Guide · by mithillessh-garg
Choosing an acetylene grade: industrial high purity and ultra high purity
KIGL fills three acetylene grades. Industrial dissolved acetylene to IS 308 at ≥98 % in acetone covers cutting, welding and flame heating. High purity at 99 % serves work industrial grade cannot. Ultra high purity at 99.99 %, dissolved in DMF rather than acetone, is for atomic absorption spectroscopy.
- Industrial grade
- ≥98 % C₂H₂
- High purity grade
- 99 %
- Ultra high purity grade
- 99.99 %
- Why DMF for UHP
- Much lower solvent carry-over than acetone
- Cylinder standard
- IS 7312
Three grades, three jobs
KIGL fills acetylene at three levels. The difference is not marketing — it is the purification the gas has been through and, at the top end, the solvent it is dissolved in.
| Grade | Purity | Solvent | Typical use |
|---|---|---|---|
| Industrial dissolved acetylene | ≥98 %, to IS 308 | Acetone | Cutting, welding, brazing, flame heating |
| High purity | 99 % | Acetone | Where industrial grade is not clean enough |
| Ultra high purity | 99.99 % | DMF | Atomic absorption spectroscopy, analytical work |
Getting this wrong is expensive in both directions
Buying too high a grade is the common mistake. A cutting torch cannot distinguish 98 % from 99.99 %. Analytical acetylene on a profile cutting table is money set on fire, several times over per cylinder.
Buying too low a grade is the expensive one. Industrial acetylene in an AAS instrument does not give a slightly worse result — it gives a wrong one, and it may be a while before anyone realises the baseline is the fuel rather than the sample.
What the solvent has to do with it
Every dissolved acetylene cylinder holds gas in a solvent inside a porous mass — the reason is on why acetylene is dissolved in acetone.
For industrial and high purity, that solvent is acetone, which has a relatively high vapour pressure, so a small amount always leaves with the gas. Invisible on a torch.
For ultra high purity it is dimethylformamide, whose vapour pressure is far lower, so much less solvent reaches the burner. UHP acetylene is not industrial acetylene filtered harder — it is a different fill in a different solvent. That is why it is a separate line, and why very few suppliers anywhere offer it.
What actually varies between grades
- Purity — the headline number, 98 % to 99.99 %
- Phosphine and hydrogen sulphide — carried over from the calcium carbide, limited by IS 308, and the real measure of whether the plant’s purification train is maintained
- Moisture — matters increasingly as purity rises
- Solvent carry-over — acetone at the industrial end, DMF at the analytical end
Higher purity on request
The standard industrial fill is ≥98 %, which is what IS 308 requires and what cutting, welding and flame heating need.
Where a process needs cleaner gas, KIGL can supply dissolved acetylene at higher purity against a specific enquiry. Tell us the purity and the volume, and we will confirm what can be held and on what lead time. What we will not do is print a figure we cannot repeat batch after batch — which is a question worth asking every supplier you compare.
Ask for the certificate
Whichever grade you buy, ask for the test certificate for your batch, and read what it measures rather than what it claims.
A certificate stating purity and impurity levels actually determined, naming the method, is evidence. One restating the limits from the standard without a single measurement is a formality. The difference tells you a great deal about a supplier long before you have a problem.
Sources
Choosing an acetylene grade — frequently asked questions
Which grade do I need for cutting and welding?
Industrial dissolved acetylene to IS 308 at ≥98 %. That is what the standard requires and what the work needs. A torch cannot tell 98 % from 99.99 %, and paying for analytical gas to cut plate is money burned for no return.
What is ultra high purity acetylene actually for?
Atomic absorption spectroscopy, and analytical or synthesis work at a similar level. At 99.99 % and dissolved in DMF instead of acetone it gives a flame clean enough that the instrument measures your sample rather than the impurities arriving with the fuel.
Why is UHP dissolved in DMF rather than acetone?
Acetone has a relatively high vapour pressure, so a little always leaves the cylinder with the gas. On a cutting torch that is irrelevant. In an instrument it shows in the baseline. DMF's vapour pressure is far lower, so much less solvent reaches the burner — which is why UHP is a separate product rather than simply a purer fill.
What impurities matter in industrial acetylene?
Phosphine and hydrogen sulphide carried over from the calcium carbide, plus moisture and solvent. IS 308 sets limits on them. They matter because they attack downstream equipment and affect flame chemistry, and because they measure whether the purification train on the generating plant is being maintained.
Can industrial grade be supplied at higher purity?
Yes, against a specific enquiry. Tell us the purity your process needs and the volume, and we will confirm what can be held and on what lead time. What we will not do is quote a purity figure without knowing it can be met batch after batch.
How do I know what I am actually getting?
Ask for the test certificate for your batch, and read what it measures rather than what it claims. A certificate stating purity and impurity levels actually determined, naming the method, is evidence. One that restates the standard's limits without a measurement is a formality.
Enquiries
Request a quotation
State the gas or equipment, the quantity or capacity, and your location. KIGL will confirm the grade, the cylinder or plant size, and whether the location can be served from Noonmati, or through our agent network.