Frequently Asked Questions

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12/10/2006  From: Million
Can someone suggest where to get an internal standards for our elemental analyzer (NA 2000). Such as Leco soil, Barley or others
no reply
9/21/2006  From: Brian Popp
We would like to use our NC 2500-conFlo II-DeltaPlus (Terri Rust says you know the system) to analyze the d15N of N2 gas in headspace samples. Do you make or sell an inlet with a septum so that we could simply inject our sample into the EA? My thought was to inject ca 20 uL of gas (esseintally air) into the EA through a septum-equipped inlet that replaces the autosampler. Any O2 and NOX in the sample would be reduced over the Cu column and the contribution to N2 from NOx/N2O should be very small. Can you help?
Thanks, Brian
We sell two devices for injecting gas or liquid into the EA. One would mount as a replacement for the autosampler, and the other is an in-line injector which would usually be installed before the water trap. The in-line injector would be used by someone who only wanted to use the GC part of the EA to get gases into the MS. If you want to have your gases run through the reactors, then the direct injection device is the one you should use. The part number for the Direct Injection Device is 41.00.130, and they are $275. Let me know if you have any questions.
7/25/2006  From: Fred Prahl
Hello Bruno
We are in the process of setting up our TCEA for D/H analysis of water samples. The TCEA is currently equipped with an autosampler for solid samples. I talked with Marilyn Fogel (Carnegie Labs) about widgets that would provide the interface to analyze liquid samples on the TCEA. She said you have one and it vends for $250. I am most interested in learning more. If what I have stated above is enough to get the ball rolling, please contact me by email with the information (including technical brochures, if available) so that we can push forward with our analysis. If what I am requesting seems too vague, please let me know when I can give a call to get my request clarified.
Fred Prahl
no reply
3/21/2006  From: jeannie
greetings! i am currently using an EA1108 CHNS elemental analyzer for the analysis of fish feeds. i am encountering continuous baseline drift (continuously increasing) even if no sample is being run through the instrument. i have tried running a blank sample for 780 sec and observed that the baseline increased from 1000 micro V (start of run) to about 5000 micro V (end of the cycle). furthermore, the voltage reading did not return to the initial 1000 micro V, instead, it continuously increased. what could be the cause of the continuous drift? how might i be able to troubleshoot this problem? thank you very much!
no reply
3/16/2006  From: Sonya Remington
Do you carry a product called Chromosorb W? I can’t seem to find it on your website? If so, what is the cost and product number? Is there only one type to choose from?
no reply
2/8/2006  From: Emma
Hi! I am running EA 1108 CHNS analyzer and have problems with analysis of highly fluorinated compounds ( F contains more then 20%), meaningly splitting of H2O peak and as a result wrong determination of hydrogen. Unfortunately I can’t use such new product as Fluorine absorber mix because I need determinate sulphur too. Is it possible to decide this problem anyway? Thanks
no reply
1/21/2006  From: Nicole Molinari
We have been running a ton of samples on our CN analyzer, as a result we have been producing quite a bit of chemical waste. I would appreciate advice on disposal of these compounds. I was unable to find MSDS sheets for:
Silvered cobalt oxide
Chromium oxide
Magnesium perchlorate &
Copper wire
It would be wonderful if you had a recycling program for these compounds (or containers), but if not please let me know how to dispose of them.
Thank you-
Nicole Molinari
no reply
12/20/2005  From: Megan Mcgroddy
I have a question about running filter samples on a CN analyser. A student in our lab has filtered water samples through glass fiber filters and want to run the filtrate ( a subsection of the filter) on the CN for total C and N- will this be a problem? any issues with GFF at high temps ( smoke? fusion?) -does the residual decrease longevity of the combustion tube? any suggestions or preferences on punching out holes in the filter for a sub sample versus cutting a strip of the filter ? - take care and many thanks Megan
There is no real problem with GFFs, but you have to pay close attention to the buildup of glass in the reactor. We recommend using the quartz inserts to catch the glass and make it easy to remove from the reactor. If you just drop it into the main combustion reactor it is almost impossible to remove.
