Z4 Single Spring Mechanical Seal

The Z4 single spring mechanical seal is the deep-seat version of Qixing's O-ring single spring family. It uses the G4 standard seat, the deeper-cavity profile fitted to many older and German-built centrifugal pumps, where the shallower G9 seat of the Z3 will not seat correctly. Shaft sizes run 10 mm to 80 mm, rated -20°C to +180°C, 1.0 MPa and 15 m/s. Buy direct from the Qixing factory in China.

If a replacement seal keeps sitting proud of the pump housing or leaking around the seat, the cavity is usually a deeper G4 profile - and the Z4 is the correct fit. Qixing supplies the Z4 single spring mechanical seal to OEM pump builders, MRO distributors and direct buyers worldwide, with same-day quotation and 3-7 day stock lead time.

Does Your Pump Use a G4 Seat?

The seat profile, not the shaft diameter, decides whether a seal fits. Four signs point to a G4 (deep-cavity) seat and therefore the Z4 rather than the Z3:

• The pump is an older European or German design, or a long-running legacy unit still in service
• A G9-seat seal sits proud of the housing face or will not seat flush when fitted
• The seal cavity is visibly deeper than the seal head, leaving a gap behind the seat
• The original seal or pump manual lists a G4 (or DIN 24960 long) seat designation

If any of these apply, the Z4 single spring mechanical seal is the drop-in fit. When unsure, send Qixing the pump make and model or a photo of the seal cavity and the team confirms G4 versus G9 before quotation.

Specifications

Dimensions Chart

All dimensions in millimetres. The values below are the Z4 seal-head envelope with the G4 standard seat. Shaft diameter d is measured at the seal cavity.

Face Materials and Media

The Z4 ships in the same five face pairings as the rest of the family: Ceramic/Carbon for clean water, Silicon Carbide/Carbon for sewage and mild abrasives, SiC/SiC for hot oil, Tungsten Carbide/Carbon for mild chemicals, and TC/TC for severe duty. Elastomer is NBR, EPDM or FKM, matched to the pumped media at order. The G4 deep seat does not limit material choice - any combination in the catalogue is available in the Z4 envelope.

Applications

• Older and legacy European centrifugal pumps needing a deep-seat replacement
• Water supply, treatment and HVAC circulation pumps
• Sewage, drainage and lift-station pumps
• Light chemical and dosing pumps (weak acids, alkalis, solvents)
• OEM pump platforms built around the G4 seat cavity

Manufacturing

Faces lapped to ≤ 0.0009 mm flatness and verified optically. The G4 seat is machined and lapped on both the running face and the static back-face so it seats square in the deep cavity without rocking. Each Z4 single spring mechanical seal is dimension-checked before packing; Certificate of Conformity and material certificate ship with the order on request.

Quotation

Send the pump model or the seal cavity depth for a same-day quotation. Stock sizes ship 3-7 days; OEM custom orders 15-25 days. Buy the Z4 single spring mechanical seal direct from the Qixing factory in China at OEM and wholesale pricing.