Five Types of CMS Poisoning: Symptoms & Remedial Solutions

June 05, 2026

Carbon Molecular Sieve (CMS) is the core consumable of PSA nitrogen generators. Once poisoned, it leads to reduced nitrogen output, insufficient gas purity and rising air-to-nitrogen ratio, shortening service life significantly. The five common poisoning causes are water soaking, oil fouling, acid gas corrosion, high-temperature degradation and dust coking. Most operators only spot CMS pulverization while ignoring poisoning as the root cause. This article analyzes symptoms, causes and field solutions for each failure.

Type of Poisoning	Symptoms	Causes	Solution
Water Flooding Poisoning	Lower N₂ purity & output; CMS caking; higher air-nitrogen ratio	Poor air drying; condensed water or moisture backflow	Long-time no-load purging; hot air drying; repair pre-drying system
Oil Contamination Poisoning	Black & sticky CMS; permanent capacity drop; unable for 99.99% high purity	Compressor oil leakage; failed pre-oil filtration	Light pollution: high-temperature N₂ regenerationHeavy pollution: replace full CMS and filters
Acid Gas Corrosion Poisoning	Brittle CMS; more powder; higher tower pressure drop; low N₂ recovery	Sulfide & acidic gas in raw air erodes carbon structure	Replace corroded CMS; add activated carbon pre-filter
High-Temperature Degradation Poisoning	Fragile CMS; failed high-purity nitrogen production; performance decay	Overheated inlet air (>45℃); poor heat dissipation	Control inlet temperature at 20–35℃; replace thermally damaged CMS
Dust Coking Poisoning	High tower pressure difference; blocked pores; reduced gas yield	Dust and organic residue coking inside micropores	Screen and regenerate CMS; install intake dust filter

In short, proper inlet air pretreatment against water, oil, acid and dust is the key to avoid CMS poisoning and keep long-term stable adsorption efficiency. Effective pre-treatment helps maintain consistent nitrogen purity and rated gas output, greatly extending the service cycle of carbon molecular sieve.