034858220-O-ring-backup-ring.1809.3-1

Short Description:

Used for BFT/BHDT pump.
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Details

Product Name: O-Ring Backup Ring / Back-up Ring 97 (Part No. 034858-220)

Description:
This component is a rigid backup ring, specifically designed for the high-pressure sealing assembly in BFT waterjet intensifier pumps . It is a precision support ring, typically manufactured from hard-wearing materials such as PTFE, PEEK, or reinforced polymer, which is installed adjacent to an elastomeric O-ring .

Its primary function is to provide critical anti-extrusion (back-up) support to the softer O-ring under ultra-high pressure conditions . By filling the extrusion gap between the O-ring and the metal gland wall, the rigid backup ring prevents the softer seal material from being forced into the clearance gap, which would otherwise cause rapid seal failure, pressure loss, and high-pressure fluid leaks . This component is rated for continuous operation at up to 60,000 PSI (approximately 4,137 bar) .

Applications:

Installed as a critical component within the high-pressure seal stack of BFT waterjet intensifier pumps .
Provides anti-extrusion support for O-rings in check valves, seal heads, and on/off valve assemblies .
Used during scheduled preventive maintenance, major pump overhauls, or when external water leakage is detected .
Compatible with BFT intensifier assemblies CP022001/2 and HT022012/172, where it is listed as Item 8 .

Features:

Rigid Support Material: Manufactured from hard, non-deformable materials (such as PTFE, PEEK, or composites) that withstand extrusion forces under extreme pressure .
Precision Dimensions: Machined to exact tolerances for a perfect fit in the designated groove, ensuring maximum support of the adjacent O-ring .
Anti-Extrusion Function: Fills the extrusion gap, preventing the softer O-ring from being forced into the gap under high pressure .
Critical Consumable Component: Designed for periodic replacement; a worn or missing backup ring will lead to immediate seal failure under high pressure .
OEM Compatibility: Direct replacement for BFT part number 034858-220, listed as Item 8 in BFT intensifier parts diagrams .

Maintenance:

Failure Diagnosis (When to Replace):

External Water Leakage: Visible high-pressure water weeping from the pump weep hole or cylinder area indicates O-ring seal failure, at which point the backup ring must also be replaced .
Pressure Drop: Inability to maintain rated cutting pressure suggests internal seal failure, often involving extrusion damage to the O-ring caused by an unsupported gap.
Regular Overhaul Schedule: It is standard practice to replace the O-ring and its backup ring together as a set during any scheduled pump maintenance or seal replacement.
Visible Damage During Disassembly: When the pump is opened, inspect the backup ring for signs of deformation, cracking, splitting, or compression set. Any visible damage warrants immediate replacement.

Inspection and Replacement Guidelines:

Always Replace with O-Rings: This is a single-use consumable component. Always replace it with a new one whenever the adjacent O-ring is replaced. Do not reuse old backup rings .
Full Depressurization (Critical): Before any maintenance, place the main electrical disconnect in the OFF position, bleed down all high-pressure lines, and follow lockout/tagout procedures.
Clean Installation: Perform the rebuild in a designated clean area. Thoroughly clean the seal groove and all mating surfaces with a soft, lint-free cloth. Remove all debris, old seal residue, and mineral deposits .
Lubrication: Apply a thin, uniform layer of manufacturer-recommended high-pressure grease to the backup ring and O-ring during installation to prevent pinching, rolling, or tearing during assembly .
Groove Inspection: Inspect the seal groove for nicks, burrs, sharp edges, or damage that could compromise the seal stack.
Replace as a Set: When servicing the high-pressure sealing stack, it is recommended to replace all components (O-rings, backup rings, and dynamic seals) simultaneously using a complete repair kit .

Cross-Reference Information:

BFT #: 034858-220
Also known as: O-Ring Backring 97
Component of Intensifier Assemblies: CP022001/2 & HT022012/172 (Item 8)
Works with: Piston Sealing (XK121/220), Wear Ring (XF56/220), Retaining Ring (S0375x3/103)
Rated Pressure: Up to 60,000 PSI (4,137 bar)