Automation 101: Combustion Leak Tester

Fuel combustion is a modern technological process found in nearly all industry sectors the world over.  From heating your home to generating electricity for millions of people, combustion plays a role in all facets of daily life, albeit a largely under appreciated one.  Making the topic even more expansive, we can all appreciate that fuel combustion also dips into contemporary concerns around sustainability and climate change.  Across all of these fronts, manufacturers of components that are used in combustion equipment feel the pressure to deliver the highest quality, most reliable, most conservational parts possible.  The primary way that manufacturers can achieve these goals is by performing robust combustion leak tester within their manufacturing processes, which we take a deep dive into below.   

Leak Testing in Combustion Component Manufacturing   

When we hear the word “combustion,” most of us immediately think of a combustion engine such as those found in our gas-fueled vehicles. Beyond engines, combustion can describe any number of processes that ignite a consumable fuel source for the purpose of creating heat or light energy. Burning natural gas, diesel, gasoline, fuel oil, wood, fibers and many other consumable materials are all examples of combustion, and can be found in just as many applications across manufacturing industries. In order to operate reliably and safely, components used in combustion processes have to be ultra-precise, heavy duty and most importantly, leak free.   

Why are combustion components especially sensitive to leaks? It varies slightly between application, but the main commonality is that the uncontrolled flow of a liquid or gaseous fuel typically leads to a significant safety hazard. Leaking natural gas, for example, can displace the oxygen in a room and lead to asphyxiation, not to mention it could violently ignite. For these reasons and more, leak testing components, assemblies and full products to be used in combustion applications is of paramount importance. This testing starts on the manufacturing line.  

As we’ve covered in other recent articles, manufacturing leak testing involves subjecting a component to pressure or vacuum conditions that measure how much leakage occurs across the component. All materials are permeable to some level – with severe enough conditions, even solid plastics and metals can pass a measurable amount of microscopic molecules through their surfaces. Manufacturers design test procedures that first define an acceptable level of leakage either through the part or through its connections (such as where parts are bolted together and sealed with gaskets), and then use precision instrumentation to physically confirm that the part’s leakage falls at or below that acceptable level.        

Combustion technologies are found in many industries, all of which require a level of quality control and safety testing to be performed during manufacturing. Examples of combustion equipment by industry include:   

• Automotive: internal combustion engines 
• Agriculture: electrical generators, natural gas heaters, weed control torches and barn space heaters
• Oil and gas: gas flaring, thermal gas separators, catalytic reactors and crude oil heaters
• Industrial combustion: steam boilers, water heaters, thermal tempering heaters and under-flooring oil heaters
• Transportation: vehicle cabin heaters, road snow-melt torches, ship engine pre-heaters and ship engine room space heaters
• Manufacturing: product ovens, fryers, dryers, blast tunnels, coating applicators, roasters, tempering systems and evaporators

Components used on any of the above equipment’s combustion trains are ideal candidates for leak testing during manufacturing. Assuring acceptable leakage profiles for these components will help manufacturers comply with regulatory, safety, warranty, environmental protection and customer satisfaction requirements.  

Combustion Leak Tester Methodology  

With the heightened safety considerations involved in testing combustion component leakage, defining a leak testing methodology starts with understanding all of the unique demands involved.

• Combustion involves a volatile fuel source, which can cause exponential harm if leakage occurs.
• Very tight regulatory requirements exist for fuel combustion, from varying agencies (OSHA, DOT, ASME, NFPA and more). 
• Combustible fuels can be liquids, gasses or solids, and each form has substantial differences in physical properties. 
• Test designs should be based on extrapolated requirements considering actual operating conditions (or actually be performed at operating conditions, where practical).
• Test designs must heavily consider the potentially extreme environments to be experienced in normal conditions, and from there, should further consider “abnormal” conditions such as elevated pressures, temperatures and physical wear. For example, a diesel space heater used for winter construction work could experience a large spectrum of temperatures, atmospheric pressures and physical wear, and cannot leak at any point on this spectrum.
• Certification or validation of test procedures is especially important, and should include a bulletproof documentation trail on both the test procedure and test results for every product manufactured. 
• Testing systems installed within manufacturing workflows should be highly customizable, in order to adjust over time as component designs, features and test requirements evolve.
• Tolerance for test failures and test system downtime are marginal at best, requiring very precise, highly repeatable, extremely reliable test processes. 

Given the significant precision and accuracy required of combustion component leak testing, two testing methods are commonly employed during manufacturing of these components.   

• The pressure decay method consists of charging the test part with a prescribed pressure of compressed gas, and then monitoring any drop in pressure within the part over a fixed period of time. If the pressure measured inside of the part decreases during the test, a leak to the atmosphere would be suspected. For parts where a certain amount of leakage is acceptable, the difference between initial and final pressure readings is used to determine pass or fail.  
• The vacuum decay method consists of pulling a vacuum on a test chamber, in which the test part resides and is sealed. The vacuum level in the chamber is monitored for any increase in pressure (or decrease of vacuum) over a fixed period of time. If the chamber’s vacuum level decreases, a leak through the part that added air into the test chamber would be suspected. As with the above test, if a certain leakage rate is acceptable, the difference in initial and final vacuum readings determines a pass or fail.  

How to Automate Combustion Component Leak Detection    

From the above, we understand that testing combustion components is vital to the safe, reliable, long-term use of the equipment that these components are installed into. We have two methods available to conduct this testing.  Now, how do we put these concepts into play in a real manufacturing environment?  

We design and deploy testing equipment, is how.  

Testing combustion component leakage can be performed in a single machine or station, using precision instruments and a standardized procedure to subject the part to potential leakage. This test will either pass or fail based on parameters that we define within the test procedure. For high-volume testing and large manufacturing capacities, we can utilize multiple test machines, multi-fixture single machines or even an inline combustion leak tester (for continuous production lines).  

Choosing the right automation partner is a key step in developing your combustion component leak tester solution. Technical details, system design and ongoing support are significant elements of the project that require the attention of an experienced partner. Further, designing a system with the future in mind is of special interest in today’s manufacturing environment, solving for foreseeable challenges in the following areas:  

• Labor. Systems designed as manual or semi-automated should allow for future upgrades to become fully automated, offsetting labor availability constraints.
• Sustainability. Systems should be built in a modular fashion, fully allowing for key upgrades and expansion instead of being fully replaced, which saves significant resources in the long run.
• Customer expectations. Systems should allow for adaptation to changing customer demands, such as rapid component redesigns, added test requirements and more visibility into the part’s production history through expanded reporting and traceability documentation.

Automated Machines Systems designs, builds and services testing systems for combustion component leak testing with exactly these thoughts in mind. From manual to fully automated systems, AMS can help develop a solution for your testing application using our 17-Step Process, decades of industry experience and an ingrained devotion to customer satisfaction.   

AMS offers semi-automated and fully automated leak detection systems to meet your most demanding combustion component applications. Our flagship LT-401 Automated Leak Testing platform is a fully automated, fully customizable, self-checking, multi-parameter system that can be designed to accept practically any vehicle part or assembly. Our LT-401 system offers the following standard features and options:  

• Pressure decay, vacuum decay and mass flow test procedures
• PLC-controlled test process, from initial part load to final part removal 
• Multiple personnel safety systems including light curtains, two-hand starts, easily accessible emergency stop buttons and automatic machine halts on alarm conditions 
• Pre-test inspection sensors including position, presence, orientation, color, optical and proximity detection. The test machine will reject a part that might have been mis-assembled or is missing a component prior to starting a leak test 
• Automated reporting of test result documentation for quality and regulatory compliance 
• Incredibly customizable platform that can be modified for future part changes or entirely new parts   

As demand for combustion component parts continues to grow, the need to produce and quality-check these parts is expanding faster than ever. Implementing an automated leak detection solution into your workflow offers a wealth of benefit in both customer confidence and internal total cost reduction (by way of needing less labor to produce higher quality products, with fewer downstream failure claims). To learn more about how automated leak testing can help your combustion part business, please contact AMS’s engineers today.