气体分析-气体采样导则第一部分-英文

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TECHNICAL REPORT© ISO 2007 – All rights reservedISO/TR 976 Rev1:2007(E) 24 Rubber and plastics hoses and hose assemblies — Guidance on the layout of ISO and CEN standards Rubber and plastics hoses and hose assemblies — Guidance on the layout of ISO and CEN standardsE2007-01-01(60) PublicationISOISO    Technical Report 2007ISO/TR 976 Rev1ISO/TR 976 Rev1ISO/TR 976 Rev1 DSMHoses (rubber and plastics)Rubber and rubber products 145 2Heading 2Heading 1    02 STD Version 2.1c260   4C:\DOCUME~1\NAGES\LOCALS~1\TEMP\N1181_Layout_document-1.doc            ISO TC 158

Date:   2012-12-01

ISO XXXX:XXXX

Secretariat:  NEN  

 

Gas analysis —Sampling 

 

Part1 General

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Document type: International Standard

Document subtype: Work draft

Document stage:

Document language: E

 


Contents

Foreword

Introduction 6

1 Scope 7

2 Normative references 7

3 Terms and definitions 7

4 Sampling scheme 9

5 SAMPLING SYSTEM 10

5.1 SUMMARY 10

5.2 Sampling equipment and requirement 10

5.3 Sampling container 10

5.3.1 Summary 10

5.3.2 Nonmetal container 10

5.3.3 Metal container 11

5.3.4 Dewar 12

5.4 regular and flow mete 12

5.5 Sampling tube 12

5.6 Sampling device 13

6 Ready for sampling 13

6.1 Treatment of Sampling line and sampling container 13

6.2 Sampling device and leak detection 13

6.2.1 Sampling device construction 13

6.2.2 Leak detection 13

7 Sample pretreatment 13

7.1 Summary 13

7.2 Filtration 14

7.3 Dehydration 14

7.4 Cooling or increase temperature 14

7.5 Sampling pressure or sampling volume 14

8 sampling method 15

8.1 Summary 15

8.2 fullfill liquid purge 15

8.3 moving plugger purge method 15

8.4 pressurize and release to purge 15

8.5 vacuum/purge method 16

8.6 continue purge method 16

9 sampling program 17

10 error analysis for sampling 17

10.1 summary 17

10.2 Gas layer generation 17

10.3 Issues of sampling system 17

10.4 gas flow change 17

10.5 pipeline of sampling 17

10.6 sampling system purge 17

10.7 Sealing liquid 18

11 Safety in sampling 18

11.1 Summary 18

11.2 general requirement 18

11.3 Compressed gas sampling 19

11.4 Sampling of Cryogenic liquefied gases 19

11.5 Sampling of toxic gas 19

11.6 Sampling of flammable gases 20

Annex A 21

(informative) 21

Compatibilities between common gases and materials of packaging containers & pipelines 21

Annex B 23

(informative) 23

Solubility of partial gases 23

Annex C 24

(informative) 24

Explosion limit of common flammable gases 24

Bibliography 25

 


Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.

International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.

The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights.

ISOXXXX  was prepared by Technical Committee ISO/TC 158, Analysis of gases.


Introduction

 

Sampling method of gas is very important for measuring and analysis of gas components, purity, impurities and other properties. In general, sampling of gases is the first step of analysis and also it is the key step to analysis. It is very important to design the sampling pipeline valve fitting and sampling method that is sampling process to ensure to get analysis accuracy, safety etc, any errors during sampling will impact final result and give incorrect solution.

Gases in general storage and distribution in container as compressed gas, liquefied gas and also supplied by pipeline.

Gas is with high permission, diffusion property and the components are homogenous at the normal condition. It seems no more issues when sampling, but actually many issues exist when sampling and gases often are contaminated so that it induces analysis variance.

This international standard will give guideline to describe how to sampling compressed gases, liquefied gases and pipeline gases. ISO XXXX has been prepared in several parts:

Part1General

Part2Sampling of compressed gas

Part3Sampling of liquefied gas

Part4Sampling of pipeline gas

Part5Sampling of special gas

 

 

 

 

 

Notice-this standard could not avoid all risk refer to safety during sampling. If you follow the standard to process analysis, you also need follow your local safety regulations and standard.

