Can I retain the pump's non-return valve?
In order to minimise its weight, the riser should be empty when lifting the pump for inspection. This has often been done by removing the pump’s non-return valve or drilling it through so that the water drains back at a controlled rate. Unfortunately, the life of the pump and motor can be reduced by this as they will suffer the repeated stresses of starting against zero head every time they are used. The Break-Off Plug System has been developed to avoid this : the non-return valve is retained intact and a hollow stainless steel drainer plug is fitted across the lower Boreline coupling. When it is necessary to drain the riser, the plug can be broken off, at a weak point, with a special ‘torpedo’ lowered down the hose.