Designed as air aspirating discharge devices, Chemguard foam makers are used principally for the protection of dikes, open floating-roof storage tanks, and rim seals, and where low-velocity foam streams are desired. Foam makers generally are installed in the line of a semi-fixed or fixed foam fire-protection system, mounted either horizontally or vertically.
UL Listed, Chemguard's foam makers feature all-brass construction for use in harsh and corrosive environments. Foam maker air inlets are covered with stainless steel mesh, and the foam makers are supplied with standard NPT threaded inlets and outlets.
1. High Back Pressure Foam Makers
The Chemguard High Back-Pressure Foam Maker (CFM) is designed to produce expanded foam that is introduced into a cone roof storage tank by sub-surface injection. The sub-surface method should only be used on tanks containing standard hydro carbon based fuels such as: diesel, kerosene, gasoline, etc. It is not suitable for use on tanks that contain alcohols or polar solvent type liquids that are miscible in water. The foam maker is normally installed in a dedicated fire protection line or the tank product line and is generally located outside the dike area that surrounds the storage tank. In accordance with NFPA 11 subsurface injection is not recommended for any tank having a floating roof.
The CFM is capable of producing expanded foam with an expansion ratio of between 2:1 to 4:1. It is designed to discharge expanded foam against a back pressure, which can be as high as 40% of the operating inlet pressure of the CFM. A minimum of 100-psi inlet pressure at the CFM is recommended for satisfactory operation.
The CFM is suitable for use with various types of foam solution generating devices. These include bladder tanks, balanced pressure foam pump proportioning systems, in-line balanced pressure proportioning units and foam pumper trucks. Unless high water pressure is readily available, in-line eductorsare generally not suitable for use with sub-surface systems, because in-line eductors have a relatively high-pressure loss through the eductor. The residual pressure available on the discharge side of the eductor is often not high enough to ensure correct operation of the CFM and overcome friction loss in the piping and head pressure of the product stored within the storage tank.