BS 750:2006 pdf download

BS 750:2006 pdf download.Specification forunderground fire hydrants and surface boxframes and covers.
7 Stem drive
7.1 Dimensional and performance requirements
The stem shall be provided with a cast iron cap conforming to
BS 5163-2.
7.2 Closing direction
The hydrant shall be closed by turning the stern in a clockwise direction when viewed from above (as required in BS EN 14339).
8 Draining system
8.1 Each screw-down type hydrant and each duck-foot bend on a wedge-gate type hydrant shall be provided with a drain boss on the outlet side. It shall be located at the lowest practicable point that will permit the fitting of a blank plug, drilled drip plug or self operating frost valve.
NOTE The requirements of the draining system are taken from
BS EN 14339.
8.2 Where fitted to the hydrant, the draining system shall perform in accordance with BS EN 1074-6:2004, 5.6. In addition, the manufacturer shall declare the volume of retained water and the time for draining.
9 Coating
9.1 All ferrous components liable to corrosion shall be prepared and coated in accordance with WIS 4-52-0 1 and WIS 4-52-02 or other equivalent standard.
NOTE Where an equivalent standard is chosen, its equivalence should be demonstrated.
9.2 Fasteners involved in the construction of a hydrant shall either be of an appropriate grade of stainless steel having a minimum chromhtrn content of 13% or be coated in accordance with WIS 4-52-03 or equivalent standard for a barrier and galvanic coating system.
NOTE Where an equivalent standard is chosen, its equivalence should be demonsti a ted.
9.3 Details of coating process or standard used shall be declared in the manufacturer’s literature.
10 Maintenance of water purity (potable water systems only)
All non-metallic parts of the hydrant, including materials, lubricants and coatings, which may be in contact with water intended for human consumption shall be in accordance with BS 6920-1.
11 Type requirements
11.1 General
A single set of tests only is required to ascertain that the hydrant design meets the stated requirements of the relevant part of this standard and
BS EN 1074-1, BS EN 1074-2, BS EN 1074-6 and BS EN 14339.
11.2 Hydraulic characteristics
‘When fitted with a standard round thread outlet as shown in Figure 3, the hydrant shall have a K. value of not less than 92.
NOTE K,, is defined in BS EN 14339. The K,, value of 92 is equivalent (02000 1/mm at 170 kPa (1.7 bai).
11.3 Load/deflection requirements of screwed outlets
11.3.1 Ten sample outlets shall be subjected to the test method of A. 1.
11.3.2 Five of these samples when sub.jected to the procedure
of A.1.3.1 shall have exhibited a maximum angular deflection of not greater than 7.5° and shall have a residual angle of deflection of not greater than 2°, both measured from the unloaded datum position.
11.3.3 The samples, in addition, shall exhibit no fractures and shall not have suffered damage so as to prevent subsequent reconnection of the standpipe.
11.3.4 The remaining five samples when subjected to the test method of A. 1.3.2 shall exhibit no leakage during the test.
11.4 Strength and leak-tightness requirements of
type 2a and type 2d screwed outlets: Resistance of screwed outlets to rotational force
Outlets shall be tested in accordance with A.2. The following shall apply.
a) There shall be no visually detectable movement of the outlet
occurring during the application of the initial (50 ± 2.5) Nm torque in either direction.
b) Outlets shall withstand a torque of (300 ± 15) Nm applied in both clockwise and anticlockwise directions for a minimum of 30 s
whilst subjected to the pressures specified with no visible signs of leakage at the outlet/body joint for the duration of the test.
c) There shall be no damage that would impair subsequent
performance of the hydrant or connection of a standpipe.
d) The total rotational movement (from fully clockwise to fully
anticlockwise) durmg the application of the (:300 ± 15) Nm torque shall not exceed 10°.
Leakage at the outlet/body joint, when testing with oniy one of the security systems, shall not be deemed a failure.