3  Application and maintenance

3.1  The application shall be conducted in accordance with the design working pressure noted on hose to prevent the hose from rupture and damage caused by excessive pressure or shortening the service life of hose and resulting in the danger of human injury.

3.2  During laying the hose, sudden twist shall be avoided to prevent from hydraulic pressure resistance reducing; and the torsion shall also be avoided to prevent the hermaphroditic hose coupling from disengaging due to hose rotation after filling water.

3.3  Where the hose is laid vertically, it should be fixed at intervals of about 10 m to prevent from missing the opportunity for combat and crushing personal due to hose fracture.

4.3  Length

The length and size tolerance of hose shall be in accordance with those specified in Table 2.

Table 2                                                                     In: m

4.4  Design working pressure, test pressure and minimum burst pressure

The design working pressure and test pressure of hose shall meet those specified in Table 3, and the minimum burst pressure shall not be less than those specified in Table 3. When the hose blasts, warp broken condition shall not occu

Table 3                                                                              In: Mpa

4.5  Seepage amount of wet hose

4.5.1  Under 0.5MPa hydraulic pressure, the water seepage on the wet hose surface shall be uniform and free of water jetting phenomenon; the seepage amount within 1min shall be greater than 20 mL/m·min.

4.5.2  Under the design working pressure, the wet hose shall be free from water jetting phenomenon and the seepage amount within 1min shall not be greater than those specified in Table 4.

Table 4                                                                     In: mL/m·min

4.6  Mass per unit length

The mass per unit length of hose shall not exceed those specified in Table 5.

Table 5                                                                              In: g/m

5  Test Methods

5.1  Appearance quality inspection

5.1.1  Braid layer appearance inspection

Unfold and spread out the specimen and then inspect it visually to judge whether it meets the requirements of 4.1.1.

5.1.2  Lining (or cover layer) quality inspection

Randomly split 1m long specimen and inspect it visually to judge whether it meets the requirements of 4.1.2.

5.2  Inside diameter measurement

5.2.1   The inside diameter of specimen shall be measured by a plug gauge. The plug gauge is made of metal, its structure is as shown in Figure 1, its size and tolerance shall be according to those specified in Table 7 and the surface roughness, Ra, of working portion shall be 1.60.

5.3  Length measurement

Unfold and spread out the specimen and then measure the length by a steel tape. Where the hose length does not exceed 50m, the measuring range of steel tape shall not be less than the length of sample to be measured; where the specimen length exceeds 50m, steel tape with a measuring range of 50m may be adopted for measurement by segments. The minimum indicating value of steel tape shall be 1mm.

5.4  Hydraulic test and burst test

5.4.1  During the test, connect one end of a 1.20 m long specimen with water source and seal the other end with a sealing device having exhaust valve. Keep the specimen straight and flat, fill the specimen with water and fully exhaust the air therein, and close the exhaust valve. Boost the pressure to the test pressure in Table 3 at a rate of 5.0 MPa/min ~ 10.0 MPa/min, keep it for 5min and the specimen shall be free from leakage. Then, boost the pressure at such rate till the specimen blasts and judge whether the requirements in Table 3 are met.

5.4.2  When the strength of materials in fabric layer is different in dry state and wet state, the burst pressure test shall be carried out according to the state with lower strength.

5.5  Measurement for seepage amount of wet hose

5.5.1  Randomly take a 1.2 m long specimen, connect its one end with water source, seal the other end with a sealing device having exhaust valve, and keep the specimen straight and flat. Water the specimen and close the exhaust valve after fully exhaust the air. Uniformly boost to 0.5 MPa and collect water for 1 min with the header tank specified in 5.5.2 after pressure maintaining for 5 min; the collected water shall be equal to the seepage amount of this specimen at 0.5 MPa hydraulic pressure. Simultaneously, inspect the water seepage uniform condition of water hose surface, subsequently, uniformly raise the hydraulic pressure to the design working pressure, keep the pressure for 5 min and then collect water for 1 min with the header tank specified in 5.5.2. The collected water shall be equal to the seepage amount of this specimen at design working pressure.

5.5.2  The test devices shall meet the following requirements:

a)  Pressure test bench: shall be in accordance with those specified in 5.4.3 a);

b)  Hydraulic pressure source: its working pressure shall not be less than the burst pressure of corresponding wet hose and the flow shall not be less than 0.55 L/s;

c)  Pressurizer: shall be in accordance with those specified in 5.4.3 c);

d)  Pressure display device: shall be in accordance with those specified in 5.4.3 d);

e)  Header tank: shall be made from smooth and nonabsorbent material, its length is (1,000 ± 5) mm and its width and depth shall not be less than 100 mm;

f)  Glass measuring cylinder: its precision shall not be less than 10% of the measured seepage amount;

g)  Stopwatch: its accuracy shall not be less than ± 1s (within 15 min).

