Designed for use with Fernox TF1 in-line system filters or other similar filters, this unique inhibitor package includes an active dispersant which is proven to aid the safe collection of corrosion, debris and scale via a filter. The Protector+ Filter Fluid F9 enhances the performance of a system filter whilst offering full protection against corrosion and scale formation. This innovative, proven formulation also extends system life and maintains optimum efficiency, while still being an environmentally friendly formulation. Concentration levels should be checked as part of the annual maintenance system service.
The recommended ‘in use’ concentration of Protector+ Filter Fluid F9 is 0.385%. A single dose treats and protects a larger sized property with a heating system of 130 litres, up to 16 radiators or 250 sqm of underfloor heating. For open vented systems add via the feed and expansion tank. For sealed systems add via a suitable dosing point (e.g. a towel rail, or an in-line system filter). Alternatively, use a suitable dosing vessel to inject the product into the system. In single feed indirect cylinders, e.g. ‘Primatic’ or similar, potable water chemicals must be used. We recommend that untreated, or sludged systems are thoroughly cleaned and flushed in accordance with BS 7593:2019 and Benchmark using Fernox Cleaner F3/F8, before treating with Fernox Protector+ Filter Fluid F9, as existing debris can damage the installation.
Fernox Protector+ Filter Fluid F9 must be used with the Fernox TF1 Filter range, or other in-line system filters. Use in microbore systems is not recommended. Fernox Protector+ Filter Fluid F9 is an enhanced corrosion inhibitor, combining corrosion inhibition with dispersant properties. It is specifically formulated to prevent settling and aggregation of corrosion deposits and contaminants within central heating systems, to deliver the debris directly to an in-line filter (such as one from the Fernox TF1 Filter range) for fast removal and containment. This function allows systems to run more efficiently by minimising the settling of debris in low flow areas such as radiators, which causes cold spots, and facilitates further corrosion underneath the debris.
Protector+ Filter Fluid F9 gives long-term protection of domestic central heating systems against internal corrosion and limescale formation. It is suitable for all types of boiler, radiators and pipework systems. Protector+ Filter Fluid F9 is compatible with all metals and materials commonly used in central heating systems. It is suitable for use with all types of water, including softened water and deionised water.
Protector+ Filter Fluid F9 has been formulated to have best-in-class pH buffering ability, which keeps system water pH between 6.5-8.5, providing optimum protection for mixed-metal systems. To comply with BS 7593:2019, Protector+ Filter Fluid F9 levels should be checked annually. The concentration of the product can be easily measured on-site using a Fernox Protector Test Kit, or by using the Fernox Water Quality Test postal service. BS 7593:2019 also states that after five years, systems should either be re-dosed, or a laboratory test performed, such as the Fernox Water Quality Test.
Fernox Protector+ Filter Fluid F9 is supplied in 500 ml bottles.
Fernox Protector+ Filter Fluid F9 is classified as non-hazardous for human health, but as with all chemicals, keep out of reach of children. In case of contact with eyes or skin, rinse immediately with plenty of water.
Fernox Protector+ Filter Fluid F9 Express is a blend of corrosion and scale inhibitors and dispersants:
Form: Yellow liquid
Odour: Slightly aromatic
pH (conc): 8.4
pH (in-use): 7.8-8.5
SG: 1.17 at 20 °C
Single Unit Dimensions
Single Unit Barcode
Outer Carton Dimensions
Outer Carton Barcode (ITF)
52 × 88 × 182 mm
195 x 265 x 180 mm