If you use the inserts, place about a cm of quartz wool in the bottom, then put 2-3 mm of the chromium oxide catalyst on top. This will protect the quartz wool, and should make it easier to remove the residue. Don’t try to run too many samples before removing the insert as they will get stuck if the glass runs out the slots.
The glass does not cause a problem unless the filters have a high halogen content. That would cause early degradation of the reactor tube. You should get the same life out of the reactors and catalysts unless the glass is "poisoning" the catalysts.
Most groups either run the whole filter or use a punch to get a sub-sample.
I honestly don’t know if taking a punch or a strip would make a difference.
I guess it depends on how evenly the material is distributed on the filter.
You might want to try taking several punches from the same filter and seeing what kind of precision you get. If the results are close enough then take the punch from the same place on every filter you analyze.
Let me know if you have any other questions.
Best wishes and Happy Holidays!
Bruno Lavettre
11/17/2005  From: lakha
I am running EA 1108 CHN analyzer with single combustion/reduction tube configuration. I have also installed an He carrier gas humidifier, my problem is H peak is tailing. My run time for CHN analysis is 430 sec. If I increase this analysis time I find that my std shoot High for C. Has anyone solve the problem of H peak tailing. Please contact me thru my e mail. Thx
I’m not sure why you are adding H2O with a humidifier; this is not something which is normally done on an EA. Is this application related?
The H2O peak will always tail, there is no way to get it to look like either nitrogen or carbon. 430 seconds is actually a rather short run time for NCH, usually it is more like 480-600 seconds depending on the sample type, %H, and sample mass. The single reactor configuration helps with peak shape and tailing for N and C, but there is not much you can do about the H2O peak shape.
You didn’t mention what type of samples you are analyzing. Some samples can build up a residue in the Teflon tubing (if you have any installed), which needs to be removed by replacing the tubing. I also don’t understand how increasing the run time would affect your carbon values; this makes no analytical sense. The only thing that would happen is that you would be sure the H2O peak comes back to baseline.
Without more information on your application, instrument settings, etc. I can’t really give any more advice. If you would like to fax me a typical chromatogram I can look at it and see if I see anything peculiar. Our fax number is 661-297-5492.
Bruno Lavettre
2/23/2005  From: David Velinsky
what is the best packing material for running NCS (NA 2500 and Flash Units) and which GC column works best..
Dear David,
For NCS on the NA 2500, I would recommend using our pre-packed reactors for sulfur, which are packed with Tungstic oxide and long copper wires. These will give you the best peak shape for sulfur.
As far as a GC column goes, our two meter GC column for sulfur will separate the N,C, and S peaks. If the GC column can go down to a low enough temperature, you might be able to use the shorter 0.8 meter GC column. That would work for sample matrices such as soils, sediments, or catalysts, where the carbon concentration is usually very low.
Best regards,
Bruno Lavettre
12/1/2004  From: gerard.olack
We are setting up our EC4010 to run sulfur samples that are going to be analyzed on a ThermoFinnigan DeltaPlus for 34S. We have the appropriate reactor and GC column. The manual from Thermo suggests using teflon tubing in place of stainless, and I’ve been told not to use brass fittings. Should we replace the stainless steel tubing with teflon tubing ? What about the brass fittings on the drying tube, should they be replaced?
no reply
9/13/2004  From: Natacha Ripoche
Dear Costech,
we have an EA EuroPyr(OH) Eurovector for HD and 18O analysis in water.
We need stainless steel tubing : 2 mmOD , 1 mm ID for carriere gas.
So can you tell your price and dealy for this product.
Thanks for your answer.
