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है”ह”ह

IS/ISO 7425-1 (1988): Hydraulic Fluid Power - Housings forElastomer-Energized, Plastic-Faced Seals - Dimensions andTolerances, Part 1: Piston Seal Housings [PGD 16: FluidPower]

iS/lSO 7425-1:1988

@kTm Wfa3— $MP-ti’lyxin

11’wWJFFra?r—3mFrcFf&

/ndian Standard

HYDRAULIC FLUID POWER — HOUSINGS FORELASTOMER-ENERGIZED, PIASTIC-FACEDSEALS — DIMENSIONS AND TOLERANCES

PART 1 PISTON SEAL HOUSINGS

UDC 621.8.032:621-762,8: 621-213

@ BIS 1995

13UREA UOF IN DIAN STANDARDSMANAK +3HAVAN, 9 BAHADUR SHAH ZAFAR MARG

NEW DELHI 110002

June 1995 Price Group 2

Basic Fluid Power Sectional Committee, PE 14

NATIONAL FOREWORD

This Indian Standard which is identical with ISO 7425-1:1988 ‘Hydraulic fluid power — Housingsfor elastomer-energized, plastic-faced seals — Dimensions and tolerances — Part 1 : Piston sealhousings’, issued by the International Organization for Standardization (ISO), was adopted by theBureau of Indian Standards on the recommendations of the Basic F Iuid Power Sectional Comm”meeand approval of the Production Engineering Division Council.

The text of ISO standard has been approved as suitable for publication as Indian Standard withoutdeviations. Certain conventions are however not identical with those used in the Indian Standards.Attention is particularly drawn to the following:

a) Wherever the words ‘International Standard’ appear referring to this standard, they shouldbe read as ‘Indian Standard’.

b) Comma (,) has been used as a decimal marker in the International Standards while in IndianStandards, the current practice is to use a point (.) as the decimal marker.

In the adopted standard, reference appears to certain International Standards for which IndianStandards also exist. The corresponding Indian Standards which are to be substituted in their placeare listed below along with their degree of equivalence for the editions indicated:

International Corresponding Degree ofStandards Indian Standards Equivalence

ISO 286-2:1988 IS919 (Part 2) :1993 ISO system of limits and fits: IdenticalPatt 2 Tables of standard tolerance grades andlimit deviations for holes and shafts

ISO 3320:1987 IS 8208:1976 Sizes for cylinder bores and piston Technicallyrod diameter for fluid power systems Equivalent

ISO 5598:1985 IS 10416: 1992 Fluid power systems and com- Identicalponents — Vocabulary (first revision)

i

The technical committee responsible for the preparation of this standard has reviewed the provisionsof ISO 4394-1 : 1980 ‘Fluid power systems and components — Cylinder — Barrels — Part 1 :Requirements for steel tubes with specially finished bores’ and has decided that it is for use inconjunction with this standard,

lS/lSO 7425-1: 198Q

Indian Standard

HYDRAULIC FLUID POWER — HOUSINGS FORELASTOMER-ENERGIZED, PLASTIC-FACEDSEALS — DIMENSIONS AND TOLERANCES

PART 1 PISTON SEAL HOUSINGS

1 Scope

This part of ISO 7425 specifies the dimensions and associatedtolerances for a series of piston seal housings to accommodateelastomer-energized, plastic-faced seals used in reciprocatingapplications.

It is not the intention of this part of ISO 7425 to stipulate detailsof seal design, since the manner of construction of seals varieswith each manufacturer. The design and material of the sealsand any associated anti-extrusion components are determinedtry conditions such as temperature and pressure.

This part of ISO 7425 applies only to the dimensionalcharacteristics of products manufactured in accordance withthis part of ISO 7425. It does not apply to their functionalcharacterist its.

2 Normative references

The following standards contain provisions which, throughreference in this text, constitute provisions of this part ofISO ?425. At the time of publication, the editions indicatedwere valid. All statrdards are subject to revision, and parties toagreements based on this part of ISO 7425 are encouraged toinvestigate the possibility of applyinb the most recent editionsof the standards listed below. Members of IEC and ISO main-tain registers of currently valid International Standards.

ISO 286-2:1988, ISO system of limits and fits – Pert 2:Tables of standard tolerance gredes and limit deviations forholes and shafts.

ISO 3320: 1937, Fluid power systems and components –Cylinder bores and piston rod diameters – Metric series.

ISO 5593: 19S5, Fluid power systems and components –Vocabulary.

3 Definitions

For the purposes of this part of ISO 7425, the definitions givenin 1S0 ‘559S apply.

4 Letter symbols

Letter symbols used in this part of ISO 7425 areas follows:

D = bore diameter (outside diameter of the seal housing)

d = piston seal groove diameter (inside diamatsr of the sealhousing)

JD -d)- radial depth (cross-section) of the seal

2’housing

L, = axial length (seal groove length) of the seal housingwithout back-up rings

L2 = axial length (seal groove length) of the sealhousingwith back-up rings

C = axial length of the lead-in chamfer

d~ = clearance diamatar of the piston

5 Seal housings

5.1 General

5.1.1 An illustrated example of a typical hydraulic cylinderpiston seal housing covered by this part of ISO 7425 is given infigure 1.

NOTE - The figureis diagrammaticonly and doss not representanendorsementor recommendationof a particularhousingdesign.

5.1.2 All sharp edges and burrs shall be removed from thesuppofiing surfaces, although it should be borne in mind thatthese surfaces are required to provide maximum supportagainst extrusion.

5.1.3 The seal manufacturer shall be consulted for details ofhousing design which are not spacifiad in this part of ISO 7425.

1

1S/1S0 7425-1:1988

5.2 Axial length

Axiallengths for the nominal piston diameters shown are givenin table 2.

