Vacuum Traps, Getters, and Filters Information

Vacuum traps and vacuum filters are used to remove tramp gases with a cooled surface, molecular sieve, filtration, or other processes. There are many types of vacuum traps and filters. Examples include the vacuum cold trap, liquid nitrogen cold trap, vacuum inlet trap (VIT), molecular sieve trap, cryogenic trap, and dry ice trap. A vacuum cold trap is a device used to trap particles by freezing them to the walls of a chamber. A liquid nitrogen cold trap is utilized to remove water, acidic, basic, solvent, contaminant rich air streams, or other items that can cause difficulty when introduced into a vacuum pump sublimates a gas molecule. A vacuum inlet trap (VIT) protects vacuum pumps, by condensing, absorbing, and neutralizing process byproducts from applications that generate volatiles, organic solvents, and acids. A molecular sieve trap contains tiny pores of a precise and uniform size that is used as an adsorbent for gases and liquids. A cryogenic trap is means for trapping organic compounds. A dry ice trap is recommended as a pre-trap to collect liquids and to dramatically reduce processing time. Other vacuum traps and filters are commonly available.

How Vacuum Traps, Getters and Filters Function

Vacuum traps and vacuum filters function in a variety of ways. A vacuum cold trap works on condensable gases such as water and solvents. The principle is called sublimation in which the gas molecule goes to a crystal state (or frost) from a gas state, bypassing its liquid form. The gas then crystallizes on the cold metal surface appearing as "frost" on the trap. The outer body and cold well of a vacuum trap is available as electro-polished ID/OD 304 stainless steel. Vacuum cold trap viewing rings and lid are clear acrylic plastic. A liquid nitrogen cold trap sublimates a gas molecule, thereby the molecule transforms from a gas phase to a crystalline phase by passing the liquid phase. A liquid nitrogen cold trap should provide a durable liquid nitrogen reservoir, good pumping speeds, and high reliability. A liquid nitrogen cold trap is available in vertical or horizontal configurations with a manual or pneumatic isolation valve option. A vacuum inlet trap (VIT) sometimes features three or four customizable stages of effluent trapping, where the first stage is a 200 in.² baffle shield surrounded by ID cooling coils. A vacuum inlet trap is available as a compact unit constructed from stainless steel and can be equipped with an optional bottom cooling section which has ¼ in. NPT drain plug. A molecular sieve trap includes a molecular sieve charge and a regeneration heater. The molecular sieve trap heater is held in place with a clip allowing the trap to be mounted in any position. A 4.0 inch diameter trap heater is rated at 120V, 125W; 6.0 inch at 120V, 230W; and 8.0 inch at 120V, 350W. A 240 volt regeneration molecular sieve trap heater is also available. Standard molecular sieve trap finish is bead blasted. A molecular sieve trap may also have an electropolish finish, custom flange configurations, and larger body size. A cryogenic trap usually consists of a liquid nitrogen container within a housing. The liquid nitrogen-cooled surface will condense oil as a solid, but it will also freeze out water vapor entrained in the gas flow during pumpdown. A cryogenic trap is designed for rapid cooling and efficient reheating, ensuring reproducibility, and optimum peak shape. A dry ice trap is a liquid solvent collecting device for use with filtration manifolds, gel dryers, rotary evaporators and vacuum concentrators where the desired solvent collection capacity does not exceed 1000 ml. Vacuum traps and filters are designed and manufactured to meet most industry specifications.


Vacuum traps and vacuum filters are used in a variety of applications. Vacuum traps and vacuum filters are utilized to protect pumps from vapors and particles, minimize oil backstreaming from oil-sealed pumps, minimize oil misting of rotary vane pumps, trap toxic or corrosive chemicals and vapors, and extend pump oil life by filtration.

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Schutte & Koerting
Precision Polymer Engineering Ltd.