5.4 水锤 Water hammer

5.4 水锤 Water hammer

5.4.1 Principle of water hammer test

The principle is to verify, that the peak of pressure is limited when the tap closes. This applies only to devices intended for use on water systems of Type 1.

5.4.2 Test apparatus

A test rig as described in Figure 15 is to be used:

Figure 15.png

Key

1 Supply by pump with variable speed drive at a static pressure of (0,5 ⁺⁰_-0,02) MPa [(50,5 ⁺⁰_-0,2) bar]

2 Air vessel of 5 l capacity half-filled with air at a static pressure of 0,5 MPa (5 bar)

3 Supply circuit comprising 9 m of copper pipe (see Table 11) wound into a coil of 260 mm internal radius minimum or composed of straight lengths incorporating a maximum of 5 bends with an internal radius greater than 260 mm

4 Pressure tee complying with EN ISO 5167-1 with pressure sensor capable of measuring 0 MPa (0 bar) to 2,0 MPa (20 bar) with a frequency of more than 5 kHz; the recording shall be made at a frequency exceeding 1 kHz

5 Tap to be tested

Figure 15 — Test rig for water hammer test

Table 11 — Dimensions of the supply pipe for water hammer test

5.4.3 Procedure

The supply circuit shall deliver cold water at a static pressure of ((0,5 ⁺⁰_-0,02) MPa [(50,5 ⁺⁰_-0,2) bar], with a pump with variable speed. Procedure of filling of the air vessel in order to fill it at 50 % air:

a) depressurize the test rig;

b) fill the vessel with compressed air to 0,25 MPa (2,5 bar);

c) pressurize the rig with water at 0,5 MPa (5 bar) by regulating the pump speed:

1) connect the sample (5) at the test rig, directly after the pressure tee (4);
2) open the tap at minimum 5 times in order to completely de-aerate the circuit;
3) adjust the static pressure at 5 bar;

d) disable speed regulation of pump;

e) operate the tap 5 s in order to stabilize the pressure, record the pressure and the flow rate;

f) allow the tap to close, whilst continually recording the pressure.

If a mixing valve is being tested, both inlets are connected, and the test is conducted at full cold, full hot and mid-blend positions. Follow the procedure 3 times.

5.4.4 Requirements

The average of the 3 tests of the peaks of pressure for each position (hot, cold, mid-blend) between the maximum pressure on closure and the static pressure of 5 bar (0,5 MPa) shall be less than or equal to 0,3 MPa (3 bar).