Water Treatment: Mechanical Seal Solutions for Clean Water & Wastewater

Water and wastewater facilities run 24/7. From raw-water intake and high-lift pumps to sludge transfer and chemical-dosing skids, every rotating shaft must stay leak-free despite solids, chemicals, start-stops, and occasional dry-run. This page explains the typical challenges in water treatment and how the right mechanical seal design, materials and support systems keep equipment reliable and maintenance costs down.

Where seals are used in water treatment

• Raw-water / high-lift / distribution pumps (clean to slightly sandy water)
• Wastewater / sewage pumps (solids, fibrous media, gas entrainment)
• Sludge and slurry pumps (abrasive particles)
• Chemical dosing metering pumps (hypochlorite, coagulants, pH control)
• Recycling & backwash pumps (variable duty, intermittent operation)
• Mixers & agitators in equalization tanks and clarifiers

Typical sealing challenges

• Abrasive wear from sand, grit, and sludge
• Chemical attack from disinfectants and coagulants
• Poor lubrication / dry-run during priming or air entrainment
• Intermittent service causing start-stop thermal shock
• Misalignment & vibration in large vertical turbine pumps
• Clogging around springs in dirty fluid

Recommended sealing strategies

1) Clean/treated water

• Design: Single balanced pusher seal with protected springs
• Faces: Carbon vs. SiC (cost-effective), or SiC vs. SiC for longer life
• Elastomers: EPDM for chlorinated water; FKM (Viton®) when traces of oil/solvent exist
• Notes: Use a small flush (API 11/13 style) to remove heat

Sakowitz fit: general-purpose single seals like MG1/MG12, Type 2/Type 82, 2100 series; compact cartridge options for easy installation.

2) Wastewater / sewage with solids & fibers

• Design: Double mechanical seal (pressurized barrier) or tandem arrangement
• Why: Prevents product ingress, tolerates air pockets and poor lubrication
• Barrier fluid: Water-glycol or light oil in a Plan 53-style system
• Extras: Particle-resistant SiC/TC faces; anti-clog spring layout

Sakowitz fit: 318-type mechanical seal for sewage pumps, double cartridge options (e.g., Cartex DN class) for retrofit work.

3) Sludge & abrasive service

• Design: Double cartridge seals with hard-hard faces (SiC/SiC or TC/TC)
• Support: External flush/plan 32 if plant water is available to keep faces clean
• Hardware: 316/duplex wetted parts for corrosion resistance

Sakowitz fit: heavy-duty double cartridge assemblies; custom sleeves and gland patterns for common sludge pumps.

4) Chemical dosing skids

• Fluids: Sodium hypochlorite, alum, ferric chloride, caustic, acids
• Design: Single balanced seal; for strong oxidizers use PTFE secondary seals
• Metals: 316L or duplex; consider coatings if crevice corrosion risk is high

Sakowitz fit: fluoroelastomer/PTFE configured single seals; OEM-replacement compact seals for metering pumps.

Materials selection guide

• Faces
  • Carbon vs. SiC – economical for clean water
  • SiC vs. SiC – best all-rounder for grit and occasional dry-run
  • TC vs. TC – extreme abrasion (sludge)
• Metals: 304/316 standard; duplex 2205 available for chloride-stress environments
• Elastomers: EPDM (chlorinated water), FKM/Viton® (oils/solvents), PTFE (strong oxidizers)

Installation & reliability tips

• Align pump and check shaft run-out before installation
• Pre-lube faces and vent air; protect faces from dry-start
• For double seals, set the barrier system 1.5–2.0 bar above stuffing-box pressure
• Record flush flow, barrier pressure, and temperature for easy troubleshooting

Why facilities choose Sakowitz

• Application know-how across clean water, wastewater, and sludge service
• Fast OEM cross-reference by pump model or old seal dimensions
• Cartridge designs that cut installation time and reduce start-up leaks
• Stocked materials (SiC, TC, 316/duplex, EPDM/FKM/PTFE) for short lead time

Featured products for Water Treatment

• 318-Type Mechanical Seal – built for sewage and wastewater pumps, stable in solids-laden media.
• Cartridge Mechanical Seals (e.g., Cartex-DN class) – single and double cartridge for quick retrofit and safer assembly.
• General-Purpose Single Seals – MG1, MG12, Type 2, Type 82, 2100 series for clean/treated water pumps.
• O-Ring & Rubber-Bellows Seals – H7N/H74N family for compact housings and economical maintenance.

Need a direct replacement? Send your shaft size, box bore/length, and old seal photos—we’ll match or upgrade one-to-one.

FAQ

Q1: When should I upgrade from a single to a double seal?
 A: Consider a double (pressurized) seal for sewage, sludge, or any service with air entrainment/poor lubrication. It prevents product ingress and drastically extends life.

Q2: Which elastomer should I use in chlorinated water?
 A: EPDM is typically preferred; switch to FKM/PTFE if oils/solvents or strong oxidizers are present.

Q3: Can you cross-reference my pump model?
 A: Yes. Share the pump nameplate and basic seal cavity dimensions—we’ll recommend a compatible Sakowitz model or cartridge kit.

Q4: Do you supply glands/sleeves and flush plans?
 A: Yes. We provide complete kits (gland, sleeve, hardware) and guidance for API-style Plan 11/32/53 arrangements.