High Head Self Priming Pump

The High Head Self Priming Pump combines two critical capabilities: the ability to generate high discharge pressure (heads up to 100 meters) and the ability to automatically prime from a dry suction line. This combination is essential for applications where the pump is located above the water source but must deliver water to elevated tanks or through long pipelines with significant elevation changes. Standard self priming pumps typically achieve heads of 30 to 50 meters. Our high head design, using multistage impellers or high-speed single stage impellers, achieves heads up to 100 meters while maintaining self priming capability. Applications include remote water supply systems, high rise building booster stations, hilltop water storage filling, and industrial pressure boosting.

The self priming mechanism is specifically adapted for high head operation. The priming chamber volume is larger than standard self priming pumps to provide adequate liquid reserve for the higher flow rates. The recirculation port design is optimized to maintain the liquid seal under higher operating pressures. A check valve in the priming chamber prevents discharge pressure from forcing liquid back into the suction line. For multistage configurations, the priming chamber is located on the first stage only, with subsequent stages contributing to pressure generation. The priming mechanism functions independently of the number of stages.

The pump hydraulics are optimized for high head generation. For heads up to 60 meters, a single-stage high-speed impeller (2,900 RPM) provides the required pressure. The impeller is specifically designed for self priming operation, with optimal vane angles for both priming and pumping. For heads from 60 to 100 meters, we offer two-stage or three-stage configurations. In these designs, the first stage impeller is optimized for priming (vacuum generation), while subsequent stages are optimized for pressure generation. The stages are arranged in series within a single casing, providing high head without requiring excessive impeller diameter or speed.

The casing is specifically designed for high pressure self priming service. The casing is manufactured from high strength cast iron (GG25 or GGG40) with reinforcement ribs to withstand the higher internal pressures. The priming chamber is integrated into the upper part of the casing, with sufficient volume to maintain prime during high flow operation. The casing design incorporates a diffuser section between stages that converts velocity energy to pressure energy with minimal loss. For the highest pressure applications, the casing is of the radial split design to contain the internal pressure.

Materials are selected for high pressure water service. The standard casing material is cast iron GG25 with epoxy coating. For higher pressures or corrosive water, ductile iron GGG40 provides superior strength and impact resistance. For potable water, all wetted surfaces are coated with FDA-approved epoxy. Shaft material is stainless steel (SS420 or SS630) for corrosion resistance. Impellers are cast iron or bronze, with bronze recommended for hot water or corrosive water service. Wear rings are replaceable and available in cast iron, bronze, or stainless steel.

The shaft sealing system must withstand higher discharge pressure while operating under suction lift conditions. For most high head self priming applications, we recommend gland packing with split PTFE or graphite rings. Gland packing tolerates the dry running during the priming cycle and can be adjusted to seal against higher discharge pressure. A water flush connection (gland water) is provided to cool and lubricate the packing. For applications requiring zero leakage, we offer double mechanical seals with a barrier fluid, but these must be used with caution as mechanical seals can be damaged by the dry running during priming.

The bearing system is oversized for the higher loads generated by high head operation. For close-coupled designs, the motor bearings are specified with higher load capacity. For frame-mounted designs, the bearing housing is of heavy-duty construction with spherical roller bearings with L10 life exceeding 50,000 hours. Bearing lubrication is oil or grease, with oil preferred for continuous high load operation. Bearing temperature monitoring (RTD sensors) is standard for larger pumps. The bearing housing is isolated from the pump casing by extended spacers to minimize heat transfer from the pumped fluid.

The driver is typically a high efficiency electric motor with TEFC enclosure. For heads above 60 meters, the motor may require higher power than standard self priming pumps. For power ratings above 30 kW, we recommend high-voltage motors (3.3kV, 6.6kV, or 10kV) to reduce current and cable size. For variable flow applications, we offer VFDs with inverter-duty motors. The VFD can be used to adjust pump speed and maintain constant pressure across varying flow rates.

Installation requires attention to suction piping. Because the pump generates high suction lift (up to 8 meters), the suction pipe must be properly sized and sealed. Use eccentric reducers (flat side up) on the suction inlet to prevent air pockets. The suction pipe should have a continuous upward slope toward the pump (minimum 1 cm per meter). For long suction pipes (over 15 meters), consult our engineering team for priming time estimates.

In summary, the High Head Self Priming Pump delivers the unique combination of automatic priming capability and high discharge pressure, making it ideal for challenging water supply applications.