bulletin 918b selecting purifiers for gas chromatography while protecting columns and detectors....

Bulletin 918B

T197918B ©1999 Sigma-Aldrich Co.

Selecting the proper purifiers for a GC system begins withdetermining the contaminants to be removed from the gas,the levels to which the contaminants must be reduced, theflow and pressure needs of the system versus the flowmaximums for effective operation of various purifiers, andthe desired frequency of changing purifiers. The best purifiersystem includes multiple purifiers that help protect eachother while protecting columns and detectors. This bulletinincludes information needed to select suitable purifiers forcarrier gas, and for air and hydrogen used as fuel gases.

Key Words:• carrier gas • gas purifiers • gas chromatography

OverviewMost analysts realize the importance of using gas purifiers inpacked and capillary gas chromatography systems. It is knownthat capillary columns can degrade when exposed to oxygen orwater vapor in the carrier gas. In addition, hydrocarbons andother contaminants in the carrier gas can appear as peaks fromcommonly-used thermal conductivity detectors (TCD) and flameionization detectors (FID). With compound-specific detectors(sulfur, nitrogen/phosphorus, electron capture), hydrocarbons,oxygen, and water may be unseen, but they still can hinderquantification of analytes.

Establishing a gas purification scheme for a GC system can be acomplicated process. In selecting the proper purifiers for yoursystem, you must consider:

1. What contaminants must be removed from the gas andthe levels to which these contaminants must be reduced.

2. The flow and pressure needs of your system versus theflow maximums for effective operation of variouspurifiers.

3. The frequency with which you are comfortable withchanging purifiers.

Dozens of purifiers are listed in various catalogs, but informationensuring that a particular purifier will work for a particularapplication, or allowing cross-comparison, is lacking. This bulle-tin is an attempt to summarize all the information you need toselect appropriate purifiers for carrier gas, fuel air, and hydrogenused as a fuel gas. Performance characteristics of purifiers forremoving hydrocarbons, water, and oxygen from carrier gas aresummarized in three separate tables.

Carrier Gas PurificationIn carrier gas purification there truly is safety in numbers. The bestpurifier system includes multiple purifiers that help protect eachother while protecting your columns and detectors. Surges ofoxygen and/or water greater than 100ppm often are the result ofaccidental contamination of cylinders, regulators, and lines whenroom air enters the system during the process of changingcylinders. A single purifier that is intended for removing oxygen

Selecting Purifiers for Gas Chromatography

Figure A. Recommended Configuration for Carrier Gas Purifiers

Carrier GasCylinder

ShutoffValves

PressureReliefDevice Hydrocarbon Trap

PressureGauge

ShutoffValve

To Other GCs

OMI Tube

ShutoffValve

ShutoffValve

ShutoffValve

PressureGauge

In-LineFilter

PressureGauge

Molecular Sieve 5A Drying Tube

Oxygen / WaterVapor Trap

GC

x

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and water can be overwhelmed by these high levels of contami-nants; some oxygen/water traps even could be damaged. Forexample, an indicating purifier or heated purifier could overheat,possibly releasing previously trapped oxygen and water. Worse,overheating could break down the catalyst particles or coatedbeads in the purifier, generating contaminating breakdown prod-ucts and/or possibly plugging the purifier or greatly increasingthe back pressure.

For maximum system protection and longest purifier lifetimes inmost GC systems, we recommend a carrier gas purificationscheme consisting of a hydrocarbon trap, a water vapor trap, andan oxygen/water trap in series, as shown in Figure A. There isalways a possibility that a gas line or valving can contain residualhydrocarbons. For this reason, we recommend including a hydro-carbon trap in typical purification situations. The primary functionof the hydrocarbon trap is to trap most hydrocarbons, but somehydrocarbon traps, like our Supelcarb™ HC trap, contain acarbon molecular sieve that also retards the elution of oxygen andwater. Surges of oxygen and water that enter the gas line duringthe installation of a new cylinder of gas enter the hydrocarbontrap and are released slowly, diluted by the clean carrier gas fromthe new cylinder to levels that are more effectively dealt with bythe water vapor and oxygen/water traps downstream. (Note thathydrocarbon traps do not trap methane under normal condi-tions.) The water vapor trap, which typically contains a zeolitemolecular sieve, receives a reduced oxygen/water surge. It re-moves most of the water and continues to slow the movement ofoxygen, further reducing its concentration. Gas reaching the highefficiency oxygen/water trap contains significantly reduced con-centrations of contaminants. This conserves the purifying mate-rial in the trap, minimizing the frequency of replacement, andensures the trap will reduce oxygen and water levels to less than1ppm, the desired level of carrier gas purity to ensure best columnperformance and long column lifetimes.+

It is a decided advantage to have a visual indication of when toreplace these purifiers. We recommend installing an indicatingpurifier immediately before the gas line connection to the chro-matograph, as shown in Figure A. The indicating purifier shouldbe of glass construction; oxygen and water vapor can penetratethe wall of a plastic-bodied indicating purifier. In most systems anOMI™-2 indicating purifier will serve ideally.

An ideal GC configuration also includes valving that can purge thesystem upstream from the purifiers (x in Figure A). For detailedinformation on designing gas supply schemes for your GCsystem, request Bulletin 898 Gas Management Systems for GC.

One purification device, the UOP purifier, combines the functionsof hydrocarbon, water, and oxygen removal into a single system(Figure B). If you use one of these devices, you will need to replaceit more often than if you use larger capacity individual devices fortrapping hydrocarbons, water, and oxygen. If your gas usage isconstant, and you replace the device on schedule, you can use thecalculations discussed in How to Establish a Purifier Replace-ment Schedule (page 6 of this bulletin) to predict when toreplace a UOP purifier. On the other hand, an OMI-2 indicatingtube, installed downstream from the UOP purifier, is a simpler andmore reliable indicator of when to replace the device.

