Determination of Closed‑Cup Flash Point for Petroleum Products

Overview

The flash point of petroleum products is a key indicator for evaluating the fire hazard of oil products. The closed‑cup flash point refers to the minimum temperature at which vapors generated by heating an oil product mix with air and produce a flash upon exposure to an open flame under closed conditions.

The flash‑point value directly reflects the volatility and safety risk level of oil products, and serves as an important reference for oil production, storage, transportation and application. A low flash‑point value indicates a high content of light‑end fractions and higher fire‑explosion risks. An excessively high flash point can also help identify fraction deterioration or external contamination of oil samples.

Closed‑cup flash‑point testing is widely required in petroleum, electric power, chemical, commodity inspection and other industries. This test is performed in accordance with GB/T 261‑2021 and ASTM D93 standards using the SH105B Automatic Closed‑Cup Flash Point Tester.

Experimental Purpose

To determine the closed‑cup flash point of petroleum products, assess their fire‑safety characteristics, judge product quality and contamination status, and provide reliable data support for oil storage, transportation and quality acceptance.

Test Sample

Petroleum product to be tested

Experimental Apparatus

1. SH105B Automatic Closed‑Cup Flash Point Tester
2. Auxiliary consumables: sample cup, petroleum ether (for glassware cleaning), etc.

Operating Procedures

1. Thoroughly clean the sample cup with petroleum ether and allow it to dry. Fill the test oil sample up to the graduation mark of the sample cup, then place the filled sample cup steadily inside the instrument heating chamber.
2. Power on the instrument. The 7‑inch color touch‑screen boots up and enters the operation interface. Select the applicable test standard GB/T 261‑2021 or ASTM D93 under condition settings, choose the corresponding test procedure A/B/C, and enable or disable the print function as required.
3. On the setting page, enter the estimated flash‑point value of the sample and input local ambient atmospheric pressure for flash‑point result correction.
4. After verifying all test parameters, click Start. The test arm lowers automatically. The instrument heats the sample at the heating rate specified by standards and performs periodic automatic ignition when approaching the expected flash‑point temperature.
5. The instrument automatically captures and locks the flash‑point temperature the instant a flash occurs. The test arm lifts automatically. Test results can be viewed on‑screen or printed out via the thermal printer. Upon test completion, forced air‑cooling is activated to cool down the unit.
6. To abort the ongoing test, click the Stop button. The test arm will rise and heating will stop immediately.

Data Analysis & Result Evaluation

Two groups of petroleum samples were tested in parallel to verify the performance of the SH105B.

• Low‑flash‑point sample (≤110 ℃): five sets of measured data: 72 ℃, 72.5 ℃, 71.5 ℃, 72 ℃, 71 ℃. The results satisfy the repeatability requirement of ±1 ℃ specified in GB/T 261‑2021.
• High‑flash‑point sample (>110 ℃): five sets of measured data: 182 ℃, 183 ℃, 181 ℃, 183 ℃, 182 ℃. The data complies with the national standard tolerance of ±2 ℃ as well as ASTM D93 requirements with minor fluctuation.

The instrument supports atmospheric‑pressure correction to eliminate test deviations caused by altitude differences. It can store up to 500 complete test records with print output for quality‑inspection archiving. Platinum resistance temperature sensing and automatic electric ignition minimize human error, while forced air cooling shortens the interval between consecutive tests. If test results exceed allowable tolerances, inspect the condition of glassware, samples and ignition components.

Tests demonstrate that the SH105B delivers excellent repeatability and high‑level automation, suitable for batch closed‑cup flash‑point testing of oil products in petrochemical, power and commodity‑inspection laboratories.