After the duty point and quote scope are corrected, the €80,000 RITZ HP-49 offer can be compared fairly with the €33,000 alternative and the direct-well concept can be screened without relying on nominal model claims. Follow the water path first: the source supplies the requested flow, the pump adds energy, and static elevation, pipe friction, fittings, valves, and required outlet pressure consume that energy.
Where does the pumping path consume head?
The stated installation has two lifts. An existing submersible pump raises water from a well approximately 120 m below station level into a deposit. A second pump then sends 270 m3/h through an 8-inch steel pipe to a channel 320 m above station level. The proposed RITZ HP-49 is a high-pressure, horizontal multistage pump package for the second lift.
The alternative is a single submersible installation lifting directly from the well to the channel. The nominal static elevation is 440 m only if the pumping water level is 120 m below station level and the channel is 320 m above it. Actual total dynamic head is higher because the pump must also overcome friction and any required residual pressure. Well drawdown can increase the direct-lift head while the pump is running.
| Path element | Known value | What must be added or checked |
|---|---|---|
| Required flow | 270 m3/h, equal to 0.075 m3/s | Minimum, normal, and maximum operating flow |
| Deposit-to-channel static lift | 320 m | Pipe friction, minor losses, and channel outlet condition |
| Well-to-deposit lift | Approximately 120 m | Pumping water level, drawdown, column losses, and delivery pressure |
| Direct well-to-channel lift | 440 m under the stated elevation assumption | Drawdown and all direct-pipeline losses |
| Discharge pipe | Nominal 8-inch steel | Actual internal diameter, length, roughness condition, fittings, and pressure rating |
At 320 m of water head, the static differential pressure is approximately 3.14 MPa or 31.4 bar, using water density of 1,000 kg/m3. At 440 m it is approximately 4.32 MPa or 43.2 bar. These are static values, not design pressures. Shutoff head, transient pressure, elevation profile, and component allowances must be checked against the pipe, valves, flanges, seals, and casing ratings.
What duty point must every supplier quote?
A supplier needs flow, total dynamic head, and suction conditions at the pump flanges. A system layout alone transfers too much interpretation to the bidder and makes responsibility unclear if the installed pump misses the required duty.
Calculate total dynamic head for the deposit-to-channel service as:
For the direct-well alternative, use:
Do not substitute the 120 m well depth for pumping water level without a drawdown test. The relevant elevation begins at the dynamic water surface, not automatically at the bottom of the well.
Pipe loss can be calculated with Darcy-Weisbach:
h_f = f × (L/D) × (v²/(2g)), with v = Q/A.
The nominal 8-inch designation is insufficient for an exact result. Obtain the actual internal diameter, total developed length, material condition, fitting inventory, and valve data. Calculate losses at each required flow, because friction changes approximately with velocity squared within a fixed hydraulic regime.
| Symptom or proposal risk | Likely mechanism | Deciding check |
|---|---|---|
| Pump reaches pressure but not 270 m3/h | System head exceeds the quoted duty or the pump curve was selected at a different speed | Plot the calculated system curve against the certified pump curve |
| Flow starts correctly and falls | Well drawdown, suction restriction, air entry, or changing reservoir level | Trend suction pressure, water level, discharge pressure, and flow together |
| Noise, vibration, or unstable flow | Insufficient suction margin, operation away from the preferred region, or hydraulic recirculation | Compare available suction conditions with the supplier's requirement across the operating range |
| Direct submersible will not fit | Motor or pump outside diameter exceeds the existing well clearance | Compare certified assembly dimensions with the measured well casing and restrictions |
Which pumping arrangements should be compared?
Three technically distinct arrangements deserve screening. They cannot be compared from model names or purchase price alone.
| Arrangement | Primary advantage | Controlling constraints | Evidence needed |
|---|---|---|---|
| Existing well pump plus RITZ HP-49 for the 320 m lift | Retains the intermediate deposit and separates the well duty from the transfer duty | Horizontal multistage package cost, suction conditions, building space, pressure rating, and efficiency at 270 m3/h | Certified curve, efficiency, absorbed power, suction requirement, materials, package scope, and dimensional drawing |
| Existing well pump plus another supplier's 320 m lift package | Creates a direct commercial and technical comparison | Quotes must use identical duty, speed basis, materials, accessories, testing, and delivery scope | Complete deviation schedule and itemized scope |
| Single direct submersible, with HDM-61 as a candidate | May remove the intermediate pumping stage and deposit dependency | Approximately 440 m static lift, well yield, casing diameter, cable and power system, installation depth, column losses, retrieval, and maintenance | Certified curve at the required flow, motor data, assembly diameter, thrust limits, cable design, well test, and lifecycle cost |
A vertical lineshaft pump with an external motor is another physical arrangement, but a 120 m well makes shafting, alignment, column construction, and infrastructure major design considerations. A submersible avoids a rotating lineshaft from the pump to the surface, but moves the motor, cable, and connections into the well. Neither layout is automatically superior.
The HDM-61 designation alone does not prove that it can deliver 270 m3/h at the direct system head. Read the required number of stages, operating speed, absorbed power, efficiency, motor size, outside diameter, and permissible operating range from the manufacturer's selected curve and dimensional documents.
How do the two quoted prices compare?
