The most common question a buyer lands on after reading a prescription is the one the prescription itself rarely answers directly: do I need a 5 LPM concentrator or a 10 LPM one? The short answer is that your prescribed flow rate chooses the device class — but the longer answer involves price, noise, power, and the likely trajectory of your therapy. This guide walks through the decision step by step.
What LPM actually measures
Litres per minute (LPM) is the volumetric flow rate of oxygen delivered at the outlet of the concentrator. A “5 LPM concentrator” means the machine can sustain 5 LPM at its rated purity (typically 93% ± 3%). It does not mean the machine runs at 5 LPM by default, nor that the full 5 LPM is always clinically appropriate.
A prescription will specify a flow rate — commonly 1 to 3 LPM for typical long-term oxygen therapy (LTOT) in COPD, and 2 to 4 LPM for moderate interstitial lung disease. Occasional patients run at 4 to 5 LPM steady state, and a smaller group above that.
The concentrator’s rated maximum should comfortably exceed the prescribed flow, with a margin for upward revision if the disease progresses.
Clinical indications for each class
5 LPM concentrator — use when:
- The prescription is ≤ 4 LPM steady state.
- The patient has COPD with stable hypoxaemia on existing therapy.
- The patient has ILD with documented but stable resting hypoxaemia.
- The patient is a post-acute convalescent expected to taper off supplemental oxygen within months.
- A second device as a backup at a different location (travel home, rental etc.) is needed.
10 LPM concentrator — use when:
- The prescription is 5 LPM or higher.
- The therapy is high-flow nasal cannula (HFNC) at home, which draws on the concentrator for the O₂ blend at the blender.
- The patient’s disease is progressive and a flow-rate escalation in the next 12–24 months is plausible.
- Two users on the same household prescription share via a Y-splitter (this must be physician-authorised and purity-verified at the delivered flow to both endpoints).
- A patient with severe obstructive sleep apnea and concomitant daytime hypoxaemia is stepped up to high-flow supplemental oxygen during daytime mobility.
The conservative reading: the device should be able to deliver the prescribed flow at rated purity. A 5 LPM concentrator at 5 LPM is typically 85–89% pure, at the lower end of its label; a 10 LPM unit delivering 5 LPM will usually read closer to 93% at that setting because it is operating below its rated peak.
Cost differential in the Indian market
Prevailing 2026 pricing in India:
- 5 LPM concentrators: ₹40,000 – ₹55,000 for established brands with a functioning service network. Entry-level models from less-established brands sit at ₹28,000 – ₹38,000 but often involve service network and purity trade-offs.
- 10 LPM concentrators: ₹80,000 – ₹1,50,000 for the dual-flow category that dominates Indian stock. Imported premium 10 LPM units run ₹1,60,000 – ₹2,25,000.
On a pure-hardware basis, a 10 LPM unit is roughly twice the price of a 5 LPM unit. That does not track linearly to twice the performance; it tracks to twice the compressor capacity and sieve volume and a proportionally beefier frame.
Power draw difference
Measured continuous power draw during our bench runs (see methodology):
- 5 LPM class: typically 300 – 400 VA at rated flow, with compressor cycling behaviour that averages slightly below the peak.
- 10 LPM class: typically 500 – 650 VA at rated flow, with a noticeably larger compressor running near its peak capacity.
Over an 18-hour per day use pattern at a typical Indian domestic electricity tariff of ₹7/kWh:
- 5 LPM at 350 VA ≈ 6.3 kWh/day × ₹7 = ~₹44/day, ₹1,300/month.
- 10 LPM at 580 VA ≈ 10.4 kWh/day × ₹7 = ~₹73/day, ₹2,180/month.
A 10 LPM unit costs roughly ₹900–1,000 more per month in electricity. Over five years, that is a second entry-level stabiliser’s worth of added running cost — worth knowing when the clinical case for 10 LPM is marginal.
Noise difference
A 5 LPM concentrator in the best-in-class band sits around 42–45 dB(A) at 1 m; a typical mid-market unit sits at 46–49 dB(A). A 10 LPM concentrator is audibly louder: best-in-class around 48–50 dB(A), mid-market around 52–55 dB(A). For overnight use in the same room as the patient, the class difference is significant. Many patients running 10 LPM overnight extend the cannula to place the machine in an adjoining room — a valid and common workaround.
Decision flow
A short, pragmatic decision flow:
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Is the prescribed flow ≤ 4 LPM?
- Yes → start the shortlist on 5 LPM units.
- No → skip to step 3.
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Is progression of the underlying disease likely to push flow above 4 LPM in the next 24 months?
- No → 5 LPM is the correct class.
- Yes → consider 10 LPM now if the budget supports it; otherwise 5 LPM is still fine, with the plan to escalate to 10 LPM when the prescription changes.
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Is the prescribed flow 5–6 LPM?
- Consider a 6 LPM or 7 LPM-rated unit if available in your market (some models carry a 7 LPM peak on a 5 LPM chassis) — otherwise 10 LPM.
-
Is the prescribed flow 7 LPM or higher, or is HFNC involved?
- 10 LPM unit. Verify sustained purity at 7 LPM and 10 LPM on the specific model.
-
Dual-user household with a Y-splitter?
- 10 LPM, with purity measured at both outlets. Get physician sign-off on the splitter configuration.
Special cases
- Paediatric home oxygen — the prescribed flow is almost always low (often 0.25–1 LPM), but the consistency of flow at low settings matters more than headroom. Choose a 5 LPM unit with a clean low-flow regulator, not a 10 LPM unit running far below its optimal operating point.
- Intermittent heavy exertion — a patient whose baseline is 2 LPM but who desaturates to needing 5 LPM during activity can be served by a 5 LPM unit with a second portable for the activity window, or a single 10 LPM with a flow change routine. Both work; the right choice depends on lifestyle.
- Backup planning — some households with severe prescriptions run two 5 LPM units rather than one 10 LPM, on the redundancy argument. This can be cost-neutral at the margin, especially if the second unit is a refurbished or ex-rental device, and has the advantage that a single device failure does not interrupt therapy.
The short version
If the prescribed flow is ≤ 4 LPM and the trajectory is stable, a 5 LPM concentrator is the right device. If the prescription runs higher, or if progressive disease makes escalation likely, go 10 LPM. Price and running-cost differences are real but not prohibitive, and the clinical consequence of under-speccing is more significant than the cost of slight over-speccing. As always, consult your pulmonologist before making the final call — and take the prescription with you to the purchase decision, not after it.
This guide is editorial opinion and general information. It is not medical advice. Consult your physician for therapy decisions, and verify all specifications with the manufacturer before purchase.