The purification scheme in Figure A will not always be the mosteconomical or practical approach. The following are examples ofsituations requiring other schemes.

Some analysts use a single gas chromatograph infrequently and/or with very low carrier gas flow rates. Their total carrier gas usemay be only one to a few cylinders per year. Further, the analysesthey perform may be at low column temperatures (e.g., 100°C orless) and the column may be relatively insensitive to water vapor.Under these types of low-demand conditions an oxygen purifier,such as one of those that call for changing with each cylinder ofgas, may be sufficient protection (Figure C). Our recommenda-tion is a 120cc Supelpure™-O tube, an Oxisorb® tube, or anOxiclear® cartridge; each device economically removes bothoxygen and water vapor when the incoming gas contains lessthan 10-15 ppm of each impurity.

Conversely, some analysts make extreme purity demands on theirsystems, in order to ensure maximum detection/quantificationcapability. In these situations, carrier gas purification needs can bemet with a hydrocarbon trap and a GateKeeper® purifier (FigureD). The electropolished stainless steel cartridge design, face-sealfittings or compression fittings, and highly efficient catalyticmedium enable the GateKeeper purifier to deliver gas with lowppb levels of hydrocarbons, water, and oxygen for very demand-ing applications, for a long time, at high flow rates. Because of itscost, a GateKeeper purifier should be used only in these specialcases, and when the incoming gas is of high purity or better.

Gas purification schemes for multiple GC systems are shown inFigures E and F. Scheme 1 in Figure F places more emphasis onwater vapor removal than on oxygen removal. A 750cc Supelpure-O trap has less capacity for oxygen than a High Capacity HeatedPurifier, but can be operated at higher maximum flow rates (10liters/minute, versus 1.1 liter/minute) that typically are needed tooperate multiple instruments. Scheme 2 emphasizes oxygenremoval by including a High Capacity Heated Purifier for eachbench of chromatographs, yet accommodates the lower maxi-mum flow allowed by the heated purifier.

Figure D. Purifier Scheme for a Systemwith High Purification Demands

Carrier GasCylinder

GateKeeperPurifier

Hydrocarbon Trap GC

+ Although detectors have requirements for gas purity, the purity needs of thecolumn generally are more demanding.

G000609

Figure C. Simple Purifier Configuration for aSingle-GC System with Undemanding Requirements

GCCarrier Gas

Cylinder

Supelpure-O (120cc),Oxisorb,

or Oxiclear TubeG000608

Figure B. UOP Purifier Combines Hydrocarbon,Water, and Oxygen Removal in One System

GCOMI-2 Indicating Tube

Carrier GasCylinder

UOP Purifier

G000607

3SUPELCOBulletin 918

Figure E. Purifier Scheme for a Multiple GC System: 2-5 Units, Total Flow of 1 Liter/Minute or Less

GC #1

Carrier GasCylinder

Large-CapacityHydrocarbon Trap

(750cc Supelcarb Tube)Large-Capacity Water Vapor Trap(750cc Molecular Sieve 5A Tube)

Large-Capacity Oxygen/Water Trap(High Capacity Heated Purifier or

750cc Supelpure-O Tube)

1/8" Lines and Fittings

GC #2 GC #3 GC #4 GC #5


t

s

tt

Figure F. Purifier Scheme for a Multiple GC System: Multiple Benches, 2-5 Units/Bench,Total Flow of More Than 1 Liter/Minute


Bench#6

Bench#2

Bench#3

Bench#4

Bench#5

Scheme 1

Carrier GasCylinder

Large-Capacity Hydrocarbon Trap(750cc Supelcarb Tube)

GC #1 GC #2 GC #3 GC #4 GC #5

Large-Capacity Water Vapor Trap(750cc Molecular Sieve 5A Tube)

OMI-2Tubefor

EachGC

Large-Capacity Oxygen/Water Trap(750cc Supelpure-O Tube)


1/8" Linesand Fittings

Scheme 2

OMI-2 Tubefor Each GC

HighCapacityHeated

Purifier forEach Bench

(Plus OMI-2Tube forEach GC)

1/8" Linesand Fittings

Carrier GasCylinder

Large-Capacity Hydrocarbon Trap(750cc Supelcarb Tube)

Large-Capacity Water Vapor Trap(750cc Molecular Sieve 5A Tube)

High Capacity Heated Purifier


GC #1 GC #2 GC #3 GC #4 GC #5

Bench#6

Bench#2

Bench#3

Bench#4

Bench#5

OMI-2 Tubefor Each GC

G000610

G000611, G000612

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The first step in deciding which purifiers to use is to determine,based on the number and types of chromatographs in yoursystem, what the gas flow through the purifiers will be. Exceedingthe flow rate that a purifier is designed for will reduce the contacttime between the gas and the medium in the purifier, and thepurifier may not reduce the contaminants in the gas to theadvertised levels of purity. If the total flow in your system is 1 liter/minute or less, smaller purifiers (typically containing 100-120cc ofadsorbent material) can be used. If the flow is between 1 liter/minute and 10 liters/minute, a large capacity purifier of each type(typically 750cc of adsorbent material) can be used. For flowsgreater than 10 liters/minute, we recommend using two or morelarge purifiers of each type in parallel (Figure G). In the larger flowsystems, which typically serve 5 or more chromatographs, anideal carrier gas purification scheme consists of a large purifier (orpurifiers) for removing hydrocarbons, a large purifier (or purifiers)for removing most water, and a large capacity oxygen/water trap,plus a small capacity, high efficiency oxygen/water indicatingtrap in the line to each chromatograph. The indicating trap willremove the last traces of contaminants, including any contami-nants introduced by leaks at connections, valves, or regulators. Aslarge purifiers, we recommend a 750cc Supelcarb™ HC hydrocar-bon trap, a 750cc molecular sieve 5A water vapor trap, and a750cc Supelpure-O trap or our High Capacity Heated Purifier.OMI™-2 or OMI-4 indicating purifiers will remove the last tracesof oxygen and water from the carrier gas, any oxygen or waterentering the system at leaks downstream from the main purifier.

