Non-Clog Submersible Pump Manufacturer — CNC Series

The Cosmos CNC is a non-clog submersible vortex pump built for wastewater, sewage bypass, and construction sumps where solids block standard dewatering pumps. Its bottom discharge handles solids up to 70mm — larger than most competitor non-clog pumps — making it the contractor’s choice for manhole cleaning and 14-inch diameter installations. Available in 6–20 HP, the CNC operates at SG up to 1.2, covering municipal sewage, sump sludge, and light slurry.

Manufactured at Cosmos Pumps’ Faridabad NCR facility and certified to ISO 9001:2015, CE, ZED Gold, NSIC, UL, and EAC, the CNC is deployed across municipal sewage infrastructure, construction dewatering, and ETP/STP bypass contracts in India and 22+ export countries.

CNC Series — Technical Specifications

Wastewater and sewage bypass applications

The CNC is specified as a wastewater and sewage bypass pump across three categories of application.

Construction sites where sewage meets solids. Basement excavations, tunnel sumps, and bored piling operations fill with groundwater carrying cement fines, bentonite slurry, and organic construction debris. Standard CDW dewatering pumps, rated to 4–12mm solids, block within hours on active piling or sewage-contaminated sites. The CNC handles solids up to 70mm via bottom discharge — no pre-screening required.

Municipal sewage bypass during sewer rehabilitation. When a sewer main or pump station goes offline for maintenance, bypass routing of raw sewage is mandatory under State Pollution Control Board guidelines — zero overflow is a regulatory requirement. The CNC covers branch sewer and wet well bypass at flows up to 1,500 LPM, SG up to 1.2, and 22–30M head. For main sewer bypass requiring flow above 1,500 LPM or solids above 70mm, the CSW Sewage Pump (775–33,000 LPM) is the correct specification.

Manhole cleaning and wet well maintenance. Accumulated sludge in inspection chambers and wet wells requires pump-out through 14-inch (355mm) access openings. The CNC passes through standard manhole frames and operates under single-operator surface deployment, without a confined-space entry team.

Vortex impeller design: how the CNC prevents clogging

Standard centrifugal pumps force water through narrow gaps between impeller vanes and volute. Fibres, rags, and solids larger than 10–12mm pack into this gap within minutes, causing blockages.

The Cosmos CNC uses a recessed vortex impeller — a single-vane or semi-open disc where the impeller does not directly contact the pumped medium. The rotating impeller creates a centrifugal vortex inside the volute chamber, drawing liquid and suspended matter through hydraulic suction rather than mechanical displacement.

This design allows:

• Solids up to 70mm to pass freely through the casing
• Fibrous materials to travel through without wrapping around the impeller hub
• SG up to 1.2 without motor overload
• Lower impeller wear rates compared to open-impeller designs on abrasive sludge

Trade-off: slightly lower hydraulic efficiency than closed-impeller designs at equivalent horsepower. This is acceptable for sewage bypass and manhole cleaning duty where solids passage matters more than maximum flow.

70mm solids handling: bottom discharge configuration

The CNC handles spherical solids up to 70mm in diameter. Standard CDW dewatering pumps pass 4–12mm; most competitor non-clog pumps pass 50–65mm. The bottom discharge is the key to this rating. Flow runs straight from the pump inlet through to the discharge connection, eliminating the internal elbow bend where large solids accumulate in top-discharge designs.

Volute material: SS-304 stainless steel (pH 5–8 corrosion resistance). Impeller: nitride-hardened SS-410 at HRC 52–55 for abrasive grit resistance in sewage and sludge.

CNC vs. CSW vs. CDW: construction bypass and wastewater duty

For construction sites with both clean groundwater dewatering and sewage bypass requirements, CNC and CDW units are commonly deployed in parallel — CDW for the groundwater, CNC for the contaminated or sewage-impacted sumps.

Applications

Manhole cleaning: 14-inch access

Municipal sewage maintenance requires frequent desludging of wet wells and inspection chambers. The CNC passes through a standard 14-inch (355mm) manhole access opening on a guide chain. Its compact aluminium alloy housing allows single-operator surface deployment.

• Handles accumulated sludge at SG 1.2, solids up to 70mm
• Bottom discharge connects to 3–4 inch delivery hose to a tanker
• Reduces confined-space entry requirements for routine municipal maintenance

Sewage bypass pumping: Pollution Control Board compliance

Sewage bypass is required when sewer mains, wet wells, or pump stations go offline. During bypass, raw or partially treated sewage must continue flowing without ground discharge — a regulatory obligation enforced by State Pollution Control Boards.

