For all standard gases, we carry out cylinder treatment according to their composition and concentration, and manufacture them using the gravimetric method, an absolute measurement method that conforms to the ISO 6142 standard. We transfer a fixed amount of the parent gas with two or more components (pure gases or a gas mixture manufactured through the gravimetric method) to a cylinder to be filled and evenly mix the components for manufacturing. Then, we verify the manufactured standard gas, in accordance with the ISO 6143 standards, and give it attribute values and an uncertainty in measurement before we deliver it to the customer.

In general, we can manufacture standard gases of various concentrations ranging from 2 to 3 μmol/mol to tens of cmol/mol. The level of concentration varies depending on the gas components.
Although we can manufacture them at low concentrations in the level of nmol/mol for some compositions, technical reviews may be necessary to determine whether we can manufacture or analyze them. For other details, contact the overseas sales staff(sales@rigas.co.kr) of the Management Planning Division.

Uncertainty in measurement is defined in The Guide to the Expression of Uncertainty in Measurement (the GUM) published by the International Organization for Standardization (ISO) as "the parameter associated with the result of a measurement or analysis that characterizes the dispersion of the values that could reasonably be attributed to the measured." You may regard an uncertainty in measurement as a quantitative method for expressing measurement reliability, which characterizes the range of the expressed values within which the true value of a measured lies. In 1993, for defining and expressing the quality of measurement results with a unified parameter, the ISO published the GUM in association with international organizations such as the BIMP, IES, IFCC, IUPAC, IUPAP, and OLML. According to the GUM, uncertainty is calculated using four steps: 1) setting a relational model for the parameters; 2) calculating the input estimates and standard uncertainty of each input estimate; 3) determining the combined standard uncertainty; and 4) determining the expanded uncertainty.

Before we determine an expiration date, we carry out short- and long-term stability assessments based on gas composition, concentration, and cylinder type. In addition, the expiration date is determined based on the period in which stability is assured. Expiration dates may vary depending on gas components, concentrations, cylinder materials, valve types, etc.
If you want to extend the basic expiration date that is determined based on the product specifications, we may conduct a technical review to determine if the expiration date can be extended. At this time, chances are high that the uncertainty in measurement may be adjusted partially. For another method for extending a product expiration date, you may request us to conduct a reanalysis and renew the expiration date starting from the reanalysis date.

B/T refers to the practically allowable gap between the target concentration of a product requested by the customer and the actual concentration of the product that is manufactured and supplied.
B/T may be influenced by the following factors:
• Blending method (weight method and pressure method)
• Reaction of the blended components (influence of impurities and other components, and the influence of their reaction with the inner surface of the cylinder)
• Impurities of raw materials, etc.

The warranty period of our regulators is one year from the delivery date. During the warranty period, we provide substitutes or spare parts if regulator failures or damages occur due to a cause clearly imputable to us. (Losses caused by product failures are not included in the scope of the warranty.) If you need to have a regulator repaired, you may return it to us. We will then proceed with the repair after determining whether it can be repaired. We charge a certain repair fee for this type of service.

To extract gas from a cylinder at high pressure, you need a depressurizing device, namely, a regulator. We provide various regulators to meet customer requirements.

The methods for checking the amount of gas in cylinders are different for compressed gases and liquefied gases.

For a compressed gas, the amount (in liters) can be calculated by measuring the filling pressure and multiplying it by the volume (in liters) of the gas cylinder.
(Filling amount = filling pressure × cylinder volume)

For a liquefied gas, the amount (in kilograms) can be calculated by measuring the weight (in kilograms) of the cylinder filled with the gas and subtracting the weights (in kilograms) of the empty gas cylinder and the valve.
(Filling amount = weight of the filled cylinder – weight of the empty cylinder – weight of the valve)

They are different in terms of glossiness, design, and weight. Although distinguishing them using the naked eye may be difficult, if no comparable cylinder is available, or if the cylinder is painted, steel cylinders can be distinguished by testing whether magnets will adhere to them.

We can apply a shot treatment to the inner surface of cylinders. As the cost varies depending on the sizes of the cylinders, contact the overseas sales staff (sales@rigas.co.kr) for further details