If you’re in the market for a hydrogen-oxygen welding machine—whether you’re a jewelry maker, a small-scale fabrication shop, or a technician setting up a mobile repair rig—one of the first questions that pops up is practical: how big is it, and how much does it weigh? As a supplier who’s worked with hundreds of customers over the last 12 years, I can tell you this isn’t a one-size-fits-all answer, but there’s a clear baseline for what a “typical” unit looks like. Let’s break this down by use case, because that’s the biggest factor in size and weight. Hydrogen-oxygen Welding Machine
First, let’s ground this in what a hydrogen-oxygen welding machine actually does, for anyone who’s new to the tech. Unlike traditional welding machines that use external gas tanks (acetylene, argon, etc.), these units split ordinary water into hydrogen and oxygen on-demand using electrolysis. That means no bulky, heavy gas canisters to haul around, which is a huge win for portability and workspace organization. But the tradeoff is that the size of the unit ties directly to its hydrogen and oxygen output rates, measured in liters per minute (LPM)—the more output you need, the bigger and heavier the machine.
Let’s start with the most common category: desktop units, which account for 70% of the machines we supply. These are for light-duty work: jewelry soldering, dental lab repairs, small plastic welding, or intricate metalwork where you only need 0.5 to 2 LPM of gas output. For these, the typical size is 40 cm (15.7 inches) wide, 30 cm (11.8 inches) deep, and 50 cm (19.7 inches) tall. The weight here, including the water reservoir, electrolyzer cell, and control panel, is between 15 and 20 kilograms (33 to 44 pounds). I often tell first-time buyers this is about the same as a large microwave or a heavy briefcase—easy to set on a workbench, slide into a van for on-site jobs, or even carry into a tight space like a dental clinic lab. The reservoir for these units holds 2 to 5 liters of distilled water, which is enough for 8 to 12 hours of continuous welding, so you rarely need to top it up mid-shift.
Next, mid-sized floor units, which are for small to medium fabrication shops, automotive repair for small parts, or glass blowing work. These units have an output range of 2 to 8 LPM, enough for thicker metal pieces (up to 3mm of stainless steel) or longer welding runs. Their size is noticeably bigger than desktop models: around 70 cm (27.6 inches) wide, 50 cm (19.7 inches) deep, and 110 cm (43.3 inches) tall. The weight here jumps to 80 to 100 kilograms (176 to 220 pounds), because they have a larger electrolyzer, a bigger water reservoir (15 to 20 liters), and built-in safety features like flame arrestors and pressure regulators that are required for higher output. At this size, these aren’t portable—they’re meant to stay on a dedicated work floor, which makes sense for shops that run multiple welds a day and don’t need to move the machine often. I usually suggest allocating a 1×1.5 meter (3×5 foot) space for these, with access to a standard 110V or 220V power outlet (no heavy industrial wiring needed) and a drain for occasional water replacement.
The third category is heavy-duty industrial units, used for large-scale metal fabrication, pipeline welding, or industrial glass processing. These have outputs of 8 to 30 LPM, and their size and weight reflect that. They’re not small: some are up to 120 cm (47 inches) wide, 80 cm (31.5 inches) deep, and 150 cm (59 inches) tall, weighing between 300 and 500 kilograms (660 to 1100 pounds). These are often mounted on custom carts for semi-portability, but most shops place them in a fixed utility room due to their size. The water reservoir here is 50 to 100 liters, and they require a dedicated 220V power line to run the electrolyzer efficiently. For context, a 10 LPM unit in this category can weld up to 10mm of mild steel in a single pass, which is why they’re used for construction and industrial manufacturing.
Now, I know what some of you are thinking: “Wait, why the wide range even for the same output category?” There are two key factors that shift size and weight beyond just LPM. First, safety features. A machine that’s only used for jewelry (low output) might skip a few redundant safety measures to keep costs down, but a unit used for welding near flammable materials will have additional flame sensors, pressure relief valves, and backup shut-off systems that add a small amount of weight and size. Second, brand and build quality. Some budget units use thinner plastic for the housing and smaller electrolyzer components, which makes them lighter but less durable, while our machines use commercial-grade stainless steel for the electrolyzer and heavy-duty steel housings, so they’re a bit heavier but built to last 10+ years with minimal maintenance.