CHU Hotel Dieu 3 étage
place Alexis Ricordeau
44093 Nantes Cedex 1
fax : 00 33 (0)2 40 08 75 44
no reply
6/2/2004  From: Jamie
I’m a new technician running a Carlo Erba EA (NC2500). I’ve heard bits and pieces of a valve membrane that prevents or regulates the flow of oxygen into the helium carrier flow. I can’t seem to find more info than that. Where exactly is this membrane located? How often (if at all) does this membrane need to be replaced? Is there a way to detect a leaky membrane? I’ve noticed that the fittings directly above the oxidation tube (to the autosampler) on our EA gets hotter sporadically. Could this be related to the valve membrane? Thank you!
Hi Jamie,
The valve you are describing is called the bi-matic valve, and it was used in older CE analyzers to inject the oxygen for sample combustion. It was a six port switching valve which was air actuated. There was a viton membrane in the valve which controlled the flow of gases in and out of the valve and it needed to be replaced every few years.

The NC 2500 does not have the bi-matic valve. In the NC 2500 electrovalves control the flow of gases and are used to inject the oxygen for combustion. So, you don’t have to worry about replacing the membrane.

The SS plate on top of the NC 2500 will get rather hot when you are running the analyzer. The insulation between the furnace and the top of the analyzer is not very good, so heat collects beneath the SS plate and is somewhat transferred to the bottom of the autosampler. This is normal in that instrument, so unless is gets unusually hot it’s nothing to be concerned about.
11/7/2003  From: Frank T.
We have a NA 1500 Series I coupled with ELAB software for data acquisition. Recently, we have been noticing small dropouts below the baseline, which affect peak area calculations. The dropouts are not consistent with any events (e.g. sample drop). In the process of chasing down the culprit, the slide in the autosampler has been replaced, new combustion and reduction reactors installed, as well as replacing the separation column. The problem still persists. Have you ever seen anything like this? Is it possibly an electronics problem? Thank you for your attention.
Costech: A few questions we have for you are: Is this instrument connected to a mass-spectrometer? What exactly do you mean by ‘dropout’ and do these at least occur at the same time in each chromatogram? If you are able to, please send us one of these chromatograms by email or fax: (661) 297-5492.

Frank: The NA1500 is not attached to a mass-spec. The noise/dropout does not occur at the same time in each chromatogram and does not coincide with any particular event.

Costech: At this point it does seem to be an electronics or power issue. Is it possible that there is some new or temporary piece of heavy equipment in or near the building? One of our customers found that the equipment used by some painters working nearby the lab caused sporadic electrical problems with his instrument. That’s not to say that it isn’t an issue with the instrument’s, A/D converter’s or PC’s electronics. A good test would be to get a hold of a strip chart recorder and check the instruments output that way.

Frank: I don’t believe there’s any heavy equipment being used nearby; the unit is also plugged into a high capacity UPS, so power conditions are stable. I do have a voltmeter attached to the unit and can monitor the baseline that way. Thanks.

10/24/2003  From: richard.daw
I was looking to purchase tin boats for CHN analyses of liquid (MeOH) samples. I was also wondering if you supplied Acetanilide as a standard for this also. Is it possible that you could send me information about what is available to purchase and possibly a catalogue of similar consumables. Thanks!
no reply
9/2/2003  From: Peibing Qin
I am grauate student in Syracuse University. We already bought the CHN machine for you. Now I need to buy tin capsules for measuing PC and PN. But I can’t find how to order them? Could you tell me the code of it? Thanks,
no reply
8/25/2003  From: antiquus
Due to a lab renovation, I recently shut down and moved our Fison’s 1108. As I brought the EA back on line, it seems that the Eager 200 sw isn’t connecting with the EA. The PC is seeing the chromcard, and it has found the security key. The connections are all good. Could it be that the configuration has changed? What is the baud rate set to for an 1108? I would greatly appreciate any insights. Thanks! - Mark
no reply
7/21/2003  From: dhooge
We have an EA1108 and have previously packed our own combustion tubes. I recently bought your 061110 pre-packed reactor for CHNS. My questions are: Did I buy the correct tube? The copper is in a long wire form instead of copper chips. Also, the tube is clear where as when we packed our own tubes, we used the opaque quartz tube. Does this make a difference?
