The fabric hydrostatic test and the pressure test are both methods used to assess the performance of fabrics in terms of water resistance. However, there are differences in how these tests are conducted and the specific aspects they evaluate. Here's an explanation of these differences:

1. Fabric Hydrostatic Test:

   - Purpose: The fabric hydrostatic test measures the resistance of a fabric to water penetration under a static pressure.

   - Test Method: In this test, a fabric sample is subjected to a constant pressure, typically applied using a hydrostatic pressure tester. The test measures the pressure at which water begins to penetrate the fabric and the extent of water penetration, if any.

   - Evaluation: The hydrostatic pressure value obtained during the test indicates the fabric's ability to withstand water pressure without allowing water to pass through. Higher hydrostatic pressure values indicate better water resistance.

2. Pressure Test (Air or Water):

   - Purpose: The pressure test, whether conducted using air or water, evaluates the overall durability and integrity of a fabric or a finished product.

   - Test Method: In a pressure test, the fabric or product is subjected to pressure, which can be applied using either air or water. The test aims to determine if the fabric or product can withstand the specified pressure without any structural failures, such as bursting or leakage.

   - Evaluation: The main focus of the pressure test is to assess the fabric or product's ability to withstand the applied pressure without any physical damage, rather than specifically testing for water penetration. Test results typically indicate whether the fabric or product passed or failed the test based on the occurrence of visible damages or malfunctions.

In summary, the key difference between the fabric hydrostatic test and the pressure test lies in their primary purposes and the specific aspects they evaluate. The fabric hydrostatic test specifically measures the resistance of a fabric to water penetration under static pressure, while the pressure test assesses the overall durability and structural integrity of a fabric or finished product when subjected to pressure, regardless of whether it is water or air.