Calpeda GQV Submersible Sewage Pump

The GQV is Calpeda's free-flow vortex submersible, built in two frame sizes on a 2-pole motor. Calpeda puts it on civil and industrial wastewater that is not aggressive to the pump materials, on dirty water carrying solids, on emptying flooded rooms and tanks, and on drawing water from ponds, streams and rainwater collection pits. One note before you read the source data: Calpeda publishes the GQV in a shared catalogue with the vertical-discharge GQS, so check the model prefix on the row you are pricing.

The 50 frames, on a G 2 or DN50 connection with a 50 mm free passage:

The 65 frames, on a G 2 1/2 or DN65 connection with a 65 mm free passage:

Read the frame, not the range. The 57 m³/h headline belongs to the 2.6 kW GQV 65-15 and arrives at 2 m of head. At the same rating the GQV 50-18 gives 18 m at shutoff but only reaches 48 m³/h. The 65 frames buy flow and passage size; the 50 frames buy head.

When the vortex is the right call

Specify the GQV when the medium carries rag, wipes or fibre, and the cost of a site visit to lift a blocked pump is the number that matters.

Calpeda states the case in the instructions covering the GQ, GX and GM ranges: where the liquid has a high solid content or carries filamentous particles, use the free-flow vortex or the grinder build. The channel-impeller GQN is not on that list, and it passes exactly the same 50 mm sphere as a GQV 50. Free passage is not what separates them. What separates them is what happens to a length of fibre once it is inside.

A vortex impeller sits back out of the flow. The liquid is moved by the swirl the impeller sets up in the casing rather than by direct contact with a vane, so fibre has far less to catch on and far less to wrap around. A channel impeller works the medium through a hydraulic passage, which is efficient right up until something ropey wedges in it.

What the vortex costs

The vortex costs you head at any given motor size, and Calpeda's coverage charts put a figure on it. Up to 1.5 kW you can buy either wet end on the same DN50 body:

The gap widens the further right you go. At 1.1 kW and 36 m³/h the vortex gives 2 m and the channel build gives 5 m, and past 36 m³/h the GQV 50-13 has run off the end of its curve while the channel pump is still working.

In practice that means going up a frame. A duty of 24 m³/h at 8 m sits on the 1.1 kW GQN 50-15 at 8.3 m and draws 3.3 A at 400 V. To reach it with a vortex you take the 1.5 kW GQV 50-15, which gives 8.5 m and draws 4 A. That is a bigger motor and more current, every hour, for the life of the installation.

Whether that is worth paying is an arithmetic question about your chamber, not a matter of preference. One blocked impeller a year on a pump that needs lifting will cost more than the extra frame. A clean sump that has never blocked anything will not.

Above 1.5 kW the trade disappears. The 2 kW and 2.6 kW GQV frames have no channel-impeller counterpart in this range, and neither does the 65 mm free passage, so at that end you are choosing the GQV on duty and passage size rather than against a channel alternative.

Neither build is a macerator. Where a chamber is putting through more wipes than any impeller was going to clear, the answer is screening or maceration upstream. Fitting a vortex to a station that is genuinely overwhelmed just moves the blockage further down the rising main.

Threaded, flanged, and the 65 mm frame

The GQV brings its discharge out horizontally, which is the practical difference from the vertical-discharge builds. On the 50 frames that is a G 2 thread or a DN50 flange; on the 65 frames a G 2 1/2 thread or a DN65 flange. Calpeda's installation drawing for the DN65 shows the pipe taken off with a counterflange to EN 1092-2 PN 10.

A horizontal port suits a pump that sits on the floor of a chamber with the rising main leaving sideways, and the flanged version suits a fixed installation you expect to break for service. The threaded version takes pipe screwed straight into the port or union couplings, which is quicker to fit and slower to remove.

The 65 frames want more water over them. Minimum immersion is 355 mm against 275 mm on the 50 frames, so a chamber sized for the smaller pump will not simply accept the bigger one.

Where the GQV stops

The GQV takes liquid to 35°C and no hotter, at pH 6 to 11 and a density up to 1100 kg/m³. Maximum immersion is 5 m and the motor is rated for continuous duty only while submerged. Maximum permissible working pressure in the pump body is 25 m, which is 2.5 bar.