 

 

 

 

 

 

 

Gas analysis — Sampling 

Part1 General

Scope

This part of ISO XXXX gives the general principles of gas sampling that can be used for different gases containing compressed gas, liquefied gas, pipeline gas and special gas. It should enable the user to select judiciously the proper method for different gases.

This Standard it suitable for compressed gases, liquefied gases and gases supplied by pipeline

This international standard is not applicable to sampling of ambient air and exhaust gas.

Normative references

The following references documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced documents (including any amendments) applies.

ISO 6206: 1979 Chemical products for industrial use; Sampling; Vocabulary

ISO 7504: 2001 Gas Analysis – Vocabulary.

ISO ×××××××× Sampling of compressed gas

ISO ×××××××× Sampling of liquefied gas

ISO ×××××××× Sampling of pipeline gas

ISO ×××××××× Sampling of special gas

Terms and definitions

ISO 7504, ISO 6206 defined below term and definition is suitable for the Standard

 

3.1   Gas

The boiling point of the material is between -273.15C to 20 at 101.3Kpa.

3.2   Liquefied gas

Storage and transfer with liquid phase, it is the general terms of high pressure liquefied gases, low pressure liquefied gases and cryo liquefied gas.  

3.3 High pressure liquefied gas

Gas with critical temperature between -50 and 70, partially show liquid phase owing to compression

3.4 Low pressure liquefied Gas

Critical temperature is more than 70C, the gas which partially showed liquid phase owing to compression.

3.5  Low temperature liquefied gas

    Critical temperature is less than -50, the gas which partially showed liquid owing to low temperature.

3.6  Compressed gas

Critical temperature is less -50, totally showed gas phase under pressure.

3.7  Toxic gas

    LC50 of the gas is not more than 5000X10-6(V/V)

3.8  Spot sample

Sampling from dedicate place or dedicate time, it express one moment or dedicate place sample

3.9  Sample transfer

The sample to container then transfer to the instrument site.

3.10 Sampling equipment

The equipment includes sampling pipeline, regulators, gas flower, sampling container and fittings etc.

 

3.11 Sampling device

Gas transmission and control device built with gas storage container or transfer line output interface, sampling pipes, pressure regulator, flow regulator, sampling container or analytical instruments.

3.12 Representative Sampling

Consistency of sub-sample and original sample.

3.13 Direct sampling

Sampling to instrument directly

3.14 Indirect sampling

Sampling from container

Sampling scheme

4.1  Summary

Sampling purpose is to take out representative sample. Because gas has the properties of permission, diffusion and easy to be contaminated.In fact,sampling faces many issues. The key point should ensure sampling system without leak, adsorbtion, contamination, it need purge well before sampling.Different sampling system should be selected according to gas properties(gas phase or liquid phase, pressure and temeperature etc), purity,concentration also should consider its package, storage place, transfer line etc.Before sampling, we must design the sampling system and sampling procedure.

4.2  Design of sampling program

Design of sampling program is shown in Figure 1.

Figure 1 – Sampling flowchart

 

 

 

Designed sampling program include:

— Sample pre-treatment program, see Chapter 7.

— Sampling container. Transfer the sample in accordance with the requirements of 5.3 to select the sampling vessel.

— Construction of sampling devices (including the sampling device selection), program described in provisions 5.6.

— Sampling Method, see Chapter 8.

— Sampling security measures, in accordance with Chapter 11.

Sampling system

5.1 Summary

Sampling system is consist of products and transfer outlet, pipeline, regulator or flower, control valve, sample container or instrument, vent or vacuum system, preparation system if needed, or gas vent disposal system.

Sampling system design relies on product property, product storage, transfer or physical state (gas phase or liquid phase) pressure and temperature, compatibility between sampling equipment material and products, products analysis variance etc.

Sampling system should be: cleaned, dried, no leak, material has no permission, reaction and absorption with sample.

5.2 Sampling equipment and requirement

Sampling device mainly consist of sampling container, regulator, flower, pipeline, vent line and disposal equipment etc.

Sampling equipment material must compatible with sample, it could not react with sample, permission, adsorption, it should be good machining stress

Sampling equipment selection also should consider gas product storage or transfer type, composition, purity, concentration, property and sample temperature, pressure etc. higher purity, lower component concentration, sampling equipment should be stricter.

