PSA generation replaces cylinder deliveries above a certain continuous demand and loses money below it. What sets the threshold, what purity you actually get, and why the compressed air side decides whether the plant works.
Bangladesh's hospitals, research laboratories, aquaculture farms and industrial plants have historically depended on delivered compressed-gas cylinders or liquid oxygen dewars, a supply chain that is expensive, logistically fragile and increasingly unreliable as demand grows. Pressure Swing Adsorption (PSA) technology, first described in the Skarström patent of 1960 and manufactured by Oxymat A/S of Denmark since 1978, offers an alternative: generate oxygen or nitrogen continuously on-site from compressed air, at a fraction of the delivered-gas cost. Vvon Technologies Limited is the authorised partner for Oxymat in Bangladesh. The useful question is not whether generation is cheaper in principle, but whether your consumption profile sits above the line where it becomes cheaper in practice.
A PSA generator passes compressed air (typically 6 to 8 bar) through two columns packed with a molecular sieve adsorbent, zeolite for oxygen and carbon molecular sieve for nitrogen. The adsorbent selectively retains nitrogen (for O₂ production) or oxygen (for N₂ production), allowing the product gas to pass through at high purity. The two columns alternate between adsorption and regeneration cycles automatically, producing a continuous gas stream. The Oxymat Nordic series uses an optimised cycle algorithm that reduces compressed-air consumption by up to 40% compared to conventional PSA designs, the key driver of its low operating cost.
Almost every PSA installation that disappoints does so on the air side rather than in the generator. The molecular sieve is destroyed by oil and degraded by water, so the compressed air quality specification is not advisory. Vvon specifies ISO 8573-1 Class 1.4.1 at the generator inlet, and that means a properly selected compressor, a dryer sized for Dhaka's humidity rather than a European ambient, and filtration that is actually changed. A site that saves money on the dryer pays for it twice, in sieve replacement and in purity that never reaches specification.
The second thing the air side decides is the electricity bill. The generator itself draws very little. The compressor is the load, which is why the economics are really a comparison between your electricity tariff and the delivered price of gas, not between two pieces of equipment.
The economics of PSA generation depend on the site's gas consumption rate, local electricity tariff and delivered-gas price. As a rule of thumb, PSA becomes cost-effective above approximately 3 to 5 Nm³/h of continuous consumption. At Bangladesh's current industrial electricity tariff (approximately BDT 8 to 10 per kWh) and delivered oxygen cylinder price (approximately BDT 300 to 400 per Nm³), a medium-sized hospital consuming 20 Nm³/h of oxygen can expect a simple payback of 2 to 4 years on an Oxymat O200 Nordic installation, with operating cost savings of 60 to 75% over delivered cylinders thereafter. Vvon Technologies can provide a site-specific financial model at the quotation stage.
Purity is the other half of the specification and the part most often assumed rather than checked. PSA oxygen reaches up to 95%, which is the medical oxygen standard and is entirely adequate for aquaculture, ozone generation and wastewater treatment. It is not the same thing as the higher purities some analytical instruments demand. PSA nitrogen reaches up to 99.5%, sufficient for inerting, blanketing and most laser cutting assist duties, and short of what a glove box handling air-sensitive chemistry may want. Where higher nitrogen purity is needed, a purifier such as the NH 20-400 goes downstream of the generator; where the requirement is low purity at low flow, a membrane unit from the NM series is often the cheaper machine.
| Model | Type | Capacity | Purity | Key application |
|---|---|---|---|---|
| O200 Nordic | Oxygen | Up to 84 Nm³/h | Up to 95% | Hospital medical O₂, aquaculture, ozone generation |
| O60 Nordic | Oxygen | Up to 21 Nm³/h | Up to 95% | Lab gas supply, wastewater treatment, laser cutting assist gas |
| Half-Pallet Nordic | Oxygen | 2 to 10 Nm³/h | Up to 95% | Small lab, clinic, field hospital |
| N200 Nordic | Nitrogen | 133 to 405 Nm³/h | Up to 99.5% | Inerting, blanketing, food packaging, electronics |
| Pallet N60 Nordic | Nitrogen | 21 to 90 Nm³/h | Up to 99.5% | Lab purge gas, laser cutting assist, pharmaceutical |
Packaging matters as much as capacity when the site is constrained. The wider range of twenty-two units includes the O200 and O60 Nordic Supreme variants, half-pallet nitrogen units, twin-tower oxygen and nitrogen generators, compact integrated PSA generators with the compressor built in, silenced versions of the same for installation near occupied areas, and X-series frame-mounted generators. For sites with no plant room at all, or for a project phase where the building is not ready, containerised and in-frame installations put the whole plant outside on a slab.
Bangladesh experienced acute medical oxygen shortages during the COVID-19 pandemic, exposing the vulnerability of cylinder-dependent supply chains. An Oxymat O200 Nordic PSA generator, sized to the hospital's peak demand across ICU, operating theatres and ward piped supply, provides a continuous, autonomous oxygen supply that is independent of cylinder deliveries. The system operates 24/7, requires only a compressed-air supply and periodic molecular sieve replacement (every 5 to 7 years), and can be monitored remotely via Modbus. Oxymat's medical-grade systems carry CE marking and comply with ISO 7396-1 (medical gas pipeline systems) and ISO 10083 (oxygen concentrator supply systems for use with medical gas pipeline systems).
Two design points a hospital should insist on. Size to peak demand with a stated diversity assumption written down, not to average consumption, because the peak is what an ICU surge looks like. And keep a cylinder manifold as the emergency reserve with automatic changeover, because a generator is a single point of failure and a piped medical gas system is not permitted to have one. Generation replaces the routine deliveries, not the backup.
University and industrial research labs use oxygen and nitrogen across a wide range of applications: oxygen for combustion analysis (bomb calorimetry, TGA and DSC), ozone generation, wastewater treatment pilot plants and aquaculture research tanks; nitrogen for glove box inerting, Schlenk line chemistry, HPLC carrier gas, laser cutting assist gas and electronics soldering. A single Oxymat O60 Nordic or Pallet N60 Nordic unit can supply an entire research building's gas manifold, eliminating the cylinder store, the cylinder change labour and the safety risks associated with high-pressure cylinder handling.
It is worth being blunt about the cases where a generator is the wrong purchase. Low and intermittent demand, a few cylinders a month, will not repay the capital or the compressor's standing losses. Analytical purities beyond what PSA delivers need a different technology or delivered gas. A site with unreliable power and no generator backing will find the plant off exactly when demand peaks. And a laboratory with nobody responsible for filter changes and dew point checks will have a generator producing out-of-specification gas within a year, which is worse than cylinders because nobody will know.
Oxymat Nordic generators are skid-mounted, plug-and-play units that require only a compressed-air connection, electrical supply and product gas outlet. Installation typically takes 1 to 3 days. Vvon Technologies provides the full project scope: compressed-air quality assessment, piping design, electrical connection, commissioning, operator training and a 12-month warranty. Annual service contracts include filter replacement, dew-point measurement, purity verification and cycle-time optimisation.
Ask for the purity verification to be a recorded measurement with an instrument, taken at the point of use rather than at the generator outlet, and repeated at each service. Piping picks up moisture and leaks pick up air, and the number that matters is the one at the outlet a patient or an instrument is connected to.