Thank you. Noel Dhooge
Yes, you purchased the correct reactor assuming you wish to set up the EA 1108 for sulfur analysis (NCS or CHNS). We pack the reactor with the wire in the long form because that gives the best peak shape for sulfur. Sometimes it is difficult to get repeatable results when you pack the reactors with the cut copper wires but the long wires always give a nice peak shape.
Also Noel, check out the News item ’New quartz reactor tubes!’ on the home or news page of this site.
5/6/2003  From: Richard Deck
Please provide this office with a material safety data sheet for the product:
Silvered Cobalt(II,III) Oxide Part # 011007 Reference part # 338-245-00.
Thank you
no reply
5/2/2003  From: Gregg
Concerning Costech part number 080001 (6MB Nuts) -
Is there a technical name for this type of fitting, and can I get a fitting with the same size thread that will take a 1/8" steel tube? (this will not go into the my EA)
no reply
1/29/2003  From: hojeongko
I’m Korean student, and then I have poor english writter.
I have got your product. code number 011017: COPPER WIRE PURE(for sulfur determination) . How to degree of purify is it ?
please reply to do(ex. 5 nine, or 6 nine, etc.)
The purity of code number 011017: COPPER WIRE PURE (for sulfur determination) is 99.9% pure. Thank you for your inquiry.
6/10/2006  From: Jeff Anning
Hello, we are just getting to know our new 4010 and have a question or two. We are finding that the quartz wool appears to be melting in the combustion tube and eventually clogs the tube, we started running at the specified temperature of 1040 and then dropped to 1000 but had the same result. Is this a common problem, can we reduce the temperature further without risking incomplete combustion or affecting our isotope ratios? We are a bit puzzled by this as our previous systems never had this problem.
no reply
3/8/2006  From: Jarvis Erickson
What to do if the pressure on the oxygen valve cannot be decreased?
There is the possibility that the ox. needle valve is closed, however, chances are there is a restriction (some trapped debris or plug) in the oxygen circuit of the system. One likely occurrence is that a small piece of rubber plugged the ox. vent on the front of the instrument, it happens when the cap is over-tightened and the vent cuts into the rubber insert inside the cap. Also, just a reminder: when the instrument is in "standby" mode the oxygen is cut off which would produce the same symptom of the pressure not decreasing.
10/7/2006  From: Michael Navatta
I have my EA connected to my IRMS, set to run CN. The chromatagrams on the IRMS look as though I am having an incomplete combustion with a carbon monoxide peak increasing the size of my N2 peak. It also shows up in the CO2 peak being smaller than expected. Is this possible? What could be my problem?
Hi Michael,
Have you watched the sample combustion through the EA autosampler? The combustion should start a few seconds after the sample drops; it looks like a little supernova, getting brighter and brighter, then fades. If you do not see this then the combustion will be incomplete.
By any chance do you have the data acquisition software for the EA? If so, there is a way to check the combustion efficiency. Let me know.
In general, the things that affect combustion are leaks, little or no oxygen, bad sample timing, and restrictions in the system. I assume you know how to check the EA for leaks. Check the oxygen flow rate at the oxygen vent; it should be around 25 ml/min. If your He flow rate is set for 100 ml/min, then the sample should drop into the combustion reactor at about 10-15 seconds. As I mentioned above, you should see the sample start to combust in just a few seconds. If there is a delay of 15-20 seconds until the start of combustion, then there may be a restriction in the analytical circuit.
Best regards,
Bruno Lavettre
5/19/2006  From: Kalle Ljung
I am using an EC4010 for sulphur measurments on sediemnt samples and have problems getting good peaks. When running small smaples or samples with low S content (0.1-0.3 mg S, marine standard 1.29%S) no peaks or poor peaks show up. Larger samples with higher sulphur content produce better peaks. This is a new problem, previously samples of the same size and S content produced good peaks and calibration.
