The filter element is the "heart" of the filter. The quality of the filter element directly determines the filtration ability of the filter, so it is very important to test the integrity of the filter element. Only the filter that passes the integrity test can guarantee the efficiency of the whole filtration process.

Hualinkena PFA series perfluoro filter

The PFA series perfluorine filter element is made of high cleanliness PTFE membrane and PFA fluorine material, which is suitable for all fluid (strong acid, strong alkali, etc.) liquid filtration.

·Seals are available in various models

·The filter membrane pore size distribution is uniform

·Strengthen the support layer, no damage under the high pressure work

·The folding design increases the filter surface area

·The center rod and the end cover are all using the hot melt welding technology

·Clean room production

·A 100% integrity test

What is the membrane integrity

（The tants ants greater than the membrane pores）

 Complete filter film                                          Incomplete filter film

It can be clearly seen that there is no pollutant in the downstream of the complete filter membrane, while the defect of the non-complete filter membrane will be the downstream existence of pollutants, which will affect the filtration effect.

Three methods for filter element integrity testing

1. Bubble-up point test

The test principle:

It takes a certain amount of pressure to allow the gas to break through the wet filter membrane, and the pressure value of the gas flowing out of the membrane hole is the bubble point of the membrane.

Test method:

① When the downstream (filter outlet tube) is filled with liquid, and after slowly pressurized, the liquid outflow volume of the downstream tube suddenly increases, the pressure at this time is the bubble point pressure;

② There is no liquid in the downstream pipe, after slow pressure, to a continuous bubble outflow, the pressure at this time is the bubble point pressure.

Bubble point test diagram:

2. Diffusion flow test

The test principle:

When the filter film is moistened by the liquid, the upper fluid passes into compressed air or nitrogen; when there is pressure differences on both sides of the film, the gas molecules dissolve into the liquid and diffuse out on the other side of the film. The flow rate of this diffusing gas is the diffusing flow.

Test method:

When used to measure the diffusion flow, the flow of gas is required to keep the upstream pressure constant (below the bubble point pressure) to measure the flow from upstream to downstream.

Diffusion flow test diagram:

3. Pressure holding test

The test principle:

The principle of the pressure retention test is the same as the gas diffusion test, except that the measured parameters are different. Pressure holding is the detection of the decay of upstream pressure caused by diffusive flow over a certain time. The diffusion flow is independent of the upstream volume, while the pressure holding test must consider the upstream volume.

Test method:

When the pressure of the test gas rises to a given value (generally the pressure during the measured diffusion flow), the gas source is closed, and the gas diffuses out through the water in the membrane hole, resulting in the loss of the upstream pressure. Filter integrity is determined by detecting the loss of upstream pressure at a certain time period.