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The water washout cap 5" (148mm) with air relief is a safety cleaning accessory for concrete pump delivery pipelines. Installed at the end of the line after pouring, it enables compressed-air cleaning while providing a built-in pressure relief mechanism to prevent dangerous blowout during disassembly.
This blow-out cap features two ball valves:
Air Inlet Valve: Connects to an air compressor to input compressed air, pushing a sponge cleaning ball through the pump pipe. The sponge ball scrapes residual concrete from the pipe inner wall and forces concrete out from the far end.
Air Relief Valve (Safety Bleeder): A critical safety design. Before disassembly, this valve releases trapped pressure inside the pipeline to prevent sudden blowout injury or hose whipping.
Safe Operation: Built-in pressure relief valve prevents hose whipping accidents during end-of-line disassembly.
Fast Cleaning: Compressed air pushes sponge balls through the full pipeline length quickly.
Waste Reduction: Recovers leftover concrete instead of dumping it.
Pipe Protection: Prevents concrete from setting inside the line, reducing blockage risk.
Reusable: Solid construction for repeated washout cycles.
Insert a sponge cleaning ball (cleaning pig) into the pump pipe.
Mount this blow-out cap onto the pipeline end. Confirm size match (5" / 148mm).
Close both valves. Connect air compressor to the inlet valve.
Open the air inlet valve slowly. Compressed air pushes the sponge ball through the full pipeline.
After cleaning completes, open the relief valve fully to release all pressure before detaching the cap.
| Product Name | Water Washout Cap / Blow-Out Cap |
| Size | 5" (148 mm) |
| Feature | With Air Relief (dual ball-valve design) |
| Valves | Air inlet valve + Air relief / safety bleeder valve |
| Category | Blow-Out Caps / Pipeline Cleaning Accessories |
| Application | Concrete pump delivery line washout and cleaning |
| Brand | Not stated on source page |
| Material | Not stated on source page |
Never disassemble the cap before pressure is fully vented. Compressed-air cleanout is high-risk work. The relief valve is a mandatory safety feature — always open it before loosening or removing the cap. Failure to release pressure can cause fatal hose whipping or explosive disassembly.
Order Water Washout Cap 5" (148mm) with Air Relief — confirm pipe size before dispatch.