Air PurificationAir used as fuel for a flame-type detector does not require thesame degree of purification as is required for carrier gas. Effectiveair purification consists of removing the hydrocarbons and reduc-ing the water level to 50ppm or less. The approach to airpurification differs, however, depending on whether the source ofthe air is cylinders, an air compressor, or an air generator.

Figure H shows the purification scheme for air from low-gradecompressed air cylinders is relatively simple. An air compressor,however, may complicate the issue. Most air compressors havebuilt-in water vapor traps, but the heat generated by the unit cancause significant amounts of water vapor to still be present in theair produced. A water vapor trap downstream from the hydrocar-bon trap will reduce the water content in the air (Insert B, FigureH). Depending on whether the compressor is oil-sealed or oilless,the quantity of hydrocarbons will vary greatly. Even an oillesscompressor can allow hydrocarbon levels that should causeconcern. (The location of the air intake for the compressor is very

important in determining hydrocarbon levels.) If you use an oil-sealed air compressor, we recommend installing three specialfilters between the compressor and the hydrocarbon and watervapor traps: a large particle (40µm) trap, followed by an oil-removing (coalescing) filter, followed by an oil vapor removingtrap (Insert A, Figure H). We recommend placing the filters andtraps some distance from the compressor, to allow the air to coolprior to filtration/purification.

As an alternative to air cylinders or compressors, a modern, low-maintenance zero air generator will provide air at a purityexceeding the quality demands of your chromatograph.

As with carrier gas, determine your total air flow requirement, anduse purifiers of suitable capacity.

Hydrogen (Fuel) PurificationFor hydrogen used as fuel for a flame-type detector, the samepurification system is used as for air from cylinders. We do notrecommend using plastic bodied purifiers to purify fuel hydrogenbecause they are permeable to oxygen and water in the atmo-sphere. Instead of reducing the oxygen and water content, thesetraps can allow the oxygen and/or water level to become toohigh.

Evaluating Carrier Gas NeedsA gas chromatograph normally is a two-column unit with twopacked columns, one packed column and one capillary column,or two capillary columns. Knowing the flow needs of each of theseunits will enable you to calculate the number of cylinders of gasyou will need each month.

Typical carrier gas requirements are shown in Table 1. To deter-mine your gas consumption per month, determine how manychromatographs you have with each combination of columns,and estimate the gas flow to each chromatograph. You can useTable 1 to estimate the number of cylinders of carrier gas requiredby each chromatograph each month. Add these values to deter-mine your cylinder per month needs. The lines in Table 1 separate1 liter/minute flows from higher flows. If your gas requirement ison the high side of the line you should use large purifiers to ensureefficient removal of impurities and to minimize the frequency ofchanging purifying devices.

Purifier Selection TablesThe values in Tables 2, 3, and 4 are reasonable expectations ofpurifier performances, based on several assumptions.

Figure G. Parallel Purifier Configuration for System Requiring High Gas Flows

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From GasSource

Purifier

Purifier

Purifier

To GCs


In developing the information in these tables, we began withstoichiometric reactions between the purifier media and thecontaminant indicated, to determine the number of grams ofcontaminant theoretically absorbed by one gram of each me-dium. But, typically, contaminants start to break through apurifier after about 75% of the theoretical capacity is expended.This is because the contaminants react with the medium alongthe center of the purifier tube before they react with the mediumalong the periphery of the tube, creating a cone-shaped profile(Figure I). When the tip of the cone reaches the end of the tubebreakthrough begins, although there is still a large amount ofunreacted medium in the tube. In Tables 2, 3, and 4, we haveadjusted the purifier lifetime values to 75% of the theoreticalvalues, to allow for this phenomenon.

Purifier lifetimes, in numbers of cylinders, are based on 9" x 51",218 cubic foot cylinders of helium carrier gas containing 50ppmof hydrocarbons (Table 2), water (Table 3), or oxygen (Table 4).Even inexpensive grades of carrier gas offer better initial puritythan this, but we use this high value to account for other sourcesof contaminants, such as oxygen and water entering the gassystem during the cylinder changing process. The fewer andsmaller the sources of contaminants in your system, the greater isthe likelihood that your purifiers will have longer lifetimes. Use ofcylinders of other sizes or pressures also will affect these estimates.

Pick purifiers from Tables 2, 3, and 4 based on the flow andpressure needs of your system and the frequency with which youwould prefer to change purifiers (e.g., once a month, once every6 months, once a year). It is possible to choose purifiers that workfor years under the flow and gas purity demands of your system.Typically these are forgotten about and never changed. For thisreason, we recommend routinely changing purifiers semi-annu-ally or annually, unless they need more frequent replacement.

Notice that the indicating purifiers listed in Tables 2, 3, and 4 havevery small capacity. These purifiers are intended for installationdownstream from larger purifiers – their primary function is togive notice of when the larger purifiers must be changed.

Indicating purifiers will require frequent changing if they are usedas the only purifiers in the system.