Gas sampling line, sampling container material compatibility with products listed in appendix A

5.3 Sampling container

5.3.1 Summary

Sampling container is used to sample collection, storage and transfer, it suitable for indirect sampling.

Sampling container can be nonmetal or metal, the material meet this standard 5.2 item’s requirement

In general, nonmetal container is suitable for 1atm and low pressure gas sample, it is not used for high pressure sample or liquid sample, and neither the trace component or adsorbed component sample.

Metal container is usually applied to sample compressed gas and liquefied gas.

Sampling cryogenic liquid should use Dewar as container

Trace moisture and trace sulfide material which is easy to adsorbed to container, at this case, it could not select container for indirectly sampling.

5.3.2 Non-metal container

5.3.2.1 Glass container

Glass container is inert, lower adsorption (its adsorption relies on lubricate oil on plunger).it is often used lower pressure gas sampling.

Glass Syringe is one kind of glass container which is used for gas sampling.

2 ends equipped plungers(coated lubricated oil) of glass sampling container is showed in figure 1.

 

 

 

Figure 1 -Glass sampling container

5.3.2.2 Rubber gas bag

Rubber gas bag as sampling container is cheap, convenient, but the inner surface adsorped hydrocarbon, it is easy to permission hydrogen, helium. Sample composition maybe change, after sampling, sample must be analysis at once, it is used for normal gas analysis without high accuracy. It is not suitable for H2, He, and hydrocarbon sampling, also could not use it as sampling container to analyze moisture, sulfide, trace O2, trace N2 and trace hydrocarbon.

5.3.2.3 Aluminium inner surface gas bag

This gas bag is used to sampling sample which pressure is slightly higher than 1atm, it is much better than rubber gas bag on gas adsorption, permission. There are different kinds of gas bag, what kind of gas bag can be selected relies on gas property.

Aluminium inner surface gas bag is usually applied to atmospheric pressure and low pressure gas sampling, it is not suitable for the analysis of trace oxygen or trace nitrogen.

5.3.3 metal container

5.3.3.1 Small volume cylinder

Small volume cylinder is used to compressed gas and high pressure liquefied gas sampling.

Frequently used small cylinder include stainless stell cylinder, carbon steel cylinder, aluminium cylinder etc. some equipped valve on one end, some equipped valves on 2 ends. See figure 2

Cylinder volume is from 0.1L--10L, pressure is 0.1—15Mpa

Compatibility between cylinder material and gases attached in appendix A

When the gases possess strong adsorption, reaction, we need use container which inner surface treated with polish, coating or passivation

Container should follow local regulation and local standard, period test and leak detection needed.

(a)              b               c

Figure 2-Small volume cylinder

5.3.4 Dewar

In general, Dewar is used as container for Sampling Cryogenic liquid (such as LN2, LAr, LH2, LHe)from container or tank.

Dewar equipped valve see figure 3, it is applied to sample high purity liquid. Open dewar( no valve equipped) is applied to inaccurate analysis sample.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 3-Metal Dewar

5.4   Regular and flow meter

Gas sampling often use regulator, flow meter to adjust sample pressure and gas flow. Sometimes use fixed pressure valve or fixed flow valve.

Indicating pressure on regulator should be fit for gas sample.

If sampling continues online, suggest using fixed pressure valve or fixed flow meter to keep stable flow.

For high pressure liquefied gas sampling, to avoid gas condense owing to temperature decrease when gas expanded, we should adjust regulator pressure to low pressure.

5.5   Sampling tube

Sampling pipeline material can be stainless steel, Carbon steel, Brass or Copper, Aluminium, Hose, Glass, Quartz, PTFC, PVC, Rubber etc.

Sampling line material should be considered the compatibility with product property, temperature, pressure, state etc, material compatibility with product listed in appendix A.

The length of sampling line should be short as possible as you can, inner diameter should be smaller, when you must use longer sampling line, you need consider purge time and ensure sample should be same as actual product.

In general, nonmetal sampling line is not suitable for high temperature, middle and high pressure gas and liquid. Rubber and plastic pipe is normally used for sampling of percentage analysis, they are not be used to analyze moisture, sulfide and high adsorbed gases

High purity gas, corrosive gas, and purpose to analyze trace O2 and N2 sampling, pipeline should be selected with metal pipe such as stainless steel.

