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Zeolite towers
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What we check on a CAMC visit
Home / Oxygen plants
PSA oxygen plant installation, repair and CAMC
Oxygen made on site, at 93 ± 3 %.
UNISSI installs PSA oxygen generator plants, restores plants that have stopped, and runs and maintains them under CAMC with operators on site. We work on plants from 160 to 1,500 LPM, including PM CARES and DRDO installations.
How a PSA plant works
Air in, 93 % oxygen out.
A PSA plant makes oxygen by pushing dry, clean air through zeolite that holds back nitrogen. Two towers take turns: one makes oxygen while the other vents the nitrogen it has collected. Tap any part of the plant to see what it does and what we check on a CAMC visit.
- A makes O₂ · B vents
- Equalise
- B makes O₂ · A vents
- Equalise
Swipe sideways to see the whole plant.
Running normally. Tower A is making oxygen while tower B vents nitrogen.
- Oxygen purity
- 94.5 %
- Plant output
- 700 LPM
- Dryer dew point
- +3 °C
- Hospital supplied from
- PSA plant
PSA plant sizing
How big a plant does your hospital need?
Enter your bed mix to get a first estimate of oxygen demand and the plant size to match. Our site survey confirms the final number.
Recommended plant—
- Connected load
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- Typical demand
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- With headroom
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- D-type cylinders it replaces
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Running cost, per month
- Same oxygen from cylinders
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- Plant electricity
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- Saving
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- Payback on the plant
- Add the plant cost
A planning estimate only. Flow per bed follows common planning figures; your clinical team and our site survey set the final capacity. Cylinder figure assumes about 7,000 litres of gas per D-type cylinder. Running costs use typical demand and leave out CAMC, operators and spares; change the figures under “Running cost figures” to match your hospital.
Ask for a site surveyPlant down?
First checks before our engineer arrives.
Pick what you are seeing. These are checks a plant operator or the hospital's biomedical engineer can make safely. Send us what you find and we will tell you the next step.
Patients first. If purity or pressure is low, make sure supply has switched to the cylinder manifold or LMO tank before anything else. Do not open valves, filter housings or vessels that are under pressure.
- Note the analyser reading, the flow on the flow meter and the O₂ receiver pressure.
- Check whether the hospital is drawing more than the plant's rated LPM. If it is, purity falls; bring flow down to the rating and watch whether purity recovers over 15 to 20 minutes.
- Check the air dryer is running and its auto-drain is discharging water. Wet air is the most common cause and damages the zeolite.
- Watch the two tower pressure gauges. They should swing each time the plant switches beds. A gauge that stays still points to a stuck switching valve.
- Write down the fault code or message on the compressor controller.
- Check incoming voltage on the servo stabilizer display and that all three phases are present.
- Check the compressor room temperature and that the cooler and ventilation openings are not blocked. High temperature is a common trip.
- Reset no more than twice. Repeated restarts on a fault can burn the motor.
- Note the O₂ receiver pressure and the line pressure after the regulator.
- Read the pressure-drop gauge on the outlet and bacterial filters. A clogged element cuts pressure.
- Check that line and area valves are fully open, and listen for leaks at joints. Use soapy water to find a leak, never a flame.
- Tell us whether the low pressure is in one ward or the whole hospital.
- Keep supply on the cylinder manifold or LMO tank and isolate the plant from the pipeline. Dust must not reach patients.
- Keep the dusty filter element for our engineer to inspect.
- Dust usually means the zeolite is breaking down, often after moisture got in. This needs an engineer visit.
- Read the panel: which gas, and whether it shows high or low pressure.
- Check the source for that gas: the plant or LMO tank for O₂, the manifold for N₂O, the plant room for air and vacuum. A manifold may simply need its cylinders changed.
- If only one ward alarms, check its area valve box is fully open.
- Silence the buzzer only after someone is working on the cause.
Inside a PSA plant
What we install, service and repair.
Every stage of the plant, with the air treatment that keeps the zeolite alive.
FEED
Air compression
- Rotary screw compressor, 7.5 to 10 bar
- Heavy-duty intake filters
- Variable speed drive where specified
TREATMENT
Drying and filtration
- Water separator
- Refrigerated air dryer
- 1 micron, 0.01 micron and activated carbon filters
- Air buffer tank
CORE
Oxygen generator
- Twin adsorber towers
- Zeolite molecular sieve
- Pneumatic switching valves and silencer
- PLC control panel
- Oxygen analyser
OUTPUT
Storage and delivery
- Oxygen surge tank
- Bacterial filter
- Flow meter
- Tie-in to the hospital MGPS
FILLING
Cylinder filling (optional)
- High-pressure oxygen booster to 150 bar
- Cylinder filling ramp
SAFETY
Power and safety
- Servo stabilizers up to 150 kVA
- Automatic changeover to DG power
- Automatic changeover to cylinder manifold
- Safety relief and auto-drain valves
- Plant-room ventilation and ducting
Recent oxygen plant work
Plants we have restored and run.
- SKIMS MCH, Bemina, SrinagarZeolite replacement, 750 LPM plant (2026)
- GMC & AH, RajouriRestoration of 1,000 LPM PM CARES DRDO plant
- District Hospital, RambanRepair of skid II, 1,500 LPM plant
- District Hospital, KishtwarSkid repair, 1,500 LPM plant; plant operation
- GMC KathuaOperation of 960 LPM plant
- NHM AssamRepair and CAMC of plants at 29 district and sub-divisional hospitals
- Haflong Civil Hospital, Assam150 kVA servo stabilizer for the oxygen plant (2026)
- Military Hospital, NainitalOxygen plant CMC
Plant repair and restoration →Zeolite replacement →CAMC in Jammu & Kashmir →CAMC in Assam →
Questions hospitals ask us
Oxygen plant questions
Do you maintain oxygen plants that another company installed?
Yes. Most of the PSA oxygen plants under our CAMC were installed by other firms, including PM CARES and DRDO plants and L&T and Ozcan makes, with capacities from 160 to 1,500 LPM.
What is included in a PSA oxygen plant CAMC?
Preventive maintenance visits, breakdown repairs and spares. Where the contract asks for it, we also station trained operators at the plant.
What oxygen purity does a PSA plant produce?
Medical PSA plants deliver 93 ± 3 % oxygen. An oxygen analyser monitors purity continuously, and if it falls below 90 % the supply switches automatically to the cylinder manifold.
When does the zeolite in a PSA plant need replacing?
When the plant can no longer hold purity at its rated flow even after the compressor, dryer and filters are serviced. Oil or moisture reaching the sieve shortens its life, so air treatment is checked on every visit.
What size of PSA oxygen plant does a hospital need?
It depends on the number of ICU, HDU and general beds with oxygen and on how many operation theatres the plant feeds. Use the calculator on this page for a first estimate, then ask us for a site survey.
Contact
Plant down, or planning a new one?
Send us the plant capacity, make and location. We will come back with a survey date or a quotation.
Registered office · Gurugram
WW10, Windchants, Experion, Sector 112,
New Palam Vihar, Gurugram, Haryana 122017
Delhi
Plot No 20, Village Raghopur,
Najafgarh, New Delhi 110071
Jaipur
Khasra No 53, Rajpura Patalwas,
Bassi, Jaipur, Rajasthan 303305