Vertical Multistage Pump
If you've ever stood at the 25th floor of a hotel and watched the shower sputter while someone flushes a toilet upstairs, you've felt the problem this pump solves. The VS series vertical multistage centrifugal pump exists because single-stage pumps can't build enough pressure for high-rise water supply, RO membranes, or boiler feed — and horizontal pumps take up too much floor space.
The VS stacks multiple stainless steel impellers on a vertical shaft, so you get high head (up to 350 m) from a pump that installs directly into a horizontal pipe like a valve. No concrete foundation, no long-coupled alignment, roughly half the floor space of a horizontal equivalent. We build these in 304, 316L, and duplex 2205, from 1 to 270 m³/h.
Cross-section: stacked impellers on a vertical shaft, inline suction and discharge.
Technical Specifications
| Parameter | Range | Notes |
|---|---|---|
| Flow rate (Q) | 1 – 270 m³/h | Continuous duty at BEP |
| Total head (H) | Up to 350 m | Stacked impeller stages; can series-connect for higher head |
| Motor power | 0.37 – 200 kW | IE3 standard, IE4 optional |
| Port size | DN25 – DN200 | Threaded up to DN50, flanged above |
| Wet end material | SS304 / SS316L / duplex 2205 | 304 standard; 316L and duplex on order |
| Fluid temperature | -20 °C to +120 °C | High-temperature seal option up to 160 °C |
| Pressure rating | PN16 / PN40 | Depends on model and stage count |
| Voltage / frequency | 380V/50Hz standard | 220V/240V/415V/440V/460V, 50/60 Hz on request |
| Mechanical seal | Cartridge SiC / carbon / EPDM | Double seal for hot or hazardous fluids |
| NPSHr | 2.0 – 5.0 m | Depends on flow and speed; low-NPSH first stage available |
How a Vertical Multistage Pump Works
A single impeller can only add so much pressure — typically 15–25 m of head at one stage. The VS stacks between 2 and 30 impellers on one vertical shaft, each one adding its share of pressure. Water enters at the bottom, gets pushed through the first impeller and diffuser, then moves to the next stage, and the next, until it exits the top nozzle at the required pressure. That's how a 5.5 kW motor can deliver 150 m of head without spinning at 3,500 RPM like a single-stage high-speed pump. More stages = more head; bigger impeller diameter = more flow.
The inline design means suction and discharge sit on the same centerline, so the pump installs in a straight horizontal pipe like a valve — no bend, no foundation, no alignment check between pump and motor.
How to Select the Right VS Model
Don't start with a catalog. Start with three numbers, and the model falls out:
1. Required flow (m³/h). Sum the peak demand of everything the pump feeds — fixtures, membranes, boilers, cooling circuits. Size the pump so your design flow sits at or near the best efficiency point (BEP), not at either end of the curve. Running far left of BEP causes internal recirculation and heat buildup; running far right overloads the motor.
2. Total dynamic head (m). This is not just the height of the building. Add the static elevation plus friction loss in the riser, fittings, and valves plus the required pressure at the outlet (typically 2–3 bar at the farthest fixture). For a 100 m building, plan on 140–160 m of total head, not 100 m.
3. Fluid and temperature. Clean water below 80 °C: 304 is fine. Above 80 °C, or any chloride-containing water: go 316L. RO feed, seawater, or chemical dosing: duplex 2205. Match the seal to the fluid — SiC/SiC faces for abrasive or hot service, not carbon/SiC.
Four Selection Mistakes We See on Every Project
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1. Sizing head to the building height only A 100 m tower does not need a 100 m pump. You need enough pressure to push water through 30 years of scaly pipe, a few dozen gate valves, and still deliver 2 bar at the top floor. Plan for 140 m. We've seen too many booster sets undersized this way. |
2. Using 304 in hot water over 80 °C Austenitic stainless steel loses pitting resistance as temperature climbs. Above 80 °C, 304 in a closed heating loop with make-up water starts pitting within two years. Specify 316L for anything above 80 °C, even if the water looks clean. |
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3. Ignoring NPSHr on the suction side Vertical multistage pumps are usually fed from a tank at near-atmospheric pressure. If the water in the tank is warm, or the suction pipe is long with a strainer and a valve, you can lose the NPSH margin before the pump ever starts. Check NPSHa against the curve — don't assume. |
4. Sizing the motor to BEP, not shut-off Multistage pumps draw the most power at zero flow (closed discharge). If you size the motor to the BEP power and the operator closes the discharge valve for any reason, the motor trips. Oversize by at least the next frame up when in doubt. |
Where the VS Series Actually Runs
High-rise pressure boosting
In buildings over 50 m, a multistage vertical pump in a duty/standby VFD set is the standard arrangement. The VS installs inline in the mechanical room, the VFD holds constant outlet pressure regardless of how many taps are open, and the noise level (below 75 dB(A)) means the set can sit adjacent to guest rooms without complaint.
