Various manufacturers have developed their own cross-flow plates for coalescing oil, probably through empirical testing. You would have to contact the manufacturers for design information as there are no universal design parameters. Each oil water separating application also tends to be a little unique as well.
Here are some things to look for:
Accessibility to perform maintenance and provisions in place to clean the plates. Plates spacing per manufacturers recommendations is typically between 1/2 and 1 1/4 inches. Note that suspended solids create a potential for the plates to clog. Coalescing plates should not be used with significant suspended solids concentrations.
Poor performance may be a result of oil/water emulsions which cannot be separated by gravity or with coalescing plates. These emulsions are typically created by pumps, dirt, or emulsifying chemicals.
Most separators are installed without adequate capacity to handle surges in flow. If flow surges exist, the
water leaving the separator may not have adequate detention time for the separator to work properly.
