ISO 9908:1993 pdf free download.Technical specifications for centrifugal pumps – Class III.
ISO 9908 is the third of a set dealing with technical specifications of centrifugal pumps; they are designated as Classes I, II and Ill Class I (see ISO 9905) comprises the most severe and Class III (ISO 9908) the least severe requirements. For requirements for Class II centrifugal pumps, see ISO 5199.
The selection of the class to be used is made in accordance with the technical requirements for the application for which the pump is intended. The class chosen is to be agreed between purchaser and manufacturer/supplier.
The safety requirements of the field of application are furthermore to be taken into account.
However, it is not possible to standardize the class of technical requiremerits for centrifugal pumps for a certain field of application, because each field of application comprises different requirements. All classes (I. II and III) can be used in accordance with the different requirements of the pump application. It may happen that pumps built in accordance with Classes I, II and Ill may work beside each other in one plant.
Further text covenng specific applications or mdustry requirements are dealt with later in separate standards.
Criteria for the selection of a pump of the required class for a certain application may be based on:
— rel bility,
— operating conditions,
— environmental conditions.
Throughout ISO 9908, text written in bold letters indicates where a decision may be required by the purchaser, or where agreement is required between the purchaser and manufacturerlsupplier.
1.1 ISO 9908 covers Class Hirequirernents for centrifugal pumps of single stage, multistage. honzont& or vertcal construction (coupled or close-coupled) with any drive and any installation for general application.
1.2 ISO 9908 includes design features concerned with installation, maintenance and safety of such pumps including baseplate. coupling and auxhary piping but excluding the driver. if it is not an integral part of the pump.
1.3 Where the application of ISO 9908 has been called for:
a) end requires a specific design feature, alternative designs may be offered which meet the intent of ISO 9908 povided that the alternative is described in detail.
b) pumps not complying with all requirements of ISO 9908 may be offered for consideration. provided that all deviations are stated.
2 Normativ. references
The following standards contain provisions which.
through reference in this text, constitute provisions of ISO 9908. At the time of publication, the editions indicated were valid. All standards are subject to revision, arid parties to agreements based on ISO 9908 are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below.
Members of IEC and ISO maintain registers of currently valid International Standards.
ISO 76:1987, Rolling bearings — Static load ratings.
ISO 2811990. Rolling bearings — Dynamic load ratings and rating life.
ISO 2372:1974. Mechanical vibration of machines with operating speeds from 10 to 200 rev/s — Basis for specifring evaluation standards.
ISO 2548:1973. Cenrnfugal, mixed flow and axial pumps — Code for acceptance tests — Class C (It is planned to combine ISO 2548 with ISO 3555 during their next revision to create a new International Stan dard).
ISO 3069:1974. End suction centrifugal pumps — Dimensions of cavities for mechanical seals and for soft packing.
ISO 3555:1977, Centrifugal, mixed flow and axial pumps — Code for acceptance tests — Class B (It is planned to combine ISO 3555 with ISO 2548 during their next revision to create a new International Standard).
ISO 7005-1:1992. Metallic flanges — Parr 1: Steel flanges.
ISO 7005-2:1988. Metallic flanges — Part 2: Cast iron flanges
ISO 7005-3:1988, Metallic flanges — Parr 3: Copper alloy and composite flanges,
ISO 9905:_l). Technical specifications for centrifugal pumps — Class l.
4.4 Pressure-containing parts
4.4.1 Pr.ssur..t.mp.ratur. rating
The pressure hmit (maximum allowable working pressure) of the pump at the most severe operating conditions shall be clearly defined by the man ut acturerlsuDper. In no case may the rated pressure of the pump (casing and cover, including shaft seal housing and gland foliowerlend plate) exceed that of the pump flanges.
The basic design pressure of the pump shall be a gauge pressure of at least 6 bar” at 20 °C when made of cast iron, ductile iron, carbon steel or stainless steel.
For materials the tensile requirements of which do not permit the 6 bar rating, the pressure-temperature rating shall be adjusted according to the stress- temperature rating for the material and shall be clearly stated by the manufacturer!supplier.
