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