About the ISO 8573 1 Standard Update Tcm1340-3536498

8/13/2019 About the ISO 8573 1 Standard Update Tcm1340-3536498

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About the ISO 8573-1 standard


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History of ISO 8573

The original version of 1991 (edition1) standard defined 5 classes onoil concentration

The best Class 1, specifying an

oil concentration of 0,01 mg/m3

at 1 bar(a) 14.5 psia and 20oC

(68F)

Conformance to Class 1 was

sometimes called a technically

oil-free solution


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ISO 8573-1 (1991)

Unusually, the standard recommended methods to remove oil from the compressedair.

Quote Oil may be removed by high efficiency filters

It also cautioned users about using oil-free compressors

Quote The quality of air delivered by non-lubricated compressors is influenced by the quality of the

intake air and the compressor design

Oil vapors, which are not removed by coalescing filters were accorded negligibleimportance (when in fact quantity of vapors may be higher than aerosols)

Quote Therefore below approximately 35 oC (95 oF), the oil vapor content may be disregarded

In effect, the provisions in the standard were not adequate to assure the purity levelsdemanded by the industry and a new edition of the standard evolved: edition 2.


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Forms of oil in pipelines

When oil is present in pipelines, itis always in these three forms:

Aerosols are partially removed bycoalescing filters and appear ascondensate

Wall flow either appears in

condensate or travels to the process

Vapors are not removed by

coalescing filters!


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ISO 8573-1 (2001)

Major changes: The standard now spoke about total oil content (aerosol, liquid and vapour)

A standard was introduced on measurement of oil vapour ISO 8573 part 5

A new class (Class 0) was introduced to cover more stringent quality requirements

The clause which recommended ways to remove oil was deleted

Representative samples were asked


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ISO 8573-1 Testing Methods

ISO 8573-1 Part 2 Measurement of Aerosols

ISO 8573-1 Part 5 Measurement of oil fumes and vapors


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ISO 8573-1 Part 2 - Aerosols

Method B1

Measurement of full flow with

membranes. Measures all aerosols and wall

flow


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ISO 8573-1 Part 2 - Aerosols

Method B2

Sampling probe at the center of the

pipe is used. Wall flow is not measured


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ISO 8573-1 Part 5 - Vapors

Chemical absorption of oil by useof activated carbon.


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ISO 8573-1 Temperature factor

Reference Conditions: The reference conditions are

specified as 20o

C (68o

F) and 1 bar(a) (14,5 psia).

The above conditions are notrepresentative. Filters receive airat 4-10 oC (7-18 oF) above coolingmedium temperature which could

reach 30 oC (86 oF)! Also, theworking conditions of thecompressor are at higherpressures.

Oil carry over will be greater athigher temperatures !


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Atlas Copcos test

TV tested Atlas Copcos Z series of oil-free rotary screw compressors at: Three different temperatures: 20 oC, 40 oC and 50 oC at the measurement point

2 different pressures: 1 bar(a) and 8 bar(a)

Why is this important? Temperatures: oil carry-over increases exponentially with increasing temperatures.

Especially at 8 bar(a), the oil concentration goes up as compared to 1 bar(a)

As production environments change from place to place, country to country

and application to application, it is important to test at all possible conditions.


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ISO 8573-1 Filter factor

Another factor influencing test results when measuring oil residue incompressed air:

using lubricated compressors in combination with filters

The saturation level of the filter may affect oil carry-over.


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Committed to

sustainable productivity.

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About the ISO 8573 1 Standard Update Tcm1340-3536498

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