Air Ejectors Cheaper Than Steam

When all the cost factors are considered, the air-operated ejector often proves to be the superior method for producing vacuum. Here are figures you can use.

For many years the air-operated ejector has been a neglected child in the field of vacuum producing apparatus. It has been greatly overshadowed by its highly successful, fully reliable and popular kin, the steam ejector. The popularity of the steam ejector has been somewhat justified because air-operated ejectors have been limited in their use by a relatively expensive and somewhat scarce supply of high-pressure motive air. Major reasons for selecting steam rather than air to operate ejectors have been the unavailability of air compressors and the relatively high cost of compressed air in most localities.

Improvements in air compressors have greatly reduced the cost of compressed air as compared to 20 years ago; and the greater availability of compressed air in process plants today makes the air ejector a reasonable and in some instances a preferred means of producing a vacuum.

The fact that air is a non-condensible gas under common conditions of temperature and pressure, limits its use as a propelling material for ejectors to two or three stages....

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