How to judge whether the filter bag needs to be replaced?

To judge whether the industrial purification filter bag needs to be replaced, we can consider the following aspects:

pressure change

Principle: With the process of filtration, impurities will gradually accumulate on the surface of the filter bag, which will lead to the increase of filtration resistance, thus increasing the pressure difference between the inlet and outlet of the filter system.

Judgment method: When the pressure difference reaches or exceeds the limit value specified by the equipment manufacturer, it usually means that the filter bag has been blocked seriously and needs to be replaced. For example, some filtration systems stipulate that when the pressure difference exceeds 0.1MPa, the filter bag should be replaced.

Flow drop

Principle: After the filter bag is blocked by impurities, the effective filtering area decreases, and the speed of fluid passing through the filter bag will slow down, which will lead to the decrease of flow.

Judgment method: If under normal operating conditions, it is found that the filtered fluid flow rate is obviously lower than the initial set value or production requirement value, and other factors that may affect the flow rate (such as pump failure, pipeline blockage, etc.) are eliminated, it is likely that the filter bag needs to be replaced. Generally speaking, when the flow rate drops to 70%-80% of the initial flow rate, it is necessary to consider replacing the filter bag.

observational check

Principle: The appearance of the filter bag will change due to the attachment and accumulation of impurities during use.

Judgment method: Open the filter equipment regularly and observe the appearance of the filter bag. If it is found that the surface of the filter bag is obviously discolored, damaged or deformed, or a large amount of impurities are accumulated, or even filtrate leaks, then it is necessary to replace the filter bag in time.

The filtration effect becomes worse.

Principle: With the extension of the service time of the filter bag, its filtration accuracy may decrease, resulting in some impurities that should have been intercepted entering the filtrate through the filter bag.

Judgment method: The filtered fluid is detected. If the impurity content in the filtrate exceeds the specified standard, or there are turbidity and foreign bodies visible to the naked eye, it means that the filtering effect of the filter bag can no longer meet the requirements and needs to be replaced.

Use time

Principle: The service life of the filter bag is limited, even if there is no obvious blockage or damage, long-term use may lead to its performance degradation.

Judgment method: According to the material, use environment and past experience of the filter bag, make a general replacement cycle. For example, some common industrial filter bags may need to be replaced every 1-3 months under the condition of continuous operation; For some high-performance and corrosion-resistant filter bags, the replacement cycle may be relatively long. But this is only a reference, and it needs to be combined with other judgment methods to determine the specific replacement time in actual use.