BS ISO 19893 pdf download

BS ISO 19893 pdf download Plastics piping systems — Thermoplastics pipes and fittings for hot and cold water — Test method for the resistance of mounted assemblies to temperature cycling
1 Scope
This International Standard specifies a method for testing the resistance to temperature cycling of joints forpiping systems with rigid or flexible thermoplastics pipes.
lt is applicable to thermoplastics piping systems intended to be used in hot and cold water pressureapplications.
2Principle
A test assembly of pipes and fittings (see Figure 1) is subjected to temperature cycling by the passage ofwater under pressure using hot and cold water alternately, for a specified number of cycles.
While being subjected to temperature cycling, parts of the assembly of pipes and fittings are maintained undertensile stress and/or flexural strain using static clamps.
During and after the test, the assembly is monitored for signs of leakage.
NOTE lt is assumed that the following test parameters are set by the reference product standard (i.e. the standardmaking reference to this International Standard):
a)the test temperatures (see 3.1,3.2 and 6.1);
b) the duration of a complete cycle and each part of the cycle (see 3.1,3.2 and 6.1);c)the test pressure (see 3.6 and 6.1);
d)the tensile stress (see 3.8 and 5.3);
e)the bending radius (see Clause 4 and Figures 1 and 2);
f)the total number of cycles, including the first five cycles (see 6.2 and 6.3).
3 Apparatus
3.1 Cold water source, capable of all of the following:
a) supplying the water volume necessary to maintain the temperature variation throughout the test piece within the specified maximum difference (see 6.2);
b) supplying this water at the lowest temperature specified in the reference product standard with an accuracy of 2°C;
c) supplying this water for the duration of at least each cycle as specified in the reference product standard.
If not specified otherwise in the reference product standard, to an accuracy of the duration time of1 minute(s).
3.2 Hot water source, capable of all of the following:
a) supplying the water volume necessary to achieve the required water velocity (see 6.2);
b) supplying this water at the highest temperature specified in the reference product standard to an accuracyof2°c;
c) supplying this water for the duration of at least each cycle as specified in the reference product standard.
lf not specified otherwise in the reference product standard,to an accuracy of the duration timeof1 minute(s).
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3.3 Balancing valves, capable of regulating the water velocity as necessary to maintain the temperaturevariation throughout the test piece within the specified maximum difference (see 6.2).
3.4 Alternation equipment,capable of achieving each change in hot and cold water temperatures at theinlet within 1 min.
3.5 Thermometer(s), capable of checking conformity to the specified test temperatures (see 3.1,3.2 and6.2).
3.6 Pressure gauge(s) and a device,for regulating the water pressure in the test assembly at thepressure specified in the reference product standard to an accuracy of 0,5 bar1)( 0,05 MPa), except forbrief pressure spikes, which can occur if the temperature of water is changed.
3.7 Supporting brackets, as appropriate, comprising anchor brackets (fixed points) capable of restrainingpiping components and guide brackets，capable of supporting piping components without inhibitinglongitudinal movement (see Clause 5 and Figure 1).
3.8 Tensioning device, capable of applying the required initial tensile stress(see 5.3).
NOTE This is to simulate stress which can be induced in any fixed pipe section as a result of contraction caused bycooling to temperatures below those prevailing during installation.
4Test assembly
The test assembly shall comprise an assembly of pipes and fittings jointed and clipped in accordance withFigure 2 and the manufacturer’s recommended practice, except as follows.
lf, while following the manufacturer’s recommended practice, the pipe cannot be bent to the configurationshown for branch C in Figure 2, for instance, because of the material, wall thickness andlor outside diameterof the pipe, branch C shall conform to Figure 3.
The test assembly as shown in Figure 2 shall include the following:
a) for branch A: at least three prestressed pipes linked by straight connectors stressed in accordance with
5.3, where the free length of such combination shall be (3 000100) mm;
b) for branch B: at least two straight pipes,each free to move and having a minimum free length of
(30010) mm;