5.6 Sampling device

Sampling device is defined as the equipment of sampling line, regulator, flow meter, sampling container and instrument, vent line connect by fittings.

Sampling device can be fixed for long term use or temporary set up, but they could not be shared for different sampling.

The sampling device can be divided into two categories: Analysis instrument directly sampling and sampling container indirect sampling.

The component material of sampling device should comply with requirements of international standard 5.2, in addition, the key of sampling device should be no leakage, no penetration, no reaction and no adsorption.

Before sampling get ready

6.1  The treatment of sampling catheter and container

Sampling line, sampling container maybe container contamination such as lubricate oil, oil, solid waste and other contamination, before use them they must be cleaned in advance. According to contamination case, different cleaning method can be selected, such as inner surface polish, chemical treatment including washes with acid, base, passivation or electrochemical treatment.

Sampling container and pipeline should be dried without moisture.

Sample that has high active and low concentration measurement, metal container and tube inner surface must be treated by polish and passivation. Glass container must be treated by silanization.

6.2  Sampling device and leak detection

6.2.1 Sampling device construction

Use correct fittings to connect tube, regulator, flow meter, sample container or instrument to fix a sampling device, to sampling to instrument directly or indirectly.

Gas sampling device has following 3 kinds according to gas package and transfer type

a. Compressed gas sampling device

b. Liquefied gas sampling device,

c. Pipeline transfer sampling device.

6.2.2 Leak detection

Before sampling to instrument, sampling device must do leak detection. The device leak detection must consider all connecting joints, welding place.

a. Seal outlet, pressurize the system then close the gas source to observe the pressure gauge, whether the pressure change or not within fixed time period.

b. Pressurize the system, and keep the pressure, use leak detection liquid coat to connection joint to see any leak exist or not.

c. Use helium leak detection instrument to do leak check.

 Sample pre-treatment

7.1 Summary

The sample maybe is at ambient, lower or higher temperature, also container particle, oil, free water. Before sampling to instrument, it must be treated in advance to ensure sample is cleaned, dried, and the sample must be in gas phase at ambient or close ambient temperature.

Pretreatment include: filtration, oil-water isolation, drying, adjust sample temperature.

The principle of the pretreatment is to ensure not to change the composition of the sample and not to change the content of the analyte.

7.2 Filtration

Use filter to remove particles. To avoid filter block, the filter device commonly used filter face down.

Particle separation device includes:

a. Grid, sieve or strainer, available metal fabric, perforated plates, sintered blocks or slag composition, sheet material and trapped to mechanical retention larger particles (size is greater than 2.5 µ m).

b. Filters made of a metal, ceramic or natural and synthetic fibers porous plate.

c. Various special devices: Magnetic or electrical device, impactor, bubbler, scrubbers, condenser, cyclones and so on.

7.3 Dehydration

Dehydration method relies on sample’s property.

Common dehydration method is as follow:

a. Gas-water isolator, permission film.

b. Cold trip to remove water: gas sample through the condense container which is at close 0C to remove water. Please note maybe some component also condense together water at 0C.

c. Drying by chemical reaction or adsorption: common drying agent include Cal2, H2SO4, P2O5, Mg2ClO4, K2CO3, CaSO4;

d Physical adsorption: general adsorption agent include Silica gel, active Al2O3, Molecular sieve etc. Available adsorbent capability is based on the drying level, gas phase before through it, temperature and gas pressure. Please note: adsorbent maybe adsorb some components and then original sample composition change.

7.4 Cooling or increase temperature

If the sample is under higher temperature, it need cool down, but it could not condense when cooling to vary the composition. When moisture condense to water, sample need be Separated water and gas, if nessasory, drying sample. Drying method should be available to keep the composition and component concentration as same as original.

For Cryogenic or liquefied sample, it should be vaporized at high temperature, please note some liquefied component must be fully vaporized.

7.5  Sampling pressure or sampling volume

Before sampling, sampling pressure or required sampling volume should be clarified.

Sampling pressure is relies on products pressure, we must consider sampling volume, container working pressure to ensure sampling presure safety.

Sampling volume should be enough to complete whole analysis.

Sampling method 

8.1 Summary

in general, sampling system fill with air. Before sampling, The key point is to purge the systen with sampling to ensure sample is same as the product.

