Liquid distributor Type: weir trough distributor Material: PVC Diameters: larger than 1000 mm Fouling resistant Features: Distributors that are designed for the highest flow rates use triangular weirs. If fouling is not severe, distributors that are designed for lower flow rates use slotted weirs for better flow control. Vapor passage is provided by the space between troughs. Liquid is metered to the closed-end troughs by one or more parting boxes. The standard turndown ratio is 2.5:1. Higher turndown ratios can be achieved with special parting box design.