Question 1

If my gas is already 5N, why do I still need a purifier?

Accepted Answer

5N (99.999%) means total impurities below 10 ppm, but advanced semiconductor processes require ppb or even ppt levels — three to six orders of magnitude lower. Residual moisture, oxygen, carbon monoxide, carbon dioxide and hydrocarbons form oxide layers at epitaxial interfaces and create defects in thin films. Moreover, as gas travels from the cylinder or tank through piping to the point of use, outgassing from pipe walls and micro-leaks at fittings reintroduce impurities — which is why purifiers are normally installed at the point of use rather than at the gas source.

Question 2

How do I choose between ambient POU, heated, and fully automatic types?

Accepted Answer

It comes down to flow rate and whether CH₄ or N₂ must be removed. Flow of 5–4000 SLPM with no need for automatic regeneration or CH₄ removal → ambient POU (BSP): compact, no heating or purge gas, lowest installation cost. Flow of 0.2–150 LPM but CH₄ or N₂ must be removed → heated type (BSH), using a getter alloy at elevated temperature for higher removal efficiency. Flow of 10–50000 Nm³/h with 24-hour uninterrupted supply required → fully automatic type (BSS series), with multiple adsorption beds in parallel alternating through regeneration.

Question 3

What is the difference between adsorption (ADS), getter (GET) and catalytic (CAT)?

Accepted Answer

Adsorption retains impurities on the adsorbent by physical or chemical adsorption; it can be regenerated at high temperature, lasts over 20 years and suits high flows. A getter removes impurities at high temperature through an irreversible chemical reaction — the deepest removal available, capable of handling N₂ and CH₄ — but it cannot be regenerated, so the getter column is replaced once saturated (3–5 year life). A catalytic bed converts CH₄, CO and similar species at high temperature into forms that adsorb readily; it needs neither regeneration nor replacement and normally sits in series ahead of the adsorption beds. Combined configurations such as CAT+ADS or ADS+GET are common in practice.

Question 4

What happens when the adsorbent saturates, and how often does that occur?

Accepted Answer

It depends on the type. Ambient POU units are returned to the factory for regeneration roughly every 1–2 years, with a body life of over 20 years. Heated units need no factory return — the getter column is replaced on site at end of life, lasting 3–5 years or more with a source gas quality of 5N or better. Fully automatic units (BSS series) regenerate in place at high temperature using parallel beds — one supplying while another regenerates — so under normal operation the adsorbent is never replaced and equipment life exceeds 20 years. The large-flow ambient type (BSS14) can be returned to the factory or regenerated on site by service personnel.

Question 5

Why is N₂ the hardest impurity to remove from inert gases?

Accepted Answer

The nitrogen molecule has no dipole moment and low polarizability, so its interaction with ordinary adsorbents is very weak and it is not stably adsorbed at ambient temperature. Its molecular size is also close to that of argon, so molecular-sieve pore-size separation alone cannot distinguish them. Pure adsorption designs such as BSS5-A are therefore largely ineffective against N₂. There are only two viable routes: use a high-temperature getter so the nitrogen takes part in an irreversible chemical reaction (BSS5-G / BSS5-H), or cool the adsorption bed into the liquid-nitrogen range to raise capacity dramatically (cryogenic types such as BSS7-C).

Question 6

What information do you need to specify a purifier?

Accepted Answer

Six items: the gas type (including the composition of any mixture); flow rate (maximum and nominal quoted separately); source gas quality (upper limit of each impurity at inlet); required outlet quality (target value for each impurity); operating environment and usage pattern (continuous or intermittent, working pressure, ambient temperature, whether explosion-proof construction is needed); and any other special requirements such as footprint limits, integration with facility monitoring, or certification needs. The more complete the information, the more accurate the selection and quotation.

Question 7

What do the letters and numbers in the model code mean?

Accepted Answer

Taking BS-P-G-500-N-HV as an example, the six fields read left to right as follows. BS is the Baisheng company prefix. The second field is the series: P for ambient-temperature POU inline units, H for small-flow heated units, S for large-flow fully automatic units, with the S series adding a number for the gas — S5 covers Ar / He / Kr / Ne / Xe, S7 is H₂, S8 and S9 are N₂, S22 is CDA. The third field is the technology and applies only to the S series: A for adsorption, G for getter, H for the combined type, C for cryogenic. The fourth field is flow rate, expressed in LPM for the P and H series and in Nm³/h for the S series. The fifth field is used only on small-flow heated units to indicate the gas type. The sixth field carries options such as HP for high pressure, SP for super high pressure and GT for cabinet type. Once you can read these six fields, the specification is visible directly in the model number.

Question 8

How is the purified gas quality verified?

Accepted Answer

ppb and ppt are two different measurement regimes and call for different instruments. Moisture and oxygen at ppb level can be monitored continuously with online trace moisture and trace oxygen analysers. ppt level targets — for example the organics, acids, bases and refractory compounds in XCDA — require dedicated methods such as APIMS, thermal desorption GC-MS or ICP-MS, and the sampling line itself must be built from high-purity material, otherwise the reading reflects the sampling line rather than the gas source. In practice, on-site instruments at a CDA or N₂ outlet can read H₂O concentrations in the 0.001 to 0.006 ppbV range. We recommend agreeing the acceptance method and sampling procedure at the procurement stage and building a baseline from regular sampling — a trend is far more reliable than a single reading.

Series	Flow range	When to choose it	Technical focus
P series (POU ambient)	5–4000 LPM	Small flow, no automatic regeneration and no CH₄ removal needed	Ambient catalytic adsorption; compact, low cost, easy to install, returnable for regeneration
H series (heated)	0.2–150 LPM	Small flow, but CH₄ or N₂ must be removed	Alloy getter operating at elevated temperature; deeper removal than ambient adsorption, getter replaced on site
S series (fully automatic)	10–50000 CMH	Large flow, fully automatic operation with 24-hour uninterrupted supply	Adsorption beds switch and regenerate automatically; PLC control and safety interlocks, service life over 20 years

Gas Purifiers — Semiconductor-Grade Ultra-High-Purity Systems

How to Choose: Model Code, Selection Inputs and Series Comparison

Model Code Structure

Six Inputs Needed for Selection

Telling P, H and S Apart

Heated Gas Purifier

POU Ambient-Temperature Gas Purifier

High-Pressure POU Gas Purifier

High-Pressure Gas Purifier

Large-Flow Ambient-Temperature Gas Purifier

Ammonia Purifier

XCDA Clean Dry Air Purifier

Carbon Dioxide Purifier

Supercritical CO₂ Purifier

Carbon Dioxide Purifier (Catalytic)

Rare Gas Purifier

Oxygen Purifier

Hydrogen Purifier

Cryogenic Hydrogen Purifier

Nitrogen Purifier

Nitrogen Purifier (CH₄ Removal)

Frequently Asked Questions

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