Different purge mothed can be select according to product property,storage and trasfer type.no matter what purge mothod selected,multipurge with sample needed or purge enough time.Especially for first time sampling with long sampling pipeline, purge time should be enough.

If sampling the sample contain trace concentration component, it must multipurge and enough time purge to ensure the sample is the same as product.

8.2  Fullfill liquid purge

Fullfill liquid purge mothed is descrobed as a method that select a liquid fullfill to container, then gas sample push the liquid out to fill in container to comlete sampling.

Water and satuated salt water is usually used as fullfill liquid. The principle to select liquid is to aviod trace component solve in the liquid.

Water is most convinient and widely used fullfill liquid. solubility of some gases in water listed in apprendix B.

Gas solubility is smaller in saturated salt water or dilute acid than in water, so satuarted salt water is also usually used for fullfill liquid.

Saturated with sample gas, because of the influence of gas temperature change and air agitation, closed the original liquid saturation may become less saturated or supersaturated, Which part of the gas to dissolve or a part of the release of gases so that the sample composition changes.

In general, fullfill liquid sampling mothed is only used for atomspare gas sampling and persentage analysis.

8.3  Moving plugger purge method.

Moving plugger of sampling equipment is shown as figure 4.

1-Inlet, Outlet; 2-Container; 3-Moving piston; 4-Mobile piston sampler

Push plugger to remove air, open sample source and draw plugger to sampling to syrine then push plugger, repeat several times to clean the syrine and sampling.

8.4 Pressurize and release to purge

Pressurize and release purge method process is shown in figure 5(a)

Open the sample gas, close sample line outlet, to pressurize sampling system to some pressure (the pressure must be smaller the sampling system pressure), then close gas source. Open outlet and release pressure. Repeat the process to purge sampling system.

How many times to repeat the process relies on analysis objective, if analyze trace component, it need more times to repeat the process. It can also be defined by experiment.

The method is easy, simple and purge quickly, so it is often used, it can purge well for dead volume in sampling system.

The method can be contaminated by back fill air, so when release pressure, don’t release to atmosphere.

 

1-Storage container2-The storage container output valve3-Vacuum valve4-Pressure vacuum gauge

5-Flow control valve6-Three-way valve7-Sample containers or analytical instrumentsa);8-Globe valve

9-Emptying or links pumps10-Vent

Fig.5. Sampling flow diagram

8.5 Vacuum/purge method.

Connect vacuum pump to outlet of sampling system, vacuum the system, then switch the valve to fill gas to some pressure, release gas then vacuum the system, repeat the process for some times, in general, repeat 3 times, the system is cleaned.

 Vacuum/purge method is known as the most available method to clean the system up to now.

8.6 Continue purge method.

This method is often used online instrument analysis and pipeline transfer gas sampling.

Purge sampling pipeline system with sampling gas continuasly. The system cleaning relies on purge time and purge gas volume. In genral, when component concentration is lower, adsorbility stronger, pipeline longer, purge time need be longer, more purge gas volume needed.

Pipeline transfer line with sample gas purge may cause hysteresis. Increase purge gas volume or open bypass valve can solve the issue.

Sampling system should not have dead volume when use this method, if the system has dead volum, we need to select pressurize and relelase pressure method together continues purge method.

When the sample contain strong adsorbed component or trace component, continue purge method is more available. The benefit of the method not only to purge air but also to ensure the representative sample in system is same as product. It is much better than other method. Therefore, even if selecting pressurizing and release method or select vacuum/purge method, we still need continue purge the system to ensure the sampling sample is same as product.

Sampling program

Compressed gas sampling according to ISO ××××——××××Part 2.

Liquefied gas sampling according to ISO ××××——××××Part 3.

Pipeline gas sampling according to ISO ××××——××××Part 4.

Special gas sampling and analysis according to ISO ××××——××××Part 5.

10 Error analysis for sampling

10.1  Summary

Gas processes permission, diffusion property and easy to be contaminated. Some gases also have adsorption and reactivity. If sampling process is not considered all effective factos, sample may not be as repressentitive sample. Sampling error is the variance between the sample and its parent, it express representative sample’s real level.

It is not possible that the sample has not any error. All root cause of sample error must be investigated in advance before sampling so that to make the error as less as possible.

10.2  Gas layer generation

Gas layer maybe happened when Gas in container to keep in place without any movement to make gases not homogenous.

