ISO16925 涂料和清漆.涂层耐压力水喷射的测定

1 Scope
This International Standard specifies a test method for the assessment of the resistance of coatings to
pressure water-jetting. The test method simulates the effects pressure water-jetting has on a coating.
5 Apparatus ａnd materials
Ordinary laboratory apparatus, together with the following:
5.1 Pressure water-jet, consisting of a high-pressure pump ａnd a nozzle.
A high-pressure pump conveys the water from a storage bin. To avoid influences from variations in
pressure, it is necessary that the pressure ａnd the volumetric flow rate be adjustable at the nozzle
described below.
The water temperature shall be adjustable to ± 2 °C.
The temperature shall be adjusted in accordance with Annex A. Necessary safety devices on the pressure
side of the unit, as e.g. pressure relief valve ａnd by-pass valve, shall exist. If the jetting is unsteady, a flow
calming section may be installed in front of the nozzle. A pulsation of the water jet at the opening of the
pump is inadmissible. In order to reach a reproducible result, the nozzle shall be solidly mechanically
fixed ａnd the test specimen shall be secured against slipping. For the adjustment of the volumetric flow
rate, a nozzle with a jet angle of 25° ａnd a volumetric flow rate of 6 l/min at 2 MPa (20 bar) is required
(see Annex A).
The following technical data should be attainable:
— volumetric flow rate: 8 l/min to 14 l/min
— pressure: 4 MPa (40 bar) to 13 MPa (130 bar)
— temperature: 20 °C to 80 °C
— jetting time: 10 s to 300 s

Figure 3 — Jetting area

9 Evaluation
9.1 General
Damage is recognizable when the coating loosens or flakes, regardless of which coat sustains the damage.
9.2 Evaluation with pictures to compare
Carry out the evaluation visually, comparing the specimen with the pictures.
In the course of the visual evaluation, a characteristic value is laid down by comparing with the
illustrations in Figures 4 to 9. A characteristic value between 1 ａnd 5 results, depending on the degree
of damage. No damage corresponds to the characteristic value 0. In addition to the evaluation, if
applicable, the attribution of the separation from the main separation level or to the respective film
shall be indicated.
The result of the visual assessment is indicated in dependence of the applied method, for example:
— method A: characteristic value A;
— method B: characteristic value B;
— method C: characteristic value C.
NOTE In addition, by measuring the areas of flaking (maximum width, in millimetres, or area, in square
millimetres), the overall damage can be evaluated. The overall damage is calculated by summing up all damaged
areas of the test specimen. Even the smallest areas of flaking are measured ａnd calculated, ａnd all areas added to
the overall damage.

Figure 5 — Characteristic value 1 for pressure water-jet damage

Figure 6 — Characteristic value 2 for pressure water-jet damage


Figure 7 — Characteristic value 3 for pressure water-jet damage

Figure 8 — Characteristic value 4 for pressure water-jet damage

Figure 9 — Characteristic value 5 for pressure water-jet damage

 
Annex A
(normative)
Calibration of the test apparatus
A.1 Apparatus ａnd materials
Ordinary laboratory apparatus, as well as the following.
A.1.1 Temperature measuring device, with sensor, capable of measuring to 0,5 °C.
A.1.2 Balance, weighing to 10 g.
A.1.3 Time measuring device (swatch), capable of measuring ± 0,1 s.
A.1.4 Container, for the determination of the volumetric flow rate for at least 20 l of water.
A.1.5 Plastic block, made of polystyrene rigid plastic foam.
The kind of the polystyrene rigid plastic foam shall be agreed by the interested parties.
A.1.6 Length measuring device, capable of measuring ± 0,1 mm.
A.2.4 Calibration of the water jet
The conditions for the calibration of the jetting are in accordance with method B. For the calibration of
the jetting, a stainless steel precision flat film extrusion die with a volumetric flow rate of the nozzle of
6 l/min at 2 MPa (20 bar) ａnd a jet angle 25° is used. This nozzle is required to produce an even liquid
distribution during the entire jetting.
When using an automatic pressure-water apparatus, fasten the polystyrene rigid plastic foam in the
apparatus so that the jet cannot move the block. When using a manual apparatus, fasten the block in a
similar fixture.
After jetting, the length ａnd the width of the impact are measured. See Figure A.1.
The mean length of the impact shall be (73 ± 5) mm ａnd the mean width (8 ± 1) mm on average.


Figure A.1 — Measures of the washed-out areas in the polystyrene rigid plastic foam

原创作者：上海鼎振仪器设备有限公司