5.6  Inspection on mass per unit length

During test, weigh out the mass of the full disk of specimen and then measure the specimen length according to those specified in 5.3.

The mass per unit length shall be calculated according to Formula (1):

A=G/L                                                                                                 (1)

Where,

A- the mass per unit length, g/m;

G- the mass of specimen, g;

L- the measured length of specimen, m.

5.7  Elongation, expansion rate and torsion direction tests

5.7.1  The specimen length shall not be less than 15 m; connect one end with hydraulic pressure source and fix the another end on the special fixture. Water the specimen and close the exhaust valve after fully exhaust the air. Boost the pressure to 0.1 MPa, determine the specimen length and the arithmetic mean value of specimen perimeters at both ends and the center when the specimen extension is stable; then, uniformly boost the pressure to the design working pressure specified in Table 3, and again determine the specimen length and the arithmetic mean value of specimen perimeters of the corresponding three positions and observe its torsion direction after the specimen extension is stable.

The elongation and expansion rate shall be calculated according to Formula (2) and Formula (3):

                                                     (2)

Where,

ΔL- the elongation of specimen, %;

L0- the length of specimen at the pressure of 0.1 MPa, m;

L1- the length of specimen at the design working pressure, m.

                                                      (3)

Where,

ΔS- the expansion rate of specimen, %;

S0- the arithmetic mean value of specimen perimeters of three positions at the pressure of 0.1 MPa, mm;

S1- the arithmetic mean value of specimen perimeters of three positions at the design working pressure, mm.

5.7.2  The test devices shall meet the following requirements:

a)  Test bench: its effective length shall not be less than the specimen length and measures shall be taken to reduce the friction between test bench and hose. Special fixture shall be able to move longitudinally and rotate axially around the specimen. Test bench shall be equipped with exhaust valve;

b)  Hydraulic pressure source: shall adopt with double cylinder or above electric reciprocating pump and its working pressure shall not be less than the design working pressure of specimen;

c)  Pressurizer shall be in accordance with those specified in 5.4.3 c);

d)  Pressure display device: the lower measuring limit is 0, the upper measuring limit is 1.5 to 2.0 times of the design working pressure of specimen and the precision shall not be less than ± 0.03 MPa;

e)  The steel tape shall be in accordance with those specified in QB/T 2443.

5.8  Bendability test

5.8.1  After the test in 5.7, clamp the specimen on the bending test device, water and fully exhaust the air therein, close the exhaust valve and uniformly adjust the pressure to 0.8 MPa. Judge whether the test result meets the requirements of 4.8.

5.8.2  The test devices shall meet the following requirements:

a)  Bending test rack: the structure sizes are as shown in Figure 2 and R in the figure is the hose bending radius specified in Table 6;

b)  Hydraulic pressure source: shall adopt with double cylinder or above electric reciprocating pump and its working pressure shall not be less than 0.8 MPa;

c)  Pressure display device: the lower measuring limit is 0, the upper measuring limit is 1.6 MPa and the precision shall not be less than ± 0.03 MPa.

5.9  Adhesion test

5.9.1  The shape and dimension of specimen shall be same as those of the pressure-holding surface of pressing block. During the test, wash out and wipe up the lining (or cover layer ) surface of specimen, overlap the two linings (or cover layers) in opposite direction, place it in the electrically heated drying oven at (55±1)℃, apply 0.01 MPa pressure to specimen and keep for 168h, and then take out the specimen; judge whether the test result meets the requirements of 4.9.

5.9.2  The test devices shall meet the following requirements:

a)  The electrically heated drying oven shall be in accordance with those specified in JB/T 5520. The temperature fluctuation is ± 1℃ and the temperature uniformity coefficient is ± 0.025;

b)  The pressure-holding surface of pressing block shall be flat and smooth and its shape is round with the diameter less than belt width.

5.10  Low temperature resistance test

5.10.1  During test, wind up the specimen (no less than 15 m) with interface, store it in a cryogenic box for 10h at (-30 ±3)℃.Carry out the test after taking the specimen out, and judge whether the test result meets the requirements of 4.10.

5.10.2  After the hose is tested according to the requirements of 5.10.1, take a 1.20 m long specimen from one end of the specimen inner ring and store it for 1h at the room temperature; and then, apply pressure to the design working pressure of specimen according to the requirements of 5.4.1. Observe whether there is leakage phenomenon on the specimen.

5.10.3  After the wet hose is tested according to the requirements of 5.10.1, take a 1.20 m long specimen from one end of the specimen inner ring and store it for 1h at the room temperature; and then, apply pressure to the design working pressure of specimen according to the requirements of 5.5.1. Observe whether there is water spray phenomenon on the specimen.

5.10.4  Both the temperature fluctuation and temperature uniformity of cryogenic box shall not exceed ±3℃. The work room dimension shall at least be able to place a stick of specimen of which the full disk has been winded up.

