When cleaning manholes, choosing the right cleaning agent is of utmost importance. Here are some suggestions for the suitable cleaning agents for cleaning manholes: 

1. Special cleaning agent 

For the cleaning of industrial equipment such as manholes, it is advisable to use specialized industrial cleaners. These cleaners usually have strong decontamination capabilities and good control over corrosion, which can efficiently remove dirt and grease from the equipment surface without causing damage to the equipment itself. When choosing, it is important to select cleaners that are compatible with the material of the equipment and meet the cleaning requirements. 

II. Mild Cleanser 

If there are no obvious stubborn stains on the manhole surface, a mild cleaning agent can be chosen for cleaning. Such cleaning agents usually do not cause corrosion or damage to the equipment surface, and have good decontamination effects. For example, some neutral cleaners or weakly acidic/weakly alkaline cleaners can be considered for use. 

III. Cleaning Agents to Avoid Using 

1. Strong corrosive cleaners: Avoid using strong corrosive cleaners, such as strong acid or strong alkali solutions, as they may cause severe corrosion and damage to the equipment surface. 

2. Flammable and Explosive Cleaners: Avoid using flammable and explosive cleaners to ensure safety during the cleaning process. 

3. Unverified cleaners: Do not use unverified or unknown-source cleaners as they may cause unpredictable damage to the equipment. 

IV. Principles for Selecting Cleaners 

1. Targeted approach: Select the appropriate cleaner based on the type of dirt on the manhole surface and the material properties. 

2. Safety: Ensure that the selected cleaner will not pose any harm to humans or the environment during use. 

3. Economy: While ensuring the cleaning effect, choose the cleaner with higher cost-effectiveness. 

V. Cleaning Precautions 

1. Pre-treatment: Before cleaning, the surface of the manhole should be pre-treated first, such as removing loose dirt and grease from the surface. 

2. Cleaning method: Based on the instructions of the cleaner and the material characteristics of the equipment, select the appropriate cleaning method, such as wiping, rinsing or soaking, etc. 

3. Protective Measures: During the cleaning process, necessary protective measures should be taken, such as wearing protective glasses and gloves, to prevent the cleaning agents from causing harm to the human body. 

4. Post-processing: After the cleaning is completed, the manhole should be thoroughly rinsed and dried to ensure the cleanliness and dryness of the equipment surface. 

In conclusion, when cleaning manholes, one should select the appropriate cleaner based on the material of the equipment, the type of dirt, and the cleaning requirements, and follow the correct cleaning methods and precautions to ensure the cleaning effect and the safety of the equipment.