What could be the problem?
no reply
12/21/2005  From: cmiller
I am planning a new line of research. I want to examine growth in plankton animals by very large numbers of carbon analyses, preferably CN analyses. I would like to get down to the levels of sensitivty touted by Salonen (1979 - Limnol. Oceanogr. 24:177-183) of 0.01 ugC. I would do very well, however, with 0.1 and well enough at 1 ugC. I must measure individual animals. I must work at sea - CN analysis at sea. I would like to use animals blotted but not dried and there will be some salt from body fluids. I cannot weigh the animals ahead, so I am not after elemental proportions, but need to obtain carbon (and nitrogen?) mass estimates from calibration of the analyzer response to a range of standards.
Can the EC4010 be used in this way? Can it provide the necessary sensitivity? Can I afford to buy one? How many samples (1 to 200 ugC) can be put through a column?
I will also be interested in automatic dispensing of samples (so I and helpers working at sea can sleep). Your larger autosampler approaches our daily expected throughput, which would be good. Will we need a nitrogen purged system such that we should consider your 50 sample system?
Your company, specfically the talents of Bruno Levette, have been recommended to my attention by Prof. Fred Prahl of our department.
Thanks for your help.
Charles B. Miller
Prof. Emer. Oceanography
Oregon State University
Corvallis, OR
Dear Charles,
If you have a copy of the paper you’ve referenced in pdf form, would you send me a copy? I don’t know how it would be possible to quantitate carbon at 0.01 ug carbon. There is about 0.25-0.5 ug C in the tin capsules, which would make an analysis at those levels impossible. In any case, I don’t know how the carbon values were determined or what type of instrument was used, so it would be good to have the reference.
Another difficulty would be how to calibrate the analyzer at those levels. It would not be possible to weigh out a small enough standard sample, especially while at sea.
I’ll wait to make any other comments until I’ve seen the paper. Please give Fred my regards if you see him.
My best regards,
Bruno Lavettre
11/29/2005  From: becky
What is the column packing in the GC column on the ECS 4010? We have been using one for CO2 and N2 analysis, and now are trying O2 analysis. For O2 analysis we will need molecular sieve, but what column packing is in there now?
Hi Becky,
The GC column packing for nitrogen and carbon analysis is a porous polymer, HayeSep Q. For oxygen analysis we use a molecular sieve column of 1 meter length. Our part number is 051084.
You cannot separate nitrogen from CO with the column for N/C analysis. With the molecular sieve column there is plenty of separation between the two peaks.
Best regards,
Bruno Lavettre
6/25/2005  From: Lisa
We’re starting our instrument up after it has not been used for 9 months. I’m wondering if there are any additional steps that need to be taken after not using the machine for awile. Also, it would be really helpful if the manual had some sort of a quick-start guide in future versions. Is all that needs to be done is to check the flow rate of the gasses? I changed the insert, the water trap and reactor still have enough use left in them to run my samples. Is it likely that anything was done to the machine to prepare it for long term shut-down that I need to undo? Someone in the lab mentioned some vents may be capped, but wasn’t sure exactly what was done.
Thanks so much,
no reply
5/13/2005  From: veldboom.jaso
I was wondering why you (costech) changed the type of quartz wool that you supply? It seems alot more frothy and harder to condense and the samples that drop seem to "burn" right through it.
no reply
4/27/2005  From: harveyel
We have an EC4010, and we are having problems reaching the baseline after the nitrogen peak. It almost looks like we have one large peak with two separate smaller peaks on it. This causes the computer to then integrate the peaks incorrectly. We have tried to use the troubleshooting tips in the instruction manual, but to no avail. I was wondering if you had a more detailed way to fix this problem.
no reply
1/18/2005  From: Laura Lawton
Could you please provide the compresed gsaes and purity specs for all gases required for Could you please provide the compresed gsaes and purity specs for all gases required for the operation of the EC4010?