The RITZ price is €80,000 for the pump, motor, bedplate, and coupling, excluding installation. A KSB package was quoted at €33,000 for the same stated capacity and at 2,900 rpm. That difference is commercially significant, but “same capacity” must mean the same guaranteed flow and total dynamic head, not merely a similar motor rating or discharge connection.
| Comparison field | RITZ offer | KSB offer | Required normalization |
|---|---|---|---|
| Price | €80,000 | €33,000 | Currency basis, taxes, freight, validity, and payment terms |
| Package scope | Pump, motor, bedplate, coupling; no installation | Described as a same-capacity kit | Itemized motor, coupling, guard, base, seals, instruments, valves, and controls |
| Speed | Not stated | 2,900 rpm | Certified performance at the offered speed and supply frequency |
| Hydraulic guarantee | Not stated | Not stated beyond same capacity | Guaranteed flow, head, efficiency, absorbed power, and tolerances |
| Materials and testing | Not stated | Not stated | Casing, impellers, shaft, wear parts, test type, and certificates |
| Installation and commissioning | Installation excluded | Not stated | Alignment, grouting, field supervision, startup, and performance testing |
A price-per-horsepower rule is not a defensible award method for this service. It ignores head, number of stages, metallurgy, pressure containment, efficiency, test requirements, motor construction, baseplate design, and commercial scope. Use it only as a coarse screening signal, never as the selection calculation.
What arrangement should be recommended first?
Use the existing two-stage arrangement as the procurement baseline, then evaluate the direct submersible as a separate lifecycle project. The baseline requires fewer unverified changes: the deposit already separates well production from channel transfer, and competing 320 m lift packages can be quoted against the same flange-to-flange duty.
Do not award the €80,000 offer or reject it solely because the €33,000 quote is lower. Issue a common request for quotation and require every bidder to complete the same data schedule. The large price gap should trigger a scope and guarantee reconciliation.
Advance the direct submersible option only after four gates pass:
- Confirm that the well can sustainably yield 270 m3/h at the measured pumping water level.
- Confirm that the selected pump, motor, cable, and joints fit through the complete well profile, not just the nominal casing diameter.
- Confirm that the electrical supply can start, run, protect, and isolate the offered motor without unacceptable voltage drop.
- Compare energy, maintenance access, retrieval cost, production interruption, pressure transients, and the value of storage against the two-stage arrangement.
If the well yield is below the delivery demand, the deposit may be operationally necessary even when a direct pump can generate the required head. Storage allows a lower or intermittent well inflow to support a higher transfer rate for a limited period.
How should the request for quotation be written?
- Survey the hydraulic path. Record elevations at the dynamic source water level, pump suction and discharge flanges, pipe high points, and channel outlet. Measure pipe lengths, internal diameters, fittings, valves, and branches.
- Define operating cases. State minimum, normal, and maximum required flow; minimum and maximum source levels; outlet pressure requirement; and all valve configurations that the pump may encounter.
- Calculate system curves. Add static head and losses at each operating case. Include the clean and expected aged-pipe conditions if internal deterioration materially changes roughness or diameter.
- State suction conditions. For the horizontal pump, give suction pressure or level range, suction-line losses, water temperature, and site elevation. Require the bidder to state the pump's suction requirement across the offered operating range.
- Specify the commercial boundary. List the pump, motor, coupling, guard, bedplate, seal system, instruments, controls, valves, spare parts, testing, freight, installation supervision, and commissioning as included or excluded items.
- Request certified data. Obtain head-flow, efficiency, absorbed-power, and suction-requirement curves; motor rating and electrical data; shutoff head; minimum permitted flow; dimensions; masses; materials; and pressure ratings.
- Request deviations explicitly. Require each supplier to identify every departure from the duty, materials, testing, documentation, and scope rather than burying differences in standard terms.
- Evaluate lifecycle cost. Calculate annual energy from absorbed power at the real operating points and operating hours. Add planned maintenance, removal access, critical spares, and production consequences.
How is the selected pump verified in the field?
Before startup, confirm rotation, alignment, lubrication, valve positions, filled and vented suction path, motor protection settings, instrument calibration, and the pressure rating of every wetted component. For a submersible unit, also record insulation test results, cable termination condition, installation depth, and measured water levels.
During commissioning, measure suction pressure, discharge pressure, flow, motor current, voltage, and speed at several stable operating points. Convert the pressure difference to pump head with elevation and velocity corrections where applicable, then compare the measured points with the certified curve. Trend vibration and bearing temperatures for the horizontal package; trend pumping water level for the well installation.
Test the credible valve states, including the condition that produces the highest system resistance. Check shutdown behavior for reverse flow and pressure transients. Do not accept the package merely because it develops pressure at reduced flow: acceptance requires the guaranteed 270 m3/h at the specified total dynamic head without motor overload, unstable operation, or loss of suction margin.
FAQ
What happens if the 320 m elevation is used as the pump head?
The pump may be undersized because 320 m covers only static lift. Add pipe, fitting, valve, and outlet losses to obtain total dynamic head.
What happens if the HDM-61 curve reaches 440 m?
That still does not complete the selection. The curve must reach the calculated direct-system head at 270 m3/h while meeting power, efficiency, well-diameter, suction, cable, and operating-range requirements.
What happens if the well cannot yield 270 m3/h continuously?
A direct pump cannot sustain the channel flow without excessive drawdown. Retaining the deposit allows well production and transfer demand to operate at different rates for a limited period.
What happens if the €33,000 and €80,000 offers show the same flow and head?
Reconcile speed, efficiency, absorbed power, materials, pressure ratings, test guarantees, accessories, installation exclusions, and warranty. Complete acceptance by measuring 270 m3/h, suction and discharge pressure, motor current, voltage, and speed, then plot the verified field duty point against the certified curve.