Low heed pumps may have a lower pressure- temperature rating if this is clearly stated by the manufacturersuppher on the nameplate and data sheet.
4.4.2 Wall thickness
Pressure casings including the shaft seal housing and gland end plate shall be of such thickness as will be suitable for containing pressure and hmiting distortion under the maximum allowable working pressure at operating temperature.
The casing shall also be suitable for the hydrostatic test pressure (see clause 6) at ambient temperature.
4.4.3 Mat.rials
The materials used for pressure-containing parts shall depend on the liquid pumped and the application of the pump (see clause 5).
4.4.4 MechanIcal f.atures
4.4.4.1 DIsmantling
The pump should be designed to permit necessary dismantling for spare pert replacement without disturbing inlet and outlet connections. lithe design is such that dismantling will cause some disturbance. then it should be so stated.
4.4.4.2 Casing gaskets
Casing gaskets shall be of a design suitable for the rated operating conditions and for hydrostatic test conditions at ambient temperature.
4.4.43 Ext.rnal bolting
Bolts or studs that connect pressure-containing parts shall be selected to be adequate for the maximum allowable working pressure and for normal tightening procedures.
4.5 Branch.. (nozzi..) and miscellaneous connections
NOTE 2 For the purpose of ISO 9908 the terms branch and nozzle are synonymous.
4.5.1 Typ. and size
Type and size of fluid connections shell be stated in the manulacturerlsupphers document.
4.5.2 Closures
Vent, pressure-gauge and drain openings shall be fitted with removable closures adequate to contain the maximum allowable working pressures and of matenal suitable for the pumped liquid
4.6 External forces and moments on branches (inI.t and outlet)
The manufacturersuppher shall provide details of allowable external forces and moments on branches on request.
4.7 Branch (nozzle) flanges
If circular flanges are used the flange envelope shall be of a size to enable flanges as specified in ISO 7005-1. ISO 7005-2 and ISO 7005-3 to be used. If th. pump manufacturer/suppliers standard pattern ntails a flange thickness and a diameter gr.at.r than that of the rating specified, the heavier flange may be supplied if requested by the manufacturer isupplier, but it shall be faced and drilled as specified above.
Bolt holes shall straddle the centreline,
4.8 Imp.llers
4.8.1 Impeller design
Impellers of closed, semiopen or open designs may be selected according to the application.
4.8.2 SecurIng of Impellers
Impellers shall be secured against circumferential and axial movement when rotating in the intended direction of rotation. Attention shall be drawn to the secure
t,cal adjustment of driver alignment to prmit compensation for pump, driver and beseplate tolerances.
If the purchaser supplies a driver or couphng. he shall provide the pump menufacturersupplier with certified installation dimensions of these components.
If the driver is not mounted by the pump manufacturerIsuppher. the driver fixing holes shall not be dnlled. it not otherwise specified
5 Materials
The materials shall be selected by the manuf.ctur.rsupp ll.r for the lnt.nded liquid to be pumped and for the Intend.d application, unless specified by the purchaser.
6 Shop inspection and tests
A hydrostatic test shall be performed for pressuracontaining parts of a pump at a test pressure of at least 1,3 times the basic design pressure.
Pumps are normally subject only to such other internal shop tests as may be decided by the manufacturer! suppler. If witnessed or nonwitnessed tests are required. this should be stated on the enquiry or order,
If a hydraulic performance test is required it shall be made in accordance with ISO 2548 and ISO 3555 Class II for clean cold water. For liquids other than clean cold water and for special operating conditions, hydraulic performance is to be calculated by the rnanufacturerlsuppher and the conversion method as to be indicated.
7 Preparation for dispatch
7.1 G.neral
All internal parts shall be drained prior to shipment Where bearings are oal-Iubncated, the bearing housings shall be drained and a label warning that prior to startup filling with oil is required, shall be f itted.
7.2 SecurIng of rotating parts for transport In order to avoid damage to bearings caused by vibration during transport, rotating parts shall be secured as required according to mode and distance of transport, mass of rotor and bearings design. In such cases a warning label shall be securely attached.
7.3 Openings
All openings to the pressure chamber shall have weather-resistant closures for transport, substantial enough to withstand accidental damage.