868 3" DUEL ROOF DRAIN

🔧 What it is

• Series: 868 roof drain system
• Size: 3" outlet connection
• Type: Dual / combination roof drain + overflow drain
• Application: flat commercial roof drainage system

In most catalogs, this refers to a unit like:

• Primary roof drain (normal drainage)
• Secondary overflow drain (emergency water relief)

⚙️ What it does

• Collects rainwater from a roof membrane
• Directs water into a 3" drain line
• Provides overflow protection if primary drain clogs or water rises too high
• Prevents roof ponding and structural overload

$Q = A \cdot v$

(Conceptually, roof drains are sized based on flow area and water velocity.)

🧱 Key features (typical 868 dual roof drain)

• Combination primary + overflow system
• 3" no-hub cast iron or PVC outlet (varies by model)
• Dome strainer to block debris (leaves, gravel)
• Waterproof membrane clamp / flashing ring
• Adjustable sump receiver (on some versions)

🏗️ Typical applications

• Commercial flat roofs
• Industrial buildings
• Schools, warehouses, retail centers
• Any roof requiring code-mandated overflow protection

🧠 Simple explanation

It’s basically a roof drain system that handles normal rainwater AND has a backup overflow drain in case the main one gets blocked, both feeding into a 3-inch pipe line.