Tapered Scraper Ring Geometry for Debris-Resistant Pump Sealing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional packing arrangements in high pressure reciprocating pumps are ineffective in controlling debris and extending the lifespan of sealing components due to limited axial space and the 'nibbling' phenomenon caused by trapped debris, which leads to premature seal failure and increased maintenance needs.
Innovation Solution
An annular scraper ring with a planar upstream face and tapered inner surface is designed to focus sealing forces at the upstream face, preventing debris accumulation and eliminating pedestals that contribute to 'nibbling, while incorporating a male chevron for redundancy and an orthogonal exterior surface for easy insertion, enhancing debris control and seal longevity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional packing arrangements are used with limited axial space, then the pump structure remains compact, but debris accumulates and causes 'nibbling' phenomenon that damages sealing elements
Solution Approach 1:
The scraper ring is positioned upstream in the packing arrangement to perform preliminary debris removal before the fluid reaches downstream sealing elements. This preliminary action prevents debris accumulation that would otherwise cause nibbling and damage to sealing elements, extending their lifespan without requiring additional axial space.
Solution Approach 2:
The scraper ring extracts debris from the fluid stream by scraping it off the plunger surface and directing it upstream toward the suction side. This extraction function removes the harmful factor (debris) from the system, preventing it from causing damage to downstream sealing components.
2Reliability
If sealing forces are distributed uniformly along the scraper ring, then the structure remains simple, but downstream components and portions of the scraper ring remain vulnerable to debris damage
Solution Approach 1:
The scraper ring features a tapered inner surface with varying thickness, creating local variations in structural properties. The upstream portion has greater thickness and structural strength to handle debris removal, while the downstream portion tapers to a thinner profile. This local quality differentiation concentrates sealing forces where needed to protect downstream components without requiring uniform complexity throughout the entire ring.
3Ease of operation
If the scraper ring includes a pedestal structure, then insertion into the pump casing is facilitated, but pockets are created that encourage nibbling phenomenon
Solution Approach 1:
The invention removes the pedestal structure entirely from the scraper ring design. By eliminating this feature, the problematic pockets that encourage nibbling phenomenon are removed as well. The scraper ring is inserted into a corresponding recess in the pump casing without requiring a pedestal, thus maintaining ease of installation while preventing the harmful nibbling effect that would reduce sealing element durability.
4Object-affected harmful factors
If the scraper ring is made wider downstream to compensate for debris, then debris protection improves, but axial space requirements increase and compression force distribution becomes less effective
Solution Approach 1:
Instead of making the scraper ring wider downstream to handle debris, the design inverts the conventional approach by concentrating width and structural strength at the upstream end where debris enters. The inner surface tapers from upstream to downstream, creating a wedge shape that is widest at the leading edge. This inverted geometry effectively controls debris at its source while minimizing axial space requirements and maintaining effective compression force distribution.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The scraper ring effectively protects downstream components from debris, prevents blow-by leakage, and extends the lifespan of sealing elements by concentrating compression forces at the upstream face and peeling off debris, thus improving the overall sealing performance and reducing maintenance requirements in high-pressure environments.
Implementation Method 1
when the scraper ring is compressed, sealing forces acting against radial expansion of the sealing ring (i.e., normal forces) will be largest at and/or adjacent the planar upstream face
Implementation Method 2
the scraper ring is widest at the planar upstream face. Thus, advantageously, when the scraper ring is compressed, sealing forces acting against radial expansion of the sealing ring
Data Source
AI summary
An annular scraper ring for a packing arrangement is disclosed. The annular scraper ring that can form a seal with a plunger included in a fluid end of a reciprocating pump and includes a planar upstream face and an inner surface with a tapered section. The tapered section tapers away from the plunger along a downstream direction so that the scraper ring is widest at the planar upstream face.