Cheap PSA nitrogen: trends and maintenance? 

Here's what's often overlooked when talking about cheap PSA nitrogen: cheap installation is just the beginning of a long story. Many people think that they bought a unit, started it up, and that’s it, profit. And then, after six months or a year, they wonder why purity is falling, why consumables eat up all the savings, and why this cheapest nitrogen suddenly became gold. I went through this myself and observed it with clients. Let's go in order, without water.

Trend towards cheaper prices: where are the real savings and where is the trap?

Now the market is flooded with offers. Particularly noticeable is the influx of companies from Asia, which offer very competitive prices for the installations themselves. Take Chengdu Yizhi Technology Co. for example. - this is their website https://www.yzkjhx.ru. They are positioned as a design institute with a significant authorized capital. Their equipment often appears in requests for inexpensive PSA. And here is the first nuance: low capital expenditure (CapEx) prices are often achieved by optimizing the design and, critically, by choosing more affordable components. Not always bad, but often with a different resource.

For example, valves. Budget installations often have general-purpose solenoid valves. The PSA cycle is thousands of switches per day. A valve not designed for this type of operation may work for a year and then begin to stick. Loss of pressure, disruption of the cycle - and now the purity of nitrogen changes. Replacement? And the original valve may not be so easy to find, or it may take a month to arrive. Savings at the purchase stage result in downtime. This is not unfounded, I saw such a situation at one of the food production plants near Moscow.

Or another trend - simplifying the system for drying and cleaning compressed air at the inlet. It would seem that there is a good refrigerated dryer, and okay. But if there is high humidity in the region, and the dew point is not selected correctly, the moisture gradually poisons the zeolite in the adsorbers. Its capacity decreases, more air is required to obtain the same purity, the load on the compressor increases - and operating costs (OpEx) creep up imperceptibly, but inexorably. Cheap PSA nitrogen requires very careful calculation of all input parameters, otherwise it is not cheap.

Maintenance is not according to schedule, but according to condition

This is where 80% of success or failure lies. Manufacturers give a maintenance schedule: change filters once a year, zeolite every few years. But this is an ideal world. In reality, everything depends on the conditions. One of the most common mistakes is ignoring air pre-cleaning. I saw an installation where there was only a carbon filter at the inlet, because there was not enough oil in the compressor. Over the course of two years, the active layers of zeolite in the columns sintered into a monolith due to microimpurities of hydrocarbons. It was not subject to restoration, only complete replacement. The cost of work and materials ate up all the benefits for 5 years in advance.

Therefore, my approach is mandatory quarterly control. Not just look, but measure key parameters: pressure drop on fine filters (using pressure gauges before and after), the dynamics of the cycle time (it begins to increase when the zeolite is depleted), and, of course, monitoring the cleanliness at the outlet with an analyzer. Not constantly, but selectively, once a week or two. This allows you to catch a problem before it becomes a disaster.

Another painful point is spare parts. For equipment from the same Chengdu Yizhi Technology Co. Ltd. logistics of spare parts may not be as fast as for local brands. So you need to plan. It is better to have critical components - valves, solenoids, pressure sensors - in stock. Yes, this freezes funds, but the cost of downtime for the line that feeds this nitrogen is usually several times higher. This is the price of reliability of a cheap PSA.

The story of one optimized solution

I would like to give an example from practice that well illustrates the false economy. The customer purchased an inexpensive PSA unit to protect against oxidation during the soldering process. Purity required was 99.5%. The first year everything is fine. Then complaints about the quality of soldering began. They began to figure it out. It turned out that to reduce the cost, the design used only one adsorber with a small supply of zeolite. Initially, the purity was at 99.7%, but the adsorbent resource was calculated under ideal conditions.

In fact, the air at the inlet was unstable in terms of humidity (the workshop was not heated during the night shift), and the load on the installation periodically increased. The zeolite was depleted 30% faster than expected. The installation was formally working, but in order to maintain pressure, it began to leak unregenerated air, and the purity at the outlet dropped to 98%. This was enough to trigger the sensors, but not enough for the technology. Soldering involved oxidation.

The solution was not to urgently replace the zeolite (although that had to be done), but to refine the system: installing a more accurate dryer at the inlet and reconfiguring the regeneration cycles for the real load. It cost money and time. Moral: Cheap PSA nitrogen often requires additional investment in the infrastructure around it. Without this it is not viable.

About consumables and myths about eternal zeolite

Many sellers talk about the service life of zeolite 5-10 years. This is only possible in laboratory conditions. In reality, everything affects the life: the quality of the source air, temperature, the presence of oil vapors or silicones from the seals of the compressor itself. I saw a zeolite that turned into stone in 3 years due to chronic ingress of paint and varnish vapors from a neighboring workshop through the air intake system.

Therefore, when choosing an installation, it is critical to look not at the rated service life of the filler, but at how its protection is organized. How many filtration stages are there, are there coalescing filters, carbon filters? For cheap PSA nitrogen, they often save money on this by installing a minimum kit. And then the replacement of zeolite, which is the main cost item in maintenance, occurs twice as often.

The advice here is this: immediately budget for the modernization of the compressed air preparation line. Good three-stage filtration (coalescing, carbon, fine filtering) and a high-quality dryer will extend the life of the heart of the installation - the adsorbers - significantly. This is not an expense, it is an investment in stability.

Results: is it worth chasing a cheap PSA?

Standing, but with open eyes. Cheap PSA nitrogen is not bad. It's a tool that works great within its own framework. For tasks where small fluctuations in cleanliness are acceptable (for example, some types of packaging, purging), where it is possible to regularly and efficiently service it, this is the optimal choice. The savings up front can be significant.

The key word is regular and quality service. If you don’t have the resources for this (human, temporary, warehouse for spare parts), then a cheap installation will turn into a black hole for the budget. It is better then to consider options for leasing nitrogen plants or a full service contract, where the risks fall on the supplier.

Overall, the trend towards affordable PSA technology is a good thing. It enables SMEs to use best practices. But, as always, free cheese is only in a mousetrap. The real cost of ownership consists of the price of the equipment, the cost of upgrading it to suit specific conditions and, most importantly, the culture of its operation. Without the latter, even the most expensive equipment will break down. And with it, cheap PSA nitrogen can work flawlessly for years, giving the very economic effect for which it was bought.