NOTE – If the extrusiongsp exceedsthe capabilitiesof the plaatic-facadmaterialto bridgesuchsgap, lengths L2 should be selected sndback-up rings (anti-extrusion rings) used. Sss clause 7.

5.3 Radial depth

5.3.1 Radial depths are given in table 2.

NOTE – This part of 1S0 7425 includesan alternativeseal housingradialdepth for bore diameters where D > 25 mm.

5.3.2 The larger radial depths shall be selected where higherstresses or wider tolerances are involved; however, corrsu!-tetion with the manufacturer is recommended when makingthe appropriate selection,

6 Dimensions and tolerances

Seal housing dimensions and tolerances shall be seiected fromtable 2.

7 Extrusion gap

Thkrextrusion gap (D - d$ see figure 1) is determined by thebore diameter and adjacent metal components on either side ofthe seal,

1 The extrusiongap willvsryconsiderablydependingon useor non-ussof non-metallic,@earingson the piston.

2 Maximum value for the extrusion gsp is achieved when the piston isin contact with one side of the cylinder or bearing.

3 The extrusion gap ia further widened by the expansion of thecylindar due to internal pressure.

4 It is recommended that details concerning the extrusion gap andneed for non-extrusion rings be subject to consultations between thehousing designer and seal manufacturer.

$ Surface finish

The requirements for the surface finish of the components incontact with the seal are dependent on the application and itslife requirement and should be subject to agreement betweenthe purchaser and seal manufacturer. I

9 Lead-in chamfer

9.1 To protect the seal from damage during assembly, lead-inchamfers are required, either as an integral part of housingcomponents or on separate assembly tools.

9.2 Reference shall be made to figure 1 for typical location oflead-in chamfers when these are part of the housing compo-nent.

9.3 The minimumaxial length of lead-in chamfers,whetheron housingcomponentsor assemblytools, is given in table 1.

Table 1 – Lead-in chamferOimenaionsin millimstres

Radial depth of 5 7,5 102,5

12,25

serd housing, S nom.3,75 15 20

5,5 7,75 10,5 12,5

Minimum axial length oflead-in chamfer. C 1,5 2 2,5 4 5 6,5 7,5 10

L,

i

R 0,3max.

&

--4--k,/ r

Figure 1 – Example of piston seal housing

2

WISO 7425-1:1988

Table 2 – D$mermionsand tolerances of seal housingsDkrranaions in miliimetrea

Borrr diameterl~ Radial depth Groove diameter Axial length

D s d L, L2 r

(without back-up rings) (with back-up rings) max.H921 nom. h~21 + 0,2 +0,2

o 0

2,5 11 2,216

3,75 8,5 3,2

2,5 15 2,220 .

3,75 32,5 3,2

3,75 “17,5 3,2

25 5,5 14 4,2

5 15 — 5 8

3,75 24,5 3,2 —32 5,5 21 4,2

5 22 5 8 0,5

3.75 32,5 3,2 —40 5,5 29 4,2

5 30 5 8

5,5 39 4,2

50 7,75 34,5 6,3

7,5 35 7,5 12,5..———.

5,5 52 4,2—

83 7,75 47,5 6,3

7,5 4$3 7,5 12,5.—

5,5 69 4,2—

60 7,75 .64,5 6,3

10 60 10 16

5,5 89 4,2

100 7,75—

84,5 6,3

10 80 10 16

7,75 109,5 6,3

125 10,5 104 8,1

10 105 10 16

7,75. 144,5 6,3

160 10,5—

139 8,1

12,5 135 12,5 20

7,75 184,5 6,3

200 10,5—

179 8,1 0,9

12,5 175 12,5 20

10,5 229 8,1

260 12,25 225,5—

8,1

15 220 15 25

10,5 299 8,1

320 12,25 285,5—

8,1

15 280 15 25.—12<25 375,5 8,1

400 15 370—

12,5

20 360 20 32

12,25 475,5 8,1

600 15 470 12,5

20 460 20 32

1) Bore diameters in accordance with ISO 3320.

2) See ISO 286-2.

3

1S/1S0 7425-1:1988

10 ~dentificatkm statement (Referenceto this part “PWon seal housing for aleetomer-energized, plastic~facedof 1s07425) seals selected-in accordancewith ISO 742%1, Hydrau/ic fluid

power – Housings for ekstonrer-energizes, plastic-faced sealsUse the following statement in test reports, cetelogues and – Dimensions end toterences – Pert 1: F%ton seelhousings.”sales Iiiereture when electing to comply with this part of1s07425:

Bureau of Indian Standards

BIS is a statutory institution established under the Bureau of Indian Standards Act, 1986 to promoteharmonious development of the activities of standardization, marking-and quality certification of goodsand attending to connected matters in the country.

Copyright

BIS has the copyright of all its publications. No part of these publications maybe reproduced in any formwithout the prior permission in writing of BIS. This does not preclude the free use, in the course ofimplementing the standard, of neeessaxy details, such as symbols and sizes, type or grade designations.Enquiries relating to copyri~ht bc addressed to the Director (Publications), BIS.

Review of Indian Standards

Amendments are issued to standards as the need arises on the basis of comments. Standards are alsoreviewed periodically, a staltdard along with amendments is reaffirmed when such review indicates thatno changes are needed; if the review indicates that changes are needed, it is taken up-for revision. Usersof Indian Standards should ascertain that they are in possessionof the latest amendments or edition byreferring to the latest issue of ‘BIS Handbook’ and ‘Standards Monthly Additions’.

This Indian Standard has been developed from Doc: No. PE 14 ( 0120 ).

Amendments Issued Since Publication

Amend No. Date of Issue Text Affected

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