CEN/TR 14920:2005

SLOVENSKI STANDARD
01-julij-2005
2GSRUQRVWGHORYFHYL]DRGSDGQHYRGHLQNDQDOL]DFLMRSULYLVRNRWODþQHPEUL]JDQMX
3UHVNXVQDPHWRGDVSUHPLþQLPEUL]JDQMHP
Jetting resistance of drain and sewer pipes - Moving jet test method
Widerstandsfähigkeit von Rohrleitungsteilen für Abwasserkanäle und -leitungen beim
Hochdruckspülen - Prüfung mit beweglicher Düse
Résistance des tubes pour les branchements et les collecteurs d'assainissement durant
le curage sous haute pression - Méthode d'essai a vitesse variable
Ta slovenski standard je istoveten z: CEN/TR 14920:2005
ICS:
93.030 Zunanji sistemi za odpadno External sewage systems
vodo
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

TECHNICAL REPORT
CEN/TR 14920
RAPPORT TECHNIQUE
TECHNISCHER BERICHT
March 2005
ICS 93.030
English version
Jetting resistance of drain and sewer pipes - Moving jet test
method
Résistance des tubes pour les branchements et les Widerstandsfähigkeit von Rohrleitungsteilen für
collecteurs d'assainissement durant le procédé de Abwasserkanäle und -leitungen beim Hochdruckspülen -
débourbage sous haute pression - Méthode d'essai Prüfung mit beweglicher Düse
This Technical Report was approved by CEN on 23 August 2004. It has been drawn up by the Technical Committee CEN/TC 165.
CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,
Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia,
Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2005 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TR 14920:2005: E
worldwide for CEN national Members.

Contents
Foreword. Page
1 Scope.4
2 Definitions and Symbols.4
2.1 Definitions.4
2.2 Further symbols.4
3 Test method.5
3.1 Principle.5
3.2 General Requirements.5
3.2.1 Water source.5
3.2.2 Pressure measurement.5
3.2.3 Test temperature.5
3.3 Apparatus.5
3.3.1 Pump unit.5
3.3.2 Flow rate and pressure accuracy.5
3.3.3 Nozzle.5
3.4 Test rig.6
3.5 Test assembly.7
3.6 Procedure.7
3.6.1 Pre-test procedure.7
3.6.2 Test procedure.7
3.7 Recording of test results .8
Annex A (informative) Guidance on the evaluation of surface damage .9
Annex B (normative) Determination of jet spread angle.10
Annex C (informative) Basic Principles for calculation of C , P and D .11
d j j
C.1 Calculation of C .11
d
C.2 Jet Power P .12
j
C.3 Jet Power Density D .13
j
Foreword
This document (CEN/TR 14920:2005) has been prepared by Technical Committee CEN/TC 165 “Waste water
engineering”, the secretariat of which is held by DIN.
High pressure water jetting has become more used in cleaning practice of drains and sewers. Considering that,
CEN/TC 165 decided to develop a test method for the resistance of pipe materials against high pressure water
jetting.
Due to a low level of experience with the newly developed test method applied to different materials and
considering some aspects of reproducibility have not been proved, a European Standard is not feasible for the time
being. Therefore CEN/TC 165 decided to give initial guidance to the market by publishing a test method as a
Technical Report (CEN/TR).
The test method specified in this document is intended to simulate the effect of high pressure cleaning on drains
and sewers.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to announce this CEN Technical Report: Austria, Belgium, Cyprus, Czech Republic, Denmark,
Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,
Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
1 Scope
This document specifies a test method for the resistance to high pressure clean water jetting of pipes, fittings and
joints used for drains and sewers.
This test method is also applicable to components for renovation and replacement of drains and sewers.
2 Definitions and Symbols
For the purposes of this Technical Report, the following definitions and symbols apply.
2.1 Definitions
2.1.1
jet power
P
j
energy per time unit of the jet leaving a nozzle
NOTE Jet Power is expressed in Watts.
2.1.2
jet power density
D
j
jet power per unit of the impinged area
NOTE Jet power density is expressed in Watts per square millimetres.
2.1.3
jet spread angle
ωωωω
spread of the jet related to its axis
NOTE Jet spread angle is expressed in degrees.
2.1.4
Nozzle
assembly of components which convert high pressure water flow into a jet (see Figure 1a)
2.1.5
Nozzle insert
special ceramic component to form a specified jet (see Figure 1c)
2.2 Further symbols
Table 1 — Symbol
Symbol Term Unit
angle of the jet axis to the test surface (see Figure B.1) °
α
C coefficient of discharge of a nozzle —
d
d orifice diameter of the nozzle insert mm
h vertical distance between the test surface and the centre of the nozzle orifice mm
p pressure measured not more than one metre upstream of the nozzle MPa
Q
flow rate l/min
3 Test method
3.1 Principle
A high pressure water jet is directed at a specified angle to and distance from the test surface. It is moved relative
and parallel to the test surface. The resulting mechanical load (expressed as jet power density) is kept within
specified limits for the duration of the test by controlling the parameters of water pressure, flow rate, distance and
jet spread angle. The nozzle and the insert to be used are specified in this document.
After the test the surface of the test piece is inspected.
3.2 General Requirements
3.2.1 Water source
The water is in accordance with drinking water quality standards in respect of chemicals and particulates.
3.2.2 Pressure measurement
A pressure measurement device with an accuracy of ± 0,1 % is connected to the water supply no more than 1 m
from the nozzle. The pipe between the position where the pressure is measured and the nozzle shall have an
unrestricted bore not less than 15 mm.
3.2.3 Test temperature
The test is carried out at an ambient air temperature of (15 ± 10) °C with water at a temperature of (15 ± 10) °C
near the pump inlet.
3.3 Apparatus
3.3.1 Pump unit
The pump unit is capable of delivering water at a pressure of at least 15 MPa and a flow rate of at least 60 l/min. A
pressure equaliser is incorporated, if necessary, to limit the pressure variations due to pump action to ± 1 % of the
mean value.
3.3.2 Flow rate and pressure accuracy
A means of measuring flow rate to an accu
...