Calpeda allows 30 starts an hour at regular intervals. On a small chamber that limit sizes the wet well as surely as the duty point does, because the drawdown volume between the float levels is what sets the cycle rate.

The published heads assume a medium behaving as water: density 1.0 kg/dm³ and kinematic viscosity no greater than 20 mm²/s. A vortex tolerates solids well, but it does not exempt you from that. Thicken the medium beyond it and the curve you selected against is no longer the curve you have.

The GQV draws the medium in through the base and moves it with a free-flow vortex impeller recessed into the casing, discharging horizontally through a threaded port to ISO 228 or a flange. Calpeda calls the arrangement a patented system. The motor is a 2-pole submersible induction motor running at about 2900 rpm at 50 Hz, and the unit is IP X8 for continuous immersion.

Why a recessed impeller passes fibre

The impeller does not sit in the path the liquid takes through the pump. It spins in a recess at the back of the casing and drives the whole body of liquid into a vortex, and it is that rotating column, rather than the vane itself, that carries the medium to the discharge. A rag passing through the casing largely misses the impeller.

That is also why it gives up head. Work transferred through a moving column of liquid is less efficient than work transferred by a vane pushing directly on it, so at the same speed and the same motor rating the vortex builds sit lower on the chart than the channel builds.

Two seals and an oil chamber

Two mechanical seals run in series on the shaft with an oil chamber between them, ceramic against carbon with NBR elastomers at both ends, in an oil for food and pharmaceutical machinery.

That arrangement matters more on a vortex than it looks. You buy this pump because the medium is dirty, and the media that justify a vortex impeller are the same ones that abrade and foul a seal face. Two seals in series means wearing the pump-side face does not put sewage into the windings, because the oil chamber is still in the way. The weak point in almost any pump is the seal. Dry running is what finishes it quickest, because a mechanical seal needs liquid to lubricate it and the faces go as soon as the film does. Watch the minimum immersion figure for your frame, and treat a float that has stopped swinging as a seal problem rather than a control problem.

The wetted materials

The pump casing and the impeller are cast iron GJL 200 to EN 1561. The motor jacket, jacket cover, casing cover and shaft are AISI 304, and the handle is polypropylene on an AISI 304 frame. Cast iron is the right call for a sewage pump carrying grit, which is what wears out a wastewater pump once rag has been dealt with.

The electrical side

Three-phase GQV runs on 230 V or 400 V ±10%. On the 50 frames the full load current runs 1.5 A at 0.55 kW to 7.5 A at 2.6 kW; on the 65 frames it is 3 A at 1.1 kW to 7.5 A at 2.6 kW. It ships with 10 m of H07RN-F 4G1 mm² cable and no plug, so the overload protection comes from your starter or your board.

Single-phase GQVM runs on 230 V ±10% with a built-in capacitor, a thermal protector and a float switch fitted as standard, on 10 m of H07RN-F 3G1 mm² cable with a CEI-UNEL 47166 plug. It covers 0.55 kW to 1.5 kW on the 50 frames and 1.1 kW to 1.5 kW on the 65. Watch the input power against the output: a 1.5 kW GQVM 50-15 draws 2.2 kW at the input and 13 A at 230 V, which is a real consideration on a domestic supply.

On request Calpeda will supply other voltages, 60 Hz, a different mechanical seal, a 20 m cable, a motor set up to run on a frequency converter, and a three-phase pump with an integral float switch.

Reading the designation

GQ is the series and V is the vortex impeller on the horizontal discharge. An M after that means single-phase, and no letter means three-phase. Then 50 or 65 is the free passage in millimetres, and the last number is the nominal total head in metres. So a GQVM 65-11 is the single-phase 1.5 kW pump with a 65 mm passage. If you are matching an existing unit, photograph the nameplate and send us the full designation and the serial number.

Where it must not go

This is worth saying plainly on a vortex page, because the duties that call for a vortex are often the ones that generate gas. Calpeda's instructions forbid installing the pump in a potentially explosive atmosphere, and forbid using it in ponds, tanks or swimming pools while people are in the water. A septic wet well that has been classified as a hazardous area needs a certified pump, and no amount of ventilation reasoning turns this one into that. Tell us the zone and we will quote the right thing instead.