seals and packing

7/27/2019 seals and packing

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I L LU S T RAT E D S O U R C E B 0 0 of ME C H A N I C A L C 0 M P0 E N T S

S E C T I O N 6

EALSRubber Seals for Oil RetentionNon-Rubbing Seals for Oil RetentionHow to Seal Air Ducts that SeparateMore Seals or Ducting that SeparateWindow Awning Unit SealingWindow Casement Unit SealsMult iple Seals & Bonding for Dam Retrofitting

6-26-46-66-86-106-116-12


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Rubbing Seals for Oil RetentionDavid C. Spaulding, JR.Rubbing seals cover all applications where a positive sliding contact exists between the sealand either the rotating or stationary member. They are limited as to type of operation andspeed because of the friction between the contacting surfaces and they should not be used in

On e piece or

]


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Seals & Packings 6-3

abrasive surroundings. Types that are held against the rotating member by spring pressure canbe used where there is a pressure head of fluids within the assembly or on the exterior. Forhigh pressure stuffing box and O-r ing type seals are used. O-rings are alsoused for zero leakage.

Bronze,bearingI\\

Housing

- Shaft

I\\Housing

haft- . L-(-- - /Garter or stomped --)

FIG. &Rubbing seals, of the type shown, (A) , have wide-spread use in all types of equipment. T he spring tensionand sealing ring material may be varied so that a variety ofappliea tions can be handled. Small units can be had wherethe 0. D. is the same as the 0. D. of the sleeve bearing, ( B ) ,thus eliminating the counterboring operation on the housing.The seal may be reversed and used to keep foreign matterou t of the assembly. A drain hole may be provided to earryaway surplus lubricant. Retention is by press fit on th eoutside diameter.

FIG. 5-Rubbing seals of the stuffing box type ( A ) , are usedwhere high pressure are encountered. It can be used for alltypes of mo tion and the pac king material can be varied de-pending upon the fluid to be sealed and the application. Forrotating motion some leakage is necessaryso it cannot be usedwhen permissible leakage is zero. O-rings can also be usedfor rotary m otion if the speed is slow. Special designs useO-ring seals (B), when zero leakage is demanded for eitherstationary or reciprocating motion.This ring is made of n atural rubber or synthetic rubber de-pending on the type of solution resistance required. Syntheticrubber, such as buna or neoprene, is resistant to aromatichydrocarbons, while natural rubber resists the action of alco-hol and glycerine.0-rings ean be located either in the shaft or in the housingand any movement or pressure forces the ring to one side,thereby forming a tight seal.


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Non-Rubbing Seals for Oil RetentionDavid C. Spaulding, JR.There are two general types of seals: rubbing and non-rubbing. Non-rubbing seals use oilor grease to lubricate mating surfaces and exclude foreign matter by forcing the lubricantout between the bearing surfaces. These seals are not limited by operation or speed since

L ubricotiongroove -----\.

F ig . !

Oil gathering Oil gathering

Grooves--

F i g . 2

Fig. 1-Non-rubbing seal fo r grease lubrica tion.Grooves and housing are filled with grease at assemblyor an automatic feed system can be incorporated.Seal offers protection against entranc e of foreignmatter because of the outward flow of grease throughthe labyrinth passages. Clearance between shaft andseal is about 1/6 4 inch.

Fig. 2-Non-rubbing seal for oil lubrica tion. Groovescan be located in bearing, (A), or in housing, (B).Grooves are connected to an oil retu rn passage leadingto a sump in housing. This keeps oil loss to a mini-mum and maintains a constant supply to the bearing.Design does not prevent entra nce of foreign m aterial.

Lubricant

-Shaf t


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Seals 8t Packings 6-5

friction is negligible. They are, however, often more expensive than rubbing seals sincethe shaft, bearing, or housing must be grooved to distribute the lubricant. Distributionover the bearing area is, however, better. Lubricants may be forced-fed or gravity-fed.

Fig. 5-Labyrinth seals offer good protection espe-cially at high speeds where the narrow zigzag passageis used in conjunction with centrifugal force. Oil andforeign matter are separated by slinger which limitsoil flow past rotating member (A). Inner member(B) throws oil back to sump. Member (C ) throwsout foreign matter.

Fig. 6-Non-rubbing seal fo r oil lubrication. Shaftrotation throws lubricant into the inboard groove ( B )in the housing and is returned to the oil sump. Firstslinger ( D ) throws foreign material out of the assem-bly. Secnnd slinger (0) eeds foreign material outthrough groove (A) and hole at (C). Lubricant feedsbetween shaft and bearing to housing grooves.

Fig. ?'-Reservoir type feed for grease lubrica tion .Grease is distributed in annular groove and feedsthrough holes in bearing to lubricate the shaft.Foreign matte r can be excluded if clean grease is used.Grease will be lost through open bearing ends andassembly must be repacked periodically.

Fig. 8-Reservoir type feed for oil lubrica tion. Twobearings are used forming an oil reservoir betweenthem. If porous wall type bearings are used oil willsaturate and feed through bearings to the shaft.Outward flow of oil prevents entry of foreign mate-rial. Reservoir must be periodically refilled with newoil. Bearings are a press fit in the housing.


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How to Seal Air Ducts that SeparateThese slip joints reseal and realign ducting that i s often taken apart. They also take care ofexpansion, vibration, and joint locations difficult to reach.James H. LaPointe

&-=I SPLIT RUBBER TUBING AND EDGE-ROUED ANGLE

Bend ouf

L i p con keep co n t ra / gaske tond preven f c o n f o c tw i t h point, smoke, e t c .


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Afour or moreguide brockefs -I

/ I

[- FLAT RUBB ER AND GUIDE BRACKETS FO R CENTERING

fHeavyconfocf

Angle CU T onrubber owoy

Vor io f io n from 2"

sea/ edge w i l l fo rcef rom opening

Seam //Ae f a / t u b i n u He ldRive# orspof we/d


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More Seals for Ductingthat SeparatesSix more seals for round ducts and others. Make sure thegasket material can withstand the ducted media.James H. LaPointe

U U

WEOGE-GUIDE SEALn 2 /Hole re in fo rcemenf(doubler)


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NONCENTERING SEALS-FLAT RUBBERaA

SLIP SLEEVES THATSEAL WITHOUT GASKETS

I

A BMETAL TUBING GUIDE AND VARIATIONS


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Window Awning Unit SealingIllustrated by Robert 0. Parmleyn

rn$'"L- LEFT JAMB-

A 'A IL- RIGHT JAMB-

/


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Window Casement Unit SealingIllustrated by Robert 0. Parmley

- RlGHf . JAMB-


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