Essential Components: The Indispensable Requirements for Effective Spectrometry

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While using any fine piece of equipment, there are certain methods/rules to ensure optimum use and to get the best results possible.

Here are a few rules to follow to ensure the effective use of an OES Spectrometer.

Sample Preparation: Sampling / Sample preparation is very important for getting good, stable, accurate & precise analysis results

Argon Gas: The Quality of Argon gas should be 99.9995% pure. No compromise on Argon Quality use only Spectro Grade like XL Grade/UHP grade.

Machine Stabilization: Give the Proper Stabilization Time. Follow the Daily Start-up Procedures. The LAB environment should be favourable as per the need of the instrument.

Standardization: The instrument should be recently standardized following the procedures. And has to be cross-verified using the CRM / Check Sample

Sampling

It is a technique of obtaining the coin sample from the furnace to know the chemical composition of liquid metal before casting by Optical Emission Spectrometer. Tons of Liquid metal chemistry is decided by the small <100gram coin sample. So, it is very important to get a sound coin sample which shall duplicate the liquid metal in the furnace.

The following shall be done before getting the Coin Sample from the furnace.

  • The Liquid metal shall be properly mixed.
  • The Liquid metal shall be purged with Purge gas (Nitrogen)
  • Remove the slag properly on the top of the Liquid metal.
  • The Lollypop sample/coin sample is taken at the proper depth.

The above liquid metal is poured in a proper made of Cast Iron block for Aluminum or

Copper Block for steel and iron sample to obtain the Coin/Mushroom chill cast sample.

The sample thus obtained needs to be freshly prepared for Spectro Analysis.

Sample Preparation

It is very important for getting a good, stable, accurate and precise Spectro Analysis report the sample must be

  • Homogeneous
  • The analysing area / prepared area must be Flat /single-plane
  • Free from Pin Holes
  • Free from oil/dust/moisture and other foreign bodies
  • Freshly prepare
  • Prepared portion not to be touched.
  • Not to rub with any cloth

Why Argon

Inert Gas:

As Argon is an Inert Gas it does not React with the elements in the Alloy while the Sparking Process undergoes.

Displace Oxygen:

As it is denser than the air it to flush out the Oxygen and other Atmospheric Gas from the Spark Chamber which can cause an issue during the spark.

Abundant:

Argon is the third-most abundant gas in the Earth's atmosphere, at 0.934% (9340 ppmv). It is more than twice as abundant as water vapour (which averages about 4000 ppmv but varies greatly), 23 times as abundant as carbon dioxide (400 ppmv), and more than 500 times as abundant as neon (18 ppmv).

Cheap:

The price of Argon is relatively inexpensive, typically, the price of inter gases from the cheapest one to the most expensive one: Argon <Helium < Neon < Krypton or Xenon

Instrument Stabilization

For the Routine Operation after the Instrument is turned ON the Optical System temperature is stabilized using the internal heating system. It normally takes 15 to 20 Mins to reach the required temperature.

Also, the Argon Gas is turned ON to flush out the atmospheric air in the Optical Chamber and fill the chamber with Argon which acts as the medium for the light emitted from the sample sparking.

Once the Optical System is stabilised few Rough Sparks have to be taken to remove the contaminants in the Spark Chamber.

Even after these processes are completed before starting the Analysis it is recommended to verify the instrument using a Check Sample. If variation is seen in the results then the instrument has to be Standardised.

Standardization

What, Why & When

What is Standardisation?

It is the process by which the Instrument takes its new reference for the present instrument environment condition. In simple words, it is the method by which the Instrument calculates its correction factor for the present working condition.

Why Standardisation is Required?

Argon Gas is one of the important parameters which is continuously changing. The Purity of Argon gas will not be the same within the cylinder. As the quantity changes the quality of argon gas also changes. Since the Optical Emission Spectrometer is very sensitive to these changes. The light energy emitted by the Spark Chamber which is analyzed by the Optics Chamber will have an effect due to this small change in Argon Quality. Due to this, the spectrometer may give inconsistent results. By Doing Standardization the spectrometer applies the correction factors to the calibration curve and will give correct, stable and repeatable results. The standardization process updates the machine for these changes.

