Fusible Loop on Pumps

Regarding installation on fusible loop around process pumps and motors, how close should the fusible loop be around the pumps?

I saw an installation that has fusible loops plugs pointed directly at pump shafts where the process temperatures and the heat from the shaft could cause the plug to fail.

Looking at the installation I personally think this installation is wrong and is not a proper but would greatly appreciate any help from anyone on this forum with pictures and guidance on how a fusible loop can be installed and how far should a plug be from the system that it was designed to protect.

I will try add some pictures soon.

1 Like

The specific installation distance and positioning of fusible loops can vary depending on several factors including the type of equipment, the potential for heat generation, the melting point of the fusible plug, and industry or local safety standards.

Fusible loops function through the melting of the fusible plug, which is typically designed to melt at a specific temperature indicative of a fire or excessive heat situation. If the plug is placed in direct proximity to a heat source under normal operating conditions, such as a pump shaft, there is indeed a risk that it could melt prematurely and activate the fire protection system, even when there is no fire.

Fusible loops

Here are some general guidelines for fusible loop installation, but remember to consult with a safety engineer or other qualified professional to ensure compliance with all relevant standards and safety requirements:

  1. Away from Normal Heat Sources: The fusible loop should be positioned away from areas where it might be exposed to high temperatures during normal operation.
  2. Close to Potential Fire Sources: While it should not be in contact with normal heat sources, the fusible loop should be close enough to potential fire sources that it will quickly detect a fire if one starts.
  3. Not in Direct Contact: The fusible loop generally should not be in direct contact with equipment surfaces, as this could lead to premature melting.
  4. Maintain Safe Distance: As a general guideline, maintaining a distance of around a foot (30cm) or more from normal heat sources can help to prevent premature activation, but the specific distance can depend on many factors, including the heat output of the equipment and the melting point of the fusible plug. This is a general estimate and should be verified with an engineer familiar with the specific application and its associated risks.

Again, it’s important to consult with a safety engineer or other qualified professional to make sure your installation is appropriate for your specific situation and compliant with all relevant safety standards. Also, manufacturer guidelines should be followed for proper installation of these safety systems.