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19
2026
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01
Red Alert: 68℃ ZST Fire Sprinklers - The Fire Protection Code of Two Sizes
In automatic sprinkler systems, 68℃ ZST standard fire sprinklers are the "basic guardians" of building fire protection. The two mainstream sizes, 1/2-inch and 3/4-inch, directly determine fire suppression efficiency and application scenarios. Beneath these seemingly minor specification differences lies a rigorous fire protection design logic. This article will unlock the core knowledge points for you.
In automatic sprinkler systems, 68℃ ZST standard fire sprinklers are the "basic guardians" of building fire protection. The two mainstream sizes, 1/2-inch and 3/4-inch, directly determine fire suppression efficiency and application scenarios. Beneath these seemingly minor specification differences lies a rigorous fire protection design logic. This article will unlock the core knowledge points for you.
I. Core Understanding: What is a 68℃ ZST Fire Sprinkler?
ZST is the general code for sprinkler heads in automatic sprinkler systems. The prefix "ZS" stands for automatic sprinkler system, "T" specifically refers to sprinkler head, and subsequent letters distinguish installation types (e.g., Z for upright type, X for pendent type). This type of sprinkler uses a glass bulb filled with thermal expansion liquid as the heat-sensitive element. 68℃ is its nominal operating temperature, corresponding to a red glass bulb color code, making it the most commonly used specification in civil buildings.
According to the national standard GB 5135.1-2019, the operating temperature of a 68℃ sprinkler must be at least 30℃ higher than the maximum ambient temperature. It is suitable for most general environments such as offices, shopping malls, and residences. When a fire breaks out, the ambient temperature rises to the threshold, the glass bulb bursts, and water sprays automatically to achieve early fire control.
II. Key Differences: Showdown Between 1/2-Inch and 3/4-Inch Sizes
The core differences between the two sizes lie in flow characteristics, application scenarios, and installation compatibility. Specific parameters and applications can be clearly distinguished through the following points:
1. Core Parameter Differences
The 1/2-inch (DN15) sprinkler corresponds to a connecting thread R1/2, with a nominal flow coefficient K=80±4. Under standard pressure (0.1MPa), the flow rate of a single sprinkler is approximately 80L/min. The 3/4-inch (DN20) sprinkler has a thread R3/4 and a flow coefficient K=115±6, achieving a flow rate of up to 115L/min under the same pressure with a wider water spray coverage. Both have a rated working pressure of 1.2MPa, and the factory test pressure must reach 3.0MPa to ensure structural strength.
2. Application Scenario Division
With moderate flow rate and compact size, the 1/2-inch sprinkler is suitable for light hazard areas, such as small offices, residential bedrooms, convenience stores, and other small spaces. The protection area of a single sprinkler generally does not exceed 16㎡, and it is compatible with pipes of DN20 and below. It is widely used in simple sprinkler systems for "small-scale venues", and a DN25 pipe can carry up to 6 such sprinklers.
The 3/4-inch sprinkler, with larger flow rate, is suitable for medium hazard areas, such as large shopping malls, warehouses, and hospital outpatient buildings. It can quickly cover larger spaces and cope with scenarios with higher combustible density. It requires a compatible pipe diameter of ≥DN25, which can meet higher fire water demand, especially suitable for scenarios where pipe network pressure is limited but flow rate needs to be increased.
3. Installation and Selection Notes
Selection should be based on the hazard level of the venue, space size, and pipe network design: for light hazard and compact spaces, the 1/2-inch sprinkler is preferred for higher cost-effectiveness; for medium hazard, large spaces, or areas with more combustibles, the 3/4-inch sprinkler is required to ensure fire suppression efficiency. Meanwhile, the color code of the glass bulb of both sprinklers must not be covered by paint to avoid affecting thermal sensitivity, and the integrity of the glass bulb should be regularly inspected after installation.
III. Common Misconceptions and Code Points
Many people believe that the larger the size, the better, but this is not the case: blindly selecting 3/4-inch sprinklers will increase the pressure load of the pipe network. If the pipe pressure is insufficient, the water spray effect will be reduced instead. In addition, 68℃ red sprinklers cannot be used in high-temperature areas such as kitchens and boiler rooms; 93℃ green sprinklers should be selected for such areas to avoid false activation.
According to fire protection codes, the distance between the sprinkler deflector and the ceiling must comply with regulations and must not be blocked. Both sizes of sprinklers must pass CCCF certification or ISO standard testing to ensure they meet safety requirements.
As the "first line of defense" in building fire protection, the size selection of 68℃ ZST sprinklers is directly related to fire suppression effectiveness. The 1/2-inch size is designed for precise adaptation to small spaces, while the 3/4-inch size focuses on high-flow fire control. Only by selecting on demand and installing in accordance with regulations can this "red guardian" truly fulfill its role.
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