Could you please provide the compresed gsaes and purity specs for all gases required for the operation of the EC4010?
no reply
9/7/2004  From: Rocio Martinez
Hello, I would like to know the energy requirements for the Elemental Combustion System, Model 4010. Thanks.
Dear Rocio,
The ECS 4010 operates at 220V, 50/60 Hz. The power consumption is about 1200-1300 VA, so a standard 220V circuit, 10-15 amps is more than adequate.
Please let me know if you need additional information.
Bruno Lavettre
3/12/2004  From: -
we recently purchased the ECS4010 and we cannot the balance (Sartorius micro) to communicate with the pc to get the weight reading into the sample table.
no reply
2/25/2004  From: eigenbro
We use silver boats for carbon analysis in our EA. What is the flash combustion temperature when silver boats are used instead of SnO2?
no reply
11/12/2003  From: -
I am purchasing a Costech EC 4010 and I have a question about electrical power. My building line voltage is 208 V. Will this be adequate for the instrument?
no reply
1/6/2003  From: Nathan
I run an EA in series with a ThermoFinnigan Delta Plus Mass Spec for C an N stable isotopes analysis. There have been some questions about our method. We fume dried sediment samples with HCl in order to get rid of the inorganic C in the sediment. Does this method leave residual Cl in the samples? Is it your recommendation that we should use silvered copper wool in our column in order to get rid of the Cl? The entire setup is new this past September and my superior doesn’t want the Cl to hurt/affect the new Mass Spec. Thanks for your help!
There is some residual chlorine left behind anytime a sample has been acidified with HCl. This generally does not present a problem because the silvered cobaltous/ic oxide removes small amounts of any halogen. It certainly will not hurt to use the silvered copper wool to ensure removal. For the best results we recommend adding about a centimeter of the silvered copper wool below the silvered cobaltous/ic oxide and reducing the chromium oxide layer by one centimeter to compensate.
12/2/2002  From: Chris Osburn
What is the purpose of the Purge valve on our FISONS EA 1108 and should it remain open during operation and closed during Stand-By? What should be the flow rate for the purge?
The purge valve on that model EA is used exactly as you assumed. During operation it must remain opened in order to keep the sample purged of atmosphere and during stand-by closed to conserve purge gas. The purge flow rate (measured by removing the tubing and fitting from the autosampler) should be about 55 – 60 ml/min. for the AS-200 and about 70 – 80 ml/min. for the AS-128 using helium as the purge.
9/23/2002  From: Anonymous   -
How often should I be changing the combustion and reduction columns in my EA?
Like most maintenance tasks performed on an EA, the frequency of replacing combustion and reduction columns is proportional to the types and sizes of samples that are run through them. Following is a table of rough guidelines:

Soils and plant materialsGFFsOils and other liquids
0-5 mg 800-1200 samples600-1000400-900
5-30 mg 600-800500-700300-600
30+ mg < 400< 300< 250

Beside the actual number of samples that have been run there are other ways of determining when a reaction column has been exhausted. The best example involves the most tale-tell sign that maintenance is needed. When a reduction column has absorbed as much oxygen as it can, it begins to let oxygen through which will quickly show up on a chromatogram. A peak immediately following nitrogen will pop out of nowhere and get bigger with every subsequent sample. Usually within 5 or 6 samples the O2 peak will be larger than the nitrogen peak. Although that sign for a reduction column’s exhaustion is very obvious, combustion columns don’t usually allude to their expired usefulness so readily. More often than not, poor calculated results (which of course are the least specific symptom of a problem) are the only sign of an exhausted combustion column.
1/31/2003  From: paul.zietz
Thank you for recently repairing the autosampler of our Carlo Erba 1500 NA Series II. It is working quite well now.
