A closed cup flash point tester is a device used to determine the flash point of a liquid, which is the temperature at which the vapor above the liquid is flammable. It consists of a small cup with a lid that is closed during the testing process. The liquid sample is placed in the cup and heated slowly, and the temperature at which the vapor above the liquid ignites is recorded as the flash point. This type of flash point tester is commonly used to test the flammability of fuels, solvents, and other flammable liquids.

To use a closed cup flash point tester, follow these steps:

1，Prepare the sample: Ensure that the sample is a representative portion of the liquid and that it is free of contaminants.

2，Place the sample in the cup: Pour the sample into the cup, making sure not to overfill it.

3，Close the cup: Secure the lid on the cup to ensure that the vapor above the liquid is contained during the testing process.

4，Heat the sample: Using a heating element or other heating source, slowly increase the temperature of the sample. The temperature should be increased at a rate of approximately 5°C per minute.

5，Observe for flash point: As the temperature of the sample increases, watch for the vapor above the liquid to ignite. This is known as the flash point. The temperature at which this occurs is recorded as the flash point of the liquid.

Record the results: Record the flash point of the liquid in a log or database for future reference.

The price of a closed cup flash point tester can vary widely depending on the brand, model, and features that you are looking for. Some basic models may cost a few hundred dollars, while more advanced models with additional features and capabilities can cost several thousand dollars. It is best to shop around and compare prices from different manufacturers and suppliers to get the best deal. You may also be able to find used or refurbished units at a discounted price.