Sampling Ejectors for Gas Sampling

Analyzing Gas & Liquid samples is a routine requirement of process industry.
Gas Samples are frequently drawn to analyze and determine composition of gases
Obtaining samples for pipelines / chambers operating under pressure is easy as the internal pressure forces the gas into the sampling system.
But for systems operating at or near atmospheric pressure or under vacuum, the gas sample needs to be pulled out / extracted from the system.

Requirements from the Sampling system:

• The system must be able to generate the required flow and suction pressure/vacuum to obtain the required Sampling flow at the operating pressures.
• The system must not contaminate the sampled media and must be able to maintain its purity.
• The system must be able to handle the corrosive and abrasive nature of the media.
• Sampling being a measurement and quality control related process, it may be operated continuously or in form of batch operations. The system must be reliable enough to sustain the needs of the requirement whether continuous/batch with minimum downtime.

Sampling Ejectors are simple devices that operate on the basis of the jet Venturi principle.
Sampling Ejectors utilize the energy in compressed air/nitrogen for their operation and can be put to use to create vacuum conditions at their suction inlets.
The vacuum generated at its suction allows the Sampling Ejector or to suck the gas that is to be sampled. The sucked gas is then passed through the Analyzer to analyse the sample.

The capacity of the Sampling Ejector in terms of suction flow and max vacuum depends upon the internal design of the ejector and the operating compressed air pressure.

The Sampling ejector can develop vacuum upto 85 Torr or 110 mbar.

Sampling Ejectors are best suited for sampling systems due to their below inherent characteristics:

• Low Air / Nitrogen consumption and Ability to operate with wide range of motive (driving) pressure from 3 bar(a) to 7 bar(a).
• Ability to handle very high temperatures.
• Ease of Operation – The ejector is switched On/Off entirely by controlling the Air / Nitrogen flow to the ejector. Hence it is not necessary to access the ejector for controlling its operation.
• Can be manufactured in a large range of materials (Plastics, Stainless Steels, Exotic Materials)– it helps to select the best possible material compatible with the involved chemicals and reduces the risk of corrosion
• Sampling Ejectors do not contain any moving parts and have large internal passage areas, hence are not vulnerable to liquid entry or clogging by solid particles.
• As they have no moving parts, maintenance requirements are very less. Also it reduces largely the risk of abrupt breakdowns, helps in maintaining the regular production schedule
• Compressed air is a commonly available utility and hence no additional infrastructure is typically required.