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Unless otherwise agreed, the drawing and specification of standard Sinomas NPT fusible plugs are as follows:

drawing of NPT fusible plugs from Sinomas

Thread sizes H(mm) T(mm) S(mm) φ(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

φ stands for the diameter of the central venting hole.

HS code:8481809000
Yield temperature: per specified
Tolerance of yield temperature: ±3K(normally within ±1.5K)
Material of plug body: Brass  or stainless steel
Alloy: eutectic alloy with several components
Test pressure: 3.5 MPa (high pressure upon request)
Max service pressure: 10 MPa for brass, 50 MPa for stainless steel


Please supply the following information when you order fusible plugs from us:

  1. plug body material
  2. yield temperature
  3. thread specification
  4. drawing (if different from the drawing above)
  5. other requirements
  6. order quantity

Material certificate and test report can be supplied upon request. Minor service fee may be charged depending on your requirement and order quantity.

Application note:

  • We make sure that all our products function as they are designed to be. However it is the customer's responsibility to choose the right fusible plug for their application.
  • Apply anaerobic sealing adhesive or thread sealing tape for installation to avoid leakage.
  • Please check with us if the service pressure of your application is higher than 5.0 Mpa.
  • Fusible plug does not protect against over-pressure from improper charging practices. In other words, fusible plugs only operate on over temperature instead of over pressure.
  • We strongly recommend to replace the fusible plug after 12 - 18 months of service.

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