Tables 2, 3, and 4 focus on the number of cylinders that a purifierwill clean before the purifier is expended (“Stated Life in Cylin-ders”). These values are based on operation of one chromato-graph fitted with two capillary columns, each column requiringa flow of 133cc/minute. Table 1 shows other typical cases: a GCwith two packed columns, used at a range of flow rates, and a GCwith one packed column and one capillary column. If you wantto know how long a purifier will last with one of these systems,multiply the Stated Life in Cylinders value by 266 and divide bythe estimated flow in the system you choose. You can use the flowvalues in Table 1 as estimates, or measure the flows in your system.In most cases the flow requirements of the two capillary columnswill be the higher flow, therefore your estimated life in cylindersshould be greater. Likewise, you can extrapolate from the table tosituations in which a purifier is used to serve multiple GCs.Remember, however, not to exceed the maximum flow capacityof the purifiers you wish to use.

Figure H. Recommended Configuration for Purifying Fuel Gases from Cylinders

FlashbackArrestor

Hydrocarbon Trap In-Line Filter

PressureReliefDevice

ShutoffValves

Two-StagePressure Regulator

Vented to FumeHood (or other

approved outlet)

PressureGauge

ShutoffValve

ParticleFilter

OilVapor

RemovingFilter

Oil-Removing(Coalescing) Filter

t

t

Hydrocarbon Trap

PressureReliefDevice

ShutoffValves

Two-StagePressureRegulator

HydrogenCylinder(Fuel)

AirCylinder

GCShutoffValve

Pressure Gauge

In-Line Filter

B

A

A

Add These Components When Using anAir Compressor

797-0370

Molecular Sieve 5A Drying Tube

B

Figure I. Breakthrough Begins at About 75% ofApparent Purifier Capacity

Forwardmost Pointof Expended Absorbent

Spent Adsorbent

797-0371

Unspent Adsorbent75% of Length

Color Indication

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How to Establish a Purifier Replacement ScheduleTables 2-4 show values for a specific situation – one gas chromato-graph equipped with two capillary columns, each requiring133mL/minute of helium from 218ft3 cylinders. We will explainhow we arrived at the numbers in these tables, and will enableyou to calculate corresponding values for other situations: othernumbers of chromatographs, other carrier gases (hydrogen,nitrogen), other sizes of cylinders, or other levels of gas purity.

First, you must determine your carrier gas consumption permonth (G).

Sum up all gas flows to all the columns in your system to get thetotal gas flow rate per minute (Tg):Tg = (column flow + make-up gas* + split vent flow + septum

purge flow) x number of columns

If you need help in determining gas flows, consult your instru-ment manuals or refer to Bulletin 898 (available free on request).

Using the number of minutes in a year:60min/hr x 24hr/day x 365 days = 525.6 x 103 minutes/year

Determine one year’s gas demand:Tg x 525.6 x 103

If your system is not operated continuously, revise the number ofminutes per year accordingly.

G = one year’s gas demand / 12

From G, calculate the number of cylinders you need per month:cylinders/month = G (mL) / [amount of gas in a cylinder (ft3) x28,320mL/ft3]

where 28,320mL/ft3 is the factor for converting from ft3 to mL

Impurities in a cylinder of gas usually are stated in parts permillion, volumetric (ppm). Determine the amount of impuritiesfrom the concentration:

X ppm / 1,000,000 x 100% = X1% impurities

Next, convert the amount of impurities from volume to weight.You must know the density of the impurity. Knowing the volumeof the cylinder, and using 28,320mL/ft3 to convert from ft3 to mL,calculate the volume of impurities in the cylinder:

X1% x ft3 x 28,320mL/ft3 / 100% = Y mL(at standard pressure)

Table 1. Carrier Gas Flow versus Gas Consumption2 Packed Columns 1 Packed / 1 Capillary Column 2 Capillary Columns

No. Flow (cc/min) Cylinders/Month** Flow (cc/min) Cylinders/Month**GCs low Þ high low Þ high low Þ high low Þ high Flow (cc/min) Cylinders/Month**

1 40 120 0.3 0.9 153 193 1.1 1.4 266 1.92 80 240 0.6 1.7 306 386 2.2 2.7 532 3.83 120 360 0.8 2.6 459 579 3.2 4.1 798 5.64 160 480 1.1 3.4 612 772 4.3 5.4 1064 7.55 200 600 1.4 4.3 765 965 5.4 6.8 1330 9.46 240 720 1.7 5.1 918 1158 6.5 8.2 1596 11.37 280 840 2.0 6.0 1071 1351 7.6 9.5 1862 13.28 320 960 2.2 6.8 1224 1544 8.6 10.9 2128 15.09 360 1080 2.5 7.7 1377 1737 9.7 12.2 2394 16.9

10 400 1200 2.8 8.5 1530 1930 10.8 13.6 2660 18.8All values are based on 24 hour/day, 7 day/week operation. If you operate at high flow rates, but use a carrier gas saving mode at night and over weekends,consumption will be nearer the low consumption values.Flows to capillary columns assume a split vent flow of 50-100mL/minute for each column.

** Values are based on 218 cubic foot cylinders, used at standard temperature and pressure. Values will differ for other cylinder sizes or pressures. For the number ofcylinders/month for your system, determine the number of standard cubic feet in a cylinder of your carrier gas, divide by 218, then multiply the cylinders/month listedin Table 1 by this value.

Then, knowing the impurity density (D), determine the amountof impurity in the cylinder by weight:

Y mL x D grams/mL = Y1 grams

Tables 2, 3, and 4 in this bulletin indicate the amount of animpurity each purifier can remove. Therefore, you can determinehow many cylinders of gas a particular purifier can purify at a givenconcentration of a given impurity. Gases usually have less impuritythan stated, but you must be conservative in your calculations.Consider that oxygen, water vapor, and hydrocarbons also canenter the system from leaks, during the cylinder changing process(unless you have a purging system that displaces air from thetubing after the cylinder change), from defective valving, etc. Toensure a safe margin for error in your estimates, you shouldassume that concentrations of impurities in your system arehigher than the levels stated by the gas manufacturer.