RO and water treatment feed
Reverse osmosis needs a smooth, pulsation-free high-pressure feed. The VS in 316L or duplex handles 10–80 bar membrane feed on small-to-medium RO plants (up to ~270 m³/h). VFD control lets the operator ramp pressure up gradually at start-up instead of shocking the membranes.
Boiler feed and hot water
Small industrial boilers (up to ~20 bar) feed from a deaerator or condensate tank. The VS with the high-temperature seal option handles feedwater up to 120–150 °C. We pair these with a low-NPSH first-stage impeller when the deaerator sits close to floor level.
HVAC and district cooling
Chilled water loops in commercial buildings and data centers need moderate head and high reliability. The VS runs quietly, takes little floor space, and pairs with VFDs that match pump speed to actual cooling load.
316L/duplex wet end for corrosive service: RO concentrate, chemical dosing, brackish water.
Replacing a Grundfos CR or Wilo MVI
Most of the VS orders we take are direct replacements for an existing European vertical multistage pump. The mounting dimensions, flange spacing, and motor frame size follow the same industry-standard envelope, so the swap usually takes a morning. Bring us three things: the old pump's nameplate (flow, head, power), the flange pressure rating, and the operating point you actually run at. We'll match the curve — don't assume a like-for-like model number will land at the right duty point.
Two Field Cases
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Case 1 — 28-story hotel in Colombo, Sri Lanka A hotel upgraded its 15-year-old booster set. The old horizontal pumps needed a concrete base and took up half the mechanical room. We supplied two VS4-20 pumps (duty/standby) with a 5.5 kW VFD panel. The new set fits in the corner where the old control cabinet used to sit. Pressure holds at 5.5 bar on the top floor regardless of how many showers run at once. |
Case 2 — Small RO plant in Penang, Malaysia A beverage bottler needed a 12 m³/h RO feed pump at 12 bar. The local dealer quoted a European brand at roughly 3x our price. We supplied a VS2-14 in 316L with a SiC cartridge seal. Two years on, the plant runs two shifts a day and the seal has not been touched. The customer now runs a second identical set as backup. |
Cases are anonymized. If you want the reference contact for either project, ask directly and we'll put you in touch with the end user.
Installation and Maintenance Notes
- Support the pipework, not the pump. The inline flanges carry the pump weight. Long pipe runs need their own supports, or you'll put bending load on the casing.
- Vent the casing before start-up. Vertical multistage pumps trap air. Open the vent plug until water flows, then close. Running dry for even a few minutes scores the mechanical seal faces.
- Keep the suction flooded. This is not a self-priming pump. The suction tank must sit above the pump centerline, or you need a separate priming unit.
- Seal life: 2–3 years on clean water below 60 °C; inspect annually on hot or corrosive service. We sell cartridge seal kits separately so your maintenance crew can change it without a service call.
- Bearing temperature: should stay below 80 °C. Vibration under 4.5 mm/s. If either drifts, shut down and align.
Every VS pump runs on our test bench before shipment: flow, head, current, vibration, and seal check.
Frequently Asked Questions
Q1: What's the difference between a vertical inline multistage pump and a horizontal end suction pump?
Two differences matter. First, head: an end suction pump is single-stage and tops out around 80–120 m, while the VS reaches 350 m with stacked impellers. Second, footprint: the VS bolts into the pipework vertically and needs no concrete base, while an end suction pump sits on a foundation and needs shaft alignment. For flows above 200 m³/h or heads under 60 m, an end suction pump is usually cheaper. For high head, limited floor space, or clean-water service, the vertical multistage wins.
Q2: Does the VS need a baseplate?
No. The inline design bolts directly into the pipework. The pump weight hangs on the flanges, so support the pipework independently — don't let the pump carry long runs of pipe. For sets of two or more pumps, we supply a common manifold and base frame.
Q3: How often does the mechanical seal need replacing?
On clean water at 60 °C or below, expect 2–3 years on a cartridge seal. On hot water or mildly corrosive service, plan for annual inspection. We supply seal kits separately so maintenance doesn't require a service engineer on site.
Q4: Can you match a variable frequency drive?
Yes. We supply the VS with a wall-mounted or panel VFD sized to the motor, pre-programmed for constant-pressure operation with a pressure transducer included. You can also pair it with your own BMS — Modbus RTU is standard.
Related Reading
Boiler feed pump selection guide | Seawater pump material guide: 316L vs duplex
Need help selecting a VS model?
Email: zhuyaxiong@filipusi.com | WhatsApp: +86 136 2577 2667
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