How to solve the inconsistency of multi-channel pipettes?

Update:08-12-2018
Summary:

Multi-channel pipettes are relative to a single-channel […]

Multi-channel pipettes are relative to a single-channel pipette, typically with 8 and 12 heads.

Pipette
Pipettes are often used in schools, pharmaceutical companies, research institutes, hospitals, etc. They are a very common instrument.

Then, some users find that the pipette tip suction amount is inconsistent during use. What causes the multi-channel pipette tip suction amount to be inconsistent? How to solve it?

When the pipette is in use, the solution is poured into the pipette, causing the pipette or pipe to accumulate stains.

Solution: After opening, you can use a filter paper to take a small amount of pure water to clean the stains. Then dry it with filter paper to prevent rust.