There Is More Than One Way to Classify a Sewage Pump
A submersible sewage pump is often treated as one product category: put the pump in a pit, connect a discharge pipe and let it remove wastewater. That description is correct, but it is too broad for selection. Two pumps may both be called sewage pumps while using different hydraulic passages, materials, motors and installation methods.
The most useful classification begins with the wastewater. Is it ordinary building sewage, construction-site water, industrial effluent, slurry, corrosive liquid or wastewater containing long fibres? After that come the hydraulic duty, pipe system, installation and power supply. Motor power is only one result of those decisions. It is not a complete pump type by itself.
Pumps may be grouped as channel, vortex, cutter, grinder or self-cleaning designs. They may also be classed by material and installation. The MISLIER catalogue uses a practical product-family approach: standard WQ sewage pumps, GNWQ/ASWQ cutting pumps and stainless-steel WQ(D) pumps. Each family answers a different part of the selection problem.
Standard WQ Pumps Move Solids without Deliberately Cutting Them
A standard WQ pump is a close-coupled submersible centrifugal pump. The sealed motor is above the hydraulic section and drives an impeller inside the pump casing. Wastewater enters around the lower inlet, receives energy from the rotating impeller and leaves through the side discharge.
The hydraulic passage is designed for wastewater rather than clean water, so it can pass suspended solids and some fibrous material. Passing is different from cutting. A standard WQ relies on the size and shape of its inlet, impeller and casing to let material move through. It should not be described as a grinder unless a real cutting mechanism is fitted.
This distinction matters at the quotation stage. Ordinary sewage from a hotel, residential building, sump or wastewater pit may suit a standard WQ. Regular loads of cloth, rope, wipes or long fibres change the risk. The catalogue covers WQ units from compact pumps to large project models, which also shows why the letters WQ do not identify one fixed duty point. Flow, head, outlet size and the actual pump curve still have to match the system.
Impeller terminology also needs care. Channel impellers carry wastewater through defined passages, while vortex impellers keep more solids away from direct contact with the impeller. Self-cleaning designs use vane geometry to shed material. These terms describe hydraulic design, not a universal quality grade. Confirm the impeller from the model drawing rather than guessing from the WQ name.
GNWQ and ASWQ Add a Cutting Stage at the Inlet
The GNWQ and ASWQ families in the catalogue are cutting sewage submersible pumps. Their product illustrations show a cutting impeller working with a stationary cutting plate or knife near the inlet. As the rotor turns, soft material reaching the suction opening is cut before or while it enters the hydraulic passage. The pump then moves the liquid by the same centrifugal principle used by a standard WQ.
A cutting system is useful where fibrous waste is a regular part of the inflow. Examples may include textile fibres, soft cloth, plastic film and other destructible material that can wrap around an ordinary impeller. Reducing the length of that material can lower the chance of entanglement in the pump and downstream pipework.
It does not turn every object into pumpable waste. Metal pieces, stones, thick hard plastic, wire and other non-destructible objects can damage a cutter or stop the rotor. Even soft waste can arrive in a bundle larger than the inlet. A cutting pump therefore reduces a known risk; it does not remove the need for sensible waste control, correct pipe sizing and access for maintenance.
The cutter must not distract from the duty point. A model still needs enough flow and head after vertical lift, pipe friction, elbows and valves are considered. Selecting only by the word cutting can produce a pump that handles the material but cannot overcome the system resistance.
WQ(D) Changes the Material, Not the Basic Pumping Principle
The stainless-steel WQ(D) range uses stainless construction for the exposed pump body and hydraulic components. The catalogue identifies 304 and 316 material options. This family is relevant where corrosion, cleanliness or liquid compatibility makes a standard cast-iron construction unsuitable.
Stainless steel is not a universal answer to every aggressive liquid. Grade 304 and grade 316 do not have the same resistance, and neither selection should be made from the word chemical alone. 
Chloride level, pH, temperature, concentration, dissolved gases and cleaning chemicals can all affect compatibility. Abrasive sand creates a different problem from corrosion and may wear stainless hydraulic parts even when the metal does not chemically attack them.
The WQ(D) page also shows a higher stated liquid-temperature limit than the standard cast-iron pages in this catalogue. That does not mean every stainless sewage pump can handle every hot liquid. Cable material, elastomers, mechanical seals, motor insulation and duty cycle must all be checked for the selected model.
Model suffixes help only when the manufacturer's code is understood. In the WQ(D) model explanation, D identifies a single-phase version and S identifies stainless steel; three-phase versions omit D. These conventions belong to this catalogue and should not be assumed to mean the same thing in another brand's model number.
Installation Is Also Part of the Pump Type
A small pump may stand freely on the bottom of a pit and discharge through a flexible hose or fixed pipe. Larger permanent stations often use an automatic-coupling base and guide rails. The pump is lowered from the top, seats against the discharge connection at the bottom and can later be lifted without a technician undoing submerged flange bolts.
The catalogue also illustrates vertical and horizontal submerged positions. In both cases, the unit is shown covered by liquid rather than operating half exposed. That detail is important because many wet-pit motors depend on surrounding liquid for cooling. A different installation or a low stop level may require a model with an independent cooling arrangement. Installation drawings and minimum liquid levels must therefore be treated as model-specific instructions.
A useful initial selection can be made with six pieces of information: required flow, total head, discharge-pipe size and route, wastewater source, expected solids or fibres, and material compatibility. Add the power supply, pit dimensions and preferred installation method before finalising the model.
The simplest way to understand the main types is to ask what problem each design changes. Standard WQ changes the hydraulic passage for wastewater. GNWQ/ASWQ adds a cutting action for difficult soft fibres. WQ(D) changes the construction material for corrosion resistance. The correct pump may combine several requirements, but the selection should always start with the liquid and the system, not with the name printed on the casing.