001004406 Koshin code number change: 001034701→ 001004406. 

The Koshin 00100440600 (SC-25 Oil Seal) is a critical sealing component used specifically in the Koshin SB-25,  SB-20 series hand-operated drum pumps, which are commonly used for transferring oil, diesel, and non-corrosive fluids.

Purpose of the Oil Seal

The primary "purpose" of this part is containment and protection:

• Leak Prevention: It creates a tight seal around the rotating drive shaft (Part #12 in your diagram) to prevent the fluid being pumped from leaking out of the front cover.

• Pressure Maintenance: It helps maintain the internal vacuum/pressure required for the wing-style impellers to draw liquid up through the suction pipe.

• Contaminant Barrier: It prevents dust, dirt, or moisture from entering the pump housing from the outside, which protects the internal mechanical parts from wear.

Where It Is Used

Based on the technical diagram you provided for the SB-25 Model:

• Location: It is installed inside the Front Cover (No. 10).

• Assembly: It sits directly on the Shaft (No. 12). As you can see in your highlighted section (Item 14), it is the barrier between the internal pumping chamber and the external Handle Assembly (No. 7).

• Material: It is made of NBR (Nitrile Butadiene Rubber), which is specifically chosen for its high resistance to petroleum-based oils, fuels, and many chemicals.

Maintenance Tip

If you notice liquid dripping from the shaft right behind the handle while you are pumping, it is a definitive sign that this Oil Seal (No. 14) has worn out or hardened and needs to be replaced.

The Koshin SC-25 Oil Seal (Part Number 001004406) is the direct successor to the old part number 001034701. This high-grade seal is designed to prevent fluid leakage and protect the pump