• SG 1.2 capacity: covers the full density range of municipal sewage (SG 1.0–1.2)
• 70mm solids pass-through: accommodates fibrous content without pre-screening
• 22–30M head: sufficient for bypass routing 100–300 metres through 3–6 inch hose
• Class H motor insulation (180°C): rated for sustained continuous-duty operations

Construction site and tunnel dewatering: contaminated sumps

EPC contractors specify the CNC for construction sumps where:

• Sump water contains bentonite drilling slurry from bored piling operations
• Tunnel face dewatering involves mixed rock fragments and slurry
• Basement excavations dewater through contaminated urban fill
• Temporary drainage sumps accumulate storm runoff with spoil and organic material

SG 1.2 capacity: viscous sludge and light slurry

The CNC is rated to SG 1.2. This covers:

• Municipal sewage (SG 1.01–1.05) and concentrated sump sludge (SG 1.1–1.2)
• Cement-wash sumps from concrete washout residue (SG ~1.1–1.15)
• Industrial process washdown with particulates
• Tunnel face seepage with groundwater and tunnel muck (SG ~1.05–1.15)

For applications above SG 1.2 — mining slurry (SG 1.3–1.8), ash pond dewatering (SG 1.3–1.5), or dredging (SG up to 2.1) — the Cosmos CSL Hi-Chrome Slurry Pump is the correct specification.

Key engineering features

• 50 sq mm H07RNF power cable (10m): heavy-duty rubber-sheathed, rated for sustained submersion in sewage and chemically active environments. Larger conductor cross-section than standard dewatering pump cables for higher current draw at SG 1.2.
• Bottom discharge, 70mm solids pass-through: straight-line flow path from inlet to discharge outlet — no 90° or 180° internal bends where large solids lodge.
• Aluminium alloy casing: single-operator deployment through manholes and confined access points.
• Class H motor insulation (180°C): continuous duty in sewage bypass and high-temperature sludge environments.
• SS-304 volute and nitride-hardened SS-410 impeller (HRC 52–55): stainless steel wetted parts throughout — corrosion-resistant in sewage (pH 5–8), abrasion-resistant against grit and sand.
• Twin SS mechanical seals: primary and secondary seal prevents sewage ingress to motor chamber under sustained submersion.
• Sacrificial zinc anode option: for coastal or saline-adjacent sewage bypass applications where groundwater chloride levels exceed 500 ppm.

Frequently Asked Questions

What is a non-clog pump?

A non-clog pump is a submersible centrifugal pump built with a vortex or semi-open impeller that creates hydraulic suction rather than direct mechanical contact with the pumped medium. This design allows solids up to 70mm — and fibrous materials including rags, cables, and organic debris — to pass through the casing without accumulating at the impeller eye. Non-clog pumps are specified for sewage, sludge, and wastewater applications where a standard centrifugal impeller blocks within minutes.

What is the difference between a non-clog pump and a submersible dewatering pump?

A CDW submersible dewatering pump uses a closed centrifugal impeller rated for water with solids up to 4–12mm. A CNC non-clog pump uses a recessed vortex impeller that handles solids up to 70mm and fibrous materials. In practice: CDW units are for clean to turbid groundwater; CNC units are for sewage, sludge, and construction sumps contaminated with larger solids where a CDW impeller would block within the first hour.

Can a non-clog pump handle sewage bypass?

Yes. The CNC handles municipal sewage bypass at SG up to 1.2, solids up to 70mm, 22–30M head, and 1,250–1,500 LPM flow. This covers branch sewer and wet well bypass during pump station maintenance. For main sewer bypass requiring flow above 1,500 LPM, the Cosmos CSW sewage pump (up to 33,000 LPM) is the correct specification. Both CNC and CSW pumps are available on rental for bypass contracts across India.

What HP non-clog pump is used for manhole cleaning?

For standard municipal manhole and inspection chamber cleaning, 6–10 HP CNC units are typical — sufficient to pump accumulated sludge (SG 1.0–1.2) 80–150 metres via delivery hose to a tanker. On larger combined sewers with greater sludge volume, 15–20 HP CNC units are used for faster pump-out rates. All CNC models from the 6 HP entry to the 20 HP unit fit through a standard 14-inch (355mm) manhole access.

Does the Cosmos CNC pump handle 70mm solids?

Yes. The CNC is rated for spherical solids up to 70mm via bottom discharge. The straight-line flow path from the pump inlet to the discharge outlet eliminates the internal bends where large solids lodge in top-discharge designs. The SS-304 stainless steel volute and nitride-hardened SS-410 impeller (HRC 52–55) resist abrasive wear from grit-bearing wastewater. This 70mm solids rating is why the CNC is widely specified for manhole cleaning contracts, where accumulated grit and debris exceed the passage size of standard sewage pumps.

Technically reviewed by Nishant Barnwal, COO & Chief Hydraulic Engineer, Cosmos Pumps Pvt. Ltd.