The Chemical compound NITRIC ACID otherwise known as Aqua Fortis is a colourless highly toxic acid which can cause severe burns.

In various concentrations it is used in the manufacture of explosives, fertilisers and in the refining of metals.

When combined with hydrochloric acid it forms a compound known as Aqua Regia, one of the few reagents able to dissolve gold.

With increase in heavy chemical processing in the world it is unfortunate that nitric acid is a component of acid rain.

In the application of valves and pumps, the materials of construction and linings available must be carefully selected since slight changes in concentration can have major effects on corrosion rates.

There are various concentrations of Nitric Acid and it is important to ascetain the actual concentration before selecting the valve material able to offer the economic solution to its control.

Often we are faced with ‘recommendation please’ for 100% nitric acid whereas in atual fact the client is asking for a valve to handle the normally available grade of 63% nitric acid.

100% nitic acid has the ability, in some cases, to cause wood to spontaniously ignite whereas 63% would not cause this phenomina.

Below is a table showing the percentage concentration vs specific gravity and it is this initial data that is the basic starting point needed to ensure correct valve choice.

The following chart offers an indication as the materials available for Diaval Diaphragm Valves and its diaphragms.

If in doubt then please contact the Technical Section of Diaval for material recommendations.