LPS 1258 Issue 1.2 Requirements and test methods for automatic sprinkler glass bulbs with a narrow operating temperature band
This Standard defines the LPCB’s certification requirements for glass bulbs with a narrow operating temperature band for use in sprinkler heads that are intended for use in automatic sprinkler installations.
Nominal Release Temperature
The nominal release temperature and liquid colour of glass bulbs with a narrow operating temperature band shall be as specified in Table 1.
Operating Temperature
Glass bulbs with a narrow operating temperature band shall operate within the temperature range specified in Table 1 when tested in accordance with Clause 3.
Note: The minimum operating temperatures correspond to the requirements of EN 12259-1:1999, clause 4.4.2. The maximum operating temperatures are derived from the equation t ± (0.035t + 0.62)°C, where t is the nominal release temperature.
STATIC OPERATING TEMPERATURE TEST
The test shall be carried out in the liquid bath shown in Figure 1.
Glass bulbs having nominal operating temperatures less than 80°C shall be tested in a bath of demineralised water. Glycerine, with properties as specified in Table 2, shall be used for testing glass bulbs with higher nominal operating temperatures.
The test zone is located (40 ± 5)mm below the liquid surface and the temperature deviation within the test zone shall not exceed ±0.25°C.
The glass bulbs shall be located vertically, pip down, with the bulb centre within the test zone.
The operating temperature shall be measured with equipment calibrated to an immersion depth of 40mm and having an accuracy of ±0.25% of the glass bulb nominal operating temperature rating.
Properties of Glycerine
A sample of fifty glass bulbs of the same model and nominal release temperature shall be heated from a temperature of (20 ± 5)°C to (20, +2, -0)°C below their nominal operating temperature. The rate of increase of temperature shall not exceed 20°C / minute and the temperature shall be maintained for 10 minutes. The temperature shall then be increased at a rate of (0.5 ± 0.1)°C / minute until the glass bulb operates. The temperature of operation of each glass bulb shall be measured and recorded.