how to assemble the chemical cart ridge seal

Assembly of Chemical Cartridge Mechanical Seals

Chemical cartridge mechanical seals are widely used in chemical processing due to their pre-assembled design, which simplifies installation and ensures sealing reliability. Below is a detailed, professional assembly process tailored to chemical application scenarios:

1. Pre-Assembly Preparation

- Component Inspection: Check the cartridge seal for intactness—ensure no scratches, cracks, or debris on the seal faces (common materials like silicon carbide or tungsten carbide), and verify that elastomers (e.g., Viton for corrosives) are free of aging, swelling, or damage. Confirm all accessories (springs, set screws, gland plates) are complete and match the model.
- Equipment Preparation: Clean the pump shaft, sleeve, and seal chamber thoroughly to remove chemical residues, scale, or solid particles, as contaminants can cause seal face damage. Measure shaft runout (must be ≤0.1mm) and surface roughness (Ra 0.2–0.4μm) to meet assembly requirements. Prepare compatible lubricant (consistent with the chemical medium, e.g., fluorine-based lubricant for strong corrosives) to avoid medium contamination.
- Safety Precautions: Wear chemical-resistant gloves, goggles, and protective clothing, especially when handling toxic, corrosive, or flammable media. Ensure the work area is well-ventilated and equipped with emergency spill treatment tools.

2. Step-by-Step Assembly

- Lubrication Treatment: Apply a thin, uniform layer of compatible lubricant to the seal faces, elastomer contact surfaces, and the pump shaft/sleeve where the seal installs. This reduces friction during assembly and prevents dry rubbing damage to the seal faces.
- Cartridge Installation: Align the cartridge seal with the pump shaft, ensuring the seal chamber mating surface is clean and flat. Push the cartridge evenly along the axial direction—do not use hammers or hard tools to strike, as this can deform the seal face or damage internal springs. Rotate the shaft manually while pushing to ensure smooth installation without jamming.
- Positioning and Fixing: Adjust the cartridge to the correct axial position according to the manufacturer’s specifications. Tighten the set screws or fixing bolts evenly in a crisscross pattern to avoid uneven force that could cause shaft misalignment. Ensure the compression amount of the internal spring meets requirements (typically 2–5mm, check with calipers if necessary).
- Auxiliary System Connection: If the seal is equipped with a cooling, flushing, or barrier fluid system (common for double cartridge seals in chemical applications), connect the pipelines tightly. Ensure the flow direction and pressure of the fluid meet design standards—for example, the barrier fluid pressure should be 0.1–0.2MPa higher than the medium pressure to prevent medium leakage.

3. Post-Assembly Inspection and Test Run

- Pre-Run Check: Rotate the pump shaft manually for 3–5 full rotations to confirm smooth operation without abnormal resistance. Inspect all connections for looseness, and check the seal chamber and pipeline for pre-leakage.
- Test Run Procedure: Start the pump at low load first, monitoring the seal’s leakage rate (should be ≤5ml/h for liquid chemicals) and the temperature of the seal chamber (should not exceed the medium temperature by 20°C). Gradually increase to normal operating load, continuing to observe for abnormal noises, excessive temperature rise, or increased leakage.
- Problem Handling: If leakage exceeds the limit or abnormal phenomena occur during the test run, stop the pump immediately. Check for improper installation (e.g., spring compression, shaft misalignment) or component damage, and rectify before restarting.

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