If the gas transfers from pipeline, when gas flow is lower, pipe diameter is bigger, maybe cause laminar flow/

If gas or mixture layer happened, it would cause sample error.

If gas layer happened on static case, it should be rolled before sampling. If sampling from pipeline, sampling point should be selected from downstream of turbulence. Sampling from laminar flow should be avoided.

10.3  Issues of sampling system

Sampling system leakpermissionadsorptionreaction would cause the sample error.

Therefore, leak detection must be done to ensure sampling system has not any leak under pressure and vacuum before sampling. Meanwhile, the materials of sampling system has not permission, reaction with sample to ensure the sample has not any contamination, all components in sample can keep the same concentration without any varies.

Sampling for the components of analysis which could adsorbed in sampling system, any adsorption and cause sample error. But the case sometimes could not be avoided, so it would take long time to purge the system to get equilibrium of adsorption then sampling.

10.4  Gas flow change

When instrument online continues analysis, sampling flow little change will cause analysis error. Keep the stable flow is required according to instrument condition.

10.5  Pipeline of sampling.

Long sampling line would cause the sample to instrument could not match online product. So sampling line should be short as possible as we can. Increase gas flow can reduce purge time.

10.6  Sampling system purge

Sampling system purge is very important especially in trace concentration component analysis, if not purge well, sample error would happened, maybe the final result is not correct. In addition, the key point is that the purge must ensure the sample system get equilibrium with product.

10.7  Blocking solution

Using closed liquid displacement method sampling, should avoid the trace components dissolution effect. Water, dilute acid or salt water solution is usually used for sealing. The solubility of gas in water see Appendix B.

Usually the operation is to use the sample gas will be closed liquid saturation, enclosed liquid filled with sample containers, Then the sample gas will be closed out so that the full replacement of liquid, sample gas container, complete the sampling operation. But due to the influence of temperature and vibration, saturated closed liquid may become unsaturated or saturated, it will re dissolve a portion of the gas or release a portion of the gas, which leads to a change of sample gas composition.

11 Safety in sampling

11.1 Summary

In general, almost all gases may be considered as hazard gases. Even though it is Air, if it was compressed or liquefied, it posses high pressuremay cause container rupturecold injury etc.

Gas sampling risk includes:

——Oxidization, flammability, explosion

——Toxicity

——Corrosivityirritant

——Asphyxianty

——High pressure or low temperature

The risks described above often not exist with one risk, it often exist with several risks together.

When sampling gases, operator maybe get injuries from the risks or the risks could attack other peoples. One purpose of this standard is to give warning notice to operator or responsible peoples when sampling. Operator should pay more attention for safety issue to ensure sampling safety.

Beside the warning notice when sampling, Container storage, transportation and application also need follow laws, regulations and safety requirement.

11.2   General requirement.

Gas sampling should avoid any injuries, before sampling, it is necessary to consider any unexpected result may happen when sampling, such as: leakspillvalve loss control etc. to ensure no safety issue happen.

gas sampling often follow below guideline:

a. Operator should understand sample physical and chemical property and risk, know precaution to be taken for all risks, to be trained well and use appropriate personal protection equipment and safety equipment such as Extinguisher, safety glasses, respirator, protective glove and protective suit.

b. Safety equipment should be installed in sampling location, in/exit way, light and ventilation machine should meet safety condition.

c. Sampling device should include cut off, release pressure and control gas flow equipment, and scrubber etc.

d. It is necessary to ensure sampling system without any leak. Don’t free release gas from purge line when sampling, especially toxic gases. Scrubber should be included when necessary. Operator should check all opened valve in close status after sampling.

e. Sampling container and its storage transportation must follow local regulation and standard, sealed with pressure relief device. Material namerelated property and hazard must be identified and labeling on container.

f. To ensure safety, there should be second people present when sampling. The two should be specially trained, with action and protective measures should be taken in emergencies. The sampling operation, company should clearly observe the whole process of sampling operation, once discovered, should immediately report to the police, Especially for toxic gas sampling, sampling once feel discomfort should immediately stop sampling, take measures and report to the director. Except in very special circumstances, do not alone to rescue

g. Any unexpected issue happen, record it and report to supervisor.

11.3 Compressed gas sampling.

Sampling risk of high and medium pressure gases is mainly from pressure and high speed flow. Regulator and flow control equipment must be installed in sampling line when sampling.

