Fire-resistant Paint Mil Gauge and Coating Thickness Specification

Fire-resistant coating is a kind of flame-retardant material used on the combustible substrates surface to reduce the flammability of the substrate, retard the spread of fire and increase the fire resistance of the substrate. Fire-resistant paint can be divided into B and H according to the coating thickness. The thickness is different and the fire resistance limit is different. After the coating is completed, the fire-resistant paint mil gauge is required for thickness inspection and acceptance.

1. Thickness requirements of Class B and H fire retardant coatings

(1) Type B is a thin coating fire-resistant coating, also known as intumescent fire-resistant coating. The thickness is generally 2-7mm. The coating will swell and thicken when exposed to high temperatures.
       (2) Type H is a thick coating type fire-resistant coating, also known as a fire-resistant thermal insulation coating. Generally, the coating thickness is 8-50mm. The coating has granular surface, low density, low thermal conductivity and heat resistance limit of 0.5-3 hours.

2.  Fire-resistant coating thickness specifications

(1) The thick-coated steel structure fireproof coating thickness is 8-45mm. The fire resistance limit of this coating is 0.5-3 hours. It does not swell when exposed to fire. Its coating material has heat absorption, which can delay the temperature rise of steel and protect steel parts.
       (2) The thin coating fireproof coating thickness for steel structure is 3-7mm. It is generally used on building steel structures whose fire resistance limit is not more than 2 hours. The coating material expands and foams when exposed to fire, thereby forming a fire-resistant insulation layer to delay steel. 
       (3) The ultra-thin steel structure fireproof coating thickness is not more than 3mm. It is generally used on building steel structures that require a fire resistance limit of not more than 2 hours. The coating material expands and foams when it is exposed to fire, forming a dense fire insulation layer. New varieties developed in recent years.

Since the fire-resistant coating thickness must be specified, the fire-resistant coating thickness must be tested after coating. Linshang LS223 is a professional fire-resistant paint mil gauge, the measuring range of the LS223 + F5N3 probe is 0-5mm. This fire-resistant paint mil gauge is dual-use for both iron and aluminum. The minimum measurable substrate thickness is Fe: 0.2mm / NFe: 0.05mm. The accuracy of the instrument is ≤ ± (5% of reading + 2μm), which ensures that the instrument can pass the inspection of the Chinese National Metrology Institute.