What is Hydrostatic Pressure Testing?

Hydrostatic pressure testing is a key technology that uses applied liquid pressure to test the sealing and strength of materials or equipment. It is widely used in fields such as pipelines, pressure vessels, and waterproof materials.

Hydrostatic pressure testing involves injecting liquid (usually water) into a sealed container or material and gradually increasing the pressure to a set value, observing whether it leaks or deforms. Simply put, it's like giving the material a "pressure test" to verify its reliability under high-pressure conditions.

Testing Principle

During testing, liquid is injected into the object under test and pressurized, usually to a pressure value of 1.5 times or more of the design working pressure. For example, a pipe with a rated pressure of 100 psi might be tested at 150 psi. By monitoring pressure changes and material deformation, it can be determined whether there are leaks or structural defects.

Testing Methods

Static method: Maintain a constant pressure for a period of time and observe for leaks or deformation.

Dynamic method: Increase the pressure at a fixed rate and record the critical pressure value at which leakage occurs.

Dye-assisted method: Add dye to the liquid to facilitate visual detection of small leaks.

Applications of Hydrostatic Pressure Testing

1. Industrial Equipment Testing

Pipelines and pressure vessels: Testing the sealing of critical parts such as welds and valves to prevent media leakage and resulting safety accidents.

Firefighting equipment: Such as fire extinguishers and fire hoses, which require regular testing to ensure normal operation in emergencies.

2. Waterproof Performance Evaluation of Textiles

Hydrostatic pressure testing is particularly important in the textile industry, especially for testing waterproof materials such as PVC coated fabrics. For example:

Raincoats and tents: Testing the water pressure resistance value (in kPa or mmH₂O) of coated fabrics to determine their impermeability.

Medical protective clothing: Testing the material's resistance to liquid penetration under high pressure to ensure the safety of medical personnel.

3. Construction Engineering and Automotive Manufacturing

Waterproofing projects: Such as leak resistance testing of underground pipelines and roof waterproofing layers.

Automotive hoses: Testing the sealing of oil pipes and air conditioning lines under high pressure. 

Key Points for Hydrostatic Pressure Testing of PVC Coated Fabrics

PVC coated fabrics, due to their excellent waterproof and wear-resistant properties, are widely used in outdoor equipment, medical protection, and other fields. The hydrostatic pressure test requires attention to the following aspects:

1. Testing Standards

Domestic Standard: GB/T 4744 "Textiles – Determination and evaluation of waterproof performance – Hydrostatic pressure method".

International Standards: AATCC 127 (American Standard), ISO 811 (International Standard).

2. Testing Procedure

Sample Preparation: Cut a 100mm × 100mm sample, ensuring no wrinkles.

Fixture Fixing: Secure the sample in the test tank, avoiding air bubbles.

Pressure Test: Increase the pressure at a rate of 1-300 kPa/min, and record the pressure value at the third point of water penetration.

3. Acceptance Criteria

Ordinary Waterproofing: ≥5 kPa (e.g., everyday raincoats).

High Protection Requirements: ≥20 kPa (e.g., fire suits, industrial protective equipment).