The SRI MG#5 > a significant SRI “Innovation” in Gas Analysis !

. . . Other limitations / “issues”  GC design compromise(s) see further PDF “footnotes”

• SRI Installation Hints 08May20-194p.pdf

• UHP GasTraps-Hints 9p Update 2022.pdf

• SRI Install Hints-2 2023.pdf
  but also do a PDF Search “Ctrl F” on chromtech.net.au/PDF2/ > “hints”
  
  > some “random” issues still !

In practice the HaySep-D is needed for CO2 separation from methane but is somewhat limited for higher MW VOCs by column bleed and/or flow sensitivity drift of the TCD during temp programming to propane(?) EtOH, MEK for example at 180C max unless you use ultra pure He and/or Oxytraps

The HS-D packed columnc can be replaced with capillary column (PLOTs)  for more detailed resolution of high MW or polar components but CO2/CH4 may be then sacrificed !
Shincarbon Packed columns are another compromise re O2/N2 air separation ( limited to ~90% )

• Calibration of these is assisted by the on-column liquid injection port fitted standard on the MG#5 ( expande to 2 ports ( heated if necessary and with a Splitter option

The set up is somewhat convoluted and users need to understand the logic and peculiarities of the GC set-up re “Timed Events” of PeakSimple and sorting occasional duplicated & multiple-peaks etc !

Definitely NOT a “DO-All . . . Do everything” !  concept & certainly NOT for “naive” GC BEGINNERS !

• For H2 analysis ( in particular) an extended design of the MG#5 is necessary but may become too complex mechanically for many !
   / re GC internal plumpline and chassis space etc and can add to the overall price
  > a separate GC(s) using Argon carrier gas is recommended if sample through-put a problem > at high(er) concentrations !
  For H2 a simplified GC / is suggested using a CCD Detector ( 500ppM LOD) with 1 cc sample size for H2, CO, methane and C2 ( & combustibles ) > so NOT CO2 or Air ( Ar/ O2/ N2 )
   > much lower cost
• columns to be decided on MolSieve for CO from Air) and CCD Not suitable for capillary (or PLOT) columns CO2 > and non-responsive in CCD and no need to separate CO2  on HS-D; backflushing of the CCD may still be required and can suffer fcompared to the MG#5A

On-Line auto analysis of gases AND complex VOCs is fraught with difficulties particularly related to
“Headspace Gases Analysis” ( re sample size available from the process  AND re “LOD”s and the need for more sophisticated GC Detectors ( HID with adequate Gas Purification or VICI-Valco PPD to improve trace gas analysis ! ) see above

NO Equivocation here ! . . . Just stark reality ! . . . learnt the “hard way” . . . from experience !

• Yes there are some answers here ! > but . . . more complex, more expensive > ASK ! > RFQ !

Justification maybe > NEW MG#6 ( in future ? OR to Order ! ) > Trace Gases >> obscure Greenhaose Gas emissions ?

• Gas Purification > SS diapbram regulators ( NO EPCs ) > & essential !

• HID ( SRI or Vici-Valco miniPDD ) ONLY

• 1cc Auto Gas Sample Injector; Silcosteel Loop

• Gas Splitter Manual Injection System ( for high sample concentrations,>~0.1%)

• ShinCarbon HT 2 to3m 0.75mm Silcosteel Column

• Vacuum Pump Interface ( for added ease of sampling)

but real BENEFITS ? still requires

• Quantitative H2, compromised O2/N2 ~1% O2?) but on BID / PPD

• Split for > ~100:1

• Improved trace gases > <1ppM on HID low ppB on PDD

• Shincarbon limited to approx C2 HCs,  or for CO2 programmed MS5A >200degC)

• PLOT columns can be a “trade-off sensitivity vs complex VOC gas mixes etc and column cost !

ALL HIDs are limited to ~1%Max (1CC) inc NEW BID ( Shimadzu ) & LDETEK ;
 requiring a Gas splitter and/or a TCD ( > ~100ppM permanent gases) or FID-Methaniser ( for CO/CO2 LOD ~1-10ppM)

SOME  ‘more” HELPFUL HINTS ( re MG#5 and Gas Analysis)

Plenty of compromisess !  > ASK CT for Our recommendations !
HID & Methaniser > DON’T assume linearity at high(er) concentrations ( >1000ppM?)
-   TCD normally can assume linearity but spot check by at least 3 syringe dilutions
spanning sample to be analysed( accurate to a few %)
-   CO2 Analysis- Do NOT rely on using ambient Air for any sample dilutions w/out adequate “corrections”
> re TCD Calibration -   Ambient CO2 ? can be a MIN of 400ppM but can up to even > 1000ppM > Indoors !
Humid Air samples can be up to 7% water in “humid” air even if NOT being measured and correction of results are required for high(er) accuracy or Sample Drying
 

but then the IPCC sees fit to completely ignore H20 ( rain & clouds ! ) from any climate modelleing & the main contribution to GH warming by far ! . . . far too complex and more expedient to  simplify and project “climate catastrophies” for “end of mankind “ > absurdities
AND without ANY direct evidence Global Warming > a la Climate Change is in fact largely anthropogenic . . . the 97% consensus “IS A FRAUD” ! at best still specalative at huge “indirect” costs

STANDARD “LAB” GCs ? . . . Can NOT be assumed to be “Gas-Tight”  !
All tend to be compromised and can diffuse ambient Air into the GC system ( through O-rings, regulator, diaphrams, flow meters, septa even against +ve gas pressure
Process control GC and Trace Gas Analysers AL “invariably” are custom designed specifically > leak free, EPC and TCD /Temperature progranmming is not recommended; Carrier Gas with mass flow controllers but often limited isothermal “packed column”e

-   H2 Carrier gas  ( H2 Generator ) effective for most GC APPs ( faster analysis at lower overall cost compared to Helium carrier gas )
         -    bottle-less GC for portable remote/Field Apps  with  TCD/FID ( uses built-in mini air compressor

H2 Analysis > anomolous non-linearity > peak reversal at ~ 1-6%
Use Argon Carrier gas from % down to mid low ppM ( although other peaks are of
- a simple gas switching valve can be installed on carrier inlet  for H2/He to Argon if needed if sample throughput is an issue  ( but requiring duplicate analyses ) very low sensitivity )

DON’T ASSUME

• ANY “marketing” chromatograms ARE DONE ON OEM STANDARD GCs without due consideration

• Gas SUPPLIES ( He ) High Purity are bulk-tested ONLY Can be UNRELIABLE

• Always use an Oxytrap preferably a GETTER” Purifier mounted closed to the GC as possible

• ANY Manifold Purifiers are NEXT TO USELESS without an Indicating OXY-Trap verification next to the
  GC & after the “Getter” Trap.

New GSV Types 201improvements9+ > PDF

• COVID19 WW shortage of ‘chips” > “maybe” other  ? SRI to advise !

• maybe for “trace” Gas Analysis > improved Rotors re “wear& tear“

• & gas purging >essemtial for low ppB

• 2022 SRI introduces a new range of Gas Valves ( some Helium purged )

CHROMTECH :  Specialists in Chromatography
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Chromtech.net.au > Chromtech-AUS.com > Chromalytic.net.au > Videos

MalsCart  > mini SHOPPE  proto - Shop2CT > “OUR Consensus”> CC < GW & Energy BLOGs

& a
HI-TECH “Resource” > 4 U !

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