Poppet Valves – An Introduction ...
HOERBIGER KT-Asia Services
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Contents
• Hoerbiger Poppet Valves
• Advantages of Poppet Valves
• Technical Analysis- Regulation of Poppet Valves- Efficiency of Poppet Valves compared to other Types- Problems assoziated with Poppet Valves
• Life Cycle Cost Analysis• Conclusions
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Hoerbiger Poppet Valves
Single Deck Poppet Double Deck Poppet
Mini Poppet
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Hoerbiger Poppet Valves - Features
• Standard lifts usually 5-8 mm
• Poppet design to increase strength
• Seat design optimized to gain efficiency
• Carbon fibre filled material foroptimized tribology
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Advantages of Poppet Valves
• Low manufacturing costs
• Easy change of sealing elements- equal geometry independent of valve size- equal spings
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Technical AnalysisTechnical Analysis
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Efficiency of Poppet Valves
• Main valve parameters for efficiency calculation- valve design- valve lift
Lift (mm)Lift (mm)
ααααΦΦΦΦ
gas
pV
ρ∆
=Φ*2
D
areaflowequivalentdiametervalveD
D
l
l
Φ
⋅Φ=Φ
4
2 πα
VOLUME1 2 3
C
A
G
F
N
P
P
2
1
Mdischarge
valve opensdis.
valvecloses
suctionvalve closes
suctionvalve opens
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Regulation of Poppet Valves
Usual: Plug unloader Port unloader
Finger unloader (rare):
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Dynamics of Poppet Valves
Poppet
Very sensitive to opening impactdue to rather thin and fragile stem.
Danger of non-parallel impact andoverload on the stem edge
Insensitive to closing impact dueto massive poppet head and profiled seat land geometry
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Poppets in Applications
• Gas Transport (low pressure ratios)- Low opening impacts- High lifts- Good efficiency- Clearance less important
• Process Applications (high pressure ratios)- Danger of high opening impacts- Danger of sticktion effects (oil, dirt, sticky constituents, etc)- Low lifts- Low efficiency- Valve clearance problems
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Problems associated with Poppet Valves
Spring wear due to buckling (contact in the middle sections)
Pitting due to the opening impact(increases lift further)
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Problems associated with Poppet Valves
• Compressor control
- reduced flow area due to plug- increase of valve losses
- additional clearance in the case of a port unloader- reduction of volume flow
• Wear on the seat land
• Difficulty in re-machining seat ports
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Conclusions
• Poppet valve have optimum applications- low pressure ratios (high lifts)- no compressor flow regulation- e.g. Gas Transport
• For process applications- high pressure ratios (small lifts)- regulated compressors- heavy gases
Other valve designs are more favourable not only from theTECHNICAL but ESPECIALLY from the OVERALL COSTperspective.
Poppet Valves – End of Presentation
HOERBIGER KT-Asia Services