Portable Oil Analyzer

I. Product Overview

Oil is a viscous liquid that is barely soluble in water but selectively soluble in organic solvents, with a relative density generally below 1. It is divided into petroleum oils and animal and vegetable oils. Petroleum is a complex mixture of hydrocarbons of different molecular sizes with small amounts of sulphur-, nitrogen- and oxygen-containing organic compounds. Its composition varies from region to region, and it has no fixed chemical composition or physical constants. Carbon and hydrogen dominate, accounting for 95–99% in total, mainly in the form of hydrocarbons — alkanes, cycloalkanes and aromatic hydrocarbons. Oxygen, sulphur and nitrogen account for 1–4% and occur mainly as compounds, most of which are concentrated in residual oil, gum or asphalt.

Oils consist of CH, CH2 and CH3 groups, which are the inherent characteristics of all oil products. Because tetrachloroethylene has replaced carbon tetrachloride, the definition becomes: “oil is a substance that, after deducting the infrared background absorption of tetrachloroethylene, is soluble in tetrachloroethylene and has characteristic absorption at wavenumbers 3030 cm-1, 2930 cm-1 and 2960 cm-1”. These wavenumbers correspond to the infrared characteristic absorption of CH, CH2 and CH3, which are common to oils worldwide. By measuring the bond energy (absorbance) of CH, CH2 and CH3 in a sample, the oil content can be determined. The infrared oil analyser performs absorbance measurement at these three wavenumbers for quantitative analysis.

Typical uses include determination of mineral oil and animal and vegetable oil in surface water, groundwater, domestic sewage, industrial wastewater and soil, and of oil fume and oil mist emissions in exhaust gas. It is suitable for environmental monitoring stations, hydrological stations, petrochemical plants and machinery, automobile and aircraft manufacturing enterprises, as well as the pharmaceutical, agricultural science and technology and marine transport industries.

II. Measuring Principle

Petroleum substances are compositionally complex and vary with origin. Their main components are hydrocarbons — alkanes, cycloalkanes and aromatic hydrocarbons. In the infrared absorption spectrum, the ratio between methylene CH2 groups, methyl CH3 groups and Ar-H aromatic hydrocarbons varies to some extent with the origin of the oil, so individual correction coefficients are derived: X for the methylene CH2 group, Y for the methyl CH3 group and Z for the Ar-H aromatic hydrocarbon, together with F, the ratio of the methylene CH2 wavenumber 2930 cm-1 to 3030 cm-1. Using F, X, Y and Z, various petroleum oils can be measured without the result being affected by the origin of the oil.

Qualitative analysis: when infrared radiation of a given frequency passes through a molecule, any bond whose vibration frequency matches absorbs the radiation, gains energy and vibrates more strongly; bonds without a matching frequency do not absorb. Sweeping the infrared frequency across the sample therefore produces regions of stronger and weaker transmission, giving the infrared absorption spectrum. Quantitative analysis: when light of a given wavelength passes through the solution being measured, its energy is absorbed, and the degree of absorption is proportional to the concentration of the substance.

III. Key Features

1. The instrument adopts the correction-coefficient method specified by the national standard and strictly follows the standard formula, calibrating with 20 mg/L n-hexadecane, 20 mg/L isooctane and 100 mg/L benzene, then applying the calibration formula to derive the instrument correction coefficients before measuring samples (the standard curve method can also be used).

2. A mainstream Android 7.1 system with an 8-inch colour screen is used for operation; every function is accessible by touch, as easy as using a mobile phone.

3. Built-in wireless networking supports an external Wi-Fi connection for networked upload.

4. 16 GB of internal storage holds more than one million records, and data can be exported directly to a USB flash drive.

5. Automatic network time synchronisation avoids inaccurate local time after long use, which would otherwise affect the accuracy of the time on output certificates.

6. Powerful back-end data support: after measurement, results can be printed and saved locally, and can also be uploaded to the cloud platform database over Wi-Fi or 4G.

7. Beyond basic functions such as measurement settings, curve analysis and historical data, the spectrum can be zoomed in and out without limit so that low-concentration curves can be observed more clearly.

8. Highly automated procedures allow individual testing of all instrument functions through the Android system, with automatic wavelength scanning and automatic correction for more accurate results.

9. One-key program upgrade: the APP can be upgraded from a USB flash drive without an engineer visiting the site.

10. An electrically modulated light source reduces the heat generated by the source, which helps dissipate heat from the system, and eliminates mechanical light-chopping components, simplifying the structure and improving reliability.

11. Real-time automatic zeroing: the instrument acquires both the signal with the source on and the signal with the source off, achieving real-time automatic zero adjustment, which simplifies operation and improves long-term signal stability.

12. The detachable integrated optical system gives a compact instrument with a short optical path and high energy; the optical path meets the requirements of infrared spectroscopy with good stability and a high signal-to-noise ratio.

IV. Technical Parameters