When to do Standardisation?

  • When you switch on the Instrument after a long shutdown. You have to start with standardization.
  • Every 40kg drop in Argon Cylinder pressure
  • When you clean the Spark Chamber or optical entrance window.
  • If Check Sample / Certified Reference Material not giving correct result.
  • In simple whenever you make any change to your spectrometer, you have to do standardization to get stable and repeatable results.

Homogeneous & Heterogeneous Sample

Homogeneity and heterogeneity are concepts relating to the uniformity of a substance.

A homogeneous material is uniform in composition or character.

Examples of Homogeneous sample CRM, SUS, Secondary Standard, Chill Cast Coin sample, Rolled bars ……

One that is heterogeneous is distinctly non-uniform in one of these qualities.

Examples of Heterogeneous sample Casting, are INGOT sample, ASH CAST sample….

Accuracy and Precision

Accuracy is the degree of closeness of the measurements to a specific value. Accuracy is the closeness of the measured value to a standard or true value. In other words, Accuracy is how close a measurement is to the correct value for that measurement

Precision is the closeness of the measurements to each other. The precision of a measurement system refers to how close the agreement is between repeated measurements.

Repeatability and Reproducibility

Repeatability is simply the precision determined under conditions where the same methods and equipment are used by the same operator to make measurements on identical specimens. 

Reproducibility is simply the precision determined under conditions where the same methods but different equipment are used by different operators to make measurements on identical specimens.

Error

Error is the difference between the true value of the measurement and the measured value.  The total error is a combination of both systematic error and random error. Trueness is the closeness of agreement between the average value obtained from a large series of test results and the accepted truth.  Trueness is largely affected by systematic error.  Precision is the closeness of agreement between independent measurements.  Precession is largely affected by random error.  Accuracy is an expression of the lack of error.  Uncertainty characterizes the range of values within which the true value is asserted to lie with some level of confidence.

SUS & CRM

SUS

Setting Up Samples are samples used in the Standardization Process. These are special samples that are used only for standardizing the instrument. These SUS samples shall never be used as check samples like CRM (Primary Standard) / Secondary Standard for checking the performance of the instrument. From the name Setting Up Sample itself, it’s very clear that these samples are used only for setting the instrument and not for cross-checking results on the instrument.

CRM

Certified Reference Material is Primary Standard which comes with a Certificate. These Standard samples are nationally / internationally recognized/accepted primary reference material. CRM is the right sample for cross-checking the performance of the instrument. Note: The CRM is not Provided along with the Instrument, the customer has to purchase it separately as per their requirements.

Check Sample / Secondary Master

Check sample is a Secondary Standard developed by the laboratory with reference to the Primary Standard / is by averaging the inter-laboratory analysis (NABL). These Secondary Samples can be used for cross-checking the instrument performance for cost-effectiveness.

Why you NEED a Spectrometer!

Profitability

A spectrometer is capable of finding the exact chemical composition of a sample before the final process is done. You can finely control the presence of expensive elements to reduce unnecessary wastage on expensive additives and thus greatly help in reducing costs. In many cases, our customers have received a full return on investment in a matter of months and have continued to save big on unnecessary slippage

COSTOVATION in True Sense!

For Example, the current Market Price of Nickel is around 1065 Rs per 1Kg

Nickel is an important element in Stainless-Steel Production, so in order to avoid rejection if you don’t have a spectrometer you’ll add an extra quantity in the furnace which will cost you more for the production.

Even if we consider a 1 Ton of Production and even if you save 1% of Nickel you will be saving 10,650 per Ton. Also, the cost of the Instrument will be recovered within a span of 1 year.

Quality

While profitability is key, a spectrometer can help strike a precise balance between making quality products and staying extremely profitable.

Compliance

A spectrometer gives you the confidence to make high-quality products and thus opens the avenue to cater to a wider customer base especially those who want quality products

Prevents Rejection

A spectrometer in your lab ensures that you never have rejections in your production. This furthers your profitability and increases savings by minimizing costs incurred due to re-melting and time wasted there off. The goodwill gained with your customers is increased thus improving the probability of increasing business with existing clients.

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