Model: QBY-100 (4 inch), cast iron
Three 4 inch cast iron air diaphragm pumps for electroplating wastewater: the choices behind the order, from body material to diaphragms and lead time.
| Flow Rate | 0 to 30 m³/h |
|---|---|
| Head | Up to 60 m |
| Power | Compressed air, no motor |
| Inlet / Outlet Diameter | 100 mm (4") |
| Material | Cast iron body; standard or F46 (FEP) diaphragms |
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This order was for three 4 inch cast iron air-operated diaphragm pumps, for wastewater from an electroplating plant. The buyer asked for the largest flow and head available at this size. Several decisions went into the final order, and they apply to most wastewater jobs with a pump this big.
The 4 inch QBY-100 covers 0 to 30 m³/h, with head up to 60 m and solids up to 10 mm. A larger 4 inch model rated up to 70 m³/h was also offered. At the time the bigger model was short of stock in cast iron, and the factory gave a lead time of 15 to 20 days for a cast iron pump of about 60 m³/h, so the size and the delivery date had to be weighed together.
Aluminum was suggested as a way around the cast iron shortage. We advised against it. Electroplating wastewater carries dissolved heavy metals and is often acidic, and aluminum corrodes quickly in that kind of liquid. A cheaper or faster pump that fails in months is no saving.
Cast iron was the buyer’s own specification for this plant. For wastewater that is clearly acidic, a polypropylene or stainless steel body is the safer choice, so we ask for the pH before confirming the body material.
Two diaphragm options were quoted: standard rubber, and F46, a fluoroplastic from the PTFE family. F46 costs more but resists a much wider range of chemicals, which matters when the composition of plating rinse water changes from one bath to the next.
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