When using sampling container, container inspection should be done before sampling to ensure sampling container’s working pressure should be suitable with sample pressure. Joint connection between container and sampling point should be reliable.

When sampling high pressure liquefied gases with container, enough space should be left in container, in any case, the space should be 5% of container volume at least when it encounter highest temperature.

11.4  Sampling of Cryogenic liquefied gases

Temperature of Cryogenic liquefied gas is very low, boiling point is less than -90℃(-130℉)at atmosphere. Human tissue can be frostbite when contact with cryogenic liquid and vapor, Cryogenic liquid and vapor also can make carbon steel brittle and easy break, so carbon steel container could not used to sampling cryogenic liquefied gas.

All cryogenic liquid can expanse very quickly when it vaporize. If cryogenic liquid expanse, its pressure increase very fast and can make container rupture. When sampling, it must follow filling factor and could not fill over full.

When cryogenic liquid vaporize and diffuse to Air, it form visible fog or vapor cloud. For flammable, asphyxia and toxic gases, should be detected the air outside the visible vapor cloud.

When sampling, operator must ware personal protection equipment (Safety glasses, glove, face mask etc.)

Warning: Cryogenic may cause splash injury to eyes and hand etc.

11.5   Sampling of toxic gas

In a certain sense, almost all gases are harmful to heath. Toxic gases can make fatality happened. Non toxic inert gases can make asphyxia when lack of oxygen, it also has high potential risk.

The harm of toxic gas to human body is mainly from breath poisoning.   

The site is well ventilated, when sampling gases whether it is toxic or not.

When sampling toxic gases, ware respirator, operator should ware coverall when necessary, if contaminate, it could be replace with new one. Contaminated suit could not be washed directly, toxic gas should be treated from suit then to wash.

Leak check must be done to Toxic gas sampling system to ensure no leak existed. Valve should be installed in sampling line when leak found, it can be close to interrupt sampling.

Sampling container should mark toxic gas obvious label.

Inspection must be done for sampling site to ensure no any leak happened before leaving. If leak found, report it immediately.

Warning: some gases (such as Carbon monoxide) is odorless, it is senseless; Even though some gases (such as Hydrogen Cyanide) odor, but human could not recognize; people’s smelling (such as for Hydrogen sulfide) maybe is dull after continue to smell it. If any gases (except O2) diffuse to air may cause asphyxia.

11.6  Sampling of combustible gas

Sampling of combustible and explosion gas has risk to burn and explosure. LEL of some gases listed in appendix C.

Hydrogen, Natual gas(LNG and CNG)liqeufied petrolium gasethylene etc. Are all typital flammable gases.

Sampling of flammable and explosive gases must follow related regulation, fire fighting safety management and fire protection regulation. Sampling container must mark obvious flammable label.

First of all, sampling of flammable and exposive gase should protect from fire burn. The site within 20 meters, there should be no any ignition and open fire, no static electricity and spark. Extiguisher should be in sampling site.

Ensure all valve closed after sampling.



Annex A

(Informative)

Adaptability of common gas and gas packaging, pipelines materials

A.1 The suitability of different materials and various types of gas.

Table.1. Material compatibility

Gas

Material

Stainless steel

Steel

Copper/Brass

Al/Al allow

Ni/Ni alloy

Glass/silicon

Teflon

Silicon liner stainless steel

Natural rubber

Butyl rubber

Silicone Rubber

Viton

Neoprene

Rare gas

A

B

A

A

A

A

B

A

C

A


A

A

H2

A


A

A


A

B

A

C




A

O2

A

B

A

A

A

A

B

A

C

B


A

A

N2

A

B

A

A

A

A

A

A

C



A

A

CO2

A

A

A

A

A

A

B

A

C

B


A

A

CO

B

C

A

A


A

B

A

C

B

A

A

A

Alkane

A

A

A

A

A

A

B

A

C

C



A

Olefin

A


B

A

A

A

B

A

C

C




Aromatic hydrocarbon

A


C

A

A

A

B

A

C

C




NO

A


A

A

A

A

B

A

C

C

A

A


NO2

A


C


A

A

B

A

C

C

A

A


Cl2

B


A


A

A

A

A

C

B


A


HCl

B


B

C

A

A

B

A

C



A


NH3

A

A

C


A

A

C

A

C




A

H2S

B


C

A

A

A

B

A

C

C


A


SO2

A


B

A

A

A

B

A

C

C


A


氟化物

sulfide

A





A



C



A


SF6

A

A


A


A

A


C



A

A

AIR

A

A


A


A






A

A

光气

phosgene

A





A





A

A


Note:

1Marking explanation: A. Adapt; B. Limited adapt or reservations; C. Incompatible;   

2No label that is no relevant information.