Once you determine how many cylinders a purifier can purify,from the cylinders per month of gas usage calculations, you canestablish a schedule of changing cylinders and purifiers.

Example:

For a system consisting of 2 GCs, each fitted with 2 capillarycolumns, requiring a flow of 133mL/minute for each column:

2 GCs x 266mL/min x 525.6 x 103 min /[12 months/year x 218ft3 x 28,320mL/ft3]

= 4 cylinders/month

Grade 4.5 (high purity) gas usually is 99.995% pure, or has0.005% (X = 50ppm) of impurities

X1 = 50ppm x 100% / 1,000,000 = 0.005%

This means that if the 50ppm of impurities in the cylinder wereoxygen alone, there is:

Y = 0.005% x 218ft3 x 28,320mL/ft3 / 100%= 308.7mL oxygen in the cylinder (at standard pressure)

or

Y1 = 1.33g/L x 10-3L/mL x 308.7mL = 0.411g oxygenwhere 1.33g/L is the density of oxygen (gas) at 760mm Hgand 20°C.

From Table 4 we can see that at 50ppm oxygen in the system, aHigh Capacity Heated Purifier would purify approximately 36cylinders containing 218ft3 of gas. Therefore, if you are using 4cylinders per month, you must change the purifier tube every 9months.*If the make-up gas is the same as the carrier gas.


Table 2. Carrier Gas Purifiers for Hydrocarbon Removal 1

Maximum Flow and Capacity StatedName of Carrier Gases Contaminants Inlet Pressure (grams HC LifePurifer Purifed Removed Product Description 2 (cc/min) (psig) x 75%) 3 (cylinders)

Supelcarb HC He, H2, N2, Ar/CH4, C3 and higher 120cc tube 2000 250 18 16.5air hydrocarbons 1/8" 24448 1/4" 24449

750cc tube 10,000 250 120 1101/4" 24564 1/2" 24565

Supelpure HC He, H2, N2, Ar/CH4, C4 and higher 120cc tube 2000 250 9 8.0air hydrocarbons 1/8" 22445 1/4" 22446

750cc tube 10,000 250 60 55.01/4" 24518 1/2" 24519

UOP He O2, H2O, CO2, CO 364cc tube 500 250 7.5 6.9Inert Gas halocarbons, 1/8" 22680 1/4" 22681Purifier hydrocarbons,

sulfurs1 Based on 9" x 51" cylinders (218 cubic feet) of carrier gas containing 50ppm of contaminants supplying 1 chromatograph with 2 capillary columns. Ask your supplier

for specifications for the cylinders you use. To correct for other volumes of gas per cylinder, multiply values for Stated Life (cylinders) by the number of cubic feet inyour cylinders divided by 218.

2 Quantity of adsorbent material - dimensions of fittings - catalog number .3 Expressed as medium weight (C8-C20) hydrocarbons.

Table 3. Carrier Gas Purifiers for Water Removal 1

Maximum Flow and Capacity StatedName of Carrier Gases Contaminants Inlet Pressure (grams H 2O LifePurifer Purifed Removed Product Description 2 (cc/min) (psig) x 75%) (cylinders)

Molecular Sieve He, H2, N2, H2O 200cc tube 2000 250 15.6 685A Trap many others 1/8" 20619 1/4" 20618

750cc tube 10,000 250 58.5* 2531/4" 23991 1/2" 23992

High Capacity He, N2, Ar/CH4 O2, H2O, CO2, CO 32cc tube3 1100 150 16.9 73Heated Purifier not compatible 1/8" 22396 1/4" 22398

with air, O2, H2

OMI He, H2, N2, Ar/CH4 O2, H2O, CO2, CO, OMI-2, 15cc tube4 1/8" 23906 1000 150 0.2 0.8NH3,

not compatible alkynes, OMI-4, 90cc tube4 1/8" 23909 1000 150 1.3 5.8with air or O2 halocarbons,

halogens,hydrogen halides

GateKeeper He, H2, Ni2, Ar O2, H2O, H2, CO2, 35cc cartridge 24970 1000 200 0.1 0.5CO,

not compatible (removes H2 as a 500cc cartridge 24971 60,000 200 1.4 6.0with air or O2 contaminant, also

can purify H2 carriergas)

Supelpure-O He, H2, N2, Ar/CH4 O2, H2O, CO2, CO, 120cc tube 250 100 1.5 6.5NH3, 1/8" 22449 1/4" 22450

not compatible alcohols, alkanes,with air or O2 alkenes, amines,

aromatics, 750cc tube 10,000 250 10.2* 44.3diethylether, 1/4" 503088 1/2" 503096halogens, sulfurs

UOP He O2, H2O, CO2, CO, 364cc tube 500 250 26.3 114Inert Gas halocarbons, 1/8" 22680 1/4" 22681Purifier hydrocarbons,

sulfurs1 Based on 9" x 51" cylinders (218 cubic feet) of carrier gas containing 50ppm of contaminants supplying 1 chromatograph with 2 capillary columns. Ask your supplier

for specifications for the cylinders you use. To correct for other volumes of gas per cylinder, multiply values for Stated Life (cylinders) by the number of cubic feet inyour cylinders divided by 218.

2 Quantity of adsorbent material - dimensions of fittings - catalog number .3 Heat required (tube must be installed in a specially designed heater).4 Holder required.* At a flow rate of 1000cc/min.

