The Graco 104805 Back-Up Ring is an OEM support ring that reinforces O-rings and seals, preventing extrusion and maintaining system integrity under high pressure.
Use: Fits behind primary seals in pumps, valves, and spray systems
Benefit: Extends seal life and reduces maintenance frequency
Material: High-strength polymer/PTFE for durability
Graco 104805 Ring, Back‑Up – Essential Seal Support Element
Compatible Machines
Graco fluid‑handling pumps and proportioners using backup ring supported seals
Graco high‑pressure spray systems and finishing equipment with internal seal assemblies
Graco service kits for surge tanks, filters and internal modules where backup rings are required
Graco mobile and stationary equipment undergoing rebuilds of internal seal cavities
Product Description
The Graco 104805 Ring, Back‑Up is a precision‑engineered support ring designed to reside behind primary seals (such as O‑rings or lip‑seals) in demanding hydraulic, fluid‑handling and spray equipment. Its role is to reinforce the seal under pressure, prevent extrusion or deformation of the soft seal material, maintain seal geometry and thereby extend both seal and equipment service life.
Key Features
Structural support ring: Positioned immediately behind the main seal to resist extrusion under high differential pressure.
OEM‑specified component: Manufactured to match Graco’s internal cavity designs and material requirements.
Compact design: Fits seamlessly into existing seal grooves without altering clearance or performance.
Improves reliability: Helps minimize seal failure, leakage and maintenance interventions in high‑cycle systems.
Ease of replacement: Installed during standard service intervals along with seal sets to maintain optimum performance.
Technical Specifications
Specification
Details
Part Number
104805
Component Type
Backup Ring / Seal Support Ring
Function
Provides structural support behind primary seal elements
Material
High‑strength polymer or PTFE variant (industrial grade)
Service Environment
High‑pressure fluid modules, pumps and spray systems
Applications
This ring is used in critical seal cavities of Graco equipment where soft seals alone might extrude, fail or deform under load. Typical use cases include fluid‑end modules of high‑pressure pumps, manifold blocks in spray systems, filter housings and surge tanks. By installing the 104805 ring behind the seal, the system maintains correct geometry, resists material creep and prolongs the service interval.
Performance Advantages
Prevents extrusion of soft seal materials when subjected to high differential pressures.
Maintains alignment of primary seals for consistent sealing performance.
Reduces frequency of maintenance and replacement of seals, lowering downtime.
Supports stable system pressure and prevents fluid or air bypass.
Optimises equipment reliability by using an OEM‑matched support component.
Maintenance Tips
During rebuild or preventive service, remove the old backup ring and inspect the groove for damage or deformation. Ensure the new ring seats fully, clean and lubricate adjacent seal surfaces, then install the new primary seal behind it. Make sure the backup ring is undamaged, and having been properly seated, so it can perform its function of supporting the seal under pressure. Replace if you observe flattening, cracking or signs of seal extrusion to safeguard system integrity.
Frequently Asked Questions
A backup ring sits behind a soft seal element such as an O‑ring and prevents it from extruding into adjacent cavities under pressure, helping maintain seal geometry and performance.
Replace it when you service associated seal packs, if you observe seal extrusion, if the groove is damaged, or if system performance has degraded due to seal failure.
While its dimensions and material may suit other equipment, using the OEM specified ring ensures proper fit, material compatibility and supports warranty and service standards.
Clean the groove thoroughly, ensure no damage or burrs, seat the ring fully and flush with the cavity, then install the primary seal behind it. Apply light lubrication if required and verify seal travel and engagement before returning the equipment to service.
Subscribe to our newsletter to get exclusive discounts and new theme launches right in your inbox.
You may unsubscribe at any moment. For that purpose, please find our contact info in the legal notice.
