fusible plugWe are able to produce any fusible plugs according to customer specification regarding the size, type of thread and the body material. In practice NPT fusible plugs of the following sizes and yield temperatures are considered to be standard models. These plug bodies, both brass and stainless steel, are readily in stock. Their delivery time is normally shorter.

Standard model chart

Yeild Temp. Brass Stainless Steel
°F °C 1/8"NPT 1/4"NPT 3/8"NPT 1/2"NPT 1/4"NPT 3/8"NPT 1/2"NPT
136 58 AQS18-58 AQS14-58 AQS38-58 AQS12-58 AQS14-58SS AQS38-58SS AQS12-58SS
160 71 AQS18-71 AQS14-71 AQS38-71 AQS12-71 AQS14-71SS AQS38-71SS AQS12-71SS
165 74 AQS18-74 AQS14-74 AQS38-74 AQS12-74 AQS14-74SS AQS38-74SS AQS12-74SS
195 90 AQS18-90 AQS14-90 AQS38-90 AQS12-90 AQS14-90SS AQS38-90SS AQS12-90SS
212 100 AQS18-100 AQS14-100 AQS38-100 AQS12-100 AQS14-100SS AQS38-100SS AQS12-100SS
230 110 AQS18-110 AQS14-110 AQS38-110 AQS12-110 AQS14-110SS AQS38-110SS AQS12-110SS
255 124 AQS18-124 AQS14-124 AQS38-124 AQS12-124 AQS14-124SS AQS38-124SS AQS12-124SS
280 138 AQS18-138 AQS14-138 AQS38-138 AQS12-138 AQS14-138SS AQS38-138SS AQS12-138SS
350 177 AQS18-177 AQS14-177 AQS38-177 AQS12-177 AQS14-177SS AQS38-177SS AQS12-177SS
360 182 AQS18-182 AQS14-182 AQS38-182 AQS12-182 AQS14-182SS AQS38-182SS AQS12-182SS
390 199 AQS18-199 AQS14-199 AQS38-199 AQS12-199 AQS14-199SS AQS38-199SS AQS12-199SS
445 229 AQS18-229 AQS14-229 AQS38-229 AQS12-229 AQS14-229SS AQS38-229SS AQS12-229SS


fusible plug drawingThe dimension of our standard NPT fusible plugs are as follows:

Thread size H (mm) T (mm) S (mm) Orifice (mm)
1/8"NPT 16 5 12 5
1/4"NPT 21 6.5 14 5
3/8"NPT 20 6 17 7
1/2"NPT 29 8 22 8


Tolerance of yield temperature: ±3K
Plug body material: brass / stainless steel
Fusible alloy: eutectic alloy with several components
Test pressure: 3.0 MPa (higher pressure upon request)
Max service pressure: 5 MPa for brass, 15 MPa for stainless steel
HS code:8481809000