The seals, O-rings and valves - not the tank - and the failure puts chemical where the operator is.

Elastomer seals swell, soften or harden on exposure to incompatible chemistry. Once they do, the sprayer leaks at the pump collar, fails to hold pressure, or drips from the wand.

Valves stick or fail to seat, so the sprayer discharges when it should not.

The tank is generally polyethylene or polypropylene and survives far more than the seals do, which is why a sprayer can look sound and be entirely unserviceable.

The consequence is not just inconvenience: a leaking pump collar puts aggressive chemical onto the hands and forearms of whoever is pumping.

That is why aggressive products belong in a sprayer specified for them, rather than in whatever is available.

Only when the chemicals are named - resistance is specific, and a seal that survives one product may be destroyed by another.

There is no universal chemical resistance. Fluoroelastomer grades resist many solvents and are attacked by certain other chemistries; other polymers show the opposite pattern.

A label saying 'chemical resistant' without a compatibility chart tells you almost nothing.

Manufacturers publish charts listing chemicals against seal materials with ratings. Those charts are the specification and should be consulted before purchase.

Concentration and temperature both matter - a seal rated for a dilute acid may fail at concentrate strength or when warm.

Where the chemical is not on the chart, ask the chemical supplier and the sprayer manufacturer rather than assuming.

Solvents, strong acids, strong alkalis, oxidisers and some concentrated disinfectants - essentially anything beyond ordinary dilute cleaning chemistry.

Solvent-based products, including many degreasers, graffiti removers and adhesive removers, attack standard seals quickly.

Strong acids used for descaling, masonry cleaning and urinal maintenance need resistant seals and, usually, a resistant wand and nozzle.

Strong alkalis - oven cleaners, heavy degreasers, caustic products - degrade some elastomers and many plastics.

Oxidisers including concentrated hypochlorite and peracids are hard on seals over time.

Ordinary dilute detergents, general disinfectants and neutral cleaners are fine in standard equipment, which covers most day-to-day cleaning.

The rule of thumb: if the product needs gloves and eye protection to handle at concentrate strength, check the sprayer specification.

Yes - mixing residues is a safety hazard, and dedication is simpler and safer than relying on flushing.

Residue from one product meeting another can neutralise it, react, or produce hazardous gas. Acid meeting hypochlorite is the classic example and it happens in shared equipment.

Flushing rarely reaches every part of the path - the dip tube, hose, valve and nozzle all retain product.

Dedicating each sprayer to one product and labelling it clearly removes the problem entirely.

Colour coding or colour-coded tags reinforce it, especially where staff share equipment.

The cost of an extra sprayer is trivial against the consequence of mixing, and it also means seal material can be matched to each product rather than compromised across several.

Whatever the chemical's safety data sheet specifies, plus the recognition that spraying creates aerosol and increases exposure.

Spraying an aggressive chemical is a higher-exposure activity than pouring or wiping it, because fine droplets remain airborne and drift back to the operator.

Eye protection that seals - goggles rather than open safety glasses - is appropriate for anything corrosive.

Gloves must be a material rated for the chemical, with cuffs over the sleeve.

Respiratory protection should be considered for spraying corrosives, solvents or anything with an exposure limit, particularly in enclosed spaces.

Ventilation matters. Spraying solvent in a small unventilated room is a recognised cause of injury.

The safety data sheet governs, and it needs to be at the point of use rather than in an office.

Visually at each use, with a seal kit fitted as soon as swelling, hardening or leaking appears - not after a failure.

Seals that have swollen look larger and feel soft or tacky. Hardened seals look normal and have lost their flexibility, which shows as a sprayer that will not hold pressure.

Leaks at the pump collar and drips from the wand valve are the operational symptoms.

Most sprayers have seal kits available, and fitting one takes minutes and costs a fraction of a new sprayer.

Keep a kit in stock for each sprayer type in use, since a sprayer out of service usually means the aggressive chemical gets put in an unsuitable one.

Record the chemical each sprayer holds and inspect on a schedule - seals degrade gradually and the failure point is not obvious until pressure is applied.

Often yes - many manufacturers supply resistant seal kits for their standard sprayers, though wetted plastics and nozzles may still limit it.

Where the tank and body materials are compatible, fitting a resistant seal kit converts a standard sprayer for many applications, and it is far cheaper than replacement.

The kit must cover every wetted seal - pump, tank collar, hose fittings and wand valve - rather than just the obvious O-rings.

Dip tubes, hoses, wands and nozzles are also wetted parts and may need changing.

Some sprayers cannot be upgraded because the body or valve components themselves are unsuitable, and the manufacturer will say so.

Where the chemistry is severe, buying a purpose-built resistant sprayer is more reliable than assembling one - and it comes with a compatibility statement that an upgraded sprayer does not.