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Table 4. Carrier Gas Purifiers for Oxygen Removal 1

Maximum Flowand Inlet Capacity Stated

Name of Carrier Gases Contaminants Pressure (grams O 2 LifePurifer Purifed Removed Product Description 2 (cc/min) (psig) x 75%) (cylinders)

OMI He, H2, N2, O2, H2O, CO2, CO, OMI-2, 15cc tube3 1/8" 23906 1000 150 0.16 0.4Ar/CH4 NH3,not compatible alkynes, halocarbons, OMI-4, 90cc tube3 1/8" 23909 1000 150 1.19 2.9with air or O2 halogens,

hydrogen halides

High Capacity He, N2, Ar/CH4 O2, H2O, CO2, CO 32cc tube4 1100 150 15.0 36.5Heated Purifier not compatible 1/8" 22396 1/4" 22398

with air, O2, H2

Supelpure-O He, H2, N2, O2, H2O, CO2, CO, 120cc tube 250 100 0.45 1.1Ar/CH4 NH3,, alcohols, 1/8" 22449 1/4" 22450-Unot compatible alkanes, alkenes, 750cc tube 10,000 250 2.4* 5.8with air or O2 amines, aromatics, 1/4" 503088 1/2" 503096

diethylether,halogens, sulfurs

GateKeeper He, H2, N2, Ar O2, H2O, H2, CO2, CO 35cc cartridge 24970 1000 200 0.77 1.9not compatible (removes H2 as a 500cc cartridge 24971 60,000 200 9.56 23.3with air or O2 contaminant, also can

purify H2 carrier gas)

Oxisorb He, H2, N2, Ar/CH4 O2, H2O, CO2, CO 52cc cartridge3 20631 5000 90 NA5 1.05

Oxiclear He, H2, N2, Ar/CH4 O2, H2O, CO2, CO 180cc cartridge 3000 250 NA5 3.55

1/8" 22992 1/4" 22993

UOP He O2, H2O, CO2, CO, 364cc tube 500 250 2.14 5.2Inert Gas halocarbons, 1/8" 22680-U 1/4" 22681Purifier hydrocarbons, sulfurs

1 Based on 9" x 51" cylinders (218 cubic feet) of carrier gas containing 50ppm of contaminants supplying 1 chromatograph with 2 capillary columns. Ask your supplierfor specifications for the cylinders you use. To correct for other volumes of gas per cylinder, multiply values for Stated Life (cylinders) by the number of cubic feet inyour cylinders divided by 218.

2 Quantity of adsorbent material - dimensions of fittings - catalog number .3 Holder required.4 Heat required (tube must be installed in a specially designed heater).5 Data for determining oxygen capacity was not available from the manufacturer. Stated life in cylinders is the manufacturer’s recommendation.* At a flow rate of 1000cc/min.


Checklist of Products for Gas Chromatography SystemsOrdering Information:

Description Cat. No.

Fittings - Swagelok® - Please see our catalog

Fittings - Other

Diaphragm Shutoff Valveq 1/4" MNPT x 1/4" FNPT 23896q 1/4" MNPT x 1/4" MNPT 3897

Hydrogen Flash Arrestorq Brass, 1/4" female NPT 23315q Stainless Steel, 1/4" female NPT Z261858-1EA

Gas Compressorq Jun-Air Oilless Compressor 100 to150 liters/min,

w/drier & noise compression 22825

Gas Generators

Hydrogenq Packard Model 9150, 160 cc/min 27620-Uq Packard Model 9200, 250 cc/min 22751q Packard Model 9400, 500 cc/min 22801q Packard Model 9800, 1200 cc/min 22835

Zero Air Generator-GCq Packard Model 1000 (110 VAC), 1 liter/min 22824q Packard Model 1001 (220 VAC), 1 liter/min 22830-Uq Packard Model 3500 (110VAC), 3.5 liters/min 27625-Uq Packard Model 3501 (220VAC), 3.5 liters/min 27626-U

Nitrogen Generatorq Air Products, 1 liter/min

(99.9999+% pure nitrogen) 22753

Leak DetectionSnoop® Liquid Leak Detectorq 8 oz bottle 20434q 1 gallon bottle 20640-U

Leak-Tec Leak Detectorq spray bottle 20566

GOW-MAC® Gas Leak Detectorq Deluxe Model 21-250 22409

GOW-MAC Mini Gas Leak Detectorq 115 VAC/60hz 22807q 220 VAC/50hz 22808q GOW-MAC Mini Leak Detector carrying case 22809

Description Cat. No.

Regulators

Economy In-Lineq Brass body, 1/8" fittings 23883

General Purpose In-Lineq Aluminum body, 1/8" fittings 23748

High Purity In-Lineq 1/8" fittings, SS diaphragm, neoprene seals 23882q Ultra high purity in-line, 1/8" fittings,

SS diaphragm, metal seals 23884

High Purity Single Stageq CGA 580, He, N2, Ar 23876q CGA 350 H2, Ar/methane 23877q CGA 590 purified air 23878

Ultra High Purity Single Stageq CGA 580 He, N2, Ar 23870q CGA 350 H2, Ar/methane 23871

High Purity Two Stageq CGA 590, purified air 23881q CGA 346, compound air 23899q CGA 580 He, Ne, Ar 23879q CGA 350 H2, Ar/methane 23880-Uq DIN 6, He 24972q DIN 1, H2, Ar/methane 24974q DIN 13, air 24973

Ultra High Purity Two Stageq CGA 580, He, Ne, Ar 23872q CGA 350, H2, Ar/methane 23873

SUPELCOBulletin 918

10

Pressure Gaugesq 2", 1/8" brass tee, 0-30 psi 20469q 2", 1/8" brass tee, 0-60 psi 20470q 2", 1/8" brass tee, 0-100 psi 22423q 2", 1/8 NPT, 0-30 psi 20393q 2", 1/8 NPT, 0-60 psi 20394

