This should be constructed of mild steel plate at least 6mm thickness. Stainless steel is also eminently suitable although expensive. Galvanising is undesirable. At best it will be blackened by alkalis and at worst may cause dissolved Zinc to be present in the stripper and therefore in the rinse water. GRP, PVC and rubber linings are unsuitable. Very small installations could consider polypropylene tanks but there is a possibility that these may be distorted or stress cracked by solvents.

A lid is highly desirable which should be closed when the tank is not being loaded, unloaded or replenished. This will cut down any vapours in the working environment and act as an additional fire precaution.

Fit a frame on the tank base upon which stillages of work may rest, free of any sludge which may have fallen to the bottom of the tank. Allow sufficient room for any heating elements that may be required. Ensure the work in the tank does not come into contact with any other pipework or other submerged components.

The removal of the stripped residue will be enhanced by agitation to wash away the powder from the metal surface. This can be achieved by vigorous circulation. In our experience the use of eductors gives the best result. Sparge pipes are less effective in long tanks. Air agitation is also a possibility but care should be taken to avoid spray or solvent aerosols.

Eductors along tank length

Sparge Pipe

Make flange connections for the outlet pipes to the two pumped circuits about 20cm from the tank base. Make provision for the return pipes to the opposite end of the tank. The pipe from the circulation pump should be taken to a sparge pipe 20 cm above the tank base or to eductors in the lower level of the solution as recommended by their supplier. Stainless steel bolts for the flange connections are worthwhile. Gasket material should be PTFE. The gravity return from the filter press should be returned below the lowest solution level.

Tanks should be regularly inspected for leakage. In the event a serious leak could cause contamination of a water course or sewer, the tank should be bunded to 110% of its volume.

Tank Heating

WR-STRIP is normally used at 40°C up to 50°C maximum. As WR-STRIP has a Flash Point of about 100°C it is not suitable for heating with any naked flame either directly or indirectly. There are several methods which may be used. A well insulated oil jacket to the outside of the tank is ideal, stainless steel low current density heaters can be easily put into the tank but they should be mounted on a frame enabling them to be lifted out of the tank without needing to disturb the wiring for regular cleaning. Allowing sludge to bake on them will reduce their efficiency and shorten their life considerably.

Heating by steam or hot water circulated through a coil in the tank is also suitable BUT any leakage will contaminate the WR-STRIP which may alter its efficiency or at worst necessitate disposing of it. If liquids or steam are circulated in the solution, the pipework must be 316 grade stainless steel.

Rinse Tank

A separate unheated tank, otherwise identical in construction to the stripping tank is required for rinsing. Air agitation is highly beneficial. Consider filtration of stripped residues and neutralisation in order to prolong the life of the rinse water. Discharge the rinse water to a sewer only with the consent limit set by your Waste Disposal Authority. WR-STRIP rinse waters are expected to be far more suitable for discharge than rinse water from Methylene Chloride strippers.