The GBY Type is a serie of centrifugal pumps specifically engineered to handle sulphuric acid (H₂SO₄), particularly at high concentrations and often at elevated temperatures. They are a staple in the chemical processing, non-ferrous metallurgy (e.g., copper, zinc smelting), and fertilizer industries where sulphuric acid is a key process fluid.
1. Material of Construction (The Most Critical Aspect):
Pump Casing and Impeller: The standard and most common material is Cast Iron (e.g., HT200).
Why? Concentrated sulphuric acid (93-98%) reacts with cast iron to form a protective sulphate layer (FeSO₄) on the surface. This layer passivates the metal, drastically slowing further corrosion. This makes cast iron an economical and highly effective choice for concentrated acid service.
Stainless Steel (e.g., 304, 316): Generally poor resistance to sulphuric acid across many concentrations and is usually avoided unless for very specific, mild conditions.
Alloy 20 (Carpenter 20): A premium nickel-chromium-molybdenum stainless alloy with excellent resistance to sulphuric acid across a wide range of concentrations and temperatures.
High-Silicon Cast Iron (e.g., Duriron): Offers outstanding corrosion resistance but is very brittle.
Duplex Stainless Steels: For certain intermediate concentrations.
Applications
GBY pumps are used wherever concentrated sulphuric acid needs to be transferred.
Acid Plants: Transferring product acid.
Metal Smelting: In electrolytic refining processes (e.g., copper cathode production).
Fertilizer Production: (e.g., phosphate fertilizers).
Chemical Synthesis: As a reactant or catalyst in various chemical processes.
Waste Acid Handling: In recycling and recovery systems.
Advantages of GBY Type Pumps
Specialized Design: Engineered from the ground up for sulphuric acid, not just a generic pump.
Cost-Effective: The use of cast iron for concentrated acid service offers a great balance of performance and cost.
Reliable: Robust construction and appropriate seal choices lead to high operational availability.
Easy Maintenance: The back pull-out design drastically reduces downtime for repairs.
Safety: Proper material and seal selection minimize the risk of dangerous leaks.
Considerations
Material Sensitivity: Using a cast iron GBY pump for dilute acid would lead to rapid failure. The fluid concentration and temperature must be precisely matched to the pump's material grade.
Abrasion: If the acid contains suspended solids (e.g., in a dirty process stream), standard cast iron may wear quickly. A hardened material or a different pump type might be needed.
Not a Universal Pump: It is highly specialized. It should not be used for other highly corrosive chemicals (e.g., hydrochloric acid, chlorine bleach) without thorough review, as material compatibility would be completely different.
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