The low leak pump is very similar to conventional Horizontal BPO pumps in construction except that it has an additional component (as a single piece) with the impeller namely expeller.
The function of the expeller is to reduce the liquid pressure inside the stuffing box thereby reducing the liquid leakage across the gland. The pressure is reduced to such an extent that the leakage from the gland (while pump is running) is nil even when the gland ropes are loose inside the stuffing box bore.
The expeller functions only when the pump is running but not when idle (because it can perform its function only in dynamic condition). This means that when the pump is idle, if the suction and delivery valves are not closed, there will be leakage from the gland.
This pump can also be recommended for liquids containing some amount of solids.
The following are the advantages of low leak pump over conventional pumps.
- Unique impeller design facilitates reduction of gland leakage (less than 5 drops / min)L.
- Well suited for liquids containing 15-20% solids.
- Does not require frequent replacement / adjustment of gland packing.
- Low initial and maintenance cost compared to pumps with mechanical seal.