Shimming - Reverse Osmosis Plant

Advanced Reverse Osmosis Technology

Shimming - It is normal to have some movement of the membrane elements within their pressure vessel housings. This occurs because the pressure drop across the elements can cause them to compress. Fouling or high flow rates can result in significant movement, mostly when the system starts up. When it shuts down, the elements will then relax.

This movement will cause rubbing against the inter-connector O-rings, particularly in the lead end elements. With time, this can cause them to abrade and possibly break. In case of severe pressure drops, O-rings can be completely dislodged and blow out of their slots.

The potential for this movement should be minimized by making certain that the elements fit tightly within their pressure vessel. Any slop should be taken up with shims.

Shims are slices of plastic piping that have an inside diameter that just fits over the outside of an end connector, usually the end connector between the lead end element and the vessel end cap. Enough should be installed so that replacing the end cap in its vessel should be met with some resistance.

For further information or assistance please contact Reverse Osmosis Chemicals International on +44 (0) 161 877 2334 or e-mail info@rochemicals.com.