My nitrogen-hydrogen flow control panel seems to be working properly, but is there anything I should be checking?
There are many aspects of a flow control or blend panel that require periodic maintenance for proper functionality—especially those related to its safe operation. You should check the operation of the solenoids to help verify that the combustible gas flow is automatically turning off and the inert gas purge is automatically turning on as intended. They should be tested in accordance with recommended maintenance frequency—typically every six months. Plus, you should rebuild the solenoids as needed. It’s also important to check the purge timer setpoint to help confirm that it can adequately purge the furnace. And you should verify and document the low-flow alarm setpoints on the inert gas purge and process flows. These are just some of the items that should be reviewed on a regular basis.
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.
I use high-pressure gas cylinders and am concerned about safety. Is there a better way?
Traditionally, high-pressure gas cylinders have been the supply mode for users in the low- to medium-volume range. This has left companies vulnerable to safety risks associated with moving cylinders and exposure to high pressure. Consolidating to a centralized microbulk system eliminates the need to handle cylinders and reduces the risk of product mix-up. Further benefits include decreased exposure to high-pressure containers and reduced traffic congestion with less frequent supplier deliveries. Air Products developed the microbulk supply option as a cost-effective, reliable alternative to high-pressure cylinders for nitrogen, argon, oxygen, and carbon dioxide supply. In addition to efficient and flexible storage systems, innovative piping solutions are available to help you have a smooth transition from cylinders to microbulk.
Is my gas purity adequate for my process?
Industrial gases (such as nitrogen, hydrogen, and argon) for furnace atmospheres are characterized by their very high purity (>99.995%). Typical impurity levels are much less than 10 parts per million by volume (ppmv) oxygen and less than 3 ppmv moisture (<– 90° F dew point). This purity is typically adequate for many processes involving a wide array of materials. Some materials, though, due to their high reactivity, may require additional purification to reach even lower levels of impurity, especially with gases supplied via bulk or tube trailer supply modes. Some facilities install in-line purifiers as an added precaution against impurities picked up from the houseline. In-line purification typically involves the removal of oxygen and moisture. Sometimes with argon supply, it is necessary to remove trace nitrogen impurities. The choice of purifier is dependent on the gas and the type and amount of impurities to be removed.
Nitrogen - When does on-site nitrogen generation make sense versus liquid nitrogen delivery?
Can nitrogen reduce costs and improve operations in my dissociated ammonia (DA) atmosphere?
How can I address a cooling issue within my process?
In its liquid state, nitrogen is -320 degrees Fahrenheit! This makes it one of the most effective coolants available. Depending on your process, liquid nitrogen can provide temperature control, shorten cycle time, and improve product quality. Nitrogen is also a green product, as it leaves no residue and is sourced from the air we breathe. It’s used in many industrial processes and can be adapted to heat treating, machining, thermal spray, and many other applications that have problems related to excess heat.
What nitrogen purity do I need for my heat treatment process?
That depends on your process. Nitrogen-based atmospheres for metals processing have been successfully proven over many years, and due to the enormous range of requirements in furnaces for various materials and surface needs, the use of gas mixtures is now an industry standard. Different products can tolerate differing concentrations of oxidizing components in the furnace atmosphere due to additional reducing or reactive components in the blend. For this reason, the use of on-site generated nitrogen with residual amounts of oxygen can be tolerated. By understanding your oxygen tolerance levels we can help you reduce your costs.