What Kind of Hydrostatic Test Does Your Gas Cylinder Need?

To figure out the types of gas cylinder hydrostatic pressure tests, we must distinguish the types of gas cylinders first.

Types of Gas Cylinders

The gas cylinder is a pressure vessel that stores compressed gas or liquefied gas. And it is divided into low- pressure gas cylinders and high-pressure gas cylinders. Common low-pressure gas cylinders include LPG cylinders, butane cylinders, propane cylinders, refrigerant cylinders and fire extinguishing clean agent cylinders. The gas cylinder for storing compressed gases are mostly high-pressure gas cylinders, such as compressed gas cylinders, such as oxygen cylinders, nitrogen cylinders, hydrogen cylinders, carbon dioxide cylinders.

Types of Gas Cylinder Hydrostatic Pressure Test

The gas cylinder hydrostatic testing is to use clean water as the medium to perform pressure testing on gas cylinders, so as to verify whether the structural integrity and tightness of the gas cylinder meet the design requirements, thus ensuring the safety of the gas cylinder during daily use. Generally speaking, the gas cylinder hydrostatic test includes three test types: gas cylinder pressure proof test, direct expansion method gas cylinder volume deformation test, and water jacket method gas cylinder volume deformation test.

1. Gas Cylinder Pressure Proof Test

It is to inject water at the required pressure into the gas cylinder and then maintain the pressure for a while. Then observe whether the gas cylinder has pressure drop, leakage, deformation or rupture, thereby verifying the structural integrality and tightness of the gas cylinder. 

Features: The pressure proof test can only verify the structural integrity and tightness of the gas cylinder, but it does not detect the volume deformation rate of the gas cylinder, so it may not accurately reflect the slight damage of the gas cylinder.

Test equipment:  Gas cylinder hydrostatic burst pressure test machine

2. Direct Expansion Method Gas Cylinder Volume Deformation Test

This is the internal measurement method. It carries out the hydrostatic test on the gas cylinder while measuring its volumetric deformation rate from the inside of the gas cylinder. That is, directly pressurize the cylinder with water at the required pressure, and detect the gas cylinder deformation rate by measuring the amount of water entering the cylinder during pressurization and the amount of water returned after depressurization, so as to determine whether the gas cylinder is qualified and can continue to serve.

Features: The test process is affected by environmental factors, so there will be a certain test deviation. Many countries have phased out this test method.

3. Water Jacket Method Gas Cylinder Volume Deformation Test

It is the external measurement method for gas cylinder volumetric deformation test. First of all, place the gas cylinder in a water jacket, and inject water at the required pressure into the gas cylinder. Then maintain the pressure for a while. Finally, measure the amount of water overflowing from the water jacket during pressure maintenance period and the amount of water remaining after depressurization, we can detect the gas cylinder volumetric deformation rate. Normally, if the deformation rate of the gas cylinder is over 5%, there will be great danger in continuing to use the gas cylinder, so it must be scrapped.

Features: It eliminates the influence of environmental factors on the testing process and accurately reflects the deformation of the gas cylinder.

Test equipment: Water jacket gas cylinder hydrostatic test machine

How To Choose ?

For low-pressure gas cylinders, generally only the pressure test is required. However, high-pressure gas cylinders withstand very high pressure during daily use. Once the gas cylinder bursts, it will seriously endanger the safety of personnel and property. Therefore, in addition to the pressure proof test, it is also necessary to regularly conduct the volume expansion deformation hydro test on high-pressure gas cylinders. Once the deformation rate of the high-pressure gas cylinder exceeds 5%, the gas cylinder must be scrapped and cannot be used any more.