Product Overview
The pump plunger cup for plastic pump-up sprayers. It is the seal on the plunger that pushes air into the tank on each stroke.
Wear, and the Greasing Nobody Does
The plunger cup is a wearing part by design, and the single biggest thing that shortens its life is running it dry.
Hydro-Force's own AS16A documentation calls for the piston cup to be greased periodically, and supplies grease in the service kit for exactly that reason. A cup run dry wears in a fraction of the time and takes the barrel surface with it.
If your pump has become hard work, or the stroke feels loose and rough rather than smooth, this is usually the part.
Material
Not confirmed. One distributor's data field lists this cup as steel, which is not plausible for a plunger cup and looks like a data-entry error. Rather than repeat it, we have left the material off until the supplier confirms it.
Specifications
| CCW SKU | NA2254 |
| Type | Pump plunger cup |
| Manufacturer | Chapin |
| Manufacturer part number | 598328 |
| Fits | Plastic pump-up sprayers, including the TWBS range |
| Material | Not confirmed — see note above |
| Maintenance | Grease periodically |
Frequently Asked Questions
How often should I grease it?
The manufacturer says periodically without giving an interval. In practice, whenever the pump starts feeling dry or stiff, and any time the pump is apart.
What grease should I use?
The service kits for these sprayers include grease for the purpose. Contact us and we will point you at it rather than have you use something that attacks the cup.
My pump is stiff. Cup or seal?
Stiff and rough usually means the cup. Smooth but no pressure usually means the bottom check valve.
Is it the same as NA2257?
Distributor data cross-lists the two and does not explain the difference. Ask us before ordering if you have been quoted the other number.
Related Products
- Viton Check Valve (NA2256)
- Viton O-Ring Pump Barrel (NA1417)
- TWBS Pump Assembly (NA1616)
- Hydro-Force TWBS Sprayer 8 Ltr (AS202)
What We See in the Field
Before replacing the whole pump, inspect the cup for hardening, cuts and chemical deposits and check that the barrel is still smooth. Leaving mixed chemical in a pump-up sprayer between jobs is one of the quickest ways to shorten the life of these seals.
Pump gone stiff? Tell us the model and we will confirm whether it is the cup, the seal or the check valve.