Purifiers

HydrocarbonSupelcarb HC Hydrocarbon Trapq 120 cc, 1/8" fittings 24448q 120 cc, 1/4" fittings 24449q 750cc, 1/4" fittings 24564q 750cc, 1/2" fittings 24565q Supelcarb refill, 300cc 24566

Supelpure-HC Hydrocarbon Trapq 120cc, 1/8" fittings 22445-Uq 120cc, 1/4" fittings 22446q 750cc, 1/4" fittings 24518q 750cc, 1/2" fittings 24519q Supelpure charcoal refill, 400cc 22451

Mounting Clipq For 120cc trap 23993q For 750cc trap 24983

Water VaporMolecular Sieve 5A Trapq 200cc, 1/8" fittings 20619q 200cc, 1/4" fittings 20618q 750cc, 1/4" fittings 23991q 750cc, 1/2" fittings 23992q Molecular Sieve 5A refill, 1/2 lb (0.22kg) 20298


Economy Moisture-Removing Trap (air service)q 400cc, 1/8" fittings 23987q 400cc, 1/4" fittings 23988

Molecular Sieve 13X/4A Refillq 1 pint 23989

Mounting Clipq For 400cc trap 23990

OxygenOMI-2q Purifier (tube only) 23906q Holder 23921

OMI-4q Purifier (tube only) 23909q Holder 23926

High Capacity Gas Purifier (110 VAC)q 1/8" fittings (oven and purifier tube) 23800-Uq 1/4" fittings (oven and purifier tube) 23802

High Capacity Gas Purifier (220 VAC)q 1/8" fittings (oven and purifier tube) 23801q 1/4" fittings (oven and purifier tube) 23803

Supelpure-O Trapq 1/8" fittings, 200cc 22449q 1/4" fittings, 200cc 22450-Uq 1/4" fittings, 750cc 503088q 1/2" fittings, 750cc 503096


UOP mat/sen Purifier, Heliumq 1/8" fittings 22680-Uq 1/4" fittings 22681

Oxisorb Scrubberq 1/4" fittings (holder and cartridge) 20639-Uq Oxisorb replacement cartridge 20631

Oxiclear Disposable Purifierq 1/8" fittings 22992q 1/4" fittings 22993

Aeronex GateKeeper Purifierq Model 35K 1/4" FACE SEAL fittings 24970q Model 500K 1/4" FACE SEAL fittings 24971

Description Cat. No. Description Cat. No.


Point of Operation Panel-Type Purifiers and Compo-nents3-Head panelq 1/8" fitting (O2, H2O, hydrocarbons) 23994q 1/4" fitting (O2, H2O, hydrocarbons) 24984q 1/4" fitting

(O2, H2O, hydrocarbons, indicating O2) 249864-Head panelq 1/8" fitting

(O2, H2O, hydrocarbons, indicating O2) 24985QC+ Panel, 3 headq 1/8" fittings, (O2, H2O, hydrocarbons) 23999q 1/4" fittings, (O2, H2O, hydrocarbons) 23998

Cartridgesq Oxygen removing 23995q Nanochem® (oxygen removal, replaces 23995) 24989-Uq Indicating oxygen removing 24987q Water removing 23996q Hydrocarbon removing 23997q Supelcarb (hydrocarbon removal,

replaces 23997) 24567

Gas Line Filters7µm filterq 1/8" fittings 20620q 1/4" fittings 20621

7µm “T” filterq 1/8" fittings, brass 25805q 1/8" fittings, stainless steel 25807q 1/4" fittings, brass 25806q 1/4" fittings, stainless steel 25808

Particle/Vapor Filtersq Particle filter, 40µm element 24990-Uq Particle filter, 5µm element 24992q Oil removal filter 24994q Oil vapor removal filter 24996

All products are described in the current Supelco catalog. If you do not have our catalog, pleaserequest a copy from your Supelco distributor (see last page of this bulletin).

ToolsGlasrenchTM

q Model A, 9/16", for 1/4" fittings 22901q Model C, 9/16", for 1/4" fittings 22903

Wrenchq 7/16", for 1/8" Swagelok fittings 20447q 9/16", for 1/4" Swagelok fittings 20448

Tubing Cutterq Heavy duty 20425-Uq Imp 22410-U

Tubing Cutting Machineq For 1/16" and 1/8" tubing, 110 VAC 58800-Uq For 1/16" and 1/8" tubing, 220 VAC 58801

Tubing Benderq Heavy duty, for 1/8" tubing 20422-Uq Heavy duty, for 1/4" tubing 20424-Uq Multi tubing bender tool

for 1/8", 3/16", 1/4" tubing 20857

Reamerq Tubing reamer 20389

Ratchet Wrenchq 7/16", for 1/8" fittings 20447q 9/16", for 1/4" fittings 20448

Teflon® Tapeq Approved for GC use 20808-U

Crescent® Pliersq Adjustable 10", 5 position 22438-U

Screwdriver Kitq Six-in-one 22436

Crescent Wrenchq Adjustable 10", opens to 1 1/8" 22439-U

TubingStainless Steel, Premium Grade 304, Cleanedq 1/8" OD x 2.1mm ID, 50' coil 20526-Uq 1/4" OD x 5.3mm ID, 50' coil 20527q 1/16" OD x 0.254mm ID, 100’ coil 20552q 1/16" OD x 0.762mm ID, 100’ coil 20553

Copperq Cleaned, 1/8" OD x 1.65mm ID, 50' coil 20488q Cleaned, 1/4" OD x 4.83mm ID, 50' coil 20489q Regular, 1/8" OD x 1.65mm ID, 50' coil 20520-Uq Regular, 1/4" OD x 4.83mm ID, 50' coil 20522

Description Cat. No. Description Cat. No.

