Chemical Compatibility
What is chemical compatibility?
Chemical compatibility is of crucial importance with pumps. It details how compatible a liquid is with a material giving an indication of the material lifespan in conjunction with the liquid being conveyed. Every material's strength is dependent on the conditions it faces.
Effects of chemical incompatibility include:
Attack – chemical attacks material causing etching, which leads to a cavity then material failure
Swelling – gasket or plastic swells rendering useless or catching casing and damages
Brittleness – material becomes hard and brittle shortening life span
Dissolution – material dissolves in liquid
What affects chemical compatibility?
Chemical compatibility is affected by two essential points:
Concentration – the concentration of the particular chemicals in contact with the liquid. Some materials are compatible with fluids at low concentration but when it increases are no longer suitable.
Temperature – the temperature of the pumped chemical as resistance usually changes at multiple temperatures
Chemical compatibility ratings:
A - Excellent - completely compatible with liquid
B - Good - minor effect - slight corrosion – not ideal for longevity but ok
C - Fair moderate effect not suitable for continuous use – flush material between use
D - Severe effect – do not use. Emergency use only as product failure is likely
X - Information not available – material hasn’t been tested for compatibility or manufacturer has not revealed chemical makeup due to confidentiality
Is chemical compatibility everything?
Although a liquid may be compatible with a fluid, other checks must be made. Examples include flammable liquids as plastics are not atex rated unless impregnated with carbon to allow conductivity.
Some liquids may be compatible but can be abrasive meaning a shortened material lifespan, while other liquids crystallise when contact with air is made meaning they can become abrasive.
Can you pump all chemicals?
Sometimes pump manufacturers are asked if they can pump all chemicals. We can check compatibility and select a combination to suit as many fluids as possible but having one solution for all is not realistic.