5.11  Physical and mechanical properties test of lining (or cover layer)

5.11.1  Adhesion strength test

The test shall be conducted according to the requirements of adhesion strength test methods in GB/T 532 and the specimen width is 25mm. Cut out three blocks from specimen along the longitude and latitude directions of specimen respectively, calculate the arithmetic mean value of inspection result of the six specimens and judge whether the test result meets the requirements of 4.11.1.

5.11.2  Elongation at break and tensile strength at break

5.11.2.1  The elongation at break and tensile strength at break tests for rubber lining shall be conducted according to those specified in GB/T 528 and judge whether the test results meet the requirements of 4.11.2.

5.11.2.2  The elongation at break and tensile strength at break tests for plastic lining and polyurethane lining shall be conducted according to those specified in GB/T 1040.1 and judge whether the test results meet the requirements of 4.11.2.

5.11.3  Hot air aging test

5.11.3.1  The specimen for hot air aging test and its contrastive specimen shall cut out at the adjacent positions of specimen; place the specimens on the specimen holder in the hot air aging box with the distance between specimen and box wall not less than 70 mm; conduct the test for 168h at (70 ± 1)℃.

5.11.3.2  Determine the adhesion strength of aged specimen according to those specified in 5.11.1.

5.11.3.3  Determine the burst pressure of aged 1.20 m long specimen according to those specified in 5.4.

5.11.3.4  The test devices shall meet the following requirements:

a)  The hot air aging box shall be in accordance with those specified in JB/T 7444. Its temperature fluctuation shall not be greater than ± 1.5℃ and temperature uniformity shall not be greater than ± 1℃;

b)  The material tester measuring adhesion strength shall be in accordance with those specified in GB/T 532 and the tension tester measuring the elongation at break and tensile strength at break shall be in accordance with those specified in HG/T 2369.

5.12  Abrasion resistance test

5.12.1  Cut out three segments of specimen (no less than 500 mm) with same variety, same specification and same material.

5.12.2  During the test, connect one end of the specimen with water source and seal the other end with a sealing device having exhaust valve. Keep the specimen straight and flat, fill the specimen with water and fully exhaust the air therein, and close the exhaust valve. Boost the pressure to 0.5 MPa and change the hydraulic pressure between 0.45 MPa and 0.55 MPa. Stably rotate the sample at a speed of (27 ± 1) r/min.

5.12.3  Turn the grinding head pressure to the range of (105 ± 5)N, press it on the sample and it reciprocates at the speed of 18 mm/s ~ 21 mm/s; if the travel is 80 mm, the grinding head shall reciprocate 100 times and contact the sample with new abrasive belt in each reciprocation.

5.12.4  After the aforesaid test, remove the grinding head, stop the rotation of specimen, continue to boost the pressure to the corresponding design working pressure of specimen and keep the pressure for 5 min and judge whether the test result meets the requirements of 4.12.

5.12.5  The test devices shall meet the following requirements:

a)  Hydraulic pressure source: shall adopt triplex electric reciprocating pump and its working pressure shall not be less than the design working pressure of specimen. It shall be equipped with pressurizer and the pressure fluctuation value shall not be greater than ± 0.05 MPa after pressure stabilization;

b)  Specimen speed: the basic speed is (27 ± 1) r/min;

c)  Grinding head weight: the basic weight is (105 ± 5) N;

d)  Grinding head travel: (80 ± 1) mm;

e)  Grinding head speed: the base speed is 18 mm/s ~ 21 mm/s;

f)  The abrasive belt used for grinding head shall adopt the #240 abrasive grain belt specified in GB/T 2481.2.

5.13  Test for connection performance between hose and fire coupling

5.13.1  Randomly take two segments of specimen with fire coupling and the total length is 1.2m. Connect the fire couplings, connect the two ends of specimen with water source and sealing device having exhaust valve respectively, keep the specimen straight and flat, water specimen, close the exhaust valve after fully exhaust the air, uniformly boost the pressure to the corresponding test pressure and keep the pressure for 5 min. Judge whether the test result meets the requirements of 4.13.

5.13.2  The test devices shall be in accordance with those specified in 5.4.3.

3.4  After filled water, the hose shall be free from dragging on ground and shall specially be free from the contact with such sharp articles as nail and glass sheet. Where the hose is required to change the location, it shall be lifted and moved to reduce the abrasion between hose and ground. The hose shall not be dragged in V-shape to avoid frazzling it.

3.5  The hose shall not contact with corrosive chemicals such as oils as well as acid and alkali. If necessary, the hose with cover layer should be adopted.

3.6  The hose shall not be pressed by hard heavy objects; in case that any vehicle needs to pass through the hose being laid, the hose apron shall be arranged at the passing position in advance.

3.7  During laying, in case of passing railway, the hose shall pass under the rail.

3.8  Where the fire hose is applied outside the building in cold area, the hose shall not be frozen.

3.9  After application, the hose shall be cleaned, dried and preserved in a shady, cool and dry place in coil.