The same pump often comes in two or three body materials, and the parts aren’t always interchangeable between them: Banjo’s poly and cast iron 2" pumps take different seals, and Hypro’s cast iron and poly 9303 pumps take different seal kits and impellers. Knowing the material is half of identifying the pump.
How to tell by looking
- Poly (polypropylene, glass-filled plastic) — light, usually black, molded look, often with molded-in ribs and lettering. Won’t rust.
- Cast iron — heavy, rough cast surface, usually painted or e-coated. A magnet sticks. Rust shows where the paint is worn.
- Stainless steel — heavy, bare metal finish, no paint, doesn’t rust. A magnet barely sticks or not at all to 316.
How each brand marks it in the model
| Brand | Poly | Cast iron | Stainless |
|---|---|---|---|
| Banjo | No I or SS (200PO, 300PH13W) | I after the P (200POI, 300PIH13) | SS (200PO-SS, 300PHYSS) |
| Ace | 75 and 85 size pumps | Standard on FMC/FMCSC pumps | FS or SS right after the size (FMC-150FS, FMC-200SS); Platinum (PL) roller pumps |
| Hypro centrifugal | P (9303P) | C (9303C) | S (9306S) |
| Hypro roller | C, or N (Ni-Resist) | XL (Silvercast) |
One catch on Ace: an -SS at the end of the model (FMC-150-HYD-206-SS) is stainless construction and hardware on a cast iron pump, not a stainless body.
Which should you buy?
- Poly — corrosion-proof and light, and the least expensive. Good for most herbicides and liquid fertilizer. Doesn’t like freezing with liquid in it any more than cast iron does, and can be cracked by impact or overtightened fittings.
- Cast iron — tough and inexpensive for the pressure it makes. The standard for water and many chemicals; rusts if it sits wet with corrosive fertilizer, so flush it.
- Stainless — the choice for corrosive fertilizers and harsh chemicals, and for pumps that sit with product in them. Costs more.
Whatever you have, drain it before winter. A frozen pump body cracks no matter what it’s made of.
Find yours
The Pump Finder asks for the body material right after the brand and pump type, so if you know it’s “a poly Banjo on a Honda,” you’re two clicks from the exact model and its seal, impeller and kits. Or browse centrifugal pumps and pump repair kits.
Spray Center Electronics stocks pump parts and repair kits for Ace, Banjo, Hypro/SHURflo and Annovi Reverberi (AR) pumps in Spokane, WA. Part numbers here come from the manufacturers’ parts sheets; when your pump has been modified or the tag is gone, send a photo to sales@spraycenter.com or call (509) 838-2209 and we’ll match it before you order.