 

 

 

 

 

 

 

 

 

A.2. Incompatible gas with aluminum cylinder.

Table. A.2 Gas which can not be stored in an aluminum alloy cylinders

No.

Molecular formula

Gas name

No.

Molecular formula

Gas name

1

C2H2

Acetylene

8

CH3Br

Methyl bromide

2

Cl2

Chlorine

9

CH3Cl

Chloromethane

3

F2

Fluorine

10

BF3

Boron trifluoride

4

HCl

Hydrogen chloride

11

ClF3

Chlorine trifluoride

5

HF

hydrogen fluoride

12

COCl2

Phosgene

6

HBr

Hydrogen bromide

13

NOCl

Nitrosyl chloride

7

CNCl

Cyanogen chloride

14

CF2CFBr

Bromotrifluoroethylene ethylene


Annex B

(Informative)

Solubility in water of the gas

B.1 The solubility in water of the gas.

Table.B.1. The solubility in water of the gas at 1atm, 25.

Gas

Solubility

Nitrogen

Oxygen

Hydrogen

Carbon monoxide

Carbon dioxide

Hydrogen sulfide

Methane

Ethane

Ethylene

Acetylene

0.0140

0.0277

0.0172

0.0209

0.739

2.225

0.0294

0.0415

0.1064

0.811


Annex C

(Informative)

The explosion limit of common combustible gas

A.1 The explosion limit of common combustible gas

Table.C.1 The explosion limit of the combustible gas in the air

No.

Name

Molecular formula

Explosive limit (vol.%)

1

Methane

CH4

5.015.0

2

Acetylene

C2H2

2.581

3

Ethylene

C2H4

3.132

4

Ethane

C2H6

3.012.5

5

Propane

C3H8

2.29.5

6

Propylene

C3H6

2.410.3

7

N-butane

n-C4H10

1.98.5

8

Isobutane

i-C4H10

1.88.4

9

Butene

C4H8

1.69.3

10

Butene-2

C4H8

1.79.0

11

Isobutylene

C4H8

1.88.8

12

Pentane

C5H12

1.48.0

13

Chloromethane

CH3Cl

8.117.4

14

Chloroethane

C2H5Cl

3.815.4

15

Hydrogen

H2

4.075

16

Ammonia (anhydrous)

NH3

1625

17

Carbon monoxide

CO

12.574

18

Hydrogen sulfide

H2S

4.345

 

 


Bibliography

(1) ISO 3165:1976 sampling of chemical products for industrial use; Safety in sampling.

(2) ISO 6206:1979 sampling of chemical products for industrial use; Sampling; Vocabulary.

(3) ISO 7504:2001 Gas Analysis – Vocabulary.

(4) ISO 16664:2004  Gas Analysis – Handling of calibration gases and gas mixtures – Guidelines.

(5) ISO 32741876  Gaseous  halogenated hydrocarbons (liquefied gases) – Taking of a sample.

(6) ISO 8943:2007  Refrigerated light hydrocarbon fluids – sampling of liquefied natural – continuous and intermittent methods.

(7) ISO 10298: 1995  Determination of toxicity of a gas or gas mixture.

(8) ISO 10715  Natural Gas – Sampling Guidelines

(9) ISO 7382  Ethylene for industrial use – Sampling in the liquid and the gaseous phase.

(10) BS 2069:1954  Gas sampling tubes.

(11) NF X 20 251  Gas Analysis - Devices for the sampling of gases and their transfer to an analytical unit.

(12) ASTM F 307 2007  Standard Practice for Sampling Pressurized Gas for Gas Analysis.

(13) ASTM D 1265- 11  Standaed practice for sampling liquefied petroleum(LP) gases,manual method.

(14) Handbook of compressed gases(Fourth edition).

(15) MATHESON GAS DATA BOOKSeventh Edition  2001Carl L. Yaws

 


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