhole leak can cost you tens of thousands of dollars per year, depending on the size, number and severity of the leak(s). There are many ways to detect leaks; for instance, using soap tests, pressure drop tests, mass spectrometry or thermal conductivity tests. They all have their place; however, they also often come with limitations in precision, speed, difficulty or cost.
Air Products’ leak detection service can identify and repair costly leaks in your piping to help improve your part quality and bottom line.
In a short video, various methods for identifying leaks are described in more detail. You can view it online at www.airproducts.com/experts2. If you’d like to speak to a specialist about a leak detection audit of your facility, give us a call at 800-654-4567, and mention code 833.
Why do people use oxygen for combustion when air is free?
||Russell Hewertson |
Manager of Combustion Technology
Air contains almost 80% nitrogen, which doesn’t burn; it heats up and removes heat from the process as it exits in the form of hot flue gases. Combustion with oxygen eliminates this waste and provides faster melting, lower fuel usage, lower carbon dioxide generation, reduced NOx and particulate emissions and higher flame temperatures. Oxygen also efficiently burns lower quality fuels and wastes. The economics of using oxygen depend on the process and the needs of the manufacturer. Oxygen benefits are greatest for manufacturers who need extra production, have higher temperature processes (glass, steel, etc.), lack heat recovery, or have emissions issues or undersized baghouses. Oxygen is generally less attractive for just fuel savings, especially for lower temperature processes like boilers, unless fuel costs are extremely high or there are other drivers.
Can your process benefit from oxygen? Call us at 800-654-4567.