TrademarksCrescent – Cooper IndustriesGateKeeper – Aeronex, Inc.Glasrench, OMI, Supelcarb, Supelpure – Sigma-Aldrich Co.GOW-MAC – GOW-MAC Instrument Co.Nanochem – Matheson Gas ProductsOxiclear, Oxisorb – MG IndustriesSnoop – Nupro Co.Swagelok – Crawford Fitting Co.Teflon – E.I. du Pont de Nemours & Co., Inc.

High Pressure Cylinders in Your Lab...

Why risk it?

Packard Hydrogen GeneratorA hydrogen source your safety director will approve!

The safest way to obtain and use hydrogen. Available in four flow ranges:

160, 250, 500, and 1200cc/min.Requires only deionized water and electricity – no need for

hazardous liquid solutions. Delivers pressures up to 100psi.Yields carrier gas grade 99.99999+% pure.

Packard Zero Air GeneratorThis hydrogen-free generator reduces total hydrocarbon content to less

than 0.1ppm, at pressures from 2 to 125psi. Requires very short

warm-up time and extremely low maintenance.

• Model 1000/1001: 0-1000cc/minute, runs up to 3 FIDs

• Model 3500/3501: 0-3500cc/minute, runs up to 7 FIDs

Ask about our lab expansion programand our new lab discount program.Supelco offers superior technical support.For information on Packard's line of ultra-high purity gas generators, request publication T696002.

Packard Generators Save Money, Your Knuckles...and Possibly Your Life!These ultra high purity generators help you avoid

l extra costs associated with plumbing and installationl the use of bulky, dirty, cumbersome equipmentl safety hazards

BIT

For more information, or current prices, contact your nearest Supelco subsidiary listed below. To obtain further contact information, visit our websie(www.sigma-aldrich.com), see the Supelco catalog, or contact Supelco, Bellefonte, PA 16823-0048 USA.ARGENTINA · Sigma-Aldrich de Argentina, S.A. · Buenos Aires 1119 AUSTRALIA · Sigma-Aldrich Pty. Ltd. · Castle Hill NSW 2154AUSTRIA · Sigma-Aldrich Handels GmbH · A-1110 Wien BELGIUM · Sigma-Aldrich N.V./S.A. · B-2880 BornemBRAZIL · Sigma-Aldrich Quimica Brasil Ltda. · 01239-010 São Paulo, SP CANADA · Sigma-Aldrich Canada, Ltd. · 2149 Winston Park Dr., Oakville, ON L6H 6J8CZECH REPUBLIC · Sigma-Aldrich s.r.o.· 186 00 Praha 8 DENMARK · Sigma-Aldrich Denmark A/S · DK-2665 Vallensbaek StrandFINLAND · Sigma-Aldrich Finland/YA-Kemia Oy · FIN-00700 Helsinki FRANCE · Sigma-Aldrich Chimie · 38297 Saint-Quentin-Fallavier CedexGERMANY · Sigma-Aldrich Chemie GmbH · D-82041 Deisenhofen GREECE · Sigma-Aldrich (o.m.) Ltd. · Ilioupoli 16346, AthensHUNGARY · Sigma-Aldrich Kft. · H-1067 Budapest INDIA · Sigma-Aldrich Co. · Bangalore 560 048 IRELAND · Sigma-Aldrich Ireland Ltd. · Dublin 24ISRAEL · Sigma Israel Chemicals Ltd. · Rehovot 76100 ITALY · Sigma-Aldrich s.r.l. · 20151 Milano JAPAN · Sigma-Aldrich Japan K.K. · Chuo-ku, Tokyo 103KOREA · Sigma-Aldrich Korea · Seoul MALAYSIA · Sigma-Aldrich (M) Sdn. Bhd. · 58200 Kuala LumpurMEXICO · Sigma-Aldrich Química S.A. de C.V. · 50200 Toluca NETHERLANDS · Sigma-Aldrich Chemie BV · 3330 AA ZwijndrechtNORWAY · Sigma-Aldrich Norway · Torshov · N-0401 Oslo POLAND · Sigma-Aldrich Sp. z o.o. · 61-663 PoznañPORTUGAL· Sigma-Aldrich Quimica, S.A. · Sintra 2710 RUSSIA · Sigma-Aldrich Russia · Moscow 103062 SINGAPORE · Sigma-Aldrich Pte. Ltd.SOUTH AFRICA · Sigma-Aldrich (pty) Ltd. · Jet Park 1459 SPAIN · Sigma-Aldrich Quimica, S.A. · 28100 Alcobendas, MadridSWEDEN · Sigma-Aldrich Sweden AB · 135 70 Stockholm SWITZERLAND · Supelco · CH-9471 BuchsUNITED KINGDOM · Sigma-Aldrich Company Ltd. · Poole, Dorset BH12 4QH UNITED STATES · Supelco · Supelco Park · Bellefonte, PA 16823-0048 ·Phone 800-247-6628 or 814-359-3441 · Fax 800-447-3044 or 814-359-3044 · email:[email protected] H

Supelco is a member of the Sigma-Aldrich family. Supelco products are sold through Sigma-Aldrich, Inc. Sigma-Aldrich warrants that its products conform to theinformation contained in this and other Sigma-Aldrich publications. Purchaser must determine the suitability of the product for a particular use. Additional terms and conditions may apply. Please see the reverse side of the invoice or packing slip.

bulletin 918b selecting purifiers for gas chromatography while protecting columns and detectors....

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