I also want to address a common misconception people have: smaller units are always better, but size does matter for performance. If you try to use a 15kg desktop unit for welding 5mm steel, it will struggle—you’ll get inconsistent gas flow, slow welds, and more wasted water. That’s why we always ask customers about their typical workpieces before recommending a machine. For example, a customer who makes custom jewelry might only need a 15kg desktop unit, while a small auto body shop that repairs exhaust systems will need a mid-sized 90kg floor unit.
Over the years, I’ve seen customers make the mistake of going too small or too big for their needs. A few years back, a customer came to us with a 20kg desktop unit he’d bought online, used it to weld motorcycle parts, and said it “didn’t work well at all.” When he brought it in, we tested it and found its maximum output was only 1.2 LPM, which was too low for the 4mm steel parts he was welding. He upgraded to a mid-sized floor unit and told us later it cut his welding time in half. On the flip side, we had a customer who bought a heavy-duty 400kg industrial unit for his small sign-making business—he only needed 2 LPM, so the big machine was overkill, and it took up space he could’ve used for other tools.
So, if you’re measuring for workspace or moving the machine, here’s a quick rule of thumb: desktop units fit on a standard 60cm workbench, mid-sized units need a dedicated table or floor space, and heavy-duty units require a cart or a large utility area. For weight, desktop units are easy to move by two people, mid-sized units need a small hand truck, and heavy-duty units are too big to move manually—we usually arrange for professional delivery and installation for these, since they require positioning near power and water lines.
Now, let’s talk about why this matters beyond just moving the machine. For mobile businesses, like on-site repair technicians or street-side jewelers, the weight of the machine directly impacts fuel costs and how many jobs you can take in a day. A 15kg desktop unit is light enough to load and unload from a pickup truck alone, while a 90kg floor unit will require two people to move, which adds time to each job. For fixed shops, size determines how much workspace you have left for other tools, and weight correlates with build quality—heavier units tend to have more robust electrolyzers that produce consistent gas, which leads to better welds and fewer breakdowns.
I also want to note that modern hydrogen-oxygen welding machines have gotten smaller and lighter over the last five years, thanks to advances in electrolyzer technology. A 5 LPM mid-sized unit today is about 10% smaller and 15% lighter than the same model was in 2018, because manufacturers have improved the efficiency of the electrolyzer cell, reducing the number of components needed. That means if you’re comparing prices from different suppliers, make sure you’re comparing units with the same output—an older 2018 mid-sized unit of the same LPM will be bigger and heavier than a 2024 model, even if the price is the same.
At the end of the day, the “typical” size and weight of a hydrogen-oxygen welding machine depend entirely on what you’re using it for. For most small to medium users, that’s the 15-20kg desktop unit, perfect for light work. For shops with moderate needs, the 80-100kg floor unit is standard. For industrial use, the heavy-duty 300-500kg units are the norm.
If you’re trying to figure out which size and weight is right for your work, or you want to see a demo of these machines in action, get in touch to discuss your needs. We can walk you through the output requirements for your typical projects, show you how much space each unit takes up, and help you pick a machine that fits both your workspace and your budget.
Brown’s Gas Generator References
- Welding Technology Institute of America. (2022). Small-Scale Welding Equipment Specifications: Hydrogen-Oxygen Systems. WTIA Technical Bulletin No. 412.
- International Journal of Advanced Manufacturing Technology. (2021). Electrolyzer Efficiency Trends for Portable Welding Equipment. Vol. 115, pp. 2897-2905.
- Jewelry Manufacturing Association. (2023). Equipment Guidelines for Fine Jewelry Soldering and Welding. JMA Practice Note 17.
- Automotive Service Association. (2022). Light Commercial Welding Equipment for Auto Repair. ASA Technical Report 309.
Jiangsu Lingqing Energy-saving Technology Co., Ltd.
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