Really the only things that can be done to reduce the chance of large samples getting caught are: use larger capsules and shape the samples as close to a sphere as possible leaving no flat edges or protrusions. As far as the former is concerned we carry one capsule that is larger than the 5x9 mm and they are 9x10 mm. The part number is 041073 and the price
11/5/2003  From: Randi Schneider, UH Hilo Marine Science
We are preparing to purchase the EC4010 elemental analyzer. What are the electrical connections required. It takes 220VAC but how many amps and what type of plug is required? I am contracting with an electtrician. Thanks
A standard 220V outlet with 10-15 amps should be sufficient for the ECS. Have your electrician leave a matching plug for the outlet they install, we will attach that plug to the power cord of the ECS at installation.
I have attached a short site preparation guide for the ECS. Let me know if you have any questions.
9/22/2003  From: William Carrigan
I would like to request price information for the ECS 4010 with the zero blank autosampler. We plan to interface the system with a Finnigan Delta Plus isotope ratio mass spectrometer for carbon, nitrogen and sulfur isotope analyses. Please provide all neccessary information required for this application. Thank you.
no reply
10/26/2002  From: Anonymous   -
How do I perform a proper leak check?
Thorough leak checks on the pneumatic circuits, mostly the main helium carrier circuit, of an elemental analyzer are a vital maintenance task that should be done carefully and often. Here is the concept and steps necessary to ensure that your instrument is the tightly sealed analytical environment that it should be. Although the carrier circuit includes the auto-sampler, both reactor columns, traps, GC column, TCD, tubing and numerous fittings, when it is capped off and the regulator is turned down it resembles a closed cylinder of gas. With this in mind let’s go through the process.
First step is to screw a cap with a rubber seal in it onto the main vent (VHe) located in the lower right-hand corner of the instrument (usually in the lower center of Carlo Erba® and other brands of elemental analyzers.) Next, turn the He regulator clockwise until 150 kPa (1.5 bar)* is reached on the He gauge. After waiting 15 or more seconds for the gas to equilibrate turn the He regulator counterclockwise several times until it is easy to turn, shutting the flow of gas off. After at least another 15 seconds check the pressure on the He gauge. The pressure should still be holding at or just a few kPa lower than whatever value was set initially. If it is then no gas is leaking out of the system. Wait at least another minute and a half and check the pressure once more.** If the pressure has dropped more than about three kPa then there is a leak significant enough to warrant attention. Remember, the faster the pressure drops the bigger the leak is.
At this point if the carrier circuit appears to be leak free than turn the He regulator clockwise until the needle on the gauge just begins to move up again restoring pressure to the system. Remove the cap on the vent and turn the He regulator back down to normal working pressure.
In the event that a leak is discovered the procedure is as follows: First, tighten all obvious and easy-to-get-to fittings and connections and repeat leak check. If this does not rectify the situation then the next step is to start capping off the circuit at connections in between components and repeat leak checking. For example you might break the connection right before the H2O trap and install a cap on the end of the line (here you would probably use a union and a 6MB brass cap). This will remove the trap, GC column and TCD from the system in order to determine if the leak is in one of the reactor columns or the auto-sampler. Continue to cap off and leak check each component until all leaks are found. Once all leaks have been found and fixed the instrument is ready to run!

* 150 kPa is arbitrarily chosen and it is assumed that working pressure is around 100 kPa. The testing pressure need only be higher than the working pressure.
** NOTE: If the combustion furnace is at working temperature (1020°C), do not leave the carrier circuit capped off without gas flow for more than two minutes!
be really helpful if the manual had some sort of a quick-start guide in future versions. Is all that needs to be done is to check the flow rate of the gasses? I changed the insert, the water trap and reactor still have enough use left in them to run my samples. Is it likely that anything was done to the machine to prepare it for long term shut-down that I need to undo? Someone in the lab mentioned some vents may be capped, but wasn’t sure exactly what was done.
Thanks so much,