Choosing the right industrial flame arrester for ethanol, biogas, or hydrogen service is not a one-size-fits-all decision. These three fuels behave very differently when ignited, and a unit that is perfectly safe on an ethanol storage tank can fail catastrophically on a hydrogen line. At Zhenchao we have engineered tank-protection equipment since 2006 and shipped flame arresters to projects from Brazil to Kazakhstan, so in this guide we walk you through the exact steps our engineers use to specify the correct device for your application.
By the end, you will understand how to match the gas group, arrester type, operating conditions, and material to your process — and you will know exactly which questions to send to a manufacturer so you get a compliant quote the first time.
Before you compare models, you must know the explosion group of the vapor you are protecting against. Standards such as ISO 16852 and EN 12874 classify flammable gases into groups based on their maximum experimental safe gap (MESG):
| Gas / Vapor | Explosion Group | Why it matters |
|---|---|---|
| Ethanol vapor | IIA | Larger MESG — easier to arrest, lower-cost element. |
| Biogas (mostly methane + CO₂) | IIA (verify H₂S / H₂ content) | Trace hydrogen or sulfur changes the rating. |
| Hydrogen | IIC | Smallest MESG, highest flame speed — needs a certified IIC element. |
Hydrogen is the outlier: its flame speed is roughly eight times that of methane, so a hydrogen flame arrester must carry an IIC rating and a proven detonation-capable element. If you are unsure of your exact gas composition, send the safety data sheet (SDS) to your supplier — guessing the group is the single most common cause of non-compliant installations.
Once you know the group, you choose between two structural families:
For an ethanol flame arrester on a storage tank vent, an end-of-line unit is usually the correct and most cost-effective choice. If your line can develop a detonation, you must step up to a certified detonation arrester — not a deflagration-only model.
Figure 1: End-of-line vs. in-line flame arrester configurations — choose based on where flashback protection is needed.
You now need to size the device to the real conditions it will see in service:
Always size from your peak in-breathing and out-breathing rates, not from a nominal line size. If you share your tank volume, vapor flow, and set pressure with a manufacturer, you get a unit that breathes freely and still stops a flame.
Not sure how to size yours?
Send Zhenchao your tank data and gas composition. Our engineers return a sized, standards-compliant recommendation — no obligation.
Material choice is where many ethanol and biogas projects go wrong. Ethanol is mildly corrosive and can contain traces of organic acid; biogas routinely carries water vapor, CO₂, and hydrogen sulfide that attack carbon steel. For these services we recommend stainless steel elements and housings.
A biogas flame arrester in 304 or 316 stainless steel resists the acidic condensate that would rot a carbon-steel unit within a season. For hydrogen, stainless also avoids sparking and galling at the threaded joints.
You should never accept a flame arrester without documented proof it was tested to the relevant standard. The key references are:
When you request a quote, ask for the test certificate that names your exact gas group (IIA / IIB / IIC) and the arrester’s approved pipe size and pressure. A serious supplier provides this without hesitation.
A flame arrester only protects you while its element is clean and unobstructed. In biogas and ethanol service, wax, gum, and condensate can clog the element and quietly raise pressure drop until the tank vent stops working. You should set a documented inspection interval, and choose a design whose element can be withdrawn for cleaning.
Our field experience backs this up: on a Brazilian storage project, the installed flame arrester application used a drawer-type element precisely so the operator could service it without removing the whole unit from the line.
Ready to specify the right flame arrester?
Tell us your gas, tank size, and operating conditions. Zhenchao will return a priced, certified recommendation — typically within two working days.
Use this at-a-glance table as a starting point, then confirm with the standards and your manufacturer:
| Application | Typical Group | Recommended Type | Recommended Material |
|---|---|---|---|
| Ethanol storage tank vent | IIA | End-of-line | Stainless or coated CS |
| Biogas line / digester vent | IIA (verify) | End-of-line / in-line | 316 stainless steel |
| Hydrogen pipeline | IIC | In-line detonation | Stainless steel |
Can a flame arrester be installed on the liquid side of a tank?
No. Flame arresters protect the vapor space where a flammable air-fuel mixture can exist. On the liquid side there is no ignitable mixture, so an arrester adds cost and restriction with no safety benefit. Place it in the vapor path — typically at the tank vent or within the vapor return line.
What pressure drop should I expect, and how does it affect tank venting?
A clean, correctly sized element typically adds only a few millibar of pressure drop at design flow. The risk is clogging: as the element fouls, pressure drop rises and can prevent the tank from breathing, forcing over-pressure onto the relief path. Size for peak flow and plan inspection so the drop stays within your tank’s vacuum/pressure limits.
How do I size a flame arrester for a pipeline versus a tank vent?
For a tank vent you size from the tank’s total in/out-breathing rate and the vent connection. For a pipeline you size from the line’s maximum gas velocity and diameter, and you must also confirm the arrester is rated for the pipe’s pressure class. Pipeline units also need a detonation rating if the run length allows deflagration-to-detonation transition.
Are flame arresters legally required for ethanol, biogas, and hydrogen?
In most jurisdictions, yes — wherever a tank or line can form an explosive vapor mixture and connect to an ignition source or atmosphere. The exact duty depends on local codes (for example ATEX in the EU, API 2028 and OSHA/NFPA in the US, GB standards in China). Always check the applicable code for your site and fuel.
What causes a flame arrester to fail, and can it be cleaned?
Failure usually comes from element blockage (wax, gum, condensate), corrosion, or physical damage from a detonation beyond its rating. Many drawer-type elements can be withdrawn, cleaned, and reinstalled if the housing is undamaged. If the element is cracked or the housing is distorted, replace the unit — do not attempt to repair the arrester element.
How do cold or cryogenic temperatures affect selection?
Low temperatures change material behavior and can cause moisture to freeze in the element, blocking flow. For cryogenic or Arctic service you need materials rated for the temperature and, often, trace heating or a design that resists ice bridging. Tell your supplier the minimum service temperature so the element and seals are specified correctly.
About Zhenchao
Zhejiang Zhenchao Petrochemical Equipment Co., Ltd. has manufactured flame arresters, breather valves, and tank-protection equipment since 2006. Our products are supplied to storage, chemical, and energy projects worldwide, and every flame arrester is built and tested to recognized international standards.
