Snap Action Ball Float Drain Traps For loads to 1,950 lb/hr (885 kg/hr) . . . Pressures to 1,000 psig (69 bar) Continuous flow or on-off float drain traps Armstrong’s line of snap action drain traps includes two basic models available in cast iron and forged steel. The floats are light enough to handle light liquids. No. 71-A—Wide-open, tight-shut drain trap for use where fine dirt and grit may be present or where liquid load is light. A flat spring in the leverage system holds the valve closed until the trap body is nearly full of water. Then it snaps open, washing dirt through. When the trap body is nearly empty, the spring snaps the valve shut.