Phos-Chek is a brand of long-term

fire retardant A fire retardant is a substance that is used to slow down or stop the spread of fire or reduce its intensity. This is commonly accomplished by chemical reactions that reduce the flammability of fuels or delay their combustion. Fire retardants m ...

s, class A foams, and gels manufactured by Perimeter Solutions, headquartered in

Clayton, Missouri Clayton is a city in and the seat of St. Louis County, Missouri. It borders the independent city of St. Louis. The population was 17,355 at the 2020 census. Organized in 1877, the city was named after Ralph Clayton, who donated the land for the ...

Products

Fire retardants

Modular Airborne Fire Fighting System being filled with a 146th Airlift Wing C-130 Hercules in the background

Phos-Chek

s are manufactured as dry powders or as concentrated liquids and diluted with water prior to use. The retardant is applied ahead of

wildfire A wildfire, forest fire, bushfire, wildland fire or rural fire is an unplanned, uncontrolled and unpredictable fire in an area of Combustibility and flammability, combustible vegetation. Depending on the type of vegetation present, a wildfire ...

s to homes and vegetation by ground crews and

aerial firefighting Aerial may refer to: Music * ''Aerial'' (album), by Kate Bush * ''Aerials'' (song), from the album ''Toxicity'' by System of a Down Bands *Aerial (Canadian band) * Aerial (Scottish band) * Aerial (Swedish band) Performance art * Aerial sil ...

units, either

fixed-wing A fixed-wing aircraft is a heavier-than-air flying machine, such as an airplane, which is capable of flight using wings that generate lift caused by the aircraft's forward airspeed and the shape of the wings. Fixed-wing aircraft are distinct ...

or rotary-wing aircraft. As of 2022, Phos-Chek LC-95A is the most used fire retardant in the world. Phos-Chek Tank

Phos-Chek is produced in several colors, including off-white,

red iron oxide Iron(III) oxide or ferric oxide is the inorganic compound with the formula Fe2O3. It is one of the three main oxides of iron, the other two being iron(II) oxide (FeO), which is rare; and iron(II,III) oxide (Fe3O4), which also occurs naturall ...

, and a '' fugitive'' mixture that is red when dispersed but gradually fades to an earth-tone when exposed to sunlight. The red color aids aircrews in targeting drops of retardant. Some of the main components of Phos-Chek retardants include

ammonium polyphosphate Ammonium polyphosphate is an inorganic salt of polyphosphoric acid and ammonia containing both chains and possibly branching. Its chemical formula is H4 PO3sub>n(OH)2 showing that each monomer consists of an orthophosphate radical of a phosphorus ...

diammonium phosphate Diammonium phosphate (DAP; IUPAC name diammonium hydrogen phosphate; chemical formula (NH4)2(HPO4) is one of a series of water-soluble ammonium phosphate salts that can be produced when ammonia reacts with phosphoric acid. Solid diammonium phosp ...

, diammonium sulfate,

monoammonium phosphate Ammonium dihydrogen phosphate (ADP), also known as monoammonium phosphate (MAP) is a chemical compound with the chemical formula (NH4)(H2PO4). ADP is a major ingredient of agricultural fertilizers and some fire extinguishers. It also has sign ...

, attapulgus clay, guar gum (or a derivative of guar gum), and

trade secret Trade secrets are a type of intellectual property that includes formulas, practices, processes, designs, instruments, patterns, or compilations of information that have inherent economic value because they are not generally known or readily asc ...

performance additives. Fire retardants are manufactured as several different formulations with varying proportions of the above components. The

phosphate In chemistry, a phosphate is an anion, salt, functional group or ester derived from a phosphoric acid. It most commonly means orthophosphate, a derivative of orthophosphoric acid . The phosphate or orthophosphate ion is derived from phospho ...

and sulfate salts act as

s and prevent

combustion Combustion, or burning, is a high-temperature exothermic redox chemical reaction between a fuel (the reductant) and an oxidant, usually atmospheric oxygen, that produces oxidized, often gaseous products, in a mixture termed as smoke. Combusti ...

cellulosic Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of β(1→4) linked D-glucose units. Cellulose is an important structural component of the primary cell wa ...

materials. Phosphate can also act as a

fertilizer A fertilizer (American English) or fertiliser (British English; see spelling differences) is any material of natural or synthetic origin that is applied to soil or to plant tissues to supply plant nutrients. Fertilizers may be distinct from ...

once the fire danger has passed. Guar gum and

clay Clay is a type of fine-grained natural soil material containing clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4). Clays develop plasticity when wet, due to a molecular film of water surrounding the clay par ...

are

thickening agent A thickening agent or thickener is a substance which can increase the viscosity of a liquid without substantially changing its other properties. Edible thickeners are commonly used to thicken sauces, soups, and puddings without altering their t ...

s to prevent dispersal of the retardant after it is dropped from the plane. Other ingredients include corrosion inhibitors and flow conditioners. Phos-Chek and other retardants based on

ammonium phosphate Ammonium phosphate is the inorganic compound with the formula (NH4)3PO4. It is the ammonium salt of orthophosphoric acid. A related "double salt", (NH4)3PO4.(NH4)2HPO4 is also recognized but is impractical use. Both triammonium salts evolve ammoni ...

may cause algae blooms in bodies of water when washed downstream and may increase the growth of invasive plant species.

Class A foam

Phos-Chek WD-881 is a mixture of anionic surfactants, foam stabilizers, and solvents including hexylene glycol. As a fire-fighting foam, it is used as a short-term fire suppressant.

History

The first Phos-Chek retardant product was available in 1962, and was the first phosphate-based fire retardant approved by the United States Forest Service. The Phos-Chek brand belonged to the

Monsanto Company The Monsanto Company () was an American agrochemical and agricultural biotechnology corporation founded in 1901 and headquartered in Creve Coeur, Missouri. Monsanto's best known product is Roundup (herbicide), Roundup, a glyphosate-based herbic ...

until 1998, when ownership was transferred to Solutia Inc. In 2000, Astaris LLC acquired the Phos-Chek name. In November 2005, Astaris LLC was acquired by Israel Chemicals Ltd. (ICL), and the Phos-Chek brand was renamed "PHOS-CHEK Fire Safety Group" and assigned to the Performance Products division of ICL (ICL PPLP). In 2018, private investment firm SK Capital acquired the Fire Safety and Oil Additives businesses of ICL and renamed it Perimeter Solutions, and the PHOS-CHEK brand was acquired with the business.

Manufacturing

The Airbase Service Center, located in

Post Falls, Idaho Post Falls is a city in Kootenai County, Idaho, between Coeur d'Alene and Spokane, Washington. It is a suburb of Coeur d'Alene, to the east, and a bedroom community to Spokane, to the west. The population was 38,485 at the time of the 2020 cens ...

supports all bulk bases (equipment and product support to agency operated bases), SEAT bases (equipment and product support for Single Engine Air Tanker Bases), and Portable Base Operations (mobile rotor and fixed-wing bases). Various equipment maintenance and base rebuilds are performed from this location. Fabrication of liquid concentrate tanks, batch mixers, Hopper Units, and various other equipment is performed from this location.

References

External links

* {{Official, http://perimeter-solutions.com/ Fire suppression agents Flame retardants Aerial firefighting Post Falls, Idaho Companies based in Idaho Companies established in 1962