Designing clinical analyzers that deliver consistent, long-term service, efficiency, and accuracy is one tough job. But choosing the right seal can make it a lot easier. That’s why we’ve prepared this short presentation for you. It examines the relationship between seal selection and the performance of hematology, urinalysis, and other analyzer types, and it addresses important design criteria, such as seal jacket material, lip geometry, and energizer force. It also suggests some ways to avoid common sealing mistakes that may be costing you time, money, and market share.

2. Slide 2
Major Diagnostic Analyzer Types
• Hematology analyzer
 HbA1C Testing
 Accuracy, precision, and linearity
 Blood cell count
• Clinical analyzer
 Multi-industry usage
 Protein analysis
 Genome development
 Chemical analysis
• Urine analyzer
 Fluorescence flow cytometry
 Digital imaging
 Identifies organ problems

3. Slide 3
Diagnostic Pump Environment
• Operating conditions
 Low-speed reciprocation
 Medium shaft diameter
 Tight leakage criteria
 Range of temps - ambient to 40°C
 Minor shaft to bore misalignment
 Machined plastic or stainless steel
housing
• Media
 Reagents or saline
• Performance criteria
 1 Million+ cycles

4. Slide 4
Design Challenges
• Hardware
 Large hardware tolerances create potential leak
paths
 Hardware misalignment creates more wear on one side
of the seal resulting in rapid leakage
 Housing without surface treatment reduces seal
life
 Seals wear rapidly due to poor surface finish
 Lack of rinse portion allows salt crystals to form
behind the high pressure seal
 Damage to dynamic seal lip diminishes seal life

5. Slide 5
Design Challenges
• Crystallization
 Hardware misalignment, large
hardware tolerances, and
marginal seal designs allow
reagent or saline to weep under
seal ID lip
 If no rinse portion behind the seal,
salt crystals will form
 Dynamic seal lip will reciprocate
over crystals, causing scratches on
seal ID
 Over time scratches become leak
paths, causing inaccurate
dispensing of reagent
Crystals on pump piston can result
in formation of leak paths on seal.

6. Slide 6
Seals: A Critical Element
• Prevent reagent from leaking
behind seals
• Seal failure adversely impacts
pump accuracy, precision, and
linearity
• Seal designs for diagnostics must:
 Mediate friction and sealing
effectiveness to guard against salty
reagent weepage
 Consistently maintain reagent
pressure for 1,000,000+ cycles
 Prevent salt crystals forming behind
the seal and reducing life
 Minimize particle generation shedding
to reduce process contamination

7. Slide 7
Seal Performance Factors
• Housing Hardware
 Tight tolerances of < ±0.001”
 Machined stainless steel with coated or machined plastic
 Minimal clearance between housing & plunger (0.002” max)
 Suggested sealing surface of 9.1 – 14.5 µin Ra
• Piston Hardware
 Smoother surface finish is better
 Suggested dynamic surface is 7.3 - 14.5 µin Ra
 Minimum shaft hardness is 30Rc for un-filled materials.
 Higher surface hardness enhances seal performance
 Sapphire or ceramic have excellent surface finish and high
hardness with minimal porosity
 Stainless steel with hardness treatment and/or polishing

8. Slide 8
Sealing Performance Factors
• Alignment
 Review hardware tolerances to ensure proper alignment
between piston and housing
 Review tolerance stack-up if you have multiple housing
components, as this may contribute to misalignment
 Allowable misalignment recommendations are maximum conditions
 Floating plunger
 High modulus backup support ring to improve alignment and
reduce any potential side-loading on sealing lips

9. Slide 9
Design Insight
• Incorporating active
wash system with rinse
seal:
 Reduces heat generated
under pressure
 Prolongs service life
 Adds lubricity to the
application
 Reduces formation of
salt crystallization

10. Slide 10
Seal Design Considerations
LC
SP191
Polyimide-filled
UPC10
Virgin Polyethylene
Canted coil spring energizer
1 2
• Geometry
1. 15x design easier to machine hardware
 Long ID lip increases contact area
2. Flange design provides secondary OD seal
 Short ID lip reduces friction
• Jacket material
 PTFE materials (virgin or polyimide)
 High chemical resistance
 Low coefficient of friction
 USP Class VI or FDA compatible material
 UHMW PE materials (virgin or filled polyethylene)
 FDA compatible material for biocompatibility
 Higher resistance to wear and extrusion in aqueous media
• Spring energizer
 Chemical compatibility
 Biocompatibility
 Corrosion prevention (hardware)
 Consistent spring force
 Customizable loads

11. Slide 11
Optimizing Diagnostic Seal Design
Requirements Solutions
• Low-speed
reciprocation
• Chemical
compatibility
• Low-friction
• FDA compliant
• Biocompatible
• 1,000,000+
cycles
• Bal Seal® spring-energized PTFE or UHMW PE seal
• Virgin (TA) or Filled-PTFE (SP191 polyimide-filled)
• Low coefficient of friction, chemically inert,
compatible with aggressive media, self healing
• Virgin-UHMW PE (UPC10 polyethylene) or Filled-UHMW
PE (UP30 high performance polyethylene)
• Low permeability, minimal extrusion, USP Class VI,
minimal contamination, low particle generation
• Meets low drag force requirements
• Non-flange design allows for tighter tolerances & less
machining
• Flange design simplifies installation
• Bal Spring® canted coil spring energizer (stainless steel or
Hastelloy®)
• Applies consistent sealing pressure over large tolerance
range
• Large variety of bio-inert spring materials to prevent
corrosion
• Non-standard seal designs to work within retrofit hardware

12. Slide 12
Summary & Recommendations
• To eliminate costly mistakes and delays,
consider sealing requirements as part of
overall pump design
• In early design stages, collaborate with
Bal Seal Engineering to:
 Get consultative engineering advice
 Analyzer hardware design review
 Finite Element Analysis for theoretical
calculations
 Collaborative seal design discussion
 Custom design a seal that meet all your
system/application requirements
 Determine recommended test failure criteria
 Produce high-quality seal prototypes
 Set AQL of 1.0 C=0
 Test to verify performance
 Drag force evaluation at no pressure
 Scale up to full production

13. Slide 13
Resources & Contact Information
Sarah Smith
Global Market Manager, Analytical Products
Bal Seal Engineering, Inc.
ssmith@balseal.com
+1 949.460.2226
marketing@balseal.com www.balseal.com +1 949.460.2100 Design request form

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subject of issued or pending United States and foreign patents. Bal Seal Engineering, Inc. products and designs are PROPRIETARY and products may not